diff options
Diffstat (limited to 'Documentation/lguest/lguest.c')
| -rw-r--r-- | Documentation/lguest/lguest.c | 1651 |
1 files changed, 818 insertions, 833 deletions
diff --git a/Documentation/lguest/lguest.c b/Documentation/lguest/lguest.c index d36fcc0f271..950cde6d6e5 100644 --- a/Documentation/lguest/lguest.c +++ b/Documentation/lguest/lguest.c @@ -1,7 +1,9 @@ -/*P:100 This is the Launcher code, a simple program which lays out the - * "physical" memory for the new Guest by mapping the kernel image and - * the virtual devices, then opens /dev/lguest to tell the kernel - * about the Guest and control it. :*/ +/*P:100 + * This is the Launcher code, a simple program which lays out the "physical" + * memory for the new Guest by mapping the kernel image and the virtual + * devices, then opens /dev/lguest to tell the kernel about the Guest and + * control it. +:*/ #define _LARGEFILE64_SOURCE #define _GNU_SOURCE #include <stdio.h> @@ -16,6 +18,7 @@ #include <sys/types.h> #include <sys/stat.h> #include <sys/wait.h> +#include <sys/eventfd.h> #include <fcntl.h> #include <stdbool.h> #include <errno.h> @@ -45,13 +48,15 @@ #include "linux/virtio_rng.h" #include "linux/virtio_ring.h" #include "asm/bootparam.h" -/*L:110 We can ignore the 39 include files we need for this program, but I do - * want to draw attention to the use of kernel-style types. +/*L:110 + * We can ignore the 42 include files we need for this program, but I do want + * to draw attention to the use of kernel-style types. * * As Linus said, "C is a Spartan language, and so should your naming be." I * like these abbreviations, so we define them here. Note that u64 is always * unsigned long long, which works on all Linux systems: this means that we can - * use %llu in printf for any u64. */ + * use %llu in printf for any u64. + */ typedef unsigned long long u64; typedef uint32_t u32; typedef uint16_t u16; @@ -59,7 +64,6 @@ typedef uint8_t u8; /*:*/ #define PAGE_PRESENT 0x7 /* Present, RW, Execute */ -#define NET_PEERNUM 1 #define BRIDGE_PFX "bridge:" #ifndef SIOCBRADDIF #define SIOCBRADDIF 0x89a2 /* add interface to bridge */ @@ -69,38 +73,27 @@ typedef uint8_t u8; /* This will occupy 3 pages: it must be a power of 2. */ #define VIRTQUEUE_NUM 256 -/*L:120 verbose is both a global flag and a macro. The C preprocessor allows - * this, and although I wouldn't recommend it, it works quite nicely here. */ +/*L:120 + * verbose is both a global flag and a macro. The C preprocessor allows + * this, and although I wouldn't recommend it, it works quite nicely here. + */ static bool verbose; #define verbose(args...) \ do { if (verbose) printf(args); } while(0) /*:*/ -/* File descriptors for the Waker. */ -struct { - int pipe[2]; - int lguest_fd; -} waker_fds; - /* The pointer to the start of guest memory. */ static void *guest_base; /* The maximum guest physical address allowed, and maximum possible. */ static unsigned long guest_limit, guest_max; -/* The pipe for signal hander to write to. */ -static int timeoutpipe[2]; -static unsigned int timeout_usec = 500; +/* The /dev/lguest file descriptor. */ +static int lguest_fd; /* a per-cpu variable indicating whose vcpu is currently running */ static unsigned int __thread cpu_id; /* This is our list of devices. */ -struct device_list -{ - /* Summary information about the devices in our list: ready to pass to - * select() to ask which need servicing.*/ - fd_set infds; - int max_infd; - +struct device_list { /* Counter to assign interrupt numbers. */ unsigned int next_irq; @@ -112,8 +105,7 @@ struct device_list /* A single linked list of devices. */ struct device *dev; - /* And a pointer to the last device for easy append and also for - * configuration appending. */ + /* And a pointer to the last device for easy append. */ struct device *lastdev; }; @@ -121,35 +113,32 @@ struct device_list static struct device_list devices; /* The device structure describes a single device. */ -struct device -{ +struct device { /* The linked-list pointer. */ struct device *next; - /* The this device's descriptor, as mapped into the Guest. */ + /* The device's descriptor, as mapped into the Guest. */ struct lguest_device_desc *desc; + /* We can't trust desc values once Guest has booted: we use these. */ + unsigned int feature_len; + unsigned int num_vq; + /* The name of this device, for --verbose. */ const char *name; - /* If handle_input is set, it wants to be called when this file - * descriptor is ready. */ - int fd; - bool (*handle_input)(int fd, struct device *me); - /* Any queues attached to this device */ struct virtqueue *vq; - /* Handle status being finalized (ie. feature bits stable). */ - void (*ready)(struct device *me); + /* Is it operational */ + bool running; /* Device-specific data. */ void *priv; }; /* The virtqueue structure describes a queue attached to a device. */ -struct virtqueue -{ +struct virtqueue { struct virtqueue *next; /* Which device owns me. */ @@ -164,31 +153,41 @@ struct virtqueue /* Last available index we saw. */ u16 last_avail_idx; - /* The routine to call when the Guest pings us, or timeout. */ - void (*handle_output)(int fd, struct virtqueue *me, bool timeout); + /* How many are used since we sent last irq? */ + unsigned int pending_used; - /* Outstanding buffers */ - unsigned int inflight; + /* Eventfd where Guest notifications arrive. */ + int eventfd; - /* Is this blocked awaiting a timer? */ - bool blocked; + /* Function for the thread which is servicing this virtqueue. */ + void (*service)(struct virtqueue *vq); + pid_t thread; }; /* Remember the arguments to the program so we can "reboot" */ static char **main_args; -/* Since guest is UP and we don't run at the same time, we don't need barriers. - * But I include them in the code in case others copy it. */ -#define wmb() +/* The original tty settings to restore on exit. */ +static struct termios orig_term; -/* Convert an iovec element to the given type. +/* + * We have to be careful with barriers: our devices are all run in separate + * threads and so we need to make sure that changes visible to the Guest happen + * in precise order. + */ +#define wmb() __asm__ __volatile__("" : : : "memory") +#define mb() __asm__ __volatile__("" : : : "memory") + +/* + * Convert an iovec element to the given type. * * This is a fairly ugly trick: we need to know the size of the type and * alignment requirement to check the pointer is kosher. It's also nice to * have the name of the type in case we report failure. * * Typing those three things all the time is cumbersome and error prone, so we - * have a macro which sets them all up and passes to the real function. */ + * have a macro which sets them all up and passes to the real function. + */ #define convert(iov, type) \ ((type *)_convert((iov), sizeof(type), __alignof__(type), #type)) @@ -205,8 +204,10 @@ static void *_convert(struct iovec *iov, size_t size, size_t align, /* Wrapper for the last available index. Makes it easier to change. */ #define lg_last_avail(vq) ((vq)->last_avail_idx) -/* The virtio configuration space is defined to be little-endian. x86 is - * little-endian too, but it's nice to be explicit so we have these helpers. */ +/* + * The virtio configuration space is defined to be little-endian. x86 is + * little-endian too, but it's nice to be explicit so we have these helpers. + */ #define cpu_to_le16(v16) (v16) #define cpu_to_le32(v32) (v32) #define cpu_to_le64(v64) (v64) @@ -245,14 +246,15 @@ static void iov_consume(struct iovec iov[], unsigned num_iov, unsigned len) static u8 *get_feature_bits(struct device *dev) { return (u8 *)(dev->desc + 1) - + dev->desc->num_vq * sizeof(struct lguest_vqconfig); + + dev->num_vq * sizeof(struct lguest_vqconfig); } -/*L:100 The Launcher code itself takes us out into userspace, that scary place - * where pointers run wild and free! Unfortunately, like most userspace - * programs, it's quite boring (which is why everyone likes to hack on the - * kernel!). Perhaps if you make up an Lguest Drinking Game at this point, it - * will get you through this section. Or, maybe not. +/*L:100 + * The Launcher code itself takes us out into userspace, that scary place where + * pointers run wild and free! Unfortunately, like most userspace programs, + * it's quite boring (which is why everyone likes to hack on the kernel!). + * Perhaps if you make up an Lguest Drinking Game at this point, it will get + * you through this section. Or, maybe not. * * The Launcher sets up a big chunk of memory to be the Guest's "physical" * memory and stores it in "guest_base". In other words, Guest physical == @@ -260,7 +262,8 @@ static u8 *get_feature_bits(struct device *dev) * * This can be tough to get your head around, but usually it just means that we * use these trivial conversion functions when the Guest gives us it's - * "physical" addresses: */ + * "physical" addresses: + */ static void *from_guest_phys(unsigned long addr) { return guest_base + addr; @@ -275,7 +278,8 @@ static unsigned long to_guest_phys(const void *addr) * Loading the Kernel. * * We start with couple of simple helper routines. open_or_die() avoids - * error-checking code cluttering the callers: */ + * error-checking code cluttering the callers: + */ static int open_or_die(const char *name, int flags) { int fd = open(name, flags); @@ -290,12 +294,19 @@ static void *map_zeroed_pages(unsigned int num) int fd = open_or_die("/dev/zero", O_RDONLY); void *addr; - /* We use a private mapping (ie. if we write to the page, it will be - * copied). */ + /* + * We use a private mapping (ie. if we write to the page, it will be + * copied). + */ addr = mmap(NULL, getpagesize() * num, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE, fd, 0); if (addr == MAP_FAILED) err(1, "Mmaping %u pages of /dev/zero", num); + + /* + * One neat mmap feature is that you can close the fd, and it + * stays mapped. + */ close(fd); return addr; @@ -312,20 +323,24 @@ static void *get_pages(unsigned int num) return addr; } -/* This routine is used to load the kernel or initrd. It tries mmap, but if +/* + * This routine is used to load the kernel or initrd. It tries mmap, but if * that fails (Plan 9's kernel file isn't nicely aligned on page boundaries), - * it falls back to reading the memory in. */ + * it falls back to reading the memory in. + */ static void map_at(int fd, void *addr, unsigned long offset, unsigned long len) { ssize_t r; - /* We map writable even though for some segments are marked read-only. + /* + * We map writable even though for some segments are marked read-only. * The kernel really wants to be writable: it patches its own * instructions. * * MAP_PRIVATE means that the page won't be copied until a write is * done to it. This allows us to share untouched memory between - * Guests. */ + * Guests. + */ if (mmap(addr, len, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_FIXED|MAP_PRIVATE, fd, offset) != MAP_FAILED) return; @@ -336,7 +351,8 @@ static void map_at(int fd, void *addr, unsigned long offset, unsigned long len) err(1, "Reading offset %lu len %lu gave %zi", offset, len, r); } -/* This routine takes an open vmlinux image, which is in ELF, and maps it into +/* + * This routine takes an open vmlinux image, which is in ELF, and maps it into * the Guest memory. ELF = Embedded Linking Format, which is the format used * by all modern binaries on Linux including the kernel. * @@ -344,23 +360,28 @@ static void map_at(int fd, void *addr, unsigned long offset, unsigned long len) * address. We use the physical address; the Guest will map itself to the * virtual address. * - * We return the starting address. */ + * We return the starting address. + */ static unsigned long map_elf(int elf_fd, const Elf32_Ehdr *ehdr) { Elf32_Phdr phdr[ehdr->e_phnum]; unsigned int i; - /* Sanity checks on the main ELF header: an x86 executable with a - * reasonable number of correctly-sized program headers. */ + /* + * Sanity checks on the main ELF header: an x86 executable with a + * reasonable number of correctly-sized program headers. + */ if (ehdr->e_type != ET_EXEC || ehdr->e_machine != EM_386 || ehdr->e_phentsize != sizeof(Elf32_Phdr) || ehdr->e_phnum < 1 || ehdr->e_phnum > 65536U/sizeof(Elf32_Phdr)) errx(1, "Malformed elf header"); - /* An ELF executable contains an ELF header and a number of "program" + /* + * An ELF executable contains an ELF header and a number of "program" * headers which indicate which parts ("segments") of the program to - * load where. */ + * load where. + */ /* We read in all the program headers at once: */ if (lseek(elf_fd, ehdr->e_phoff, SEEK_SET) < 0) @@ -368,8 +389,10 @@ static unsigned long map_elf(int elf_fd, const Elf32_Ehdr *ehdr) if (read(elf_fd, phdr, sizeof(phdr)) != sizeof(phdr)) err(1, "Reading program headers"); - /* Try all the headers: there are usually only three. A read-only one, - * a read-write one, and a "note" section which we don't load. */ + /* + * Try all the headers: there are usually only three. A read-only one, + * a read-write one, and a "note" section which we don't load. + */ for (i = 0; i < ehdr->e_phnum; i++) { /* If this isn't a loadable segment, we ignore it */ if (phdr[i].p_type != PT_LOAD) @@ -387,13 +410,15 @@ static unsigned long map_elf(int elf_fd, const Elf32_Ehdr *ehdr) return ehdr->e_entry; } -/*L:150 A bzImage, unlike an ELF file, is not meant to be loaded. You're - * supposed to jump into it and it will unpack itself. We used to have to - * perform some hairy magic because the unpacking code scared me. +/*L:150 + * A bzImage, unlike an ELF file, is not meant to be loaded. You're supposed + * to jump into it and it will unpack itself. We used to have to perform some + * hairy magic because the unpacking code scared me. * * Fortunately, Jeremy Fitzhardinge convinced me it wasn't that hard and wrote * a small patch to jump over the tricky bits in the Guest, so now we just read - * the funky header so we know where in the file to load, and away we go! */ + * the funky header so we know where in the file to load, and away we go! + */ static unsigned long load_bzimage(int fd) { struct boot_params boot; @@ -401,8 +426,10 @@ static unsigned long load_bzimage(int fd) /* Modern bzImages get loaded at 1M. */ void *p = from_guest_phys(0x100000); - /* Go back to the start of the file and read the header. It should be - * a Linux boot header (see Documentation/x86/i386/boot.txt) */ + /* + * Go back to the start of the file and read the header. It should be + * a Linux boot header (see Documentation/x86/i386/boot.txt) + */ lseek(fd, 0, SEEK_SET); read(fd, &boot, sizeof(boot)); @@ -421,9 +448,11 @@ static unsigned long load_bzimage(int fd) return boot.hdr.code32_start; } -/*L:140 Loading the kernel is easy when it's a "vmlinux", but most kernels +/*L:140 + * Loading the kernel is easy when it's a "vmlinux", but most kernels * come wrapped up in the self-decompressing "bzImage" format. With a little - * work, we can load those, too. */ + * work, we can load those, too. + */ static unsigned long load_kernel(int fd) { Elf32_Ehdr hdr; @@ -440,24 +469,28 @@ static unsigned long load_kernel(int fd) return load_bzimage(fd); } -/* This is a trivial little helper to align pages. Andi Kleen hated it because +/* + * This is a trivial little helper to align pages. Andi Kleen hated it because * it calls getpagesize() twice: "it's dumb code." * * Kernel guys get really het up about optimization, even when it's not - * necessary. I leave this code as a reaction against that. */ + * necessary. I leave this code as a reaction against that. + */ static inline unsigned long page_align(unsigned long addr) { /* Add upwards and truncate downwards. */ return ((addr + getpagesize()-1) & ~(getpagesize()-1)); } -/*L:180 An "initial ram disk" is a disk image loaded into memory along with - * the kernel which the kernel can use to boot from without needing any - * drivers. Most distributions now use this as standard: the initrd contains - * the code to load the appropriate driver modules for the current machine. +/*L:180 + * An "initial ram disk" is a disk image loaded into memory along with the + * kernel which the kernel can use to boot from without needing any drivers. + * Most distributions now use this as standard: the initrd contains the code to + * load the appropriate driver modules for the current machine. * * Importantly, James Morris works for RedHat, and Fedora uses initrds for its - * kernels. He sent me this (and tells me when I break it). */ + * kernels. He sent me this (and tells me when I break it). + */ static unsigned long load_initrd(const char *name, unsigned long mem) { int ifd; @@ -469,12 +502,16 @@ static unsigned long load_initrd(const char *name, unsigned long mem) if (fstat(ifd, &st) < 0) err(1, "fstat() on initrd '%s'", name); - /* We map the initrd at the top of memory, but mmap wants it to be - * page-aligned, so we round the size up for that. */ + /* + * We map the initrd at the top of memory, but mmap wants it to be + * page-aligned, so we round the size up for that. + */ len = page_align(st.st_size); map_at(ifd, from_guest_phys(mem - len), 0, st.st_size); - /* Once a file is mapped, you can close the file descriptor. It's a - * little odd, but quite useful. */ + /* + * Once a file is mapped, you can close the file descriptor. It's a + * little odd, but quite useful. + */ close(ifd); verbose("mapped initrd %s size=%lu @ %p\n", name, len, (void*)mem-len); @@ -483,8 +520,10 @@ static unsigned long load_initrd(const char *name, unsigned long mem) } /*:*/ -/* Simple routine to roll all the commandline arguments together with spaces - * between them. */ +/* + * Simple routine to roll all the commandline arguments together with spaces + * between them. + */ static void concat(char *dst, char *args[]) { unsigned int i, len = 0; @@ -501,104 +540,26 @@ static void concat(char *dst, char *args[]) dst[len] = '\0'; } -/*L:185 This is where we actually tell the kernel to initialize the Guest. We +/*L:185 + * This is where we actually tell the kernel to initialize the Guest. We * saw the arguments it expects when we looked at initialize() in lguest_user.c: * the base of Guest "physical" memory, the top physical page to allow and the - * entry point for the Guest. */ -static int tell_kernel(unsigned long start) + * entry point for the Guest. + */ +static void tell_kernel(unsigned long start) { unsigned long args[] = { LHREQ_INITIALIZE, (unsigned long)guest_base, guest_limit / getpagesize(), start }; - int fd; - verbose("Guest: %p - %p (%#lx)\n", guest_base, guest_base + guest_limit, guest_limit); - fd = open_or_die("/dev/lguest", O_RDWR); - if (write(fd, args, sizeof(args)) < 0) + lguest_fd = open_or_die("/dev/lguest", O_RDWR); + if (write(lguest_fd, args, sizeof(args)) < 0) err(1, "Writing to /dev/lguest"); - - /* We return the /dev/lguest file descriptor to control this Guest */ - return fd; } /*:*/ -static void add_device_fd(int fd) -{ - FD_SET(fd, &devices.infds); - if (fd > devices.max_infd) - devices.max_infd = fd; -} - /*L:200 - * The Waker. - * - * With console, block and network devices, we can have lots of input which we - * need to process. We could try to tell the kernel what file descriptors to - * watch, but handing a file descriptor mask through to the kernel is fairly - * icky. - * - * Instead, we clone off a thread which watches the file descriptors and writes - * the LHREQ_BREAK command to the /dev/lguest file descriptor to tell the Host - * stop running the Guest. This causes the Launcher to return from the - * /dev/lguest read with -EAGAIN, where it will write to /dev/lguest to reset - * the LHREQ_BREAK and wake us up again. - * - * This, of course, is merely a different *kind* of icky. - * - * Given my well-known antipathy to threads, I'd prefer to use processes. But - * it's easier to share Guest memory with threads, and trivial to share the - * devices.infds as the Launcher changes it. - */ -static int waker(void *unused) -{ - /* Close the write end of the pipe: only the Launcher has it open. */ - close(waker_fds.pipe[1]); - - for (;;) { - fd_set rfds = devices.infds; - unsigned long args[] = { LHREQ_BREAK, 1 }; - unsigned int maxfd = devices.max_infd; - - /* We also listen to the pipe from the Launcher. */ - FD_SET(waker_fds.pipe[0], &rfds); - if (waker_fds.pipe[0] > maxfd) - maxfd = waker_fds.pipe[0]; - - /* Wait until input is ready from one of the devices. */ - select(maxfd+1, &rfds, NULL, NULL, NULL); - - /* Message from Launcher? */ - if (FD_ISSET(waker_fds.pipe[0], &rfds)) { - char c; - /* If this fails, then assume Launcher has exited. - * Don't do anything on exit: we're just a thread! */ - if (read(waker_fds.pipe[0], &c, 1) != 1) - _exit(0); - continue; - } - - /* Send LHREQ_BREAK command to snap the Launcher out of it. */ - pwrite(waker_fds.lguest_fd, args, sizeof(args), cpu_id); - } - return 0; -} - -/* This routine just sets up a pipe to the Waker process. */ -static void setup_waker(int lguest_fd) -{ - /* This pipe is closed when Launcher dies, telling Waker. */ - if (pipe(waker_fds.pipe) != 0) - err(1, "Creating pipe for Waker"); - - /* Waker also needs to know the lguest fd */ - waker_fds.lguest_fd = lguest_fd; - - if (clone(waker, malloc(4096) + 4096, CLONE_VM | SIGCHLD, NULL) == -1) - err(1, "Creating Waker"); -} - -/* * Device Handling. * * When the Guest gives us a buffer, it sends an array of addresses and sizes. @@ -609,65 +570,125 @@ static void setup_waker(int lguest_fd) static void *_check_pointer(unsigned long addr, unsigned int size, unsigned int line) { - /* We have to separately check addr and addr+size, because size could - * be huge and addr + size might wrap around. */ + /* + * We have to separately check addr and addr+size, because size could + * be huge and addr + size might wrap around. + */ if (addr >= guest_limit || addr + size >= guest_limit) errx(1, "%s:%i: Invalid address %#lx", __FILE__, line, addr); - /* We return a pointer for the caller's convenience, now we know it's - * safe to use. */ + /* + * We return a pointer for the caller's convenience, now we know it's + * safe to use. + */ return from_guest_phys(addr); } /* A macro which transparently hands the line number to the real function. */ #define check_pointer(addr,size) _check_pointer(addr, size, __LINE__) -/* Each buffer in the virtqueues is actually a chain of descriptors. This +/* + * Each buffer in the virtqueues is actually a chain of descriptors. This * function returns the next descriptor in the chain, or vq->vring.num if we're - * at the end. */ -static unsigned next_desc(struct virtqueue *vq, unsigned int i) + * at the end. + */ +static unsigned next_desc(struct vring_desc *desc, + unsigned int i, unsigned int max) { unsigned int next; /* If this descriptor says it doesn't chain, we're done. */ - if (!(vq->vring.desc[i].flags & VRING_DESC_F_NEXT)) - return vq->vring.num; + if (!(desc[i].flags & VRING_DESC_F_NEXT)) + return max; /* Check they're not leading us off end of descriptors. */ - next = vq->vring.desc[i].next; + next = desc[i].next; /* Make sure compiler knows to grab that: we don't want it changing! */ wmb(); - if (next >= vq->vring.num) + if (next >= max) errx(1, "Desc next is %u", next); return next; } -/* This looks in the virtqueue and for the first available buffer, and converts +/* + * This actually sends the interrupt for this virtqueue, if we've used a + * buffer. + */ +static void trigger_irq(struct virtqueue *vq) +{ + unsigned long buf[] = { LHREQ_IRQ, vq->config.irq }; + + /* Don't inform them if nothing used. */ + if (!vq->pending_used) + return; + vq->pending_used = 0; + + /* If they don't want an interrupt, don't send one, unless empty. */ + if ((vq->vring.avail->flags & VRING_AVAIL_F_NO_INTERRUPT) + && lg_last_avail(vq) != vq->vring.avail->idx) + return; + + /* Send the Guest an interrupt tell them we used something up. */ + if (write(lguest_fd, buf, sizeof(buf)) != 0) + err(1, "Triggering irq %i", vq->config.irq); +} + +/* + * This looks in the virtqueue for the first available buffer, and converts * it to an iovec for convenient access. Since descriptors consist of some * number of output then some number of input descriptors, it's actually two * iovecs, but we pack them into one and note how many of each there were. * - * This function returns the descriptor number found, or vq->vring.num (which - * is never a valid descriptor number) if none was found. */ -static unsigned get_vq_desc(struct virtqueue *vq, - struct iovec iov[], - unsigned int *out_num, unsigned int *in_num) -{ - unsigned int i, head; - u16 last_avail; + * This function waits if necessary, and returns the descriptor number found. + */ +static unsigned wait_for_vq_desc(struct virtqueue *vq, + struct iovec iov[], + unsigned int *out_num, unsigned int *in_num) +{ + unsigned int i, head, max; + struct vring_desc *desc; + u16 last_avail = lg_last_avail(vq); + + /* There's nothing available? */ + while (last_avail == vq->vring.avail->idx) { + u64 event; + + /* + * Since we're about to sleep, now is a good time to tell the + * Guest about what we've used up to now. + */ + trigger_irq(vq); + + /* OK, now we need to know about added descriptors. */ + vq->vring.used->flags &= ~VRING_USED_F_NO_NOTIFY; + + /* + * They could have slipped one in as we were doing that: make + * sure it's written, then check again. + */ + mb(); + if (last_avail != vq->vring.avail->idx) { + vq->vring.used->flags |= VRING_USED_F_NO_NOTIFY; + break; + } + + /* Nothing new? Wait for eventfd to tell us they refilled. */ + if (read(vq->eventfd, &event, sizeof(event)) != sizeof(event)) + errx(1, "Event read failed?"); + + /* We don't need to be notified again. */ + vq->vring.used->flags |= VRING_USED_F_NO_NOTIFY; + } /* Check it isn't doing very strange things with descriptor numbers. */ - last_avail = lg_last_avail(vq); if ((u16)(vq->vring.avail->idx - last_avail) > vq->vring.num) errx(1, "Guest moved used index from %u to %u", last_avail, vq->vring.avail->idx); - /* If there's nothing new since last we looked, return invalid. */ - if (vq->vring.avail->idx == last_avail) - return vq->vring.num; - - /* Grab the next descriptor number they're advertising, and increment - * the index we've seen. */ + /* + * Grab the next descriptor number they're advertising, and increment + * the index we've seen. + */ head = vq->vring.avail->ring[last_avail % vq->vring.num]; lg_last_avail(vq)++; @@ -678,87 +699,84 @@ static unsigned get_vq_desc(struct virtqueue *vq, /* When we start there are none of either input nor output. */ *out_num = *in_num = 0; + max = vq->vring.num; + desc = vq->vring.desc; i = head; + + /* + * If this is an indirect entry, then this buffer contains a descriptor + * table which we handle as if it's any normal descriptor chain. + */ + if (desc[i].flags & VRING_DESC_F_INDIRECT) { + if (desc[i].len % sizeof(struct vring_desc)) + errx(1, "Invalid size for indirect buffer table"); + + max = desc[i].len / sizeof(struct vring_desc); + desc = check_pointer(desc[i].addr, desc[i].len); + i = 0; + } + do { /* Grab the first descriptor, and check it's OK. */ - iov[*out_num + *in_num].iov_len = vq->vring.desc[i].len; + iov[*out_num + *in_num].iov_len = desc[i].len; iov[*out_num + *in_num].iov_base - = check_pointer(vq->vring.desc[i].addr, - vq->vring.desc[i].len); + = check_pointer(desc[i].addr, desc[i].len); /* If this is an input descriptor, increment that count. */ - if (vq->vring.desc[i].flags & VRING_DESC_F_WRITE) + if (desc[i].flags & VRING_DESC_F_WRITE) (*in_num)++; else { - /* If it's an output descriptor, they're all supposed - * to come before any input descriptors. */ + /* + * If it's an output descriptor, they're all supposed + * to come before any input descriptors. + */ if (*in_num) errx(1, "Descriptor has out after in"); (*out_num)++; } /* If we've got too many, that implies a descriptor loop. */ - if (*out_num + *in_num > vq->vring.num) + if (*out_num + *in_num > max) errx(1, "Looped descriptor"); - } while ((i = next_desc(vq, i)) != vq->vring.num); + } while ((i = next_desc(desc, i, max)) != max); - vq->inflight++; return head; } -/* After we've used one of their buffers, we tell them about it. We'll then - * want to send them an interrupt, using trigger_irq(). */ +/* + * After we've used one of their buffers, we tell the Guest about it. Sometime + * later we'll want to send them an interrupt using trigger_irq(); note that + * wait_for_vq_desc() does that for us if it has to wait. + */ static void add_used(struct virtqueue *vq, unsigned int head, int len) { struct vring_used_elem *used; - /* The virtqueue contains a ring of used buffers. Get a pointer to the - * next entry in that used ring. */ + /* + * The virtqueue contains a ring of used buffers. Get a pointer to the + * next entry in that used ring. + */ used = &vq->vring.used->ring[vq->vring.used->idx % vq->vring.num]; used->id = head; used->len = len; /* Make sure buffer is written before we update index. */ wmb(); vq->vring.used->idx++; - vq->inflight--; -} - -/* This actually sends the interrupt for this virtqueue */ -static void trigger_irq(int fd, struct virtqueue *vq) -{ - unsigned long buf[] = { LHREQ_IRQ, vq->config.irq }; - - /* If they don't want an interrupt, don't send one, unless empty. */ - if ((vq->vring.avail->flags & VRING_AVAIL_F_NO_INTERRUPT) - && vq->inflight) - return; - - /* Send the Guest an interrupt tell them we used something up. */ - if (write(fd, buf, sizeof(buf)) != 0) - err(1, "Triggering irq %i", vq->config.irq); + vq->pending_used++; } /* And here's the combo meal deal. Supersize me! */ -static void add_used_and_trigger(int fd, struct virtqueue *vq, - unsigned int head, int len) +static void add_used_and_trigger(struct virtqueue *vq, unsigned head, int len) { add_used(vq, head, len); - trigger_irq(fd, vq); + trigger_irq(vq); } /* * The Console * - * Here is the input terminal setting we save, and the routine to restore them - * on exit so the user gets their terminal back. */ -static struct termios orig_term; -static void restore_term(void) -{ - tcsetattr(STDIN_FILENO, TCSANOW, &orig_term); -} - -/* We associate some data with the console for our exit hack. */ -struct console_abort -{ + * We associate some data with the console for our exit hack. + */ +struct console_abort { /* How many times have they hit ^C? */ int count; /* When did they start? */ @@ -766,282 +784,360 @@ struct console_abort }; /* This is the routine which handles console input (ie. stdin). */ -static bool handle_console_input(int fd, struct device *dev) +static void console_input(struct virtqueue *vq) { int len; unsigned int head, in_num, out_num; - struct iovec iov[dev->vq->vring.num]; - struct console_abort *abort = dev->priv; - - /* First we need a console buffer from the Guests's input virtqueue. */ - head = get_vq_desc(dev->vq, iov, &out_num, &in_num); - - /* If they're not ready for input, stop listening to this file - * descriptor. We'll start again once they add an input buffer. */ - if (head == dev->vq->vring.num) - return false; + struct console_abort *abort = vq->dev->priv; + struct iovec iov[vq->vring.num]; + /* Make sure there's a descriptor available. */ + head = wait_for_vq_desc(vq, iov, &out_num, &in_num); if (out_num) errx(1, "Output buffers in console in queue?"); - /* This is why we convert to iovecs: the readv() call uses them, and so - * it reads straight into the Guest's buffer. */ - len = readv(dev->fd, iov, in_num); + /* Read into it. This is where we usually wait. */ + len = readv(STDIN_FILENO, iov, in_num); if (len <= 0) { - /* This implies that the console is closed, is /dev/null, or - * something went terribly wrong. */ + /* Ran out of input? */ warnx("Failed to get console input, ignoring console."); - /* Put the input terminal back. */ - restore_term(); - /* Remove callback from input vq, so it doesn't restart us. */ - dev->vq->handle_output = NULL; - /* Stop listening to this fd: don't call us again. */ - return false; + /* + * For simplicity, dying threads kill the whole Launcher. So + * just nap here. + */ + for (;;) + pause(); } - /* Tell the Guest about the new input. */ - add_used_and_trigger(fd, dev->vq, head, len); + /* Tell the Guest we used a buffer. */ + add_used_and_trigger(vq, head, len); - /* Three ^C within one second? Exit. + /* + * Three ^C within one second? Exit. * - * This is such a hack, but works surprisingly well. Each ^C has to be - * in a buffer by itself, so they can't be too fast. But we check that - * we get three within about a second, so they can't be too slow. */ - if (len == 1 && ((char *)iov[0].iov_base)[0] == 3) { - if (!abort->count++) - gettimeofday(&abort->start, NULL); - else if (abort->count == 3) { - struct timeval now; - gettimeofday(&now, NULL); - if (now.tv_sec <= abort->start.tv_sec+1) { - unsigned long args[] = { LHREQ_BREAK, 0 }; - /* Close the fd so Waker will know it has to - * exit. */ - close(waker_fds.pipe[1]); - /* Just in case Waker is blocked in BREAK, send - * unbreak now. */ - write(fd, args, sizeof(args)); - exit(2); - } - abort->count = 0; - } - } else - /* Any other key resets the abort counter. */ + * This is such a hack, but works surprisingly well. Each ^C has to + * be in a buffer by itself, so they can't be too fast. But we check + * that we get three within about a second, so they can't be too + * slow. + */ + if (len != 1 || ((char *)iov[0].iov_base)[0] != 3) { abort->count = 0; + return; + } - /* Everything went OK! */ - return true; + abort->count++; + if (abort->count == 1) + gettimeofday(&abort->start, NULL); + else if (abort->count == 3) { + struct timeval now; + gettimeofday(&now, NULL); + /* Kill all Launcher processes with SIGINT, like normal ^C */ + if (now.tv_sec <= abort->start.tv_sec+1) + kill(0, SIGINT); + abort->count = 0; + } } -/* Handling output for console is simple: we just get all the output buffers - * and write them to stdout. */ -static void handle_console_output(int fd, struct virtqueue *vq, bool timeout) +/* This is the routine which handles console output (ie. stdout). */ +static void console_output(struct virtqueue *vq) { unsigned int head, out, in; - int len; struct iovec iov[vq->vring.num]; - /* Keep getting output buffers from the Guest until we run out. */ - while ((head = get_vq_desc(vq, iov, &out, &in)) != vq->vring.num) { - if (in) - errx(1, "Input buffers in output queue?"); - len = writev(STDOUT_FILENO, iov, out); - add_used_and_trigger(fd, vq, head, len); - } -} - -/* This is called when we no longer want to hear about Guest changes to a - * virtqueue. This is more efficient in high-traffic cases, but it means we - * have to set a timer to check if any more changes have occurred. */ -static void block_vq(struct virtqueue *vq) -{ - struct itimerval itm; + /* We usually wait in here, for the Guest to give us something. */ + head = wait_for_vq_desc(vq, iov, &out, &in); + if (in) + errx(1, "Input buffers in console output queue?"); - vq->vring.used->flags |= VRING_USED_F_NO_NOTIFY; - vq->blocked = true; - - itm.it_interval.tv_sec = 0; - itm.it_interval.tv_usec = 0; - itm.it_value.tv_sec = 0; - itm.it_value.tv_usec = timeout_usec; + /* writev can return a partial write, so we loop here. */ + while (!iov_empty(iov, out)) { + int len = writev(STDOUT_FILENO, iov, out); + if (len <= 0) + err(1, "Write to stdout gave %i", len); + iov_consume(iov, out, len); + } - setitimer(ITIMER_REAL, &itm, NULL); + /* + * We're finished with that buffer: if we're going to sleep, + * wait_for_vq_desc() will prod the Guest with an interrupt. + */ + add_used(vq, head, 0); } /* * The Network * * Handling output for network is also simple: we get all the output buffers - * and write them (ignoring the first element) to this device's file descriptor - * (/dev/net/tun). + * and write them to /dev/net/tun. */ -static void handle_net_output(int fd, struct virtqueue *vq, bool timeout) +struct net_info { + int tunfd; +}; + +static void net_output(struct virtqueue *vq) { - unsigned int head, out, in, num = 0; - int len; + struct net_info *net_info = vq->dev->priv; + unsigned int head, out, in; struct iovec iov[vq->vring.num]; - static int last_timeout_num; - - /* Keep getting output buffers from the Guest until we run out. */ - while ((head = get_vq_desc(vq, iov, &out, &in)) != vq->vring.num) { - if (in) - errx(1, "Input buffers in output queue?"); - len = writev(vq->dev->fd, iov, out); - if (len < 0) - err(1, "Writing network packet to tun"); - add_used_and_trigger(fd, vq, head, len); - num++; - } - /* Block further kicks and set up a timer if we saw anything. */ - if (!timeout && num) - block_vq(vq); - - /* We never quite know how long should we wait before we check the - * queue again for more packets. We start at 500 microseconds, and if - * we get fewer packets than last time, we assume we made the timeout - * too small and increase it by 10 microseconds. Otherwise, we drop it - * by one microsecond every time. It seems to work well enough. */ - if (timeout) { - if (num < last_timeout_num) - timeout_usec += 10; - else if (timeout_usec > 1) - timeout_usec--; - last_timeout_num = num; - } + /* We usually wait in here for the Guest to give us a packet. */ + head = wait_for_vq_desc(vq, iov, &out, &in); + if (in) + errx(1, "Input buffers in net output queue?"); + /* + * Send the whole thing through to /dev/net/tun. It expects the exact + * same format: what a coincidence! + */ + if (writev(net_info->tunfd, iov, out) < 0) + errx(1, "Write to tun failed?"); + + /* + * Done with that one; wait_for_vq_desc() will send the interrupt if + * all packets are processed. + */ + add_used(vq, head, 0); } -/* This is where we handle a packet coming in from the tun device to our - * Guest. */ -static bool handle_tun_input(int fd, struct device *dev) +/* + * Handling network input is a bit trickier, because I've tried to optimize it. + * + * First we have a helper routine which tells is if from this file descriptor + * (ie. the /dev/net/tun device) will block: + */ +static bool will_block(int fd) +{ + fd_set fdset; + struct timeval zero = { 0, 0 }; + FD_ZERO(&fdset); + FD_SET(fd, &fdset); + return select(fd+1, &fdset, NULL, NULL, &zero) != 1; +} + +/* + * This handles packets coming in from the tun device to our Guest. Like all + * service routines, it gets called again as soon as it returns, so you don't + * see a while(1) loop here. + */ +static void net_input(struct virtqueue *vq) { - unsigned int head, in_num, out_num; int len; - struct iovec iov[dev->vq->vring.num]; - - /* First we need a network buffer from the Guests's recv virtqueue. */ - head = get_vq_desc(dev->vq, iov, &out_num, &in_num); - if (head == dev->vq->vring.num) { - /* Now, it's expected that if we try to send a packet too - * early, the Guest won't be ready yet. Wait until the device - * status says it's ready. */ - /* FIXME: Actually want DRIVER_ACTIVE here. */ - - /* Now tell it we want to know if new things appear. */ - dev->vq->vring.used->flags &= ~VRING_USED_F_NO_NOTIFY; - wmb(); - - /* We'll turn this back on if input buffers are registered. */ - return false; - } else if (out_num) - errx(1, "Output buffers in network recv queue?"); - - /* Read the packet from the device directly into the Guest's buffer. */ - len = readv(dev->fd, iov, in_num); + unsigned int head, out, in; + struct iovec iov[vq->vring.num]; + struct net_info *net_info = vq->dev->priv; + + /* + * Get a descriptor to write an incoming packet into. This will also + * send an interrupt if they're out of descriptors. + */ + head = wait_for_vq_desc(vq, iov, &out, &in); + if (out) + errx(1, "Output buffers in net input queue?"); + + /* + * If it looks like we'll block reading from the tun device, send them + * an interrupt. + */ + if (vq->pending_used && will_block(net_info->tunfd)) + trigger_irq(vq); + + /* + * Read in the packet. This is where we normally wait (when there's no + * incoming network traffic). + */ + len = readv(net_info->tunfd, iov, in); if (len <= 0) - err(1, "reading network"); + err(1, "Failed to read from tun."); - /* Tell the Guest about the new packet. */ - add_used_and_trigger(fd, dev->vq, head, len); + /* + * Mark that packet buffer as used, but don't interrupt here. We want + * to wait until we've done as much work as we can. + */ + add_used(vq, head, len); +} +/*:*/ - verbose("tun input packet len %i [%02x %02x] (%s)\n", len, - ((u8 *)iov[1].iov_base)[0], ((u8 *)iov[1].iov_base)[1], - head != dev->vq->vring.num ? "sent" : "discarded"); +/* This is the helper to create threads: run the service routine in a loop. */ +static int do_thread(void *_vq) +{ + struct virtqueue *vq = _vq; - /* All good. */ - return true; + for (;;) + vq->service(vq); + return 0; } -/*L:215 This is the callback attached to the network and console input - * virtqueues: it ensures we try again, in case we stopped console or net - * delivery because Guest didn't have any buffers. */ -static void enable_fd(int fd, struct virtqueue *vq, bool timeout) +/* + * When a child dies, we kill our entire process group with SIGTERM. This + * also has the side effect that the shell restores the console for us! + */ +static void kill_launcher(int signal) { - add_device_fd(vq->dev->fd); - /* Snap the Waker out of its select loop. */ - write(waker_fds.pipe[1], "", 1); + kill(0, SIGTERM); } -static void net_enable_fd(int fd, struct virtqueue *vq, bool timeout) +static void reset_device(struct device *dev) { - /* We don't need to know again when Guest refills receive buffer. */ - vq->vring.used->flags |= VRING_USED_F_NO_NOTIFY; - enable_fd(fd, vq, timeout); + struct virtqueue *vq; + + verbose("Resetting device %s\n", dev->name); + + /* Clear any features they've acked. */ + memset(get_feature_bits(dev) + dev->feature_len, 0, dev->feature_len); + + /* We're going to be explicitly killing threads, so ignore them. */ + signal(SIGCHLD, SIG_IGN); + + /* Zero out the virtqueues, get rid of their threads */ + for (vq = dev->vq; vq; vq = vq->next) { + if (vq->thread != (pid_t)-1) { + kill(vq->thread, SIGTERM); + waitpid(vq->thread, NULL, 0); + vq->thread = (pid_t)-1; + } + memset(vq->vring.desc, 0, + vring_size(vq->config.num, LGUEST_VRING_ALIGN)); + lg_last_avail(vq) = 0; + } + dev->running = false; + + /* Now we care if threads die. */ + signal(SIGCHLD, (void *)kill_launcher); } -/* When the Guest tells us they updated the status field, we handle it. */ -static void update_device_status(struct device *dev) +/*L:216 + * This actually creates the thread which services the virtqueue for a device. + */ +static void create_thread(struct virtqueue *vq) +{ + /* + * Create stack for thread. Since the stack grows upwards, we point + * the stack pointer to the end of this region. + */ + char *stack = malloc(32768); + unsigned long args[] = { LHREQ_EVENTFD, + vq->config.pfn*getpagesize(), 0 }; + + /* Create a zero-initialized eventfd. */ + vq->eventfd = eventfd(0, 0); + if (vq->eventfd < 0) + err(1, "Creating eventfd"); + args[2] = vq->eventfd; + + /* + * Attach an eventfd to this virtqueue: it will go off when the Guest + * does an LHCALL_NOTIFY for this vq. + */ + if (write(lguest_fd, &args, sizeof(args)) != 0) + err(1, "Attaching eventfd"); + + /* + * CLONE_VM: because it has to access the Guest memory, and SIGCHLD so + * we get a signal if it dies. + */ + vq->thread = clone(do_thread, stack + 32768, CLONE_VM | SIGCHLD, vq); + if (vq->thread == (pid_t)-1) + err(1, "Creating clone"); + + /* We close our local copy now the child has it. */ + close(vq->eventfd); +} + +static void start_device(struct device *dev) { + unsigned int i; struct virtqueue *vq; - /* This is a reset. */ - if (dev->desc->status == 0) { - verbose("Resetting device %s\n", dev->name); + verbose("Device %s OK: offered", dev->name); + for (i = 0; i < dev->feature_len; i++) + verbose(" %02x", get_feature_bits(dev)[i]); + verbose(", accepted"); + for (i = 0; i < dev->feature_len; i++) + verbose(" %02x", get_feature_bits(dev) + [dev->feature_len+i]); + + for (vq = dev->vq; vq; vq = vq->next) { + if (vq->service) + create_thread(vq); + } + dev->running = true; +} - /* Clear any features they've acked. */ - memset(get_feature_bits(dev) + dev->desc->feature_len, 0, - dev->desc->feature_len); +static void cleanup_devices(void) +{ + struct device *dev; - /* Zero out the virtqueues. */ - for (vq = dev->vq; vq; vq = vq->next) { - memset(vq->vring.desc, 0, - vring_size(vq->config.num, LGUEST_VRING_ALIGN)); - lg_last_avail(vq) = 0; - } - } else if (dev->desc->status & VIRTIO_CONFIG_S_FAILED) { + for (dev = devices.dev; dev; dev = dev->next) + reset_device(dev); + + /* If we saved off the original terminal settings, restore them now. */ + if (orig_term.c_lflag & (ISIG|ICANON|ECHO)) + tcsetattr(STDIN_FILENO, TCSANOW, &orig_term); +} + +/* When the Guest tells us they updated the status field, we handle it. */ +static void update_device_status(struct device *dev) +{ + /* A zero status is a reset, otherwise it's a set of flags. */ + if (dev->desc->status == 0) + reset_device(dev); + else if (dev->desc->status & VIRTIO_CONFIG_S_FAILED) { warnx("Device %s configuration FAILED", dev->name); + if (dev->running) + reset_device(dev); } else if (dev->desc->status & VIRTIO_CONFIG_S_DRIVER_OK) { - unsigned int i; - - verbose("Device %s OK: offered", dev->name); - for (i = 0; i < dev->desc->feature_len; i++) - verbose(" %02x", get_feature_bits(dev)[i]); - verbose(", accepted"); - for (i = 0; i < dev->desc->feature_len; i++) - verbose(" %02x", get_feature_bits(dev) - [dev->desc->feature_len+i]); - - if (dev->ready) - dev->ready(dev); + if (!dev->running) + start_device(dev); } } -/* This is the generic routine we call when the Guest uses LHCALL_NOTIFY. */ -static void handle_output(int fd, unsigned long addr) +/*L:215 + * This is the generic routine we call when the Guest uses LHCALL_NOTIFY. In + * particular, it's used to notify us of device status changes during boot. + */ +static void handle_output(unsigned long addr) { struct device *i; - struct virtqueue *vq; - /* Check each device and virtqueue. */ + /* Check each device. */ for (i = devices.dev; i; i = i->next) { - /* Notifications to device descriptors update device status. */ + struct virtqueue *vq; + + /* + * Notifications to device descriptors mean they updated the + * device status. + */ if (from_guest_phys(addr) == i->desc) { update_device_status(i); return; } - /* Notifications to virtqueues mean output has occurred. */ + /* + * Devices *can* be used before status is set to DRIVER_OK. + * The original plan was that they would never do this: they + * would always finish setting up their status bits before + * actually touching the virtqueues. In practice, we allowed + * them to, and they do (eg. the disk probes for partition + * tables as part of initialization). + * + * If we see this, we start the device: once it's running, we + * expect the device to catch all the notifications. + */ for (vq = i->vq; vq; vq = vq->next) { - if (vq->config.pfn != addr/getpagesize()) + if (addr != vq->config.pfn*getpagesize()) continue; - - /* Guest should acknowledge (and set features!) before - * using the device. */ - if (i->desc->status == 0) { - warnx("%s gave early output", i->name); - return; - } - - if (strcmp(vq->dev->name, "console") != 0) - verbose("Output to %s\n", vq->dev->name); - if (vq->handle_output) - vq->handle_output(fd, vq, false); + if (i->running) + errx(1, "Notification on running %s", i->name); + /* This just calls create_thread() for each virtqueue */ + start_device(i); return; } } - /* Early console write is done using notify on a nul-terminated string - * in Guest memory. */ + /* + * Early console write is done using notify on a nul-terminated string + * in Guest memory. It's also great for hacking debugging messages + * into a Guest. + */ if (addr >= guest_limit) errx(1, "Bad NOTIFY %#lx", addr); @@ -1049,71 +1145,6 @@ static void handle_output(int fd, unsigned long addr) strnlen(from_guest_phys(addr), guest_limit - addr)); } -static void handle_timeout(int fd) -{ - char buf[32]; - struct device *i; - struct virtqueue *vq; - - /* Clear the pipe */ - read(timeoutpipe[0], buf, sizeof(buf)); - - /* Check each device and virtqueue: flush blocked ones. */ - for (i = devices.dev; i; i = i->next) { - for (vq = i->vq; vq; vq = vq->next) { - if (!vq->blocked) - continue; - - vq->vring.used->flags &= ~VRING_USED_F_NO_NOTIFY; - vq->blocked = false; - if (vq->handle_output) - vq->handle_output(fd, vq, true); - } - } -} - -/* This is called when the Waker wakes us up: check for incoming file - * descriptors. */ -static void handle_input(int fd) -{ - /* select() wants a zeroed timeval to mean "don't wait". */ - struct timeval poll = { .tv_sec = 0, .tv_usec = 0 }; - - for (;;) { - struct device *i; - fd_set fds = devices.infds; - int num; - - num = select(devices.max_infd+1, &fds, NULL, NULL, &poll); - /* Could get interrupted */ - if (num < 0) - continue; - /* If nothing is ready, we're done. */ - if (num == 0) - break; - - /* Otherwise, call the device(s) which have readable file - * descriptors and a method of handling them. */ - for (i = devices.dev; i; i = i->next) { - if (i->handle_input && FD_ISSET(i->fd, &fds)) { - if (i->handle_input(fd, i)) - continue; - - /* If handle_input() returns false, it means we - * should no longer service it. Networking and - * console do this when there's no input - * buffers to deliver into. Console also uses - * it when it discovers that stdin is closed. */ - FD_CLR(i->fd, &devices.infds); - } - } - - /* Is this the timeout fd? */ - if (FD_ISSET(timeoutpipe[0], &fds)) - handle_timeout(fd); - } -} - /*L:190 * Device Setup * @@ -1122,20 +1153,24 @@ static void handle_input(int fd) * routines to allocate and manage them. */ -/* The layout of the device page is a "struct lguest_device_desc" followed by a +/* + * The layout of the device page is a "struct lguest_device_desc" followed by a * number of virtqueue descriptors, then two sets of feature bits, then an * array of configuration bytes. This routine returns the configuration - * pointer. */ + * pointer. + */ static u8 *device_config(const struct device *dev) { return (void *)(dev->desc + 1) - + dev->desc->num_vq * sizeof(struct lguest_vqconfig) - + dev->desc->feature_len * 2; + + dev->num_vq * sizeof(struct lguest_vqconfig) + + dev->feature_len * 2; } -/* This routine allocates a new "struct lguest_device_desc" from descriptor +/* + * This routine allocates a new "struct lguest_device_desc" from descriptor * table page just above the Guest's normal memory. It returns a pointer to - * that descriptor. */ + * that descriptor. + */ static struct lguest_device_desc *new_dev_desc(u16 type) { struct lguest_device_desc d = { .type = type }; @@ -1156,10 +1191,12 @@ static struct lguest_device_desc *new_dev_desc(u16 type) return memcpy(p, &d, sizeof(d)); } -/* Each device descriptor is followed by the description of its virtqueues. We - * specify how many descriptors the virtqueue is to have. */ +/* + * Each device descriptor is followed by the description of its virtqueues. We + * specify how many descriptors the virtqueue is to have. + */ static void add_virtqueue(struct device *dev, unsigned int num_descs, - void (*handle_output)(int, struct virtqueue *, bool)) + void (*service)(struct virtqueue *)) { unsigned int pages; struct virtqueue **i, *vq = malloc(sizeof(*vq)); @@ -1174,8 +1211,13 @@ static void add_virtqueue(struct device *dev, unsigned int num_descs, vq->next = NULL; vq->last_avail_idx = 0; vq->dev = dev; - vq->inflight = 0; - vq->blocked = false; + + /* + * This is the routine the service thread will run, and its Process ID + * once it's running. + */ + vq->service = service; + vq->thread = (pid_t)-1; /* Initialize the configuration. */ vq->config.num = num_descs; @@ -1185,33 +1227,31 @@ static void add_virtqueue(struct device *dev, unsigned int num_descs, /* Initialize the vring. */ vring_init(&vq->vring, num_descs, p, LGUEST_VRING_ALIGN); - /* Append virtqueue to this device's descriptor. We use + /* + * Append virtqueue to this device's descriptor. We use * device_config() to get the end of the device's current virtqueues; * we check that we haven't added any config or feature information - * yet, otherwise we'd be overwriting them. */ + * yet, otherwise we'd be overwriting them. + */ assert(dev->desc->config_len == 0 && dev->desc->feature_len == 0); memcpy(device_config(dev), &vq->config, sizeof(vq->config)); + dev->num_vq++; dev->desc->num_vq++; verbose("Virtqueue page %#lx\n", to_guest_phys(p)); - /* Add to tail of list, so dev->vq is first vq, dev->vq->next is - * second. */ + /* + * Add to tail of list, so dev->vq is first vq, dev->vq->next is + * second. + */ for (i = &dev->vq; *i; i = &(*i)->next); *i = vq; - - /* Set the routine to call when the Guest does something to this - * virtqueue. */ - vq->handle_output = handle_output; - - /* As an optimization, set the advisory "Don't Notify Me" flag if we - * don't have a handler */ - if (!handle_output) - vq->vring.used->flags = VRING_USED_F_NO_NOTIFY; } -/* The first half of the feature bitmask is for us to advertise features. The - * second half is for the Guest to accept features. */ +/* + * The first half of the feature bitmask is for us to advertise features. The + * second half is for the Guest to accept features. + */ static void add_feature(struct device *dev, unsigned bit) { u8 *features = get_feature_bits(dev); @@ -1219,15 +1259,17 @@ static void add_feature(struct device *dev, unsigned bit) /* We can't extend the feature bits once we've added config bytes */ if (dev->desc->feature_len <= bit / CHAR_BIT) { assert(dev->desc->config_len == 0); - dev->desc->feature_len = (bit / CHAR_BIT) + 1; + dev->feature_len = dev->desc->feature_len = (bit/CHAR_BIT) + 1; } features[bit / CHAR_BIT] |= (1 << (bit % CHAR_BIT)); } -/* This routine sets the configuration fields for an existing device's +/* + * This routine sets the configuration fields for an existing device's * descriptor. It only works for the last device, but that's OK because that's - * how we use it. */ + * how we use it. + */ static void set_config(struct device *dev, unsigned len, const void *conf) { /* Check we haven't overflowed our single page. */ @@ -1237,33 +1279,36 @@ static void set_config(struct device *dev, unsigned len, const void *conf) /* Copy in the config information, and store the length. */ memcpy(device_config(dev), conf, len); dev->desc->config_len = len; + + /* Size must fit in config_len field (8 bits)! */ + assert(dev->desc->config_len == len); } -/* This routine does all the creation and setup of a new device, including - * calling new_dev_desc() to allocate the descriptor and device memory. +/* + * This routine does all the creation and setup of a new device, including + * calling new_dev_desc() to allocate the descriptor and device memory. We + * don't actually start the service threads until later. * - * See what I mean about userspace being boring? */ -static struct device *new_device(const char *name, u16 type, int fd, - bool (*handle_input)(int, struct device *)) + * See what I mean about userspace being boring? + */ +static struct device *new_device(const char *name, u16 type) { struct device *dev = malloc(sizeof(*dev)); /* Now we populate the fields one at a time. */ - dev->fd = fd; - /* If we have an input handler for this file descriptor, then we add it - * to the device_list's fdset and maxfd. */ - if (handle_input) - add_device_fd(dev->fd); dev->desc = new_dev_desc(type); - dev->handle_input = handle_input; dev->name = name; dev->vq = NULL; - dev->ready = NULL; + dev->feature_len = 0; + dev->num_vq = 0; + dev->running = false; - /* Append to device list. Prepending to a single-linked list is + /* + * Append to device list. Prepending to a single-linked list is * easier, but the user expects the devices to be arranged on the bus * in command-line order. The first network device on the command line - * is eth0, the first block device /dev/vda, etc. */ + * is eth0, the first block device /dev/vda, etc. + */ if (devices.lastdev) devices.lastdev->next = dev; else @@ -1273,8 +1318,10 @@ static struct device *new_device(const char *name, u16 type, int fd, return dev; } -/* Our first setup routine is the console. It's a fairly simple device, but - * UNIX tty handling makes it uglier than it could be. */ +/* + * Our first setup routine is the console. It's a fairly simple device, but + * UNIX tty handling makes it uglier than it could be. + */ static void setup_console(void) { struct device *dev; @@ -1282,51 +1329,35 @@ static void setup_console(void) /* If we can save the initial standard input settings... */ if (tcgetattr(STDIN_FILENO, &orig_term) == 0) { struct termios term = orig_term; - /* Then we turn off echo, line buffering and ^C etc. We want a - * raw input stream to the Guest. */ + /* + * Then we turn off echo, line buffering and ^C etc: We want a + * raw input stream to the Guest. + */ term.c_lflag &= ~(ISIG|ICANON|ECHO); tcsetattr(STDIN_FILENO, TCSANOW, &term); - /* If we exit gracefully, the original settings will be - * restored so the user can see what they're typing. */ - atexit(restore_term); } - dev = new_device("console", VIRTIO_ID_CONSOLE, - STDIN_FILENO, handle_console_input); + dev = new_device("console", VIRTIO_ID_CONSOLE); + /* We store the console state in dev->priv, and initialize it. */ dev->priv = malloc(sizeof(struct console_abort)); ((struct console_abort *)dev->priv)->count = 0; - /* The console needs two virtqueues: the input then the output. When + /* + * The console needs two virtqueues: the input then the output. When * they put something the input queue, we make sure we're listening to * stdin. When they put something in the output queue, we write it to - * stdout. */ - add_virtqueue(dev, VIRTQUEUE_NUM, enable_fd); - add_virtqueue(dev, VIRTQUEUE_NUM, handle_console_output); + * stdout. + */ + add_virtqueue(dev, VIRTQUEUE_NUM, console_input); + add_virtqueue(dev, VIRTQUEUE_NUM, console_output); - verbose("device %u: console\n", devices.device_num++); + verbose("device %u: console\n", ++devices.device_num); } /*:*/ -static void timeout_alarm(int sig) -{ - write(timeoutpipe[1], "", 1); -} - -static void setup_timeout(void) -{ - if (pipe(timeoutpipe) != 0) - err(1, "Creating timeout pipe"); - - if (fcntl(timeoutpipe[1], F_SETFL, - fcntl(timeoutpipe[1], F_GETFL) | O_NONBLOCK) != 0) - err(1, "Making timeout pipe nonblocking"); - - add_device_fd(timeoutpipe[0]); - signal(SIGALRM, timeout_alarm); -} - -/*M:010 Inter-guest networking is an interesting area. Simplest is to have a +/*M:010 + * Inter-guest networking is an interesting area. Simplest is to have a * --sharenet=<name> option which opens or creates a named pipe. This can be * used to send packets to another guest in a 1:1 manner. * @@ -1340,7 +1371,8 @@ static void setup_timeout(void) * multiple inter-guest channels behind one interface, although it would * require some manner of hotplugging new virtio channels. * - * Finally, we could implement a virtio network switch in the kernel. :*/ + * Finally, we could implement a virtio network switch in the kernel. +:*/ static u32 str2ip(const char *ipaddr) { @@ -1365,11 +1397,13 @@ static void str2mac(const char *macaddr, unsigned char mac[6]) mac[5] = m[5]; } -/* This code is "adapted" from libbridge: it attaches the Host end of the +/* + * This code is "adapted" from libbridge: it attaches the Host end of the * network device to the bridge device specified by the command line. * * This is yet another James Morris contribution (I'm an IP-level guy, so I - * dislike bridging), and I just try not to break it. */ + * dislike bridging), and I just try not to break it. + */ static void add_to_bridge(int fd, const char *if_name, const char *br_name) { int ifidx; @@ -1389,9 +1423,11 @@ static void add_to_bridge(int fd, const char *if_name, const char *br_name) err(1, "can't add %s to bridge %s", if_name, br_name); } -/* This sets up the Host end of the network device with an IP address, brings +/* + * This sets up the Host end of the network device with an IP address, brings * it up so packets will flow, the copies the MAC address into the hwaddr - * pointer. */ + * pointer. + */ static void configure_device(int fd, const char *tapif, u32 ipaddr) { struct ifreq ifr; @@ -1418,10 +1454,12 @@ static int get_tun_device(char tapif[IFNAMSIZ]) /* Start with this zeroed. Messy but sure. */ memset(&ifr, 0, sizeof(ifr)); - /* We open the /dev/net/tun device and tell it we want a tap device. A + /* + * We open the /dev/net/tun device and tell it we want a tap device. A * tap device is like a tun device, only somehow different. To tell * the truth, I completely blundered my way through this code, but it - * works now! */ + * works now! + */ netfd = open_or_die("/dev/net/tun", O_RDWR); ifr.ifr_flags = IFF_TAP | IFF_NO_PI | IFF_VNET_HDR; strcpy(ifr.ifr_name, "tap%d"); @@ -1432,39 +1470,46 @@ static int get_tun_device(char tapif[IFNAMSIZ]) TUN_F_CSUM|TUN_F_TSO4|TUN_F_TSO6|TUN_F_TSO_ECN) != 0) err(1, "Could not set features for tun device"); - /* We don't need checksums calculated for packets coming in this - * device: trust us! */ + /* + * We don't need checksums calculated for packets coming in this + * device: trust us! + */ ioctl(netfd, TUNSETNOCSUM, 1); memcpy(tapif, ifr.ifr_name, IFNAMSIZ); return netfd; } -/*L:195 Our network is a Host<->Guest network. This can either use bridging or +/*L:195 + * Our network is a Host<->Guest network. This can either use bridging or * routing, but the principle is the same: it uses the "tun" device to inject * packets into the Host as if they came in from a normal network card. We - * just shunt packets between the Guest and the tun device. */ + * just shunt packets between the Guest and the tun device. + */ static void setup_tun_net(char *arg) { struct device *dev; - int netfd, ipfd; + struct net_info *net_info = malloc(sizeof(*net_info)); + int ipfd; u32 ip = INADDR_ANY; bool bridging = false; char tapif[IFNAMSIZ], *p; struct virtio_net_config conf; - netfd = get_tun_device(tapif); + net_info->tunfd = get_tun_device(tapif); /* First we create a new network device. */ - dev = new_device("net", VIRTIO_ID_NET, netfd, handle_tun_input); + dev = new_device("net", VIRTIO_ID_NET); + dev->priv = net_info; - /* Network devices need a receive and a send queue, just like - * console. */ - add_virtqueue(dev, VIRTQUEUE_NUM, net_enable_fd); - add_virtqueue(dev, VIRTQUEUE_NUM, handle_net_output); + /* Network devices need a recv and a send queue, just like console. */ + add_virtqueue(dev, VIRTQUEUE_NUM, net_input); + add_virtqueue(dev, VIRTQUEUE_NUM, net_output); - /* We need a socket to perform the magic network ioctls to bring up the - * tap interface, connect to the bridge etc. Any socket will do! */ + /* + * We need a socket to perform the magic network ioctls to bring up the + * tap interface, connect to the bridge etc. Any socket will do! + */ ipfd = socket(PF_INET, SOCK_DGRAM, IPPROTO_IP); if (ipfd < 0) err(1, "opening IP socket"); @@ -1502,6 +1547,8 @@ static void setup_tun_net(char *arg) add_feature(dev, VIRTIO_NET_F_HOST_TSO4); add_feature(dev, VIRTIO_NET_F_HOST_TSO6); add_feature(dev, VIRTIO_NET_F_HOST_ECN); + /* We handle indirect ring entries */ + add_feature(dev, VIRTIO_RING_F_INDIRECT_DESC); set_config(dev, sizeof(conf), &conf); /* We don't need the socket any more; setup is done. */ @@ -1516,93 +1563,100 @@ static void setup_tun_net(char *arg) verbose("device %u: tun %s: %s\n", devices.device_num, tapif, arg); } - -/* Our block (disk) device should be really simple: the Guest asks for a block - * number and we read or write that position in the file. Unfortunately, that - * was amazingly slow: the Guest waits until the read is finished before - * running anything else, even if it could have been doing useful work. - * - * We could use async I/O, except it's reputed to suck so hard that characters - * actually go missing from your code when you try to use it. - * - * So we farm the I/O out to thread, and communicate with it via a pipe. */ +/*:*/ /* This hangs off device->priv. */ -struct vblk_info -{ +struct vblk_info { /* The size of the file. */ off64_t len; /* The file descriptor for the file. */ int fd; - /* IO thread listens on this file descriptor [0]. */ - int workpipe[2]; - - /* IO thread writes to this file descriptor to mark it done, then - * Launcher triggers interrupt to Guest. */ - int done_fd; }; /*L:210 * The Disk * - * Remember that the block device is handled by a separate I/O thread. We head - * straight into the core of that thread here: + * The disk only has one virtqueue, so it only has one thread. It is really + * simple: the Guest asks for a block number and we read or write that position + * in the file. + * + * Before we serviced each virtqueue in a separate thread, that was unacceptably + * slow: the Guest waits until the read is finished before running anything + * else, even if it could have been doing useful work. + * + * We could have used async I/O, except it's reputed to suck so hard that + * characters actually go missing from your code when you try to use it. */ -static bool service_io(struct device *dev) +static void blk_request(struct virtqueue *vq) { - struct vblk_info *vblk = dev->priv; + struct vblk_info *vblk = vq->dev->priv; unsigned int head, out_num, in_num, wlen; int ret; u8 *in; struct virtio_blk_outhdr *out; - struct iovec iov[dev->vq->vring.num]; + struct iovec iov[vq->vring.num]; off64_t off; - /* See if there's a request waiting. If not, nothing to do. */ - head = get_vq_desc(dev->vq, iov, &out_num, &in_num); - if (head == dev->vq->vring.num) - return false; + /* + * Get the next request, where we normally wait. It triggers the + * interrupt to acknowledge previously serviced requests (if any). + */ + head = wait_for_vq_desc(vq, iov, &out_num, &in_num); - /* Every block request should contain at least one output buffer + /* + * Every block request should contain at least one output buffer * (detailing the location on disk and the type of request) and one - * input buffer (to hold the result). */ + * input buffer (to hold the result). + */ if (out_num == 0 || in_num == 0) errx(1, "Bad virtblk cmd %u out=%u in=%u", head, out_num, in_num); out = convert(&iov[0], struct virtio_blk_outhdr); in = convert(&iov[out_num+in_num-1], u8); + /* + * For historical reasons, block operations are expressed in 512 byte + * "sectors". + */ off = out->sector * 512; - /* The block device implements "barriers", where the Guest indicates + /* + * The block device implements "barriers", where the Guest indicates * that it wants all previous writes to occur before this write. We * don't have a way of asking our kernel to do a barrier, so we just - * synchronize all the data in the file. Pretty poor, no? */ + * synchronize all the data in the file. Pretty poor, no? + */ if (out->type & VIRTIO_BLK_T_BARRIER) fdatasync(vblk->fd); - /* In general the virtio block driver is allowed to try SCSI commands. - * It'd be nice if we supported eject, for example, but we don't. */ + /* + * In general the virtio block driver is allowed to try SCSI commands. + * It'd be nice if we supported eject, for example, but we don't. + */ if (out->type & VIRTIO_BLK_T_SCSI_CMD) { fprintf(stderr, "Scsi commands unsupported\n"); *in = VIRTIO_BLK_S_UNSUPP; wlen = sizeof(*in); } else if (out->type & VIRTIO_BLK_T_OUT) { - /* Write */ - - /* Move to the right location in the block file. This can fail - * if they try to write past end. */ + /* + * Write + * + * Move to the right location in the block file. This can fail + * if they try to write past end. + */ if (lseek64(vblk->fd, off, SEEK_SET) != off) err(1, "Bad seek to sector %llu", out->sector); ret = writev(vblk->fd, iov+1, out_num-1); verbose("WRITE to sector %llu: %i\n", out->sector, ret); - /* Grr... Now we know how long the descriptor they sent was, we + /* + * Grr... Now we know how long the descriptor they sent was, we * make sure they didn't try to write over the end of the block - * file (possibly extending it). */ + * file (possibly extending it). + */ if (ret > 0 && off + ret > vblk->len) { /* Trim it back to the correct length */ ftruncate64(vblk->fd, vblk->len); @@ -1612,10 +1666,12 @@ static bool service_io(struct device *dev) wlen = sizeof(*in); *in = (ret >= 0 ? VIRTIO_BLK_S_OK : VIRTIO_BLK_S_IOERR); } else { - /* Read */ - - /* Move to the right location in the block file. This can fail - * if they try to read past end. */ + /* + * Read + * + * Move to the right location in the block file. This can fail + * if they try to read past end. + */ if (lseek64(vblk->fd, off, SEEK_SET) != off) err(1, "Bad seek to sector %llu", out->sector); @@ -1630,90 +1686,31 @@ static bool service_io(struct device *dev) } } - /* OK, so we noted that it was pretty poor to use an fdatasync as a + /* + * OK, so we noted that it was pretty poor to use an fdatasync as a * barrier. But Christoph Hellwig points out that we need a sync * *afterwards* as well: "Barriers specify no reordering to the front - * or the back." And Jens Axboe confirmed it, so here we are: */ + * or the back." And Jens Axboe confirmed it, so here we are: + */ if (out->type & VIRTIO_BLK_T_BARRIER) fdatasync(vblk->fd); - /* We can't trigger an IRQ, because we're not the Launcher. It does - * that when we tell it we're done. */ - add_used(dev->vq, head, wlen); - return true; -} - -/* This is the thread which actually services the I/O. */ -static int io_thread(void *_dev) -{ - struct device *dev = _dev; - struct vblk_info *vblk = dev->priv; - char c; - - /* Close other side of workpipe so we get 0 read when main dies. */ - close(vblk->workpipe[1]); - /* Close the other side of the done_fd pipe. */ - close(dev->fd); - - /* When this read fails, it means Launcher died, so we follow. */ - while (read(vblk->workpipe[0], &c, 1) == 1) { - /* We acknowledge each request immediately to reduce latency, - * rather than waiting until we've done them all. I haven't - * measured to see if it makes any difference. - * - * That would be an interesting test, wouldn't it? You could - * also try having more than one I/O thread. */ - while (service_io(dev)) - write(vblk->done_fd, &c, 1); - } - return 0; -} - -/* Now we've seen the I/O thread, we return to the Launcher to see what happens - * when that thread tells us it's completed some I/O. */ -static bool handle_io_finish(int fd, struct device *dev) -{ - char c; - - /* If the I/O thread died, presumably it printed the error, so we - * simply exit. */ - if (read(dev->fd, &c, 1) != 1) - exit(1); - - /* It did some work, so trigger the irq. */ - trigger_irq(fd, dev->vq); - return true; -} - -/* When the Guest submits some I/O, we just need to wake the I/O thread. */ -static void handle_virtblk_output(int fd, struct virtqueue *vq, bool timeout) -{ - struct vblk_info *vblk = vq->dev->priv; - char c = 0; - - /* Wake up I/O thread and tell it to go to work! */ - if (write(vblk->workpipe[1], &c, 1) != 1) - /* Presumably it indicated why it died. */ - exit(1); + /* Finished that request. */ + add_used(vq, head, wlen); } /*L:198 This actually sets up a virtual block device. */ static void setup_block_file(const char *filename) { - int p[2]; struct device *dev; struct vblk_info *vblk; - void *stack; struct virtio_blk_config conf; - /* This is the pipe the I/O thread will use to tell us I/O is done. */ - pipe(p); - - /* The device responds to return from I/O thread. */ - dev = new_device("block", VIRTIO_ID_BLOCK, p[0], handle_io_finish); + /* Creat the device. */ + dev = new_device("block", VIRTIO_ID_BLOCK); /* The device has one virtqueue, where the Guest places requests. */ - add_virtqueue(dev, VIRTQUEUE_NUM, handle_virtblk_output); + add_virtqueue(dev, VIRTQUEUE_NUM, blk_request); /* Allocate the room for our own bookkeeping */ vblk = dev->priv = malloc(sizeof(*vblk)); @@ -1728,64 +1725,50 @@ static void setup_block_file(const char *filename) /* Tell Guest how many sectors this device has. */ conf.capacity = cpu_to_le64(vblk->len / 512); - /* Tell Guest not to put in too many descriptors at once: two are used - * for the in and out elements. */ + /* + * Tell Guest not to put in too many descriptors at once: two are used + * for the in and out elements. + */ add_feature(dev, VIRTIO_BLK_F_SEG_MAX); conf.seg_max = cpu_to_le32(VIRTQUEUE_NUM - 2); - set_config(dev, sizeof(conf), &conf); - - /* The I/O thread writes to this end of the pipe when done. */ - vblk->done_fd = p[1]; - - /* This is the second pipe, which is how we tell the I/O thread about - * more work. */ - pipe(vblk->workpipe); - - /* Create stack for thread and run it. Since stack grows upwards, we - * point the stack pointer to the end of this region. */ - stack = malloc(32768); - /* SIGCHLD - We dont "wait" for our cloned thread, so prevent it from - * becoming a zombie. */ - if (clone(io_thread, stack + 32768, CLONE_VM | SIGCHLD, dev) == -1) - err(1, "Creating clone"); - - /* We don't need to keep the I/O thread's end of the pipes open. */ - close(vblk->done_fd); - close(vblk->workpipe[0]); + /* Don't try to put whole struct: we have 8 bit limit. */ + set_config(dev, offsetof(struct virtio_blk_config, geometry), &conf); verbose("device %u: virtblock %llu sectors\n", - devices.device_num, le64_to_cpu(conf.capacity)); + ++devices.device_num, le64_to_cpu(conf.capacity)); } -/* Our random number generator device reads from /dev/random into the Guest's +/*L:211 + * Our random number generator device reads from /dev/random into the Guest's * input buffers. The usual case is that the Guest doesn't want random numbers * and so has no buffers although /dev/random is still readable, whereas * console is the reverse. * - * The same logic applies, however. */ -static bool handle_rng_input(int fd, struct device *dev) + * The same logic applies, however. + */ +struct rng_info { + int rfd; +}; + +static void rng_input(struct virtqueue *vq) { int len; unsigned int head, in_num, out_num, totlen = 0; - struct iovec iov[dev->vq->vring.num]; + struct rng_info *rng_info = vq->dev->priv; + struct iovec iov[vq->vring.num]; /* First we need a buffer from the Guests's virtqueue. */ - head = get_vq_desc(dev->vq, iov, &out_num, &in_num); - - /* If they're not ready for input, stop listening to this file - * descriptor. We'll start again once they add an input buffer. */ - if (head == dev->vq->vring.num) - return false; - + head = wait_for_vq_desc(vq, iov, &out_num, &in_num); if (out_num) errx(1, "Output buffers in rng?"); - /* This is why we convert to iovecs: the readv() call uses them, and so - * it reads straight into the Guest's buffer. We loop to make sure we - * fill it. */ + /* + * Just like the console write, we loop to cover the whole iovec. + * In this case, short reads actually happen quite a bit. + */ while (!iov_empty(iov, in_num)) { - len = readv(dev->fd, iov, in_num); + len = readv(rng_info->rfd, iov, in_num); if (len <= 0) err(1, "Read from /dev/random gave %i", len); iov_consume(iov, in_num, len); @@ -1793,25 +1776,26 @@ static bool handle_rng_input(int fd, struct device *dev) } /* Tell the Guest about the new input. */ - add_used_and_trigger(fd, dev->vq, head, totlen); - - /* Everything went OK! */ - return true; + add_used(vq, head, totlen); } -/* And this creates a "hardware" random number device for the Guest. */ +/*L:199 + * This creates a "hardware" random number device for the Guest. + */ static void setup_rng(void) { struct device *dev; - int fd; + struct rng_info *rng_info = malloc(sizeof(*rng_info)); - fd = open_or_die("/dev/random", O_RDONLY); + /* Our device's privat info simply contains the /dev/random fd. */ + rng_info->rfd = open_or_die("/dev/random", O_RDONLY); - /* The device responds to return from I/O thread. */ - dev = new_device("rng", VIRTIO_ID_RNG, fd, handle_rng_input); + /* Create the new device. */ + dev = new_device("rng", VIRTIO_ID_RNG); + dev->priv = rng_info; /* The device has one virtqueue, where the Guest places inbufs. */ - add_virtqueue(dev, VIRTQUEUE_NUM, enable_fd); + add_virtqueue(dev, VIRTQUEUE_NUM, rng_input); verbose("device %u: rng\n", devices.device_num++); } @@ -1822,22 +1806,27 @@ static void __attribute__((noreturn)) restart_guest(void) { unsigned int i; - /* Since we don't track all open fds, we simply close everything beyond - * stderr. */ + /* + * Since we don't track all open fds, we simply close everything beyond + * stderr. + */ for (i = 3; i < FD_SETSIZE; i++) close(i); - /* The exec automatically gets rid of the I/O and Waker threads. */ + /* Reset all the devices (kills all threads). */ + cleanup_devices(); + execv(main_args[0], main_args); err(1, "Could not exec %s", main_args[0]); } -/*L:220 Finally we reach the core of the Launcher which runs the Guest, serves - * its input and output, and finally, lays it to rest. */ -static void __attribute__((noreturn)) run_guest(int lguest_fd) +/*L:220 + * Finally we reach the core of the Launcher which runs the Guest, serves + * its input and output, and finally, lays it to rest. + */ +static void __attribute__((noreturn)) run_guest(void) { for (;;) { - unsigned long args[] = { LHREQ_BREAK, 0 }; unsigned long notify_addr; int readval; @@ -1848,8 +1837,7 @@ static void __attribute__((noreturn)) run_guest(int lguest_fd) /* One unsigned long means the Guest did HCALL_NOTIFY */ if (readval == sizeof(notify_addr)) { verbose("Notify on address %#lx\n", notify_addr); - handle_output(lguest_fd, notify_addr); - continue; + handle_output(notify_addr); /* ENOENT means the Guest died. Reading tells us why. */ } else if (errno == ENOENT) { char reason[1024] = { 0 }; @@ -1858,19 +1846,9 @@ static void __attribute__((noreturn)) run_guest(int lguest_fd) /* ERESTART means that we need to reboot the guest */ } else if (errno == ERESTART) { restart_guest(); - /* EAGAIN means a signal (timeout). - * Anything else means a bug or incompatible change. */ - } else if (errno != EAGAIN) + /* Anything else means a bug or incompatible change. */ + } else err(1, "Running guest failed"); - - /* Only service input on thread for CPU 0. */ - if (cpu_id != 0) - continue; - - /* Service input, then unset the BREAK to release the Waker. */ - handle_input(lguest_fd); - if (pwrite(lguest_fd, args, sizeof(args), cpu_id) < 0) - err(1, "Resetting break"); } } /*L:240 @@ -1880,7 +1858,7 @@ static void __attribute__((noreturn)) run_guest(int lguest_fd) * * Are you ready? Take a deep breath and join me in the core of the Host, in * "make Host". - :*/ +:*/ static struct option opts[] = { { "verbose", 0, NULL, 'v' }, @@ -1901,11 +1879,10 @@ static void usage(void) /*L:105 The main routine is where the real work begins: */ int main(int argc, char *argv[]) { - /* Memory, top-level pagetable, code startpoint and size of the - * (optional) initrd. */ + /* Memory, code startpoint and size of the (optional) initrd. */ unsigned long mem = 0, start, initrd_size = 0; - /* Two temporaries and the /dev/lguest file descriptor. */ - int i, c, lguest_fd; + /* Two temporaries. */ + int i, c; /* The boot information for the Guest. */ struct boot_params *boot; /* If they specify an initrd file to load. */ @@ -1913,33 +1890,33 @@ int main(int argc, char *argv[]) /* Save the args: we "reboot" by execing ourselves again. */ main_args = argv; - /* We don't "wait" for the children, so prevent them from becoming - * zombies. */ - signal(SIGCHLD, SIG_IGN); - /* First we initialize the device list. Since console and network - * device receive input from a file descriptor, we keep an fdset - * (infds) and the maximum fd number (max_infd) with the head of the - * list. We also keep a pointer to the last device. Finally, we keep - * the next interrupt number to use for devices (1: remember that 0 is - * used by the timer). */ - FD_ZERO(&devices.infds); - devices.max_infd = -1; + /* + * First we initialize the device list. We keep a pointer to the last + * device, and the next interrupt number to use for devices (1: + * remember that 0 is used by the timer). + */ devices.lastdev = NULL; devices.next_irq = 1; + /* We're CPU 0. In fact, that's the only CPU possible right now. */ cpu_id = 0; - /* We need to know how much memory so we can set up the device + + /* + * We need to know how much memory so we can set up the device * descriptor and memory pages for the devices as we parse the command * line. So we quickly look through the arguments to find the amount - * of memory now. */ + * of memory now. + */ for (i = 1; i < argc; i++) { if (argv[i][0] != '-') { mem = atoi(argv[i]) * 1024 * 1024; - /* We start by mapping anonymous pages over all of + /* + * We start by mapping anonymous pages over all of * guest-physical memory range. This fills it with 0, * and ensures that the Guest won't be killed when it - * tries to access it. */ + * tries to access it. + */ guest_base = map_zeroed_pages(mem / getpagesize() + DEVICE_PAGES); guest_limit = mem; @@ -1972,8 +1949,10 @@ int main(int argc, char *argv[]) usage(); } } - /* After the other arguments we expect memory and kernel image name, - * followed by command line arguments for the kernel. */ + /* + * After the other arguments we expect memory and kernel image name, + * followed by command line arguments for the kernel. + */ if (optind + 2 > argc) usage(); @@ -1982,9 +1961,6 @@ int main(int argc, char *argv[]) /* We always have a console device */ setup_console(); - /* We can timeout waiting for Guest network transmit. */ - setup_timeout(); - /* Now we load the kernel */ start = load_kernel(open_or_die(argv[optind+1], O_RDONLY)); @@ -1994,20 +1970,26 @@ int main(int argc, char *argv[]) /* Map the initrd image if requested (at top of physical memory) */ if (initrd_name) { initrd_size = load_initrd(initrd_name, mem); - /* These are the location in the Linux boot header where the - * start and size of the initrd are expected to be found. */ + /* + * These are the location in the Linux boot header where the + * start and size of the initrd are expected to be found. + */ boot->hdr.ramdisk_image = mem - initrd_size; boot->hdr.ramdisk_size = initrd_size; /* The bootloader type 0xFF means "unknown"; that's OK. */ boot->hdr.type_of_loader = 0xFF; } - /* The Linux boot header contains an "E820" memory map: ours is a - * simple, single region. */ + /* + * The Linux boot header contains an "E820" memory map: ours is a + * simple, single region. + */ boot->e820_entries = 1; boot->e820_map[0] = ((struct e820entry) { 0, mem, E820_RAM }); - /* The boot header contains a command line pointer: we put the command - * line after the boot header. */ + /* + * The boot header contains a command line pointer: we put the command + * line after the boot header. + */ boot->hdr.cmd_line_ptr = to_guest_phys(boot + 1); /* We use a simple helper to copy the arguments separated by spaces. */ concat((char *)(boot + 1), argv+optind+2); @@ -2021,17 +2003,20 @@ int main(int argc, char *argv[]) /* Tell the entry path not to try to reload segment registers. */ boot->hdr.loadflags |= KEEP_SEGMENTS; - /* We tell the kernel to initialize the Guest: this returns the open - * /dev/lguest file descriptor. */ - lguest_fd = tell_kernel(start); + /* + * We tell the kernel to initialize the Guest: this returns the open + * /dev/lguest file descriptor. + */ + tell_kernel(start); + + /* Ensure that we terminate if a device-servicing child dies. */ + signal(SIGCHLD, kill_launcher); - /* We clone off a thread, which wakes the Launcher whenever one of the - * input file descriptors needs attention. We call this the Waker, and - * we'll cover it in a moment. */ - setup_waker(lguest_fd); + /* If we exit via err(), this kills all the threads, restores tty. */ + atexit(cleanup_devices); /* Finally, run the Guest. This doesn't return. */ - run_guest(lguest_fd); + run_guest(); } /*:*/ |