From 5dea1c88ed11a1221581c4b202f053c4fc138704 Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Fri, 22 Jul 2011 14:39:48 +0930 Subject: lguest: use a special 1:1 linear pagetable mode until first switch. The Host used to create some page tables for the Guest to use at the top of Guest memory; it would then tell the Guest where this was. In particular, it created linear mappings for 0 and 0xC0000000 addresses because lguest used to switch to its real page tables quite late in boot. However, since d50d8fe19 Linux initialized boot page tables in head_32.S even before the "are we lguest?" boot jump. So, now we can simplify things: the Host pagetable code assumes 1:1 linear mapping until it first calls the LHCALL_NEW_PGTABLE hypercall, which we now do before we reach C code. This also means that the Host doesn't need to know anything about the Guest's PAGE_OFFSET. (Non-Linux guests might not even have such a thing). Signed-off-by: Rusty Russell --- drivers/lguest/page_tables.c | 278 +++++++++++++------------------------------ 1 file changed, 84 insertions(+), 194 deletions(-) (limited to 'drivers/lguest/page_tables.c') diff --git a/drivers/lguest/page_tables.c b/drivers/lguest/page_tables.c index d21578ee95d..00026222bde 100644 --- a/drivers/lguest/page_tables.c +++ b/drivers/lguest/page_tables.c @@ -17,7 +17,6 @@ #include #include #include -#include #include "lg.h" /*M:008 @@ -325,10 +324,15 @@ bool demand_page(struct lg_cpu *cpu, unsigned long vaddr, int errcode) #endif /* First step: get the top-level Guest page table entry. */ - gpgd = lgread(cpu, gpgd_addr(cpu, vaddr), pgd_t); - /* Toplevel not present? We can't map it in. */ - if (!(pgd_flags(gpgd) & _PAGE_PRESENT)) - return false; + if (unlikely(cpu->linear_pages)) { + /* Faking up a linear mapping. */ + gpgd = __pgd(CHECK_GPGD_MASK); + } else { + gpgd = lgread(cpu, gpgd_addr(cpu, vaddr), pgd_t); + /* Toplevel not present? We can't map it in. */ + if (!(pgd_flags(gpgd) & _PAGE_PRESENT)) + return false; + } /* Now look at the matching shadow entry. */ spgd = spgd_addr(cpu, cpu->cpu_pgd, vaddr); @@ -353,10 +357,15 @@ bool demand_page(struct lg_cpu *cpu, unsigned long vaddr, int errcode) } #ifdef CONFIG_X86_PAE - gpmd = lgread(cpu, gpmd_addr(gpgd, vaddr), pmd_t); - /* Middle level not present? We can't map it in. */ - if (!(pmd_flags(gpmd) & _PAGE_PRESENT)) - return false; + if (unlikely(cpu->linear_pages)) { + /* Faking up a linear mapping. */ + gpmd = __pmd(_PAGE_TABLE); + } else { + gpmd = lgread(cpu, gpmd_addr(gpgd, vaddr), pmd_t); + /* Middle level not present? We can't map it in. */ + if (!(pmd_flags(gpmd) & _PAGE_PRESENT)) + return false; + } /* Now look at the matching shadow entry. */ spmd = spmd_addr(cpu, *spgd, vaddr); @@ -397,8 +406,13 @@ bool demand_page(struct lg_cpu *cpu, unsigned long vaddr, int errcode) gpte_ptr = gpte_addr(cpu, gpgd, vaddr); #endif - /* Read the actual PTE value. */ - gpte = lgread(cpu, gpte_ptr, pte_t); + if (unlikely(cpu->linear_pages)) { + /* Linear? Make up a PTE which points to same page. */ + gpte = __pte((vaddr & PAGE_MASK) | _PAGE_RW | _PAGE_PRESENT); + } else { + /* Read the actual PTE value. */ + gpte = lgread(cpu, gpte_ptr, pte_t); + } /* If this page isn't in the Guest page tables, we can't page it in. */ if (!(pte_flags(gpte) & _PAGE_PRESENT)) @@ -454,7 +468,8 @@ bool demand_page(struct lg_cpu *cpu, unsigned long vaddr, int errcode) * Finally, we write the Guest PTE entry back: we've set the * _PAGE_ACCESSED and maybe the _PAGE_DIRTY flags. */ - lgwrite(cpu, gpte_ptr, pte_t, gpte); + if (likely(!cpu->linear_pages)) + lgwrite(cpu, gpte_ptr, pte_t, gpte); /* * The fault is fixed, the page table is populated, the mapping @@ -612,6 +627,11 @@ unsigned long guest_pa(struct lg_cpu *cpu, unsigned long vaddr) #ifdef CONFIG_X86_PAE pmd_t gpmd; #endif + + /* Still not set up? Just map 1:1. */ + if (unlikely(cpu->linear_pages)) + return vaddr; + /* First step: get the top-level Guest page table entry. */ gpgd = lgread(cpu, gpgd_addr(cpu, vaddr), pgd_t); /* Toplevel not present? We can't map it in. */ @@ -708,32 +728,6 @@ static unsigned int new_pgdir(struct lg_cpu *cpu, return next; } -/*H:430 - * (iv) Switching page tables - * - * Now we've seen all the page table setting and manipulation, let's see - * what happens when the Guest changes page tables (ie. changes the top-level - * pgdir). This occurs on almost every context switch. - */ -void guest_new_pagetable(struct lg_cpu *cpu, unsigned long pgtable) -{ - int newpgdir, repin = 0; - - /* Look to see if we have this one already. */ - newpgdir = find_pgdir(cpu->lg, pgtable); - /* - * If not, we allocate or mug an existing one: if it's a fresh one, - * repin gets set to 1. - */ - if (newpgdir == ARRAY_SIZE(cpu->lg->pgdirs)) - newpgdir = new_pgdir(cpu, pgtable, &repin); - /* Change the current pgd index to the new one. */ - cpu->cpu_pgd = newpgdir; - /* If it was completely blank, we map in the Guest kernel stack */ - if (repin) - pin_stack_pages(cpu); -} - /*H:470 * Finally, a routine which throws away everything: all PGD entries in all * the shadow page tables, including the Guest's kernel mappings. This is used @@ -780,6 +774,44 @@ void guest_pagetable_clear_all(struct lg_cpu *cpu) /* We need the Guest kernel stack mapped again. */ pin_stack_pages(cpu); } + +/*H:430 + * (iv) Switching page tables + * + * Now we've seen all the page table setting and manipulation, let's see + * what happens when the Guest changes page tables (ie. changes the top-level + * pgdir). This occurs on almost every context switch. + */ +void guest_new_pagetable(struct lg_cpu *cpu, unsigned long pgtable) +{ + int newpgdir, repin = 0; + + /* + * The very first time they call this, we're actually running without + * any page tables; we've been making it up. Throw them away now. + */ + if (unlikely(cpu->linear_pages)) { + release_all_pagetables(cpu->lg); + cpu->linear_pages = false; + /* Force allocation of a new pgdir. */ + newpgdir = ARRAY_SIZE(cpu->lg->pgdirs); + } else { + /* Look to see if we have this one already. */ + newpgdir = find_pgdir(cpu->lg, pgtable); + } + + /* + * If not, we allocate or mug an existing one: if it's a fresh one, + * repin gets set to 1. + */ + if (newpgdir == ARRAY_SIZE(cpu->lg->pgdirs)) + newpgdir = new_pgdir(cpu, pgtable, &repin); + /* Change the current pgd index to the new one. */ + cpu->cpu_pgd = newpgdir; + /* If it was completely blank, we map in the Guest kernel stack */ + if (repin) + pin_stack_pages(cpu); +} /*:*/ /*M:009 @@ -919,168 +951,26 @@ void guest_set_pmd(struct lguest *lg, unsigned long pmdp, u32 idx) } #endif -/*H:505 - * To get through boot, we construct simple identity page mappings (which - * set virtual == physical) and linear mappings which will get the Guest far - * enough into the boot to create its own. The linear mapping means we - * simplify the Guest boot, but it makes assumptions about their PAGE_OFFSET, - * as you'll see. - * - * We lay them out of the way, just below the initrd (which is why we need to - * know its size here). - */ -static unsigned long setup_pagetables(struct lguest *lg, - unsigned long mem, - unsigned long initrd_size) -{ - pgd_t __user *pgdir; - pte_t __user *linear; - unsigned long mem_base = (unsigned long)lg->mem_base; - unsigned int mapped_pages, i, linear_pages; -#ifdef CONFIG_X86_PAE - pmd_t __user *pmds; - unsigned int j; - pgd_t pgd; - pmd_t pmd; -#else - unsigned int phys_linear; -#endif - - /* - * We have mapped_pages frames to map, so we need linear_pages page - * tables to map them. - */ - mapped_pages = mem / PAGE_SIZE; - linear_pages = (mapped_pages + PTRS_PER_PTE - 1) / PTRS_PER_PTE; - - /* We put the toplevel page directory page at the top of memory. */ - pgdir = (pgd_t *)(mem + mem_base - initrd_size - PAGE_SIZE); - - /* Now we use the next linear_pages pages as pte pages */ - linear = (void *)pgdir - linear_pages * PAGE_SIZE; - -#ifdef CONFIG_X86_PAE - /* - * And the single mid page goes below that. We only use one, but - * that's enough to map 1G, which definitely gets us through boot. - */ - pmds = (void *)linear - PAGE_SIZE; -#endif - /* - * Linear mapping is easy: put every page's address into the - * mapping in order. - */ - for (i = 0; i < mapped_pages; i++) { - pte_t pte; - pte = pfn_pte(i, __pgprot(_PAGE_PRESENT|_PAGE_RW|_PAGE_USER)); - if (copy_to_user(&linear[i], &pte, sizeof(pte)) != 0) - return -EFAULT; - } - -#ifdef CONFIG_X86_PAE - /* - * Make the Guest PMD entries point to the corresponding place in the - * linear mapping (up to one page worth of PMD). - */ - for (i = j = 0; i < mapped_pages && j < PTRS_PER_PMD; - i += PTRS_PER_PTE, j++) { - pmd = pfn_pmd(((unsigned long)&linear[i] - mem_base)/PAGE_SIZE, - __pgprot(_PAGE_PRESENT | _PAGE_RW | _PAGE_USER)); - - if (copy_to_user(&pmds[j], &pmd, sizeof(pmd)) != 0) - return -EFAULT; - } - - /* One PGD entry, pointing to that PMD page. */ - pgd = __pgd(((unsigned long)pmds - mem_base) | _PAGE_PRESENT); - /* Copy it in as the first PGD entry (ie. addresses 0-1G). */ - if (copy_to_user(&pgdir[0], &pgd, sizeof(pgd)) != 0) - return -EFAULT; - /* - * And the other PGD entry to make the linear mapping at PAGE_OFFSET - */ - if (copy_to_user(&pgdir[KERNEL_PGD_BOUNDARY], &pgd, sizeof(pgd))) - return -EFAULT; -#else - /* - * The top level points to the linear page table pages above. - * We setup the identity and linear mappings here. - */ - phys_linear = (unsigned long)linear - mem_base; - for (i = 0; i < mapped_pages; i += PTRS_PER_PTE) { - pgd_t pgd; - /* - * Create a PGD entry which points to the right part of the - * linear PTE pages. - */ - pgd = __pgd((phys_linear + i * sizeof(pte_t)) | - (_PAGE_PRESENT | _PAGE_RW | _PAGE_USER)); - - /* - * Copy it into the PGD page at 0 and PAGE_OFFSET. - */ - if (copy_to_user(&pgdir[i / PTRS_PER_PTE], &pgd, sizeof(pgd)) - || copy_to_user(&pgdir[pgd_index(PAGE_OFFSET) - + i / PTRS_PER_PTE], - &pgd, sizeof(pgd))) - return -EFAULT; - } -#endif - - /* - * We return the top level (guest-physical) address: we remember where - * this is to write it into lguest_data when the Guest initializes. - */ - return (unsigned long)pgdir - mem_base; -} - /*H:500 * (vii) Setting up the page tables initially. * - * When a Guest is first created, the Launcher tells us where the toplevel of - * its first page table is. We set some things up here: + * When a Guest is first created, set initialize a shadow page table which + * we will populate on future faults. The Guest doesn't have any actual + * pagetables yet, so we set linear_pages to tell demand_page() to fake it + * for the moment. */ int init_guest_pagetable(struct lguest *lg) { - u64 mem; - u32 initrd_size; - struct boot_params __user *boot = (struct boot_params *)lg->mem_base; -#ifdef CONFIG_X86_PAE - pgd_t *pgd; - pmd_t *pmd_table; -#endif - /* - * Get the Guest memory size and the ramdisk size from the boot header - * located at lg->mem_base (Guest address 0). - */ - if (copy_from_user(&mem, &boot->e820_map[0].size, sizeof(mem)) - || get_user(initrd_size, &boot->hdr.ramdisk_size)) - return -EFAULT; + struct lg_cpu *cpu = &lg->cpus[0]; + int allocated = 0; - /* - * We start on the first shadow page table, and give it a blank PGD - * page. - */ - lg->pgdirs[0].gpgdir = setup_pagetables(lg, mem, initrd_size); - if (IS_ERR_VALUE(lg->pgdirs[0].gpgdir)) - return lg->pgdirs[0].gpgdir; - lg->pgdirs[0].pgdir = (pgd_t *)get_zeroed_page(GFP_KERNEL); - if (!lg->pgdirs[0].pgdir) + /* lg (and lg->cpus[]) starts zeroed: this allocates a new pgdir */ + cpu->cpu_pgd = new_pgdir(cpu, 0, &allocated); + if (!allocated) return -ENOMEM; -#ifdef CONFIG_X86_PAE - /* For PAE, we also create the initial mid-level. */ - pgd = lg->pgdirs[0].pgdir; - pmd_table = (pmd_t *) get_zeroed_page(GFP_KERNEL); - if (!pmd_table) - return -ENOMEM; - - set_pgd(pgd + SWITCHER_PGD_INDEX, - __pgd(__pa(pmd_table) | _PAGE_PRESENT)); -#endif - - /* This is the current page table. */ - lg->cpus[0].cpu_pgd = 0; + /* We start with a linear mapping until the initialize. */ + cpu->linear_pages = true; return 0; } @@ -1095,10 +985,10 @@ void page_table_guest_data_init(struct lg_cpu *cpu) * of virtual addresses used by the Switcher. */ || put_user(RESERVE_MEM * 1024 * 1024, - &cpu->lg->lguest_data->reserve_mem) - || put_user(cpu->lg->pgdirs[0].gpgdir, - &cpu->lg->lguest_data->pgdir)) + &cpu->lg->lguest_data->reserve_mem)) { kill_guest(cpu, "bad guest page %p", cpu->lg->lguest_data); + return; + } /* * In flush_user_mappings() we loop from 0 to -- cgit v1.2.3-70-g09d2 From 9f54288def3f92b7805eb6d4b1ddcd73ecf6e889 Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Fri, 22 Jul 2011 14:39:50 +0930 Subject: lguest: update comments Also removes a long-unused #define and an extraneous semicolon. Signed-off-by: Rusty Russell --- Documentation/virtual/lguest/lguest.c | 12 ++++-------- arch/x86/include/asm/lguest_hcall.h | 1 + arch/x86/lguest/boot.c | 21 +++++++++++++++------ arch/x86/lguest/i386_head.S | 18 +++++++++++------- drivers/lguest/core.c | 2 +- drivers/lguest/interrupts_and_traps.c | 4 ++-- drivers/lguest/lguest_user.c | 17 ++++++++++------- drivers/lguest/page_tables.c | 4 ++-- drivers/lguest/x86/core.c | 10 ++++------ 9 files changed, 50 insertions(+), 39 deletions(-) (limited to 'drivers/lguest/page_tables.c') diff --git a/Documentation/virtual/lguest/lguest.c b/Documentation/virtual/lguest/lguest.c index 80261d34da3..043bd7df313 100644 --- a/Documentation/virtual/lguest/lguest.c +++ b/Documentation/virtual/lguest/lguest.c @@ -51,7 +51,7 @@ #include #include "../../../include/linux/lguest_launcher.h" /*L:110 - * We can ignore the 42 include files we need for this program, but I do want + * We can ignore the 43 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 @@ -65,7 +65,6 @@ typedef uint16_t u16; typedef uint8_t u8; /*:*/ -#define PAGE_PRESENT 0x7 /* Present, RW, Execute */ #define BRIDGE_PFX "bridge:" #ifndef SIOCBRADDIF #define SIOCBRADDIF 0x89a2 /* add interface to bridge */ @@ -1359,7 +1358,7 @@ static void setup_console(void) * --sharenet= option which opens or creates a named pipe. This can be * used to send packets to another guest in a 1:1 manner. * - * More sopisticated is to use one of the tools developed for project like UML + * More sophisticated is to use one of the tools developed for project like UML * to do networking. * * Faster is to do virtio bonding in kernel. Doing this 1:1 would be @@ -1369,7 +1368,7 @@ static void setup_console(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 use a virtio network switch in the kernel, ie. vhost. :*/ static u32 str2ip(const char *ipaddr) @@ -2006,10 +2005,7 @@ 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. - */ + /* We tell the kernel to initialize the Guest. */ tell_kernel(start); /* Ensure that we terminate if a device-servicing child dies. */ diff --git a/arch/x86/include/asm/lguest_hcall.h b/arch/x86/include/asm/lguest_hcall.h index b60f2924c41..879fd7d3387 100644 --- a/arch/x86/include/asm/lguest_hcall.h +++ b/arch/x86/include/asm/lguest_hcall.h @@ -61,6 +61,7 @@ hcall(unsigned long call, : "memory"); return call; } +/*:*/ /* Can't use our min() macro here: needs to be a constant */ #define LGUEST_IRQS (NR_IRQS < 32 ? NR_IRQS: 32) diff --git a/arch/x86/lguest/boot.c b/arch/x86/lguest/boot.c index 719a32c6051..74279907bc1 100644 --- a/arch/x86/lguest/boot.c +++ b/arch/x86/lguest/boot.c @@ -71,7 +71,8 @@ #include #include /* for struct machine_ops */ -/*G:010 Welcome to the Guest! +/*G:010 + * Welcome to the Guest! * * The Guest in our tale is a simple creature: identical to the Host but * behaving in simplified but equivalent ways. In particular, the Guest is the @@ -190,15 +191,23 @@ static void lazy_hcall4(unsigned long call, #endif /*G:036 - * When lazy mode is turned off reset the per-cpu lazy mode variable and then - * issue the do-nothing hypercall to flush any stored calls. -:*/ + * When lazy mode is turned off, we issue the do-nothing hypercall to + * flush any stored calls, and call the generic helper to reset the + * per-cpu lazy mode variable. + */ static void lguest_leave_lazy_mmu_mode(void) { hcall(LHCALL_FLUSH_ASYNC, 0, 0, 0, 0); paravirt_leave_lazy_mmu(); } +/* + * We also catch the end of context switch; we enter lazy mode for much of + * that too, so again we need to flush here. + * + * (Technically, this is lazy CPU mode, and normally we're in lazy MMU + * mode, but unlike Xen, lguest doesn't care about the difference). + */ static void lguest_end_context_switch(struct task_struct *next) { hcall(LHCALL_FLUSH_ASYNC, 0, 0, 0, 0); @@ -640,7 +649,7 @@ static void lguest_write_cr4(unsigned long val) /* * The Guest calls this after it has set a second-level entry (pte), ie. to map - * a page into a process' address space. Wetell the Host the toplevel and + * a page into a process' address space. We tell the Host the toplevel and * address this corresponds to. The Guest uses one pagetable per process, so * we need to tell the Host which one we're changing (mm->pgd). */ @@ -1139,7 +1148,7 @@ static struct notifier_block paniced = { static __init char *lguest_memory_setup(void) { /* - *The Linux bootloader header contains an "e820" memory map: the + * The Linux bootloader header contains an "e820" memory map: the * Launcher populated the first entry with our memory limit. */ e820_add_region(boot_params.e820_map[0].addr, diff --git a/arch/x86/lguest/i386_head.S b/arch/x86/lguest/i386_head.S index c8c95e575c1..cfa23e37ec5 100644 --- a/arch/x86/lguest/i386_head.S +++ b/arch/x86/lguest/i386_head.S @@ -6,18 +6,22 @@ #include /*G:020 - * Our story starts with the kernel booting into startup_32 in - * arch/x86/kernel/head_32.S. It expects a boot header, which is created by - * the bootloader (the Launcher in our case). + + * Our story starts with the bzImage: booting starts at startup_32 in + * arch/x86/boot/compressed/head_32.S. This merely uncompresses the real + * kernel in place and then jumps into it: startup_32 in + * arch/x86/kernel/head_32.S. Both routines expects a boot header in the %esi + * register, which is created by the bootloader (the Launcher in our case). * * The startup_32 function does very little: it clears the uninitialized global * C variables which we expect to be zero (ie. BSS) and then copies the boot - * header and kernel command line somewhere safe. Finally it checks the - * 'hardware_subarch' field. This was introduced in 2.6.24 for lguest and Xen: - * if it's set to '1' (lguest's assigned number), then it calls us here. + * header and kernel command line somewhere safe, and populates some initial + * page tables. Finally it checks the 'hardware_subarch' field. This was + * introduced in 2.6.24 for lguest and Xen: if it's set to '1' (lguest's + * assigned number), then it calls us here. * * WARNING: be very careful here! We're running at addresses equal to physical - * addesses (around 0), not above PAGE_OFFSET as most code expectes + * addesses (around 0), not above PAGE_OFFSET as most code expects * (eg. 0xC0000000). Jumps are relative, so they're OK, but we can't touch any * data without remembering to subtract __PAGE_OFFSET! * diff --git a/drivers/lguest/core.c b/drivers/lguest/core.c index efa202499e3..2535933c49f 100644 --- a/drivers/lguest/core.c +++ b/drivers/lguest/core.c @@ -117,7 +117,7 @@ static __init int map_switcher(void) /* * Now the Switcher is mapped at the right address, we can't fail! - * Copy in the compiled-in Switcher code (from _switcher.S). + * Copy in the compiled-in Switcher code (from x86/switcher_32.S). */ memcpy(switcher_vma->addr, start_switcher_text, end_switcher_text - start_switcher_text); diff --git a/drivers/lguest/interrupts_and_traps.c b/drivers/lguest/interrupts_and_traps.c index f0c17150637..28433a155d6 100644 --- a/drivers/lguest/interrupts_and_traps.c +++ b/drivers/lguest/interrupts_and_traps.c @@ -427,8 +427,8 @@ void pin_stack_pages(struct lg_cpu *cpu) /* * Direct traps also mean that we need to know whenever the Guest wants to use - * a different kernel stack, so we can change the IDT entries to use that - * stack. The IDT entries expect a virtual address, so unlike most addresses + * a different kernel stack, so we can change the guest TSS to use that + * stack. The TSS entries expect a virtual address, so unlike most addresses * the Guest gives us, the "esp" (stack pointer) value here is virtual, not * physical. * diff --git a/drivers/lguest/lguest_user.c b/drivers/lguest/lguest_user.c index 948c547b8e9..f97e625241a 100644 --- a/drivers/lguest/lguest_user.c +++ b/drivers/lguest/lguest_user.c @@ -1,8 +1,10 @@ -/*P:200 This contains all the /dev/lguest code, whereby the userspace launcher - * controls and communicates with the Guest. For example, the first write will - * tell us the Guest's memory layout and entry point. A read will run the - * Guest until something happens, such as a signal or the Guest doing a NOTIFY - * out to the Launcher. +/*P:200 This contains all the /dev/lguest code, whereby the userspace + * launcher controls and communicates with the Guest. For example, + * the first write will tell us the Guest's memory layout and entry + * point. A read will run the Guest until something happens, such as + * a signal or the Guest doing a NOTIFY out to the Launcher. There is + * also a way for the Launcher to attach eventfds to particular NOTIFY + * values instead of returning from the read() call. :*/ #include #include @@ -357,8 +359,8 @@ static int initialize(struct file *file, const unsigned long __user *input) goto free_eventfds; /* - * Initialize the Guest's shadow page tables, using the toplevel - * address the Launcher gave us. This allocates memory, so can fail. + * Initialize the Guest's shadow page tables. This allocates + * memory, so can fail. */ err = init_guest_pagetable(lg); if (err) @@ -516,6 +518,7 @@ static const struct file_operations lguest_fops = { .read = read, .llseek = default_llseek, }; +/*:*/ /* * This is a textbook example of a "misc" character device. Populate a "struct diff --git a/drivers/lguest/page_tables.c b/drivers/lguest/page_tables.c index 00026222bde..3b62be160a6 100644 --- a/drivers/lguest/page_tables.c +++ b/drivers/lguest/page_tables.c @@ -155,7 +155,7 @@ static pte_t *spte_addr(struct lg_cpu *cpu, pgd_t spgd, unsigned long vaddr) } /* - * These functions are just like the above two, except they access the Guest + * These functions are just like the above, except they access the Guest * page tables. Hence they return a Guest address. */ static unsigned long gpgd_addr(struct lg_cpu *cpu, unsigned long vaddr) @@ -195,7 +195,7 @@ static unsigned long gpte_addr(struct lg_cpu *cpu, #endif /*:*/ -/*M:014 +/*M:007 * get_pfn is slow: we could probably try to grab batches of pages here as * an optimization (ie. pre-faulting). :*/ diff --git a/drivers/lguest/x86/core.c b/drivers/lguest/x86/core.c index ec0cdfc04e7..3b9b810cbf2 100644 --- a/drivers/lguest/x86/core.c +++ b/drivers/lguest/x86/core.c @@ -272,7 +272,7 @@ static int emulate_insn(struct lg_cpu *cpu) unsigned int insnlen = 0, in = 0, shift = 0; /* * The eip contains the *virtual* address of the Guest's instruction: - * guest_pa just subtracts the Guest's page_offset. + * walk the Guest's page tables to find the "physical" address. */ unsigned long physaddr = guest_pa(cpu, cpu->regs->eip); @@ -409,7 +409,7 @@ void lguest_arch_handle_trap(struct lg_cpu *cpu) * These values mean a real interrupt occurred, in which case * the Host handler has already been run. We just do a * friendly check if another process should now be run, then - * return to run the Guest again + * return to run the Guest again. */ cond_resched(); return; @@ -459,7 +459,7 @@ void __init lguest_arch_host_init(void) int i; /* - * Most of the i386/switcher.S doesn't care that it's been moved; on + * Most of the x86/switcher_32.S doesn't care that it's been moved; on * Intel, jumps are relative, and it doesn't access any references to * external code or data. * @@ -587,7 +587,7 @@ void __init lguest_arch_host_init(void) clear_cpu_cap(&boot_cpu_data, X86_FEATURE_PGE); } put_online_cpus(); -}; +} /*:*/ void __exit lguest_arch_host_fini(void) @@ -670,8 +670,6 @@ int lguest_arch_init_hypercalls(struct lg_cpu *cpu) /*:*/ /*L:030 - * lguest_arch_setup_regs() - * * Most of the Guest's registers are left alone: we used get_zeroed_page() to * allocate the structure, so they will be 0. */ -- cgit v1.2.3-70-g09d2