From abd41f037e1a64543000ed73b42f616d04d92700 Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Fri, 12 Jun 2009 22:27:02 -0600 Subject: lguest: fix race in halt code When the Guest does the LHCALL_HALT hypercall, we go to sleep, expecting that a timer or the Waker will wake_up_process() us. But we do it in a stupid way, leaving a classic missing wakeup race. So split maybe_do_interrupt() into interrupt_pending() and try_deliver_interrupt(), and check maybe_do_interrupt() and the "break_out" flag before calling schedule. Signed-off-by: Rusty Russell --- drivers/lguest/core.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) (limited to 'drivers/lguest/core.c') diff --git a/drivers/lguest/core.c b/drivers/lguest/core.c index 4845fb3cf74..8ca1def5b14 100644 --- a/drivers/lguest/core.c +++ b/drivers/lguest/core.c @@ -188,6 +188,8 @@ int run_guest(struct lg_cpu *cpu, unsigned long __user *user) { /* We stop running once the Guest is dead. */ while (!cpu->lg->dead) { + unsigned int irq; + /* First we run any hypercalls the Guest wants done. */ if (cpu->hcall) do_hypercalls(cpu); @@ -211,7 +213,9 @@ int run_guest(struct lg_cpu *cpu, unsigned long __user *user) /* Check if there are any interrupts which can be delivered now: * if so, this sets up the hander to be executed when we next * run the Guest. */ - maybe_do_interrupt(cpu); + irq = interrupt_pending(cpu); + if (irq < LGUEST_IRQS) + try_deliver_interrupt(cpu, irq); /* All long-lived kernel loops need to check with this horrible * thing called the freezer. If the Host is trying to suspend, @@ -227,7 +231,13 @@ int run_guest(struct lg_cpu *cpu, unsigned long __user *user) * clock timer or LHREQ_BREAK from the Waker will wake us. */ if (cpu->halted) { set_current_state(TASK_INTERRUPTIBLE); - schedule(); + /* Just before we sleep, make sure nothing snuck in + * which we should be doing. */ + if (interrupt_pending(cpu) < LGUEST_IRQS + || cpu->break_out) + set_current_state(TASK_RUNNING); + else + schedule(); continue; } -- cgit v1.2.3-70-g09d2 From a32a8813d0173163ba44d8f9556e0d89fdc4fb46 Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Fri, 12 Jun 2009 22:27:02 -0600 Subject: lguest: improve interrupt handling, speed up stream networking lguest never checked for pending interrupts when enabling interrupts, and things still worked. However, it makes a significant difference to TCP performance, so it's time we fixed it by introducing a pending_irq flag and checking it on irq_restore and irq_enable. These two routines are now too big to patch into the 8/10 bytes patch space, so we drop that code. Note: The high latency on interrupt delivery had a very curious effect: once everything else was optimized, networking without GSO was faster than networking with GSO, since more interrupts were sent and hence a greater chance of one getting through to the Guest! Note2: (Almost) Closing the same loophole for iret doesn't have any measurable effect, so I'm leaving that patch for the moment. Before: 1GB tcpblast Guest->Host: 30.7 seconds 1GB tcpblast Guest->Host (no GSO): 76.0 seconds After: 1GB tcpblast Guest->Host: 6.8 seconds 1GB tcpblast Guest->Host (no GSO): 27.8 seconds Signed-off-by: Rusty Russell --- arch/x86/include/asm/lguest_hcall.h | 1 + arch/x86/lguest/boot.c | 21 +++++++++++++++------ arch/x86/lguest/i386_head.S | 2 -- drivers/lguest/core.c | 7 ++++--- drivers/lguest/hypercalls.c | 4 ++++ drivers/lguest/interrupts_and_traps.c | 16 +++++++++++++--- drivers/lguest/lg.h | 4 ++-- include/linux/lguest.h | 4 ++++ 8 files changed, 43 insertions(+), 16 deletions(-) (limited to 'drivers/lguest/core.c') diff --git a/arch/x86/include/asm/lguest_hcall.h b/arch/x86/include/asm/lguest_hcall.h index faae1996487..f9a9f781124 100644 --- a/arch/x86/include/asm/lguest_hcall.h +++ b/arch/x86/include/asm/lguest_hcall.h @@ -17,6 +17,7 @@ #define LHCALL_LOAD_TLS 16 #define LHCALL_NOTIFY 17 #define LHCALL_LOAD_GDT_ENTRY 18 +#define LHCALL_SEND_INTERRUPTS 19 #define LGUEST_TRAP_ENTRY 0x1F diff --git a/arch/x86/lguest/boot.c b/arch/x86/lguest/boot.c index 2392a7a171c..37b8c1d3e02 100644 --- a/arch/x86/lguest/boot.c +++ b/arch/x86/lguest/boot.c @@ -205,6 +205,12 @@ PV_CALLEE_SAVE_REGS_THUNK(save_fl); static void restore_fl(unsigned long flags) { lguest_data.irq_enabled = flags; + mb(); + /* Null hcall forces interrupt delivery now, if irq_pending is + * set to X86_EFLAGS_IF (ie. an interrupt is pending, and flags + * enables interrupts. */ + if (flags & lguest_data.irq_pending) + kvm_hypercall0(LHCALL_SEND_INTERRUPTS); } PV_CALLEE_SAVE_REGS_THUNK(restore_fl); @@ -219,6 +225,11 @@ PV_CALLEE_SAVE_REGS_THUNK(irq_disable); static void irq_enable(void) { lguest_data.irq_enabled = X86_EFLAGS_IF; + mb(); + /* Null hcall forces interrupt delivery now. */ + if (lguest_data.irq_pending) + kvm_hypercall0(LHCALL_SEND_INTERRUPTS); + } PV_CALLEE_SAVE_REGS_THUNK(irq_enable); @@ -972,10 +983,10 @@ static void lguest_restart(char *reason) * * Our current solution is to allow the paravirt back end to optionally patch * over the indirect calls to replace them with something more efficient. We - * patch the four most commonly called functions: disable interrupts, enable - * interrupts, restore interrupts and save interrupts. We usually have 6 or 10 - * bytes to patch into: the Guest versions of these operations are small enough - * that we can fit comfortably. + * patch two of the simplest of the most commonly called functions: disable + * interrupts and save interrupts. We usually have 6 or 10 bytes to patch + * into: the Guest versions of these operations are small enough that we can + * fit comfortably. * * First we need assembly templates of each of the patchable Guest operations, * and these are in i386_head.S. */ @@ -986,8 +997,6 @@ static const struct lguest_insns const char *start, *end; } lguest_insns[] = { [PARAVIRT_PATCH(pv_irq_ops.irq_disable)] = { lgstart_cli, lgend_cli }, - [PARAVIRT_PATCH(pv_irq_ops.irq_enable)] = { lgstart_sti, lgend_sti }, - [PARAVIRT_PATCH(pv_irq_ops.restore_fl)] = { lgstart_popf, lgend_popf }, [PARAVIRT_PATCH(pv_irq_ops.save_fl)] = { lgstart_pushf, lgend_pushf }, }; diff --git a/arch/x86/lguest/i386_head.S b/arch/x86/lguest/i386_head.S index f7954198947..3e0c5545d59 100644 --- a/arch/x86/lguest/i386_head.S +++ b/arch/x86/lguest/i386_head.S @@ -46,8 +46,6 @@ ENTRY(lguest_entry) .globl lgstart_##name; .globl lgend_##name LGUEST_PATCH(cli, movl $0, lguest_data+LGUEST_DATA_irq_enabled) -LGUEST_PATCH(sti, movl $X86_EFLAGS_IF, lguest_data+LGUEST_DATA_irq_enabled) -LGUEST_PATCH(popf, movl %eax, lguest_data+LGUEST_DATA_irq_enabled) LGUEST_PATCH(pushf, movl lguest_data+LGUEST_DATA_irq_enabled, %eax) /*:*/ diff --git a/drivers/lguest/core.c b/drivers/lguest/core.c index 8ca1def5b14..03fbc88c002 100644 --- a/drivers/lguest/core.c +++ b/drivers/lguest/core.c @@ -189,6 +189,7 @@ int run_guest(struct lg_cpu *cpu, unsigned long __user *user) /* We stop running once the Guest is dead. */ while (!cpu->lg->dead) { unsigned int irq; + bool more; /* First we run any hypercalls the Guest wants done. */ if (cpu->hcall) @@ -213,9 +214,9 @@ int run_guest(struct lg_cpu *cpu, unsigned long __user *user) /* Check if there are any interrupts which can be delivered now: * if so, this sets up the hander to be executed when we next * run the Guest. */ - irq = interrupt_pending(cpu); + irq = interrupt_pending(cpu, &more); if (irq < LGUEST_IRQS) - try_deliver_interrupt(cpu, irq); + try_deliver_interrupt(cpu, irq, more); /* All long-lived kernel loops need to check with this horrible * thing called the freezer. If the Host is trying to suspend, @@ -233,7 +234,7 @@ int run_guest(struct lg_cpu *cpu, unsigned long __user *user) set_current_state(TASK_INTERRUPTIBLE); /* Just before we sleep, make sure nothing snuck in * which we should be doing. */ - if (interrupt_pending(cpu) < LGUEST_IRQS + if (interrupt_pending(cpu, &more) < LGUEST_IRQS || cpu->break_out) set_current_state(TASK_RUNNING); else diff --git a/drivers/lguest/hypercalls.c b/drivers/lguest/hypercalls.c index 54d66f05fef..f252b71ae79 100644 --- a/drivers/lguest/hypercalls.c +++ b/drivers/lguest/hypercalls.c @@ -37,6 +37,10 @@ static void do_hcall(struct lg_cpu *cpu, struct hcall_args *args) /* This call does nothing, except by breaking out of the Guest * it makes us process all the asynchronous hypercalls. */ break; + case LHCALL_SEND_INTERRUPTS: + /* This call does nothing too, but by breaking out of the Guest + * it makes us process any pending interrupts. */ + break; case LHCALL_LGUEST_INIT: /* You can't get here unless you're already initialized. Don't * do that. */ diff --git a/drivers/lguest/interrupts_and_traps.c b/drivers/lguest/interrupts_and_traps.c index a8c966fee1e..5a10754b479 100644 --- a/drivers/lguest/interrupts_and_traps.c +++ b/drivers/lguest/interrupts_and_traps.c @@ -131,7 +131,7 @@ static void set_guest_interrupt(struct lg_cpu *cpu, u32 lo, u32 hi, * interrupt_pending() returns the first pending interrupt which isn't blocked * by the Guest. It is called before every entry to the Guest, and just before * we go to sleep when the Guest has halted itself. */ -unsigned int interrupt_pending(struct lg_cpu *cpu) +unsigned int interrupt_pending(struct lg_cpu *cpu, bool *more) { unsigned int irq; DECLARE_BITMAP(blk, LGUEST_IRQS); @@ -149,13 +149,14 @@ unsigned int interrupt_pending(struct lg_cpu *cpu) /* Find the first interrupt. */ irq = find_first_bit(blk, LGUEST_IRQS); + *more = find_next_bit(blk, LGUEST_IRQS, irq+1); return irq; } /* This actually diverts the Guest to running an interrupt handler, once an * interrupt has been identified by interrupt_pending(). */ -void try_deliver_interrupt(struct lg_cpu *cpu, unsigned int irq) +void try_deliver_interrupt(struct lg_cpu *cpu, unsigned int irq, bool more) { struct desc_struct *idt; @@ -178,8 +179,12 @@ void try_deliver_interrupt(struct lg_cpu *cpu, unsigned int irq) u32 irq_enabled; if (get_user(irq_enabled, &cpu->lg->lguest_data->irq_enabled)) irq_enabled = 0; - if (!irq_enabled) + if (!irq_enabled) { + /* Make sure they know an IRQ is pending. */ + put_user(X86_EFLAGS_IF, + &cpu->lg->lguest_data->irq_pending); return; + } } /* Look at the IDT entry the Guest gave us for this interrupt. The @@ -202,6 +207,11 @@ void try_deliver_interrupt(struct lg_cpu *cpu, unsigned int irq) * here is a compromise which means at least it gets updated every * timer interrupt. */ write_timestamp(cpu); + + /* If there are no other interrupts we want to deliver, clear + * the pending flag. */ + if (!more) + put_user(0, &cpu->lg->lguest_data->irq_pending); } /*:*/ diff --git a/drivers/lguest/lg.h b/drivers/lguest/lg.h index 6743cf147d9..573896533ac 100644 --- a/drivers/lguest/lg.h +++ b/drivers/lguest/lg.h @@ -139,8 +139,8 @@ int run_guest(struct lg_cpu *cpu, unsigned long __user *user); #define pgd_pfn(x) (pgd_val(x) >> PAGE_SHIFT) /* interrupts_and_traps.c: */ -unsigned int interrupt_pending(struct lg_cpu *cpu); -void try_deliver_interrupt(struct lg_cpu *cpu, unsigned int irq); +unsigned int interrupt_pending(struct lg_cpu *cpu, bool *more); +void try_deliver_interrupt(struct lg_cpu *cpu, unsigned int irq, bool more); bool deliver_trap(struct lg_cpu *cpu, unsigned int num); void load_guest_idt_entry(struct lg_cpu *cpu, unsigned int i, u32 low, u32 hi); diff --git a/include/linux/lguest.h b/include/linux/lguest.h index 175e63f4a8c..7bc1440fc47 100644 --- a/include/linux/lguest.h +++ b/include/linux/lguest.h @@ -30,6 +30,10 @@ struct lguest_data /* Wallclock time set by the Host. */ struct timespec time; + /* Interrupt pending set by the Host. The Guest should do a hypercall + * if it re-enables interrupts and sees this set (to X86_EFLAGS_IF). */ + int irq_pending; + /* Async hypercall ring. Instead of directly making hypercalls, we can * place them in here for processing the next time the Host wants. * This batching can be quite efficient. */ -- cgit v1.2.3-70-g09d2 From ed1dc77810159a733240ba6751c1b31023bf8dd7 Mon Sep 17 00:00:00 2001 From: Matias Zabaljauregui Date: Sat, 30 May 2009 15:35:49 -0300 Subject: lguest: map switcher with executable page table entries Map switcher with executable page table entries. (This bug didn't matter before PAE and hence NX support -- RR) Signed-off-by: Matias Zabaljauregui Signed-off-by: Rusty Russell --- drivers/lguest/core.c | 2 +- drivers/lguest/page_tables.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) (limited to 'drivers/lguest/core.c') diff --git a/drivers/lguest/core.c b/drivers/lguest/core.c index 03fbc88c002..d0298dc45d9 100644 --- a/drivers/lguest/core.c +++ b/drivers/lguest/core.c @@ -95,7 +95,7 @@ static __init int map_switcher(void) * array of struct pages. It increments that pointer, but we don't * care. */ pagep = switcher_page; - err = map_vm_area(switcher_vma, PAGE_KERNEL, &pagep); + err = map_vm_area(switcher_vma, PAGE_KERNEL_EXEC, &pagep); if (err) { printk("lguest: map_vm_area failed: %i\n", err); goto free_vma; diff --git a/drivers/lguest/page_tables.c b/drivers/lguest/page_tables.c index a059cf9980f..496995370fb 100644 --- a/drivers/lguest/page_tables.c +++ b/drivers/lguest/page_tables.c @@ -714,7 +714,7 @@ void map_switcher_in_guest(struct lg_cpu *cpu, struct lguest_pages *pages) /* Make the last PGD entry for this Guest point to the Switcher's PTE * page for this CPU (with appropriate flags). */ - switcher_pgd = __pgd(__pa(switcher_pte_page) | __PAGE_KERNEL); + switcher_pgd = __pgd(__pa(switcher_pte_page) | __PAGE_KERNEL_EXEC); cpu->lg->pgdirs[cpu->cpu_pgd].pgdir[SWITCHER_PGD_INDEX] = switcher_pgd; -- cgit v1.2.3-70-g09d2 From df60aeef4f4fe0645d9a195a7689005520422de5 Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Fri, 12 Jun 2009 22:27:09 -0600 Subject: lguest: use eventfds for device notification Currently, when a Guest wants to perform I/O it calls LHCALL_NOTIFY with an address: the main Launcher process returns with this address, and figures out what device to run. A far nicer model is to let processes bind an eventfd to an address: if we find one, we simply signal the eventfd. Signed-off-by: Rusty Russell Cc: Davide Libenzi --- drivers/lguest/Kconfig | 2 +- drivers/lguest/core.c | 8 ++-- drivers/lguest/lg.h | 13 ++++++ drivers/lguest/lguest_user.c | 98 ++++++++++++++++++++++++++++++++++++++++- include/linux/lguest_launcher.h | 1 + 5 files changed, 116 insertions(+), 6 deletions(-) (limited to 'drivers/lguest/core.c') diff --git a/drivers/lguest/Kconfig b/drivers/lguest/Kconfig index 8f63845db83..0aaa0597a62 100644 --- a/drivers/lguest/Kconfig +++ b/drivers/lguest/Kconfig @@ -1,6 +1,6 @@ config LGUEST tristate "Linux hypervisor example code" - depends on X86_32 && EXPERIMENTAL && FUTEX + depends on X86_32 && EXPERIMENTAL && EVENTFD select HVC_DRIVER ---help--- This is a very simple module which allows you to run diff --git a/drivers/lguest/core.c b/drivers/lguest/core.c index d0298dc45d9..508569c9571 100644 --- a/drivers/lguest/core.c +++ b/drivers/lguest/core.c @@ -198,9 +198,11 @@ int run_guest(struct lg_cpu *cpu, unsigned long __user *user) /* It's possible the Guest did a NOTIFY hypercall to the * Launcher, in which case we return from the read() now. */ if (cpu->pending_notify) { - if (put_user(cpu->pending_notify, user)) - return -EFAULT; - return sizeof(cpu->pending_notify); + if (!send_notify_to_eventfd(cpu)) { + if (put_user(cpu->pending_notify, user)) + return -EFAULT; + return sizeof(cpu->pending_notify); + } } /* Check for signals */ diff --git a/drivers/lguest/lg.h b/drivers/lguest/lg.h index 040cb70780e..32fefdc6ad3 100644 --- a/drivers/lguest/lg.h +++ b/drivers/lguest/lg.h @@ -82,6 +82,16 @@ struct lg_cpu { struct lg_cpu_arch arch; }; +struct lg_eventfd { + unsigned long addr; + struct file *event; +}; + +struct lg_eventfd_map { + unsigned int num; + struct lg_eventfd map[]; +}; + /* The private info the thread maintains about the guest. */ struct lguest { @@ -102,6 +112,8 @@ struct lguest unsigned int stack_pages; u32 tsc_khz; + struct lg_eventfd_map *eventfds; + /* Dead? */ const char *dead; }; @@ -154,6 +166,7 @@ void setup_default_idt_entries(struct lguest_ro_state *state, void copy_traps(const struct lg_cpu *cpu, struct desc_struct *idt, const unsigned long *def); void guest_set_clockevent(struct lg_cpu *cpu, unsigned long delta); +bool send_notify_to_eventfd(struct lg_cpu *cpu); void init_clockdev(struct lg_cpu *cpu); bool check_syscall_vector(struct lguest *lg); int init_interrupts(void); diff --git a/drivers/lguest/lguest_user.c b/drivers/lguest/lguest_user.c index 1982b45bd93..f6bf255f183 100644 --- a/drivers/lguest/lguest_user.c +++ b/drivers/lguest/lguest_user.c @@ -7,6 +7,8 @@ #include #include #include +#include +#include #include "lg.h" /*L:055 When something happens, the Waker process needs a way to stop the @@ -35,6 +37,81 @@ static int break_guest_out(struct lg_cpu *cpu, const unsigned long __user*input) } } +bool send_notify_to_eventfd(struct lg_cpu *cpu) +{ + unsigned int i; + struct lg_eventfd_map *map; + + /* lg->eventfds is RCU-protected */ + rcu_read_lock(); + map = rcu_dereference(cpu->lg->eventfds); + for (i = 0; i < map->num; i++) { + if (map->map[i].addr == cpu->pending_notify) { + eventfd_signal(map->map[i].event, 1); + cpu->pending_notify = 0; + break; + } + } + rcu_read_unlock(); + return cpu->pending_notify == 0; +} + +static int add_eventfd(struct lguest *lg, unsigned long addr, int fd) +{ + struct lg_eventfd_map *new, *old = lg->eventfds; + + if (!addr) + return -EINVAL; + + /* Replace the old array with the new one, carefully: others can + * be accessing it at the same time */ + new = kmalloc(sizeof(*new) + sizeof(new->map[0]) * (old->num + 1), + GFP_KERNEL); + if (!new) + return -ENOMEM; + + /* First make identical copy. */ + memcpy(new->map, old->map, sizeof(old->map[0]) * old->num); + new->num = old->num; + + /* Now append new entry. */ + new->map[new->num].addr = addr; + new->map[new->num].event = eventfd_fget(fd); + if (IS_ERR(new->map[new->num].event)) { + kfree(new); + return PTR_ERR(new->map[new->num].event); + } + new->num++; + + /* Now put new one in place. */ + rcu_assign_pointer(lg->eventfds, new); + + /* We're not in a big hurry. Wait until noone's looking at old + * version, then delete it. */ + synchronize_rcu(); + kfree(old); + + return 0; +} + +static int attach_eventfd(struct lguest *lg, const unsigned long __user *input) +{ + unsigned long addr, fd; + int err; + + if (get_user(addr, input) != 0) + return -EFAULT; + input++; + if (get_user(fd, input) != 0) + return -EFAULT; + + mutex_lock(&lguest_lock); + err = add_eventfd(lg, addr, fd); + mutex_unlock(&lguest_lock); + + return 0; +} + /*L:050 Sending an interrupt is done by writing LHREQ_IRQ and an interrupt * number to /dev/lguest. */ static int user_send_irq(struct lg_cpu *cpu, const unsigned long __user *input) @@ -184,6 +261,13 @@ static int initialize(struct file *file, const unsigned long __user *input) goto unlock; } + lg->eventfds = kmalloc(sizeof(*lg->eventfds), GFP_KERNEL); + if (!lg->eventfds) { + err = -ENOMEM; + goto free_lg; + } + lg->eventfds->num = 0; + /* Populate the easy fields of our "struct lguest" */ lg->mem_base = (void __user *)args[0]; lg->pfn_limit = args[1]; @@ -191,7 +275,7 @@ static int initialize(struct file *file, const unsigned long __user *input) /* This is the first cpu (cpu 0) and it will start booting at args[2] */ err = lg_cpu_start(&lg->cpus[0], 0, args[2]); if (err) - goto release_guest; + goto free_eventfds; /* Initialize the Guest's shadow page tables, using the toplevel * address the Launcher gave us. This allocates memory, so can fail. */ @@ -210,7 +294,9 @@ static int initialize(struct file *file, const unsigned long __user *input) free_regs: /* FIXME: This should be in free_vcpu */ free_page(lg->cpus[0].regs_page); -release_guest: +free_eventfds: + kfree(lg->eventfds); +free_lg: kfree(lg); unlock: mutex_unlock(&lguest_lock); @@ -260,6 +346,8 @@ static ssize_t write(struct file *file, const char __user *in, return user_send_irq(cpu, input); case LHREQ_BREAK: return break_guest_out(cpu, input); + case LHREQ_EVENTFD: + return attach_eventfd(lg, input); default: return -EINVAL; } @@ -297,6 +385,12 @@ static int close(struct inode *inode, struct file *file) * the Launcher's memory management structure. */ mmput(lg->cpus[i].mm); } + + /* Release any eventfds they registered. */ + for (i = 0; i < lg->eventfds->num; i++) + fput(lg->eventfds->map[i].event); + kfree(lg->eventfds); + /* If lg->dead doesn't contain an error code it will be NULL or a * kmalloc()ed string, either of which is ok to hand to kfree(). */ if (!IS_ERR(lg->dead)) diff --git a/include/linux/lguest_launcher.h b/include/linux/lguest_launcher.h index a53407a4165..9de964b9058 100644 --- a/include/linux/lguest_launcher.h +++ b/include/linux/lguest_launcher.h @@ -58,6 +58,7 @@ enum lguest_req LHREQ_GETDMA, /* No longer used */ LHREQ_IRQ, /* + irq */ LHREQ_BREAK, /* + on/off flag (on blocks until someone does off) */ + LHREQ_EVENTFD, /* + address, fd. */ }; /* The alignment to use between consumer and producer parts of vring. -- cgit v1.2.3-70-g09d2 From 5dac051bc6030963181b69faddd9e0ad04f85fa8 Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Fri, 12 Jun 2009 22:27:10 -0600 Subject: lguest: remove obsolete LHREQ_BREAK call We no longer need an efficient mechanism to force the Guest back into host userspace, as each device is serviced without bothering the main Guest process (aka. the Launcher). Signed-off-by: Rusty Russell --- drivers/lguest/core.c | 11 +++-------- drivers/lguest/lg.h | 4 +--- drivers/lguest/lguest_user.c | 31 ------------------------------- include/linux/lguest_launcher.h | 2 +- 4 files changed, 5 insertions(+), 43 deletions(-) (limited to 'drivers/lguest/core.c') diff --git a/drivers/lguest/core.c b/drivers/lguest/core.c index 508569c9571..a6974e9b8eb 100644 --- a/drivers/lguest/core.c +++ b/drivers/lguest/core.c @@ -209,10 +209,6 @@ int run_guest(struct lg_cpu *cpu, unsigned long __user *user) if (signal_pending(current)) return -ERESTARTSYS; - /* If Waker set break_out, return to Launcher. */ - if (cpu->break_out) - return -EAGAIN; - /* Check if there are any interrupts which can be delivered now: * if so, this sets up the hander to be executed when we next * run the Guest. */ @@ -231,13 +227,12 @@ int run_guest(struct lg_cpu *cpu, unsigned long __user *user) break; /* If the Guest asked to be stopped, we sleep. The Guest's - * clock timer or LHREQ_BREAK from the Waker will wake us. */ + * clock timer will wake us. */ if (cpu->halted) { set_current_state(TASK_INTERRUPTIBLE); - /* Just before we sleep, make sure nothing snuck in + /* Just before we sleep, make sure no interrupt snuck in * which we should be doing. */ - if (interrupt_pending(cpu, &more) < LGUEST_IRQS - || cpu->break_out) + if (interrupt_pending(cpu, &more) < LGUEST_IRQS) set_current_state(TASK_RUNNING); else schedule(); diff --git a/drivers/lguest/lg.h b/drivers/lguest/lg.h index 32fefdc6ad3..d4e8979735c 100644 --- a/drivers/lguest/lg.h +++ b/drivers/lguest/lg.h @@ -71,9 +71,7 @@ struct lg_cpu { /* Virtual clock device */ struct hrtimer hrt; - /* Do we need to stop what we're doing and return to userspace? */ - int break_out; - wait_queue_head_t break_wq; + /* Did the Guest tell us to halt? */ int halted; /* Pending virtual interrupts */ diff --git a/drivers/lguest/lguest_user.c b/drivers/lguest/lguest_user.c index f6bf255f183..32e29712105 100644 --- a/drivers/lguest/lguest_user.c +++ b/drivers/lguest/lguest_user.c @@ -11,32 +11,6 @@ #include #include "lg.h" -/*L:055 When something happens, the Waker process needs a way to stop the - * kernel running the Guest and return to the Launcher. So the Waker writes - * LHREQ_BREAK and the value "1" to /dev/lguest to do this. Once the Launcher - * has done whatever needs attention, it writes LHREQ_BREAK and "0" to release - * the Waker. */ -static int break_guest_out(struct lg_cpu *cpu, const unsigned long __user*input) -{ - unsigned long on; - - /* Fetch whether they're turning break on or off. */ - if (get_user(on, input) != 0) - return -EFAULT; - - if (on) { - cpu->break_out = 1; - if (!wake_up_process(cpu->tsk)) - kick_process(cpu->tsk); - /* Wait for them to reset it */ - return wait_event_interruptible(cpu->break_wq, !cpu->break_out); - } else { - cpu->break_out = 0; - wake_up(&cpu->break_wq); - return 0; - } -} - bool send_notify_to_eventfd(struct lg_cpu *cpu) { unsigned int i; @@ -202,9 +176,6 @@ static int lg_cpu_start(struct lg_cpu *cpu, unsigned id, unsigned long start_ip) * address. */ lguest_arch_setup_regs(cpu, start_ip); - /* Initialize the queue for the Waker to wait on */ - init_waitqueue_head(&cpu->break_wq); - /* We keep a pointer to the Launcher task (ie. current task) for when * other Guests want to wake this one (eg. console input). */ cpu->tsk = current; @@ -344,8 +315,6 @@ static ssize_t write(struct file *file, const char __user *in, return initialize(file, input); case LHREQ_IRQ: return user_send_irq(cpu, input); - case LHREQ_BREAK: - return break_guest_out(cpu, input); case LHREQ_EVENTFD: return attach_eventfd(lg, input); default: diff --git a/include/linux/lguest_launcher.h b/include/linux/lguest_launcher.h index 9de964b9058..bfefbdf7498 100644 --- a/include/linux/lguest_launcher.h +++ b/include/linux/lguest_launcher.h @@ -57,7 +57,7 @@ enum lguest_req LHREQ_INITIALIZE, /* + base, pfnlimit, start */ LHREQ_GETDMA, /* No longer used */ LHREQ_IRQ, /* + irq */ - LHREQ_BREAK, /* + on/off flag (on blocks until someone does off) */ + LHREQ_BREAK, /* No longer used */ LHREQ_EVENTFD, /* + address, fd. */ }; -- cgit v1.2.3-70-g09d2