From: Bhavana Nagendra <bnagendr@redhat.com> Date: Fri, 15 Feb 2008 13:25:23 -0500 Subject: [xen] new vcpu lock/unlock helper functions Message-id: 20080215182522.11293.96623.sendpatchset@localhost.localdomain O-Subject: [RHEL5.2 PATCH 1] Introduce new vcpu lock/unlock helper functions Bugzilla: 430938 Resolves BZ 430938 Introduce new vcpu_lock_affinity() and vcpu_unlock_affinity() helper functions for use by x86's continue_hypercall_on_cpu(). This has two advantages: 1. We can lock out ordinary vcpu_set_affinity() commands from dom0. 2. We avoid the (in this case bogus) check for dom0_vcpus_pin. Acked-by: Rik van Riel <riel@redhat.com> Acked-by: Chris Lalancette <clalance@redhat.com> diff --git a/arch/x86/domain.c b/arch/x86/domain.c index 77a6583..9ff936e 100644 --- a/arch/x86/domain.c +++ b/arch/x86/domain.c @@ -1355,6 +1355,7 @@ static void continue_hypercall_on_cpu_helper(struct vcpu *v) { struct cpu_user_regs *regs = guest_cpu_user_regs(); struct migrate_info *info = v->arch.continue_info; + cpumask_t mask = info->saved_affinity; regs->eax = info->func(info->data); @@ -1363,7 +1364,7 @@ static void continue_hypercall_on_cpu_helper(struct vcpu *v) xfree(info); - vcpu_set_affinity(v, &v->cpu_affinity); + vcpu_unlock_affinity(v, &mask); schedule_tail(v); } @@ -1371,7 +1372,6 @@ int continue_hypercall_on_cpu(int cpu, long (*func)(void *data), void *data) { struct vcpu *v = current; struct migrate_info *info; - cpumask_t mask = cpumask_of_cpu(cpu); int rc; if ( cpu == smp_processor_id() ) @@ -1384,12 +1384,12 @@ int continue_hypercall_on_cpu(int cpu, long (*func)(void *data), void *data) info->func = func; info->data = data; info->saved_schedule_tail = v->arch.schedule_tail; - info->saved_affinity = v->cpu_affinity; + info->saved_affinity = cpumask_of_cpu(cpu); v->arch.schedule_tail = continue_hypercall_on_cpu_helper; v->arch.continue_info = info; - rc = vcpu_set_affinity(v, &mask); + rc = vcpu_lock_affinity(v, &info->saved_affinity); if ( rc ) { v->arch.schedule_tail = info->saved_schedule_tail; diff --git a/common/schedule.c b/common/schedule.c index 3d80021..b27771c 100644 --- a/common/schedule.c +++ b/common/schedule.c @@ -264,12 +264,11 @@ void vcpu_force_reschedule(struct vcpu *v) } } -int vcpu_set_affinity(struct vcpu *v, cpumask_t *affinity) +static int __vcpu_set_affinity( + struct vcpu *v, cpumask_t *affinity, + bool_t old_lock_status, bool_t new_lock_status) { - cpumask_t online_affinity; - - if ( (v->domain->domain_id == 0) && opt_dom0_vcpus_pin ) - return -EINVAL; + cpumask_t online_affinity, old_affinity; cpus_and(online_affinity, *affinity, cpu_online_map); if ( cpus_empty(online_affinity) ) @@ -277,7 +276,18 @@ int vcpu_set_affinity(struct vcpu *v, cpumask_t *affinity) vcpu_schedule_lock_irq(v); + if ( v->affinity_locked != old_lock_status ) + { + BUG_ON(!v->affinity_locked); + vcpu_schedule_unlock_irq(v); + return -EBUSY; + } + + v->affinity_locked = new_lock_status; + + old_affinity = v->cpu_affinity; v->cpu_affinity = *affinity; + *affinity = old_affinity; if ( !cpu_isset(v->processor, v->cpu_affinity) ) set_bit(_VPF_migrating, &v->pause_flags); @@ -292,6 +302,31 @@ int vcpu_set_affinity(struct vcpu *v, cpumask_t *affinity) return 0; } +int vcpu_set_affinity(struct vcpu *v, cpumask_t *affinity) +{ + if ( (v->domain->domain_id == 0) && opt_dom0_vcpus_pin ) + return -EINVAL; + return __vcpu_set_affinity(v, affinity, 0, 0); +} + +int vcpu_lock_affinity(struct vcpu *v, cpumask_t *affinity) +{ + return __vcpu_set_affinity(v, affinity, 0, 1); +} + +void vcpu_unlock_affinity(struct vcpu *v, cpumask_t *affinity) +{ + cpumask_t online_affinity; + + /* Do not fail if no CPU in old affinity mask is online. */ + cpus_and(online_affinity, *affinity, cpu_online_map); + if ( cpus_empty(online_affinity) ) + *affinity = cpu_online_map; + + if ( __vcpu_set_affinity(v, affinity, 1, 0) != 0 ) + BUG(); +} + /* Block the currently-executing domain until a pertinent event occurs. */ static long do_block(void) { diff --git a/include/xen/sched.h b/include/xen/sched.h index 3d9f190..ec6afa1 100644 --- a/include/xen/sched.h +++ b/include/xen/sched.h @@ -119,6 +119,8 @@ struct vcpu bool_t defer_shutdown; /* VCPU is paused following shutdown request (d->is_shutting_down)? */ bool_t paused_for_shutdown; + /* VCPU affinity is temporarily locked from controller changes? */ + bool_t affinity_locked; unsigned long pause_flags; atomic_t pause_count; @@ -476,6 +478,8 @@ void cpu_init(void); void vcpu_force_reschedule(struct vcpu *v); int vcpu_set_affinity(struct vcpu *v, cpumask_t *affinity); +int vcpu_lock_affinity(struct vcpu *v, cpumask_t *affinity); +void vcpu_unlock_affinity(struct vcpu *v, cpumask_t *affinity); void vcpu_runstate_get(struct vcpu *v, struct vcpu_runstate_info *runstate);