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authorAvi Kivity <avi@qumranet.com>2008-05-13 09:22:47 -0400
committerAvi Kivity <avi@qumranet.com>2008-07-20 05:42:24 -0400
commit543e42436643d68ad007d0bae2f485caac9c8a02 (patch)
tree0347cb99587feedb4dfd4520bde416a0bf8ceca9
parent4ecac3fd6dc2629ad76a658a486f081c44aef10e (diff)
KVM: VMX: Add list of potentially locally cached vcpus
VMX hardware can cache the contents of a vcpu's vmcs. This cache needs to be flushed when migrating a vcpu to another cpu, or (which is the case that interests us here) when disabling hardware virtualization on a cpu. The current implementation of decaching iterates over the list of all vcpus, picks the ones that are potentially cached on the cpu that is being offlined, and flushes the cache. The problem is that it uses mutex_trylock() to gain exclusive access to the vcpu, which fires off a (benign) warning about using the mutex in an interrupt context. To avoid this, and to make things generally nicer, add a new per-cpu list of potentially cached vcus. This makes the decaching code much simpler. The list is vmx-specific since other hardware doesn't have this issue. [andrea: fix crash on suspend/resume] Signed-off-by: Andrea Arcangeli <andrea@qumranet.com> Signed-off-by: Avi Kivity <avi@qumranet.com>
-rw-r--r--arch/x86/kvm/vmx.c24
-rw-r--r--arch/x86/kvm/x86.c27
2 files changed, 22 insertions, 29 deletions
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index b80b4d141637..4d179d106376 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -55,6 +55,7 @@ struct vmcs {
55 55
56struct vcpu_vmx { 56struct vcpu_vmx {
57 struct kvm_vcpu vcpu; 57 struct kvm_vcpu vcpu;
58 struct list_head local_vcpus_link;
58 int launched; 59 int launched;
59 u8 fail; 60 u8 fail;
60 u32 idt_vectoring_info; 61 u32 idt_vectoring_info;
@@ -93,6 +94,7 @@ static int init_rmode(struct kvm *kvm);
93 94
94static DEFINE_PER_CPU(struct vmcs *, vmxarea); 95static DEFINE_PER_CPU(struct vmcs *, vmxarea);
95static DEFINE_PER_CPU(struct vmcs *, current_vmcs); 96static DEFINE_PER_CPU(struct vmcs *, current_vmcs);
97static DEFINE_PER_CPU(struct list_head, vcpus_on_cpu);
96 98
97static struct page *vmx_io_bitmap_a; 99static struct page *vmx_io_bitmap_a;
98static struct page *vmx_io_bitmap_b; 100static struct page *vmx_io_bitmap_b;
@@ -331,6 +333,9 @@ static void __vcpu_clear(void *arg)
331 if (per_cpu(current_vmcs, cpu) == vmx->vmcs) 333 if (per_cpu(current_vmcs, cpu) == vmx->vmcs)
332 per_cpu(current_vmcs, cpu) = NULL; 334 per_cpu(current_vmcs, cpu) = NULL;
333 rdtscll(vmx->vcpu.arch.host_tsc); 335 rdtscll(vmx->vcpu.arch.host_tsc);
336 list_del(&vmx->local_vcpus_link);
337 vmx->vcpu.cpu = -1;
338 vmx->launched = 0;
334} 339}
335 340
336static void vcpu_clear(struct vcpu_vmx *vmx) 341static void vcpu_clear(struct vcpu_vmx *vmx)
@@ -338,7 +343,6 @@ static void vcpu_clear(struct vcpu_vmx *vmx)
338 if (vmx->vcpu.cpu == -1) 343 if (vmx->vcpu.cpu == -1)
339 return; 344 return;
340 smp_call_function_single(vmx->vcpu.cpu, __vcpu_clear, vmx, 1); 345 smp_call_function_single(vmx->vcpu.cpu, __vcpu_clear, vmx, 1);
341 vmx->launched = 0;
342} 346}
343 347
344static inline void vpid_sync_vcpu_all(struct vcpu_vmx *vmx) 348static inline void vpid_sync_vcpu_all(struct vcpu_vmx *vmx)
@@ -617,6 +621,10 @@ static void vmx_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
617 vcpu_clear(vmx); 621 vcpu_clear(vmx);
618 kvm_migrate_timers(vcpu); 622 kvm_migrate_timers(vcpu);
619 vpid_sync_vcpu_all(vmx); 623 vpid_sync_vcpu_all(vmx);
624 local_irq_disable();
625 list_add(&vmx->local_vcpus_link,
626 &per_cpu(vcpus_on_cpu, cpu));
627 local_irq_enable();
620 } 628 }
621 629
622 if (per_cpu(current_vmcs, cpu) != vmx->vmcs) { 630 if (per_cpu(current_vmcs, cpu) != vmx->vmcs) {
@@ -1022,6 +1030,7 @@ static void hardware_enable(void *garbage)
1022 u64 phys_addr = __pa(per_cpu(vmxarea, cpu)); 1030 u64 phys_addr = __pa(per_cpu(vmxarea, cpu));
1023 u64 old; 1031 u64 old;
1024 1032
1033 INIT_LIST_HEAD(&per_cpu(vcpus_on_cpu, cpu));
1025 rdmsrl(MSR_IA32_FEATURE_CONTROL, old); 1034 rdmsrl(MSR_IA32_FEATURE_CONTROL, old);
1026 if ((old & (MSR_IA32_FEATURE_CONTROL_LOCKED | 1035 if ((old & (MSR_IA32_FEATURE_CONTROL_LOCKED |
1027 MSR_IA32_FEATURE_CONTROL_VMXON_ENABLED)) 1036 MSR_IA32_FEATURE_CONTROL_VMXON_ENABLED))
@@ -1037,8 +1046,19 @@ static void hardware_enable(void *garbage)
1037 : "memory", "cc"); 1046 : "memory", "cc");
1038} 1047}
1039 1048
1049static void vmclear_local_vcpus(void)
1050{
1051 int cpu = raw_smp_processor_id();
1052 struct vcpu_vmx *vmx, *n;
1053
1054 list_for_each_entry_safe(vmx, n, &per_cpu(vcpus_on_cpu, cpu),
1055 local_vcpus_link)
1056 __vcpu_clear(vmx);
1057}
1058
1040static void hardware_disable(void *garbage) 1059static void hardware_disable(void *garbage)
1041{ 1060{
1061 vmclear_local_vcpus();
1042 asm volatile (__ex(ASM_VMX_VMXOFF) : : : "cc"); 1062 asm volatile (__ex(ASM_VMX_VMXOFF) : : : "cc");
1043 write_cr4(read_cr4() & ~X86_CR4_VMXE); 1063 write_cr4(read_cr4() & ~X86_CR4_VMXE);
1044} 1064}
@@ -2967,7 +2987,7 @@ static void vmx_free_vmcs(struct kvm_vcpu *vcpu)
2967 struct vcpu_vmx *vmx = to_vmx(vcpu); 2987 struct vcpu_vmx *vmx = to_vmx(vcpu);
2968 2988
2969 if (vmx->vmcs) { 2989 if (vmx->vmcs) {
2970 on_each_cpu(__vcpu_clear, vmx, 1); 2990 vcpu_clear(vmx);
2971 free_vmcs(vmx->vmcs); 2991 free_vmcs(vmx->vmcs);
2972 vmx->vmcs = NULL; 2992 vmx->vmcs = NULL;
2973 } 2993 }
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 59084a3981c0..8c14ddcaba70 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -823,33 +823,6 @@ out:
823 */ 823 */
824void decache_vcpus_on_cpu(int cpu) 824void decache_vcpus_on_cpu(int cpu)
825{ 825{
826 struct kvm *vm;
827 struct kvm_vcpu *vcpu;
828 int i;
829
830 spin_lock(&kvm_lock);
831 list_for_each_entry(vm, &vm_list, vm_list)
832 for (i = 0; i < KVM_MAX_VCPUS; ++i) {
833 vcpu = vm->vcpus[i];
834 if (!vcpu)
835 continue;
836 /*
837 * If the vcpu is locked, then it is running on some
838 * other cpu and therefore it is not cached on the
839 * cpu in question.
840 *
841 * If it's not locked, check the last cpu it executed
842 * on.
843 */
844 if (mutex_trylock(&vcpu->mutex)) {
845 if (vcpu->cpu == cpu) {
846 kvm_x86_ops->vcpu_decache(vcpu);
847 vcpu->cpu = -1;
848 }
849 mutex_unlock(&vcpu->mutex);
850 }
851 }
852 spin_unlock(&kvm_lock);
853} 826}
854 827
855int kvm_dev_ioctl_check_extension(long ext) 828int kvm_dev_ioctl_check_extension(long ext)