From d5696725b2a4c59503f5e0bc33adeee7f30cd45b Mon Sep 17 00:00:00 2001 From: Avi Kivity Date: Wed, 2 Dec 2009 12:28:47 +0200 Subject: [PATCH] KVM: VMX: Fix comparison of guest efer with stale host value update_transition_efer() masks out some efer bits when deciding whether to switch the msr during guest entry; for example, NX is emulated using the mmu so we don't need to disable it, and LMA/LME are handled by the hardware. However, with shared msrs, the comparison is made against a stale value; at the time of the guest switch we may be running with another guest's efer. Fix by deferring the mask/compare to the actual point of guest entry. Noted by Marcelo. Signed-off-by: Avi Kivity --- arch/x86/include/asm/kvm_host.h | 2 +- arch/x86/kvm/vmx.c | 9 +++++---- arch/x86/kvm/x86.c | 4 ++-- 3 files changed, 8 insertions(+), 7 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 06e0856..4f865e8 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -812,6 +812,6 @@ int kvm_arch_interrupt_allowed(struct kvm_vcpu *vcpu); int kvm_cpu_get_interrupt(struct kvm_vcpu *v); void kvm_define_shared_msr(unsigned index, u32 msr); -void kvm_set_shared_msr(unsigned index, u64 val); +void kvm_set_shared_msr(unsigned index, u64 val, u64 mask); #endif /* _ASM_X86_KVM_HOST_H */ diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index ed97c6c..d4918d6 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -89,6 +89,7 @@ struct vmcs { struct shared_msr_entry { unsigned index; u64 data; + u64 mask; }; struct vcpu_vmx { @@ -601,12 +602,10 @@ static bool update_transition_efer(struct vcpu_vmx *vmx, int efer_offset) if (guest_efer & EFER_LMA) ignore_bits &= ~(u64)EFER_SCE; #endif - if ((guest_efer & ~ignore_bits) == (host_efer & ~ignore_bits)) - return false; - guest_efer &= ~ignore_bits; guest_efer |= host_efer & ignore_bits; vmx->guest_msrs[efer_offset].data = guest_efer; + vmx->guest_msrs[efer_offset].mask = ~ignore_bits; return true; } @@ -657,7 +656,8 @@ static void vmx_save_host_state(struct kvm_vcpu *vcpu) #endif for (i = 0; i < vmx->save_nmsrs; ++i) kvm_set_shared_msr(vmx->guest_msrs[i].index, - vmx->guest_msrs[i].data); + vmx->guest_msrs[i].data, + vmx->guest_msrs[i].mask); } static void __vmx_load_host_state(struct vcpu_vmx *vmx) @@ -2394,6 +2394,7 @@ static int vmx_vcpu_setup(struct vcpu_vmx *vmx) data = data_low | ((u64)data_high << 32); vmx->guest_msrs[j].index = i; vmx->guest_msrs[j].data = 0; + vmx->guest_msrs[j].mask = -1ull; ++vmx->nmsrs; } diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 106f9f1..ce677b2 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -185,11 +185,11 @@ static void kvm_shared_msr_cpu_online(void) locals->current_value[i] = shared_msrs_global.msrs[i].value; } -void kvm_set_shared_msr(unsigned slot, u64 value) +void kvm_set_shared_msr(unsigned slot, u64 value, u64 mask) { struct kvm_shared_msrs *smsr = &__get_cpu_var(shared_msrs); - if (value == smsr->current_value[slot]) + if (((value ^ smsr->current_value[slot]) & mask) == 0) return; smsr->current_value[slot] = value; wrmsrl(shared_msrs_global.msrs[slot].msr, value); -- 2.7.4