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authorAvi Kivity <avi@qumranet.com>2008-06-24 11:48:49 +0300
committerAvi Kivity <avi@qumranet.com>2008-06-24 12:26:17 +0300
commita9b21b622958afc3f3bc5a23d266dd9ed1171fd3 (patch)
treedaed282b0f588f31cb3997a16f2ad067b37fb74d
parent4fa6b9c5dc4134bdeac341d731a87783cc11ca10 (diff)
KVM: VMX: Fix host msr corruption with preemption enabled
Switching msrs can occur either synchronously as a result of calls to the msr management functions (usually in response to the guest touching virtualized msrs), or asynchronously when preempting a kvm thread that has guest state loaded. If we're unlucky enough to have the two at the same time, host msrs are corrupted and the machine goes kaput on the next syscall. Most easily triggered by Windows Server 2008, as it does a lot of msr switching during bootup. Signed-off-by: Avi Kivity <avi@qumranet.com>
-rw-r--r--arch/x86/kvm/vmx.c19
1 files changed, 11 insertions, 8 deletions
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 02efbe75f317..540e95179074 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -566,7 +566,7 @@ static void vmx_save_host_state(struct kvm_vcpu *vcpu)
load_transition_efer(vmx);
}
-static void vmx_load_host_state(struct vcpu_vmx *vmx)
+static void __vmx_load_host_state(struct vcpu_vmx *vmx)
{
unsigned long flags;
@@ -596,6 +596,13 @@ static void vmx_load_host_state(struct vcpu_vmx *vmx)
reload_host_efer(vmx);
}
+static void vmx_load_host_state(struct vcpu_vmx *vmx)
+{
+ preempt_disable();
+ __vmx_load_host_state(vmx);
+ preempt_enable();
+}
+
/*
* Switches to specified vcpu, until a matching vcpu_put(), but assumes
* vcpu mutex is already taken.
@@ -654,7 +661,7 @@ static void vmx_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
static void vmx_vcpu_put(struct kvm_vcpu *vcpu)
{
- vmx_load_host_state(to_vmx(vcpu));
+ __vmx_load_host_state(to_vmx(vcpu));
}
static void vmx_fpu_activate(struct kvm_vcpu *vcpu)
@@ -884,11 +891,8 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data)
switch (msr_index) {
#ifdef CONFIG_X86_64
case MSR_EFER:
+ vmx_load_host_state(vmx);
ret = kvm_set_msr_common(vcpu, msr_index, data);
- if (vmx->host_state.loaded) {
- reload_host_efer(vmx);
- load_transition_efer(vmx);
- }
break;
case MSR_FS_BASE:
vmcs_writel(GUEST_FS_BASE, data);
@@ -910,11 +914,10 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, u32 msr_index, u64 data)
guest_write_tsc(data);
break;
default:
+ vmx_load_host_state(vmx);
msr = find_msr_entry(vmx, msr_index);
if (msr) {
msr->data = data;
- if (vmx->host_state.loaded)
- load_msrs(vmx->guest_msrs, vmx->save_nmsrs);
break;
}
ret = kvm_set_msr_common(vcpu, msr_index, data);

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