In case an invalid or disabled gpa is written to the SYSTEM_TIME
MSR, do not retain its value. This is not documented behaviour,
nor should be supported.
Also clear it on system reset. Not doing so can hide bugs.
Signed-off-by: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index e00050c..ed4bfb7 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1528,6 +1528,7 @@ static int kvm_pv_enable_async_pf(struct kvm_vcpu *vcpu, u64 data)
static void kvmclock_reset(struct kvm_vcpu *vcpu)
{
+ vcpu->arch.time = 0;
if (vcpu->arch.time_page) {
kvm_release_page_dirty(vcpu->arch.time_page);
vcpu->arch.time_page = NULL;
@@ -1632,8 +1633,10 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data)
kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu);
/* we verify if the enable bit is set... */
- if (!(data & 1))
+ if (!(data & 1)) {
+ vcpu->arch.time = 0;
break;
+ }
/* ...but clean it before doing the actual write */
vcpu->arch.time_offset = data & ~(PAGE_MASK | 1);
@@ -1641,8 +1644,10 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data)
vcpu->arch.time_page =
gfn_to_page(vcpu->kvm, data >> PAGE_SHIFT);
- if (is_error_page(vcpu->arch.time_page))
+ if (is_error_page(vcpu->arch.time_page)) {
vcpu->arch.time_page = NULL;
+ vcpu->arch.time = 0;
+ }
break;
}
--
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