Win10 attempts to save these registers during KiSaveDebugRegisterState
if LBR or BTF bits are set in MSR_IA32_DEBUGCTLMSR. It uses DR7 GE and LE
flags for per-thread switching of these these features so zero value that
is returned for MSR_IA32_DEBUGCTLMSR has no effect.
These registers are used for debugging and shouldn't cause #GP and
guest crash so just return zeroes just like we do for common x86 LBR
MSRs (DEBUGCTLMSR, LAST[BRANCH|INT][TO|FROM]IP).
Signed-off-by: Anton Kuchin <antonkuc...@yandex-team.ru>
---
arch/x86/kvm/vmx/vmx.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index f6915f10e584..8bc56cf027ed 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -1769,6 +1769,13 @@ static int vmx_get_msr(struct kvm_vcpu *vcpu, struct
msr_data *msr_info)
else
msr_info->data = vmx->pt_desc.guest.addr_a[index / 2];
break;
+ case MSR_LBR_TOS:
+ case MSR_LBR_NHM_FROM ... MSR_LBR_NHM_FROM + 31:
+ case MSR_LBR_NHM_TO ... MSR_LBR_NHM_TO + 31:
+ case MSR_LBR_CORE_FROM ... MSR_LBR_CORE_FROM + 7:
+ case MSR_LBR_CORE_TO ... MSR_LBR_CORE_TO + 7:
+ msr_info->data = 0;
+ break;
case MSR_TSC_AUX:
if (!msr_info->host_initiated &&
!guest_cpuid_has(vcpu, X86_FEATURE_RDTSCP))
--
2.19.1
