On 12/22/2022 7:24 PM, Like Xu wrote:
On 25/11/2022 12:05 pm, Yang Weijiang wrote:
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index cea8c07f5229..1ae2efc29546 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2120,6 +2120,13 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu,
struct msr_data *msr_info)
VM_EXIT_SAVE_DEBUG_CONTROLS)
get_vmcs12(vcpu)->guest_ia32_debugctl = data;
+ /*
+ * For Arch LBR, IA32_DEBUGCTL[bit 0] has no meaning.
+ * It can be written to 0 or 1, but reads will always return 0.
+ */
The comment looks good, please verify it with a test.
OK, I'll add the test into pmu_lbr KUT test together with arch-lbr test
cases.
+ if (guest_cpuid_has(vcpu, X86_FEATURE_ARCH_LBR))
+ data &= ~DEBUGCTLMSR_LBR;
+
vmcs_write64(GUEST_IA32_DEBUGCTL, data);
if (intel_pmu_lbr_is_enabled(vcpu) &&
!to_vmx(vcpu)->lbr_desc.event &&
(data & DEBUGCTLMSR_LBR))
