Arch LBRs are enabled by setting MSR_ARCH_LBR_CTL.LBREn to 1. On
processors that support Arch LBR, MSR_IA32_DEBUGCTLMSR[bit 0] has
no meaning. It can be written to 0 or 1, but reads will always return 0.
A new guest state field named "Guest IA32_LBR_CTL" has been added to
enhance guest LBR usage and the guest value of MSR_ARCH_LBR_CTL is
written to this field on all VM exits.
Signed-off-by: Like Xu <like.xu@xxxxxxxxxxxxxxx>
---
arch/x86/include/asm/vmx.h | 2 ++
arch/x86/kvm/vmx/pmu_intel.c | 13 +++++++++++++
arch/x86/kvm/vmx/vmx.c | 8 ++++++++
3 files changed, 23 insertions(+)
diff --git a/arch/x86/include/asm/vmx.h b/arch/x86/include/asm/vmx.h
index cd7de4b401fe..27f53c81a17f 100644
--- a/arch/x86/include/asm/vmx.h
+++ b/arch/x86/include/asm/vmx.h
@@ -243,6 +243,8 @@ enum vmcs_field {
GUEST_BNDCFGS_HIGH = 0x00002813,
GUEST_IA32_RTIT_CTL = 0x00002814,
GUEST_IA32_RTIT_CTL_HIGH = 0x00002815,
+ GUEST_IA32_LBR_CTL = 0x00002816,
+ GUEST_IA32_LBR_CTL_HIGH = 0x00002817,
HOST_IA32_PAT = 0x00002c00,
HOST_IA32_PAT_HIGH = 0x00002c01,
HOST_IA32_EFER = 0x00002c02,
diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c
index 8021fbdbd618..289c267732bd 100644
--- a/arch/x86/kvm/vmx/pmu_intel.c
+++ b/arch/x86/kvm/vmx/pmu_intel.c
@@ -19,6 +19,7 @@
#include "pmu.h"
#define MSR_PMC_FULL_WIDTH_BIT (MSR_IA32_PMC0 - MSR_IA32_PERFCTR0)
+#define MSR_ARCH_LBR_CTL_MASK 0x7f000f
static struct kvm_event_hw_type_mapping intel_arch_events[] = {
/* Index must match CPUID 0x0A.EBX bit vector */
@@ -232,6 +233,7 @@ static bool intel_is_valid_msr(struct kvm_vcpu *vcpu, u32 msr)
ret = pmu->version > 1;
break;
case MSR_ARCH_LBR_DEPTH:
+ case MSR_ARCH_LBR_CTL:
ret = guest_cpuid_has(vcpu, X86_FEATURE_ARCH_LBR);
break;
default:
@@ -398,6 +400,9 @@ static int intel_pmu_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
case MSR_ARCH_LBR_DEPTH:
msr_info->data = lbr_desc->records.nr;
return 0;
+ case MSR_ARCH_LBR_CTL:
+ msr_info->data = vmcs_read64(GUEST_IA32_LBR_CTL);
+ return 0;
default:
if ((pmc = get_gp_pmc(pmu, msr, MSR_IA32_PERFCTR0)) ||
(pmc = get_gp_pmc(pmu, msr, MSR_IA32_PMC0))) {
@@ -466,6 +471,14 @@ static int intel_pmu_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
lbr_desc->arch_lbr_reset = true;
__set_bit(INTEL_GUEST_LBR_INUSE, pmu->pmc_in_use);
return 0;
+ case MSR_ARCH_LBR_CTL:
+ if (data & ~MSR_ARCH_LBR_CTL_MASK)
+ return 1;
+ vmcs_write64(GUEST_IA32_LBR_CTL, data);
+ if (intel_pmu_lbr_is_enabled(vcpu) && !lbr_desc->event &&
+ (data & DEBUGCTLMSR_LBR))
+ intel_pmu_create_guest_lbr_event(vcpu);
+ return 0;
default:
if ((pmc = get_gp_pmc(pmu, msr, MSR_IA32_PERFCTR0)) ||
(pmc = get_gp_pmc(pmu, msr, MSR_IA32_PMC0))) {
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 6d8b1d98ae1d..9f42553b1e11 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -2054,6 +2054,14 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
__func__, data);
data &= ~DEBUGCTLMSR_BTF;
}
+
+ /*
+ * For Arch LBR, IA32_DEBUGCTL[bit 0] has no meaning.
+ * It can be written to 0 or 1, but reads will always return 0.
+ */
+ 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))
--
2.21.3
