The IA32_PERF_GLOBAL_STATUS_SET MSR is introduced with arch PMU
version 4. It allows software to set individual bits in
IA32_PERF_GLOBAL_STATUS MSR. It can be used by a VMM to virtualize the
state of IA32_PERF_GLOBAL_STATUS across VMS.
If the running VM owns the whole PMU, different VM will have different
perf global status, VMM needs to restore IA32_PERF_GLOBAL_STATUS MSR at
VM switch, but IA32_PERF_GLOBAL_STATUS MSR is read only, so VMM can use
IA32_PERF_GLOBAL_STATUS_SET MSR to restore VM's PERF_GLOBAL_STATUS MSR.
This commit adds this MSR emulation, so that L1 VMM could use it. As it
is mainly used by VMM to restore VM's PERF_GLOBAL_STATUS MSR during VM
switch, it doesn't need to inject PMI or FREEZE_LBR when VMM write it.
Signed-off-by: Xiong Zhang <xiong.y.zhang@xxxxxxxxx>
---
arch/x86/include/asm/msr-index.h | 1 +
arch/x86/kvm/vmx/pmu_intel.c | 16 ++++++++++++++++
2 files changed, 17 insertions(+)
diff --git a/arch/x86/include/asm/msr-index.h b/arch/x86/include/asm/msr-index.h
index 4fce37ae5a90..7c8cf6b53a76 100644
--- a/arch/x86/include/asm/msr-index.h
+++ b/arch/x86/include/asm/msr-index.h
@@ -1035,6 +1035,7 @@
#define MSR_CORE_PERF_GLOBAL_STATUS 0x0000038e
#define MSR_CORE_PERF_GLOBAL_CTRL 0x0000038f
#define MSR_CORE_PERF_GLOBAL_OVF_CTRL 0x00000390
+#define MSR_CORE_PERF_GLOBAL_STATUS_SET 0x00000391
#define MSR_PERF_METRICS 0x00000329
diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c
index ba7695a64ff1..b25df421cd75 100644
--- a/arch/x86/kvm/vmx/pmu_intel.c
+++ b/arch/x86/kvm/vmx/pmu_intel.c
@@ -206,6 +206,8 @@ static bool intel_is_valid_msr(struct kvm_vcpu *vcpu, u32 msr)
switch (msr) {
case MSR_CORE_PERF_FIXED_CTR_CTRL:
return kvm_pmu_has_perf_global_ctrl(pmu);
+ case MSR_CORE_PERF_GLOBAL_STATUS_SET:
+ return vcpu_to_pmu(vcpu)->version >= 4;
case MSR_IA32_PEBS_ENABLE:
ret = vcpu_get_perf_capabilities(vcpu) & PERF_CAP_PEBS_FORMAT;
break;
@@ -355,6 +357,9 @@ static int intel_pmu_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
case MSR_CORE_PERF_FIXED_CTR_CTRL:
msr_info->data = pmu->fixed_ctr_ctrl;
break;
+ case MSR_CORE_PERF_GLOBAL_STATUS_SET:
+ msr_info->data = 0;
+ break;
case MSR_IA32_PEBS_ENABLE:
msr_info->data = pmu->pebs_enable;
break;
@@ -449,6 +454,17 @@ static int intel_pmu_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
if (!msr_info->host_initiated)
pmu->global_status &= ~data;
break;
+ case MSR_CORE_PERF_GLOBAL_STATUS_SET:
+ /*
+ * GLOBAL STATUS_SET, sets bits in GLOBAL_STATUS, so the
+ * set of reserved bits are the same.
+ */
+ if (data & pmu->global_status_mask)
+ return 1;
+
+ if (!msr_info->host_initiated)
+ pmu->global_status |= data;
+ break;
default:
if ((pmc = get_gp_pmc(pmu, msr, MSR_IA32_PERFCTR0)) ||
(pmc = get_gp_pmc(pmu, msr, MSR_IA32_PMC0))) {
--
2.34.1
