[PATCH v3 2/3] KVM: x86/pmu: Limit the maximum number of supported Intel GP counters

From: Like Xu
Date: Mon Sep 19 2022 - 05:10:45 EST


From: Like Xu <likexu@xxxxxxxxxxx>

The Intel Architectural IA32_PMCx MSRs addresses range allows for
a maximum of 8 GP counters. A local macro (named KVM_INTEL_PMC_MAX_GENERIC)
is introduced to take back control of this virtual capability to avoid
errors introduced by the out-of-bound counter emulations.

Suggested-by: Jim Mattson <jmattson@xxxxxxxxxx>
Signed-off-by: Like Xu <likexu@xxxxxxxxxxx>
Reviewed-by: Jim Mattson <jmattson@xxxxxxxxxx>
---
arch/x86/include/asm/kvm_host.h | 6 +++++-
arch/x86/kvm/pmu.c | 2 +-
arch/x86/kvm/vmx/pmu_intel.c | 4 ++--
arch/x86/kvm/x86.c | 12 +++++++-----
4 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 2c96c43c313a..17abcf5c496a 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -501,6 +501,10 @@ struct kvm_pmc {
bool intr;
};

+/* More counters may conflict with other existing Architectural MSRs */
+#define KVM_INTEL_PMC_MAX_GENERIC 8
+#define MSR_ARCH_PERFMON_PERFCTR_MAX (MSR_ARCH_PERFMON_PERFCTR0 + KVM_INTEL_PMC_MAX_GENERIC - 1)
+#define MSR_ARCH_PERFMON_EVENTSEL_MAX (MSR_ARCH_PERFMON_EVENTSEL0 + KVM_INTEL_PMC_MAX_GENERIC - 1)
#define KVM_PMC_MAX_FIXED 3
struct kvm_pmu {
unsigned nr_arch_gp_counters;
@@ -516,7 +520,7 @@ struct kvm_pmu {
u64 reserved_bits;
u64 raw_event_mask;
u8 version;
- struct kvm_pmc gp_counters[INTEL_PMC_MAX_GENERIC];
+ struct kvm_pmc gp_counters[KVM_INTEL_PMC_MAX_GENERIC];
struct kvm_pmc fixed_counters[KVM_PMC_MAX_FIXED];
struct irq_work irq_work;
DECLARE_BITMAP(reprogram_pmi, X86_PMC_IDX_MAX);
diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
index 02f9e4f245bd..15625b858800 100644
--- a/arch/x86/kvm/pmu.c
+++ b/arch/x86/kvm/pmu.c
@@ -56,7 +56,7 @@ static const struct x86_cpu_id vmx_icl_pebs_cpu[] = {
* code. Each pmc, stored in kvm_pmc.idx field, is unique across
* all perf counters (both gp and fixed). The mapping relationship
* between pmc and perf counters is as the following:
- * * Intel: [0 .. INTEL_PMC_MAX_GENERIC-1] <=> gp counters
+ * * Intel: [0 .. KVM_INTEL_PMC_MAX_GENERIC-1] <=> gp counters
* [INTEL_PMC_IDX_FIXED .. INTEL_PMC_IDX_FIXED + 2] <=> fixed
* * AMD: [0 .. AMD64_NUM_COUNTERS-1] and, for families 15H
* and later, [0 .. AMD64_NUM_COUNTERS_CORE-1] <=> gp counters
diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c
index c399637a3a79..ac74fb88e3c8 100644
--- a/arch/x86/kvm/vmx/pmu_intel.c
+++ b/arch/x86/kvm/vmx/pmu_intel.c
@@ -617,7 +617,7 @@ static void intel_pmu_init(struct kvm_vcpu *vcpu)
struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);
struct lbr_desc *lbr_desc = vcpu_to_lbr_desc(vcpu);

- for (i = 0; i < INTEL_PMC_MAX_GENERIC; i++) {
+ for (i = 0; i < KVM_INTEL_PMC_MAX_GENERIC; i++) {
pmu->gp_counters[i].type = KVM_PMC_GP;
pmu->gp_counters[i].vcpu = vcpu;
pmu->gp_counters[i].idx = i;
@@ -643,7 +643,7 @@ static void intel_pmu_reset(struct kvm_vcpu *vcpu)
struct kvm_pmc *pmc = NULL;
int i;

- for (i = 0; i < INTEL_PMC_MAX_GENERIC; i++) {
+ for (i = 0; i < KVM_INTEL_PMC_MAX_GENERIC; i++) {
pmc = &pmu->gp_counters[i];

pmc_stop_counter(pmc);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 9f74c3924377..bf7eafcbe5ec 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1424,6 +1424,9 @@ static const u32 msrs_to_save_all[] = {
MSR_ARCH_PERFMON_FIXED_CTR0 + 2,
MSR_CORE_PERF_FIXED_CTR_CTRL, MSR_CORE_PERF_GLOBAL_STATUS,
MSR_CORE_PERF_GLOBAL_CTRL, MSR_CORE_PERF_GLOBAL_OVF_CTRL,
+ MSR_IA32_PEBS_ENABLE, MSR_IA32_DS_AREA, MSR_PEBS_DATA_CFG,
+
+ /* This part of MSRs should match KVM_INTEL_PMC_MAX_GENERIC. */
MSR_ARCH_PERFMON_PERFCTR0, MSR_ARCH_PERFMON_PERFCTR1,
MSR_ARCH_PERFMON_PERFCTR0 + 2, MSR_ARCH_PERFMON_PERFCTR0 + 3,
MSR_ARCH_PERFMON_PERFCTR0 + 4, MSR_ARCH_PERFMON_PERFCTR0 + 5,
@@ -1432,7 +1435,6 @@ static const u32 msrs_to_save_all[] = {
MSR_ARCH_PERFMON_EVENTSEL0 + 2, MSR_ARCH_PERFMON_EVENTSEL0 + 3,
MSR_ARCH_PERFMON_EVENTSEL0 + 4, MSR_ARCH_PERFMON_EVENTSEL0 + 5,
MSR_ARCH_PERFMON_EVENTSEL0 + 6, MSR_ARCH_PERFMON_EVENTSEL0 + 7,
- MSR_IA32_PEBS_ENABLE, MSR_IA32_DS_AREA, MSR_PEBS_DATA_CFG,

MSR_K7_EVNTSEL0, MSR_K7_EVNTSEL1, MSR_K7_EVNTSEL2, MSR_K7_EVNTSEL3,
MSR_K7_PERFCTR0, MSR_K7_PERFCTR1, MSR_K7_PERFCTR2, MSR_K7_PERFCTR3,
@@ -6916,14 +6918,14 @@ static void kvm_init_msr_list(void)
intel_pt_validate_hw_cap(PT_CAP_num_address_ranges) * 2)
continue;
break;
- case MSR_ARCH_PERFMON_PERFCTR0 ... MSR_ARCH_PERFMON_PERFCTR0 + 7:
+ case MSR_ARCH_PERFMON_PERFCTR0 ... MSR_ARCH_PERFMON_PERFCTR_MAX:
if (msrs_to_save_all[i] - MSR_ARCH_PERFMON_PERFCTR0 >=
- min(INTEL_PMC_MAX_GENERIC, kvm_pmu_cap.num_counters_gp))
+ min(KVM_INTEL_PMC_MAX_GENERIC, kvm_pmu_cap.num_counters_gp))
continue;
break;
- case MSR_ARCH_PERFMON_EVENTSEL0 ... MSR_ARCH_PERFMON_EVENTSEL0 + 7:
+ case MSR_ARCH_PERFMON_EVENTSEL0 ... MSR_ARCH_PERFMON_EVENTSEL_MAX:
if (msrs_to_save_all[i] - MSR_ARCH_PERFMON_EVENTSEL0 >=
- min(INTEL_PMC_MAX_GENERIC, kvm_pmu_cap.num_counters_gp))
+ min(KVM_INTEL_PMC_MAX_GENERIC, kvm_pmu_cap.num_counters_gp))
continue;
break;
case MSR_IA32_XFD:
--
2.37.3