From: Like Xu <likexu@xxxxxxxxxxx>
AMD only has gp counters, whose corresponding vPMCs are initialised
and stored in pmu->gp_counter[] in order of idx, so we can access this
array directly based on any valid pmc->idx, without any help from other
interfaces at all. The amd_rdpmc_ecx_to_pmc() can now reuse this part
of the code quite naturally.
Opportunistically apply array_index_nospec() to reduce the attack
surface for speculative execution.
Signed-off-by: Like Xu <likexu@xxxxxxxxxxx>
---
arch/x86/kvm/svm/pmu.c | 36 +++++++++++-------------------------
1 file changed, 11 insertions(+), 25 deletions(-)
diff --git a/arch/x86/kvm/svm/pmu.c b/arch/x86/kvm/svm/pmu.c
index 68b9e22c84d2..4668baf762d2 100644
--- a/arch/x86/kvm/svm/pmu.c
+++ b/arch/x86/kvm/svm/pmu.c
@@ -45,6 +45,16 @@ static struct kvm_event_hw_type_mapping amd_event_mapping[] = {
[7] = { 0xd1, 0x00, PERF_COUNT_HW_STALLED_CYCLES_BACKEND },
};
+static struct kvm_pmc *amd_pmc_idx_to_pmc(struct kvm_pmu *pmu, int pmc_idx)
+{
+ unsigned int num_counters = pmu->nr_arch_gp_counters;
+
+ if (pmc_idx >= num_counters)
+ return NULL;
+
+ return &pmu->gp_counters[array_index_nospec(pmc_idx, num_counters)];
+}
+
static unsigned int get_msr_base(struct kvm_pmu *pmu, enum pmu_type type)
{
struct kvm_vcpu *vcpu = pmu_to_vcpu(pmu);
@@ -164,22 +174,6 @@ static bool amd_pmc_is_enabled(struct kvm_pmc *pmc)
return true;
}
-static struct kvm_pmc *amd_pmc_idx_to_pmc(struct kvm_pmu *pmu, int pmc_idx)
-{
- unsigned int base = get_msr_base(pmu, PMU_TYPE_COUNTER);
- struct kvm_vcpu *vcpu = pmu_to_vcpu(pmu);
-
- if (guest_cpuid_has(vcpu, X86_FEATURE_PERFCTR_CORE)) {
- /*
- * The idx is contiguous. The MSRs are not. The counter MSRs
- * are interleaved with the event select MSRs.
- */
- pmc_idx *= 2;
- }
-
- return get_gp_pmc_amd(pmu, base + pmc_idx, PMU_TYPE_COUNTER);
-}
-
static bool amd_is_valid_rdpmc_ecx(struct kvm_vcpu *vcpu, unsigned int idx)
{
struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);
@@ -193,15 +187,7 @@ static bool amd_is_valid_rdpmc_ecx(struct kvm_vcpu *vcpu, unsigned int idx)
static struct kvm_pmc *amd_rdpmc_ecx_to_pmc(struct kvm_vcpu *vcpu,
unsigned int idx, u64 *mask)
{
- struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);
- struct kvm_pmc *counters;
-
- idx &= ~(3u << 30);
- if (idx >= pmu->nr_arch_gp_counters)
- return NULL;
- counters = pmu->gp_counters;
-
- return &counters[idx];
+ return amd_pmc_idx_to_pmc(vcpu_to_pmu(vcpu), idx & ~(3u << 30));
}
static bool amd_is_valid_msr(struct kvm_vcpu *vcpu, u32 msr)
--
2.36.1
