[PATCH 1/6] KVM: x86/pmu: Move PMU reset logic to common x86 code

From: Sean Christopherson
Date: Mon Oct 23 2023 - 19:40:12 EST


Move the common (or at least "ignored") aspects of resetting the vPMU to
common x86 code, along with the stop/release helpers that are no used only
by the common pmu.c.

There is no need to manually handle fixed counters as all_valid_pmc_idx
tracks both fixed and general purpose counters, and resetting the vPMU is
far from a hot path, i.e. the extra bit of overhead to the PMC from the
index is a non-issue.

Zero fixed_ctr_ctrl in common code even though it's Intel specific.
Ensuring it's zero doesn't harm AMD/SVM in any way, and stopping the fixed
counters via all_valid_pmc_idx, but not clearing the associated control
bits, would be odd/confusing.

Make the .reset() hook optional as SVM no longer needs vendor specific
handling.

Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
arch/x86/include/asm/kvm-x86-pmu-ops.h | 2 +-
arch/x86/kvm/pmu.c | 40 +++++++++++++++++++++++++-
arch/x86/kvm/pmu.h | 18 ------------
arch/x86/kvm/svm/pmu.c | 16 -----------
arch/x86/kvm/vmx/pmu_intel.c | 20 -------------
5 files changed, 40 insertions(+), 56 deletions(-)

diff --git a/arch/x86/include/asm/kvm-x86-pmu-ops.h b/arch/x86/include/asm/kvm-x86-pmu-ops.h
index 6c98f4bb4228..058bc636356a 100644
--- a/arch/x86/include/asm/kvm-x86-pmu-ops.h
+++ b/arch/x86/include/asm/kvm-x86-pmu-ops.h
@@ -22,7 +22,7 @@ KVM_X86_PMU_OP(get_msr)
KVM_X86_PMU_OP(set_msr)
KVM_X86_PMU_OP(refresh)
KVM_X86_PMU_OP(init)
-KVM_X86_PMU_OP(reset)
+KVM_X86_PMU_OP_OPTIONAL(reset)
KVM_X86_PMU_OP_OPTIONAL(deliver_pmi)
KVM_X86_PMU_OP_OPTIONAL(cleanup)

diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
index 9ae07db6f0f6..027e9c3c2b93 100644
--- a/arch/x86/kvm/pmu.c
+++ b/arch/x86/kvm/pmu.c
@@ -250,6 +250,24 @@ static bool pmc_resume_counter(struct kvm_pmc *pmc)
return true;
}

+static void pmc_release_perf_event(struct kvm_pmc *pmc)
+{
+ if (pmc->perf_event) {
+ perf_event_release_kernel(pmc->perf_event);
+ pmc->perf_event = NULL;
+ pmc->current_config = 0;
+ pmc_to_pmu(pmc)->event_count--;
+ }
+}
+
+static void pmc_stop_counter(struct kvm_pmc *pmc)
+{
+ if (pmc->perf_event) {
+ pmc->counter = pmc_read_counter(pmc);
+ pmc_release_perf_event(pmc);
+ }
+}
+
static int filter_cmp(const void *pa, const void *pb, u64 mask)
{
u64 a = *(u64 *)pa & mask;
@@ -654,7 +672,27 @@ void kvm_pmu_refresh(struct kvm_vcpu *vcpu)

void kvm_pmu_reset(struct kvm_vcpu *vcpu)
{
- static_call(kvm_x86_pmu_reset)(vcpu);
+ struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);
+ struct kvm_pmc *pmc;
+ int i;
+
+ bitmap_zero(pmu->reprogram_pmi, X86_PMC_IDX_MAX);
+
+ for_each_set_bit(i, pmu->all_valid_pmc_idx, X86_PMC_IDX_MAX) {
+ pmc = static_call(kvm_x86_pmu_pmc_idx_to_pmc)(pmu, i);
+ if (!pmc)
+ continue;
+
+ pmc_stop_counter(pmc);
+ pmc->counter = 0;
+
+ if (pmc_is_gp(pmc))
+ pmc->eventsel = 0;
+ }
+
+ pmu->fixed_ctr_ctrl = pmu->global_ctrl = pmu->global_status = 0;
+
+ static_call_cond(kvm_x86_pmu_reset)(vcpu);
}

void kvm_pmu_init(struct kvm_vcpu *vcpu)
diff --git a/arch/x86/kvm/pmu.h b/arch/x86/kvm/pmu.h
index 1d64113de488..a46aa9b25150 100644
--- a/arch/x86/kvm/pmu.h
+++ b/arch/x86/kvm/pmu.h
@@ -80,24 +80,6 @@ static inline void pmc_write_counter(struct kvm_pmc *pmc, u64 val)
pmc->counter &= pmc_bitmask(pmc);
}

-static inline void pmc_release_perf_event(struct kvm_pmc *pmc)
-{
- if (pmc->perf_event) {
- perf_event_release_kernel(pmc->perf_event);
- pmc->perf_event = NULL;
- pmc->current_config = 0;
- pmc_to_pmu(pmc)->event_count--;
- }
-}
-
-static inline void pmc_stop_counter(struct kvm_pmc *pmc)
-{
- if (pmc->perf_event) {
- pmc->counter = pmc_read_counter(pmc);
- pmc_release_perf_event(pmc);
- }
-}
-
static inline bool pmc_is_gp(struct kvm_pmc *pmc)
{
return pmc->type == KVM_PMC_GP;
diff --git a/arch/x86/kvm/svm/pmu.c b/arch/x86/kvm/svm/pmu.c
index 373ff6a6687b..3fd47de14b38 100644
--- a/arch/x86/kvm/svm/pmu.c
+++ b/arch/x86/kvm/svm/pmu.c
@@ -233,21 +233,6 @@ static void amd_pmu_init(struct kvm_vcpu *vcpu)
}
}

-static void amd_pmu_reset(struct kvm_vcpu *vcpu)
-{
- struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);
- int i;
-
- for (i = 0; i < KVM_AMD_PMC_MAX_GENERIC; i++) {
- struct kvm_pmc *pmc = &pmu->gp_counters[i];
-
- pmc_stop_counter(pmc);
- pmc->counter = pmc->prev_counter = pmc->eventsel = 0;
- }
-
- pmu->global_ctrl = pmu->global_status = 0;
-}
-
struct kvm_pmu_ops amd_pmu_ops __initdata = {
.hw_event_available = amd_hw_event_available,
.pmc_idx_to_pmc = amd_pmc_idx_to_pmc,
@@ -259,7 +244,6 @@ struct kvm_pmu_ops amd_pmu_ops __initdata = {
.set_msr = amd_pmu_set_msr,
.refresh = amd_pmu_refresh,
.init = amd_pmu_init,
- .reset = amd_pmu_reset,
.EVENTSEL_EVENT = AMD64_EVENTSEL_EVENT,
.MAX_NR_GP_COUNTERS = KVM_AMD_PMC_MAX_GENERIC,
.MIN_NR_GP_COUNTERS = AMD64_NUM_COUNTERS,
diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c
index 820d3e1f6b4f..90c1f7f07e53 100644
--- a/arch/x86/kvm/vmx/pmu_intel.c
+++ b/arch/x86/kvm/vmx/pmu_intel.c
@@ -632,26 +632,6 @@ static void intel_pmu_init(struct kvm_vcpu *vcpu)

static void intel_pmu_reset(struct kvm_vcpu *vcpu)
{
- struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);
- struct kvm_pmc *pmc = NULL;
- int i;
-
- for (i = 0; i < KVM_INTEL_PMC_MAX_GENERIC; i++) {
- pmc = &pmu->gp_counters[i];
-
- pmc_stop_counter(pmc);
- pmc->counter = pmc->prev_counter = pmc->eventsel = 0;
- }
-
- for (i = 0; i < KVM_PMC_MAX_FIXED; i++) {
- pmc = &pmu->fixed_counters[i];
-
- pmc_stop_counter(pmc);
- pmc->counter = pmc->prev_counter = 0;
- }
-
- pmu->fixed_ctr_ctrl = pmu->global_ctrl = pmu->global_status = 0;
-
intel_pmu_release_guest_lbr_event(vcpu);
}

--
2.42.0.758.gaed0368e0e-goog