[PATCH v2 41/54] KVM: x86/pmu: Introduce PMU operator for setting counter overflow

Mingwei Zhang
2024-05-06T05:31:45Z

Introduce PMU operator for setting counter overflow. When emulating counter
increment, multiple counters could overflow at the same time, i.e., during
the execution of the same instruction. In passthrough PMU, having an PMU
operator provides convenience to update the PMU global status in one shot
with details hidden behind the vendor specific implementation.

Signed-off-by: Mingwei Zhang <mizhang@google.com>
Signed-off-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
---
arch/x86/include/asm/kvm-x86-pmu-ops.h | 1 +
arch/x86/kvm/pmu.h | 1 +
arch/x86/kvm/vmx/pmu_intel.c | 5 +++++
3 files changed, 7 insertions(+)

diff --git a/arch/x86/include/asm/kvm-x86-pmu-ops.h b/arch/x86/include/asm/kvm-x86-pmu-ops.h
index 72ca78df8d2b..bd5b118a5ce5 100644
--- a/arch/x86/include/asm/kvm-x86-pmu-ops.h
+++ b/arch/x86/include/asm/kvm-x86-pmu-ops.h
@@ -28,6 +28,7 @@ KVM_X86_PMU_OP_OPTIONAL(passthrough_pmu_msrs)
KVM_X86_PMU_OP_OPTIONAL(save_pmu_context)
KVM_X86_PMU_OP_OPTIONAL(restore_pmu_context)
KVM_X86_PMU_OP_OPTIONAL(incr_counter)
+KVM_X86_PMU_OP_OPTIONAL(set_overflow)

#undef KVM_X86_PMU_OP
#undef KVM_X86_PMU_OP_OPTIONAL
diff --git a/arch/x86/kvm/pmu.h b/arch/x86/kvm/pmu.h
index 325f17673a00..78a7f0c5f3ba 100644
--- a/arch/x86/kvm/pmu.h
+++ b/arch/x86/kvm/pmu.h
@@ -45,6 +45,7 @@ struct kvm_pmu_ops {
void (*save_pmu_context)(struct kvm_vcpu *vcpu);
void (*restore_pmu_context)(struct kvm_vcpu *vcpu);
bool (*incr_counter)(struct kvm_pmc *pmc);
+ void (*set_overflow)(struct kvm_vcpu *vcpu);

const u64 EVENTSEL_EVENT;
const int MAX_NR_GP_COUNTERS;
diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c
index 485bbccf503a..aac09eb9af0e 100644
--- a/arch/x86/kvm/vmx/pmu_intel.c
+++ b/arch/x86/kvm/vmx/pmu_intel.c
@@ -881,6 +881,10 @@ static void intel_restore_guest_pmu_context(struct kvm_vcpu *vcpu)
wrmsrl(MSR_CORE_PERF_FIXED_CTR_CTRL, pmu->fixed_ctr_ctrl_hw);
}

+static void intel_set_overflow(struct kvm_vcpu *vcpu)
+{
+}
+
struct kvm_pmu_ops intel_pmu_ops __initdata = {
.rdpmc_ecx_to_pmc = intel_rdpmc_ecx_to_pmc,
.msr_idx_to_pmc = intel_msr_idx_to_pmc,
@@ -897,6 +901,7 @@ struct kvm_pmu_ops intel_pmu_ops __initdata = {
.save_pmu_context = intel_save_guest_pmu_context,
.restore_pmu_context = intel_restore_guest_pmu_context,
.incr_counter = intel_incr_counter,
+ .set_overflow = intel_set_overflow,
.EVENTSEL_EVENT = ARCH_PERFMON_EVENTSEL_EVENT,
.MAX_NR_GP_COUNTERS = KVM_INTEL_PMC_MAX_GENERIC,
.MIN_NR_GP_COUNTERS = 1,
--
2.45.0.rc1.225.g2a3ae87e7f-goog