Commit 02918f00 authored by Mingwei Zhang's avatar Mingwei Zhang Committed by Sean Christopherson
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KVM: x86/pmu: Introduce eventsel_hw to prepare for pmu event filtering 



Introduce eventsel_hw and fixed_ctr_ctrl_hw to store the actual HW value in
PMU event selector MSRs. In mediated PMU checks events before allowing the
event values written to the PMU MSRs. However, to match the HW behavior,
when PMU event checks fails, KVM should allow guest to read the value back.

This essentially requires an extra variable to separate the guest requested
value from actual PMU MSR value. Note this only applies to event selectors.

Signed-off-by: default avatarMingwei Zhang <mizhang@google.com>
Co-developed-by: default avatarDapeng Mi <dapeng1.mi@linux.intel.com>
Signed-off-by: default avatarDapeng Mi <dapeng1.mi@linux.intel.com>
Tested-by: default avatarXudong Hao <xudong.hao@intel.com>
Tested-by: default avatarManali Shukla <manali.shukla@amd.com>
Link: https://patch.msgid.link/20251206001720.468579-25-seanjc@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent 0ea0d631

arch/x86/include/asm/kvm_host.h

+2 −0
Original line number Diff line number Diff line
@@ -529,6 +529,7 @@ struct kvm_pmc { 
	 */

	u64 emulated_counter;

	u64 eventsel;

	u64 eventsel_hw;

	struct perf_event *perf_event;

	struct kvm_vcpu *vcpu;

	/*
@@ -557,6 +558,7 @@ struct kvm_pmu { 
	unsigned nr_arch_fixed_counters;

	unsigned available_event_types;

	u64 fixed_ctr_ctrl;

	u64 fixed_ctr_ctrl_hw;

	u64 fixed_ctr_ctrl_rsvd;

	u64 global_ctrl;

	u64 global_status;

arch/x86/kvm/pmu.c

+5 −2
Original line number Diff line number Diff line
@@ -900,11 +900,14 @@ static void kvm_pmu_reset(struct kvm_vcpu *vcpu) 
		pmc->counter = 0;

		pmc->emulated_counter = 0;



		if (pmc_is_gp(pmc))

		if (pmc_is_gp(pmc)) {

			pmc->eventsel = 0;

			pmc->eventsel_hw = 0;

		}

	}



	pmu->fixed_ctr_ctrl = pmu->global_ctrl = pmu->global_status = 0;

	pmu->fixed_ctr_ctrl = pmu->fixed_ctr_ctrl_hw = 0;

	pmu->global_ctrl = pmu->global_status = 0;



	kvm_pmu_call(reset)(vcpu);

}

arch/x86/kvm/svm/pmu.c

+1 −0
Original line number Diff line number Diff line
@@ -166,6 +166,7 @@ static int amd_pmu_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) 
		data &= ~pmu->reserved_bits;

		if (data != pmc->eventsel) {

			pmc->eventsel = data;

			pmc->eventsel_hw = data;

			kvm_pmu_request_counter_reprogram(pmc);

		}

		return 0;

arch/x86/kvm/vmx/pmu_intel.c

+2 −0
Original line number Diff line number Diff line
@@ -61,6 +61,7 @@ static void reprogram_fixed_counters(struct kvm_pmu *pmu, u64 data) 
	int i;



	pmu->fixed_ctr_ctrl = data;

	pmu->fixed_ctr_ctrl_hw = data;

	for (i = 0; i < pmu->nr_arch_fixed_counters; i++) {

		u8 new_ctrl = fixed_ctrl_field(data, i);

		u8 old_ctrl = fixed_ctrl_field(old_fixed_ctr_ctrl, i);
@@ -430,6 +431,7 @@ static int intel_pmu_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) 


			if (data != pmc->eventsel) {

				pmc->eventsel = data;

				pmc->eventsel_hw = data;

				kvm_pmu_request_counter_reprogram(pmc);

			}

			break;