Commit 3db871fe authored by Dapeng Mi's avatar Dapeng Mi Committed by Sean Christopherson
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KVM: x86/pmu: Reprogram mediated PMU event selectors on event filter updates 



Refresh the event selectors that are programmed into hardware when a PMC
is "reprogrammed" for a mediated PMU, i.e. if userspace changes the PMU
event filters

Note, KVM doesn't utilize the reprogramming infrastructure to handle
counter overflow for mediated PMUs, as there's no need to reprogram a
non-existent perf event.

Suggested-by: default avatarSean Christopherson <seanjc@google.com>
Signed-off-by: default avatarDapeng Mi <dapeng1.mi@linux.intel.com>
Co-developed-by: default avatarMingwei Zhang <mizhang@google.com>
Signed-off-by: default avatarMingwei Zhang <mizhang@google.com>
[sean: add a helper to document behavior, split patch and rewrite changelog]
Tested-by: default avatarXudong Hao <xudong.hao@intel.com>
Tested-by: default avatarManali Shukla <manali.shukla@amd.com>
Link: https://patch.msgid.link/20251206001720.468579-26-seanjc@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent 02918f00

arch/x86/kvm/pmu.c

+24 −0
Original line number Diff line number Diff line
@@ -520,6 +520,25 @@ static bool pmc_is_event_allowed(struct kvm_pmc *pmc) 
	return is_fixed_event_allowed(filter, pmc->idx);

}



static void kvm_mediated_pmu_refresh_event_filter(struct kvm_pmc *pmc)

{

	bool allowed = pmc_is_event_allowed(pmc);

	struct kvm_pmu *pmu = pmc_to_pmu(pmc);



	if (pmc_is_gp(pmc)) {

		pmc->eventsel_hw &= ~ARCH_PERFMON_EVENTSEL_ENABLE;

		if (allowed)

			pmc->eventsel_hw |= pmc->eventsel &

					    ARCH_PERFMON_EVENTSEL_ENABLE;

	} else {

		u64 mask = intel_fixed_bits_by_idx(pmc->idx - KVM_FIXED_PMC_BASE_IDX, 0xf);



		pmu->fixed_ctr_ctrl_hw &= ~mask;

		if (allowed)

			pmu->fixed_ctr_ctrl_hw |= pmu->fixed_ctr_ctrl & mask;

	}

}



static int reprogram_counter(struct kvm_pmc *pmc)

{

	struct kvm_pmu *pmu = pmc_to_pmu(pmc);
@@ -528,6 +547,11 @@ static int reprogram_counter(struct kvm_pmc *pmc) 
	bool emulate_overflow;

	u8 fixed_ctr_ctrl;



	if (kvm_vcpu_has_mediated_pmu(pmu_to_vcpu(pmu))) {

		kvm_mediated_pmu_refresh_event_filter(pmc);

		return 0;

	}



	emulate_overflow = pmc_pause_counter(pmc);



	if (!pmc_is_globally_enabled(pmc) || !pmc_is_locally_enabled(pmc) ||