Commit 6d88d0ee authored by Sean Christopherson's avatar Sean Christopherson
Browse files

KVM: x86/pmu: Require nr fixed_pmc_events to match nr max fixed counters 

Assert that the number of known fixed_pmc_events matches the max number of
fixed counters supported by KVM, and clean up related code.

Opportunistically extend setup_fixed_pmc_eventsel()'s use of
array_index_nospec() to cover fixed_counters, as nr_arch_fixed_counters is
set based on userspace input (but capped using KVM-controlled values).

Link: https://lore.kernel.org/r/20230607010206.1425277-4-seanjc@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent bc965899

arch/x86/kvm/vmx/pmu_intel.c

+9 −10
Original line number Diff line number Diff line
@@ -468,14 +468,15 @@ static int intel_pmu_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) 


static void setup_fixed_pmc_eventsel(struct kvm_pmu *pmu)

{

	size_t size = ARRAY_SIZE(fixed_pmc_events);

	struct kvm_pmc *pmc;

	u32 event;

	int i;



	BUILD_BUG_ON(ARRAY_SIZE(fixed_pmc_events) != KVM_PMC_MAX_FIXED);



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

		pmc = &pmu->fixed_counters[i];

		event = fixed_pmc_events[array_index_nospec(i, size)];

		int index = array_index_nospec(i, KVM_PMC_MAX_FIXED);

		struct kvm_pmc *pmc = &pmu->fixed_counters[index];

		u32 event = fixed_pmc_events[index];



		pmc->eventsel = (intel_arch_events[event].unit_mask << 8) |

				 intel_arch_events[event].eventsel;

	}
@@ -538,10 +539,8 @@ static void intel_pmu_refresh(struct kvm_vcpu *vcpu) 
	if (pmu->version == 1) {

		pmu->nr_arch_fixed_counters = 0;

	} else {

		pmu->nr_arch_fixed_counters =

			min3(ARRAY_SIZE(fixed_pmc_events),

			     (size_t) edx.split.num_counters_fixed,

			     (size_t)kvm_pmu_cap.num_counters_fixed);

		pmu->nr_arch_fixed_counters = min_t(int, edx.split.num_counters_fixed,

						    kvm_pmu_cap.num_counters_fixed);

		edx.split.bit_width_fixed = min_t(int, edx.split.bit_width_fixed,

						  kvm_pmu_cap.bit_width_fixed);

		pmu->counter_bitmask[KVM_PMC_FIXED] =