Commit d652981d authored by Sean Christopherson's avatar Sean Christopherson
Browse files

KVM: x86/pmu: Apply "fast" RDPMC only to Intel PMUs 



Move the handling of "fast" RDPMC instructions, which drop bits 63:32 of
the count, to Intel.  The "fast" flag, and all modifiers for that matter,
are Intel-only and aren't supported by AMD.

Opportunistically replace open coded bit crud with proper #defines, and
add comments to try and disentangle the flags vs. values mess for
non-architectural vs. architectural PMUs.

Fixes: ca724305 ("KVM: x86/vPMU: Implement AMD vPMU code for KVM")
Reviewed-by: default avatarDapeng Mi <dapeng1.mi@linux.intel.com>
Tested-by: default avatarDapeng Mi <dapeng1.mi@linux.intel.com>
Link: https://lore.kernel.org/r/20240109230250.424295-9-seanjc@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent 7bb7fce1

arch/x86/kvm/pmu.c

+1 −2
Original line number Diff line number Diff line
@@ -576,10 +576,9 @@ static int kvm_pmu_rdpmc_vmware(struct kvm_vcpu *vcpu, unsigned idx, u64 *data) 


int kvm_pmu_rdpmc(struct kvm_vcpu *vcpu, unsigned idx, u64 *data)

{

	bool fast_mode = idx & (1u << 31);

	struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);

	struct kvm_pmc *pmc;

	u64 mask = fast_mode ? ~0u : ~0ull;

	u64 mask = ~0ull;



	if (!pmu->version)

		return 1;

arch/x86/kvm/vmx/pmu_intel.c

+14 −2
Original line number Diff line number Diff line
@@ -20,6 +20,15 @@ 
#include "nested.h"

#include "pmu.h"



/*

 * Perf's "BASE" is wildly misleading, architectural PMUs use bits 31:16 of ECX

 * to encode the "type" of counter to read, i.e. this is not a "base".  And to

 * further confuse things, non-architectural PMUs use bit 31 as a flag for

 * "fast" reads, whereas the "type" is an explicit value.

 */

#define INTEL_RDPMC_FIXED	INTEL_PMC_FIXED_RDPMC_BASE

#define INTEL_RDPMC_FAST	BIT(31)



#define MSR_PMC_FULL_WIDTH_BIT      (MSR_IA32_PMC0 - MSR_IA32_PERFCTR0)



static void reprogram_fixed_counters(struct kvm_pmu *pmu, u64 data)
@@ -59,11 +68,14 @@ static struct kvm_pmc *intel_rdpmc_ecx_to_pmc(struct kvm_vcpu *vcpu, 
					    unsigned int idx, u64 *mask)

{

	struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);

	bool fixed = idx & (1u << 30);

	bool fixed = idx & INTEL_RDPMC_FIXED;

	struct kvm_pmc *counters;

	unsigned int num_counters;



	idx &= ~(3u << 30);

	if (idx & INTEL_RDPMC_FAST)

		*mask &= GENMASK_ULL(31, 0);



	idx &= ~(INTEL_RDPMC_FIXED | INTEL_RDPMC_FAST);

	if (fixed) {

		counters = pmu->fixed_counters;

		num_counters = pmu->nr_arch_fixed_counters;