kvm: x86: limit the maximum number of vPMU fixed counters to 3 (2e8cd7a3) · Commits · 戴 / test

Some new Intel platforms (such as TGL) already have the fourth fixed counter TOPDOWN.SLOTS, but it has not been fully enabled on KVM and the host. Therefore, we limit edx.split.num_counters_fixed to 3, so that it does not break the kvm-unit-tests PMU test case and bad-handled userspace. Signed-off-by:

Like Xu <like.xu@linux.intel.com> Message-Id: <20200624015928.118614-1-like.xu@linux.intel.com> Signed-off-by:

Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/cpuid.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -606,7 +606,7 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
		eax.split.bit_width = cap.bit_width_gp;
		eax.split.mask_length = cap.events_mask_len;

		edx.split.num_counters_fixed = cap.num_counters_fixed;
		edx.split.num_counters_fixed = min(cap.num_counters_fixed, MAX_FIXED_COUNTERS);
		edx.split.bit_width_fixed = cap.bit_width_fixed;
		edx.split.reserved = 0;

arch/x86/kvm/pmu.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -15,6 +15,8 @@
		#define VMWARE_BACKDOOR_PMC_REAL_TIME 0x10001
		#define VMWARE_BACKDOOR_PMC_APPARENT_TIME 0x10002

		#define MAX_FIXED_COUNTERS 3

		struct kvm_event_hw_type_mapping {
		u8 eventsel;
		u8 unit_mask;

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