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kvm: x86: limit the maximum number of vPMU fixed counters to 3

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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>
This commit is contained in:
Like Xu 2020-06-24 09:59:28 +08:00 committed by Paolo Bonzini
parent 761e416934
commit 2e8cd7a3b8
2 changed files with 3 additions and 1 deletions
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2
arch/x86/kvm/cpuid.c
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@ -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;

2
arch/x86/kvm/pmu.h
View File

@ -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;