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kvm: x86/pmu: Fix the compare function used by the pmu event filter 

When returning from the compare function the u64 is truncated to an
int.  This results in a loss of the high nybble[1] in the event select
and its sign if that nybble is in use.  Switch from using a result that
can end up being truncated to a result that can only be: 1, 0, -1.

[1] bits 35:32 in the event select register and bits 11:8 in the event
    select.

Fixes: 7ff775aca4 ("KVM: x86/pmu: Use binary search to check filtered events")
Signed-off-by: Aaron Lewis <aaronlewis@google.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220517051238.2566934-1-aaronlewis@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Aaron Lewis 2022-05-17 05:12:36 +00:00 committed by Paolo Bonzini
parent 6f5adb3504
commit 4ac19ead0d
1 changed files with 5 additions and 2 deletions
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7
arch/x86/kvm/pmu.c
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@ -171,9 +171,12 @@ static bool pmc_resume_counter(struct kvm_pmc *pmc)
return true; return true;
} }
static int cmp_u64(const void *a, const void *b) static int cmp_u64(const void *pa, const void *pb)
{ {
return *(__u64 *)a - *(__u64 *)b; u64 a = *(u64 *)pa;
u64 b = *(u64 *)pb;
return (a > b) - (a < b);
} }
void reprogram_gp_counter(struct kvm_pmc *pmc, u64 eventsel) void reprogram_gp_counter(struct kvm_pmc *pmc, u64 eventsel)