From 98b20e1612e69bf91185cf722a96293a136fe894 Mon Sep 17 00:00:00 2001 From: Aaron Lewis Date: Tue, 17 May 2022 05:12:36 +0000 Subject: [PATCH] kvm: x86/pmu: Fix the compare function used by the pmu event filter commit 4ac19ead0dfbabd8e0bfc731f507cfb0b95d6c99 upstream. 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: 7ff775aca48ad ("KVM: x86/pmu: Use binary search to check filtered events") Signed-off-by: Aaron Lewis Reviewed-by: Sean Christopherson Message-Id: <20220517051238.2566934-1-aaronlewis@google.com> Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman --- arch/x86/kvm/pmu.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c index 8b622ae9f2b4..e5322a0dc5bb 100644 --- a/arch/x86/kvm/pmu.c +++ b/arch/x86/kvm/pmu.c @@ -170,9 +170,12 @@ static bool pmc_resume_counter(struct kvm_pmc *pmc) 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)