From 05519c86d6997cfb9bb6c82ce1595d1015b718dc Mon Sep 17 00:00:00 2001 From: Mingwei Zhang Date: Tue, 23 Jan 2024 22:12:20 +0000 Subject: KVM: x86/pmu: Fix type length error when reading pmu->fixed_ctr_ctrl Use a u64 instead of a u8 when taking a snapshot of pmu->fixed_ctr_ctrl when reprogramming fixed counters, as truncating the value results in KVM thinking fixed counter 2 is already disabled (the bug also affects fixed counters 3+, but KVM doesn't yet support those). As a result, if the guest disables fixed counter 2, KVM will get a false negative and fail to reprogram/disable emulation of the counter, which can leads to incorrect counts and spurious PMIs in the guest. Fixes: 76d287b2342e ("KVM: x86/pmu: Drop "u8 ctrl, int idx" for reprogram_fixed_counter()") Cc: stable@vger.kernel.org Signed-off-by: Mingwei Zhang Link: https://lore.kernel.org/r/20240123221220.3911317-1-mizhang@google.com [sean: rewrite changelog to call out the effects of the bug] Signed-off-by: Sean Christopherson --- arch/x86/kvm/vmx/pmu_intel.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/x86/kvm/vmx') diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c index a6216c874729..315c7c2ba89b 100644 --- a/arch/x86/kvm/vmx/pmu_intel.c +++ b/arch/x86/kvm/vmx/pmu_intel.c @@ -71,7 +71,7 @@ static int fixed_pmc_events[] = { static void reprogram_fixed_counters(struct kvm_pmu *pmu, u64 data) { struct kvm_pmc *pmc; - u8 old_fixed_ctr_ctrl = pmu->fixed_ctr_ctrl; + u64 old_fixed_ctr_ctrl = pmu->fixed_ctr_ctrl; int i; pmu->fixed_ctr_ctrl = data; -- cgit v1.2.3