From: Sean Christopherson Date: Fri, 15 Aug 2025 00:11:51 +0000 (-0700) Subject: KVM: x86: Snapshot the host's DEBUGCTL after disabling IRQs X-Git-Tag: v6.1.149~452 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0e82f79598630664ecaf630c7ac67cdc6250c56e;p=thirdparty%2Fkernel%2Fstable.git KVM: x86: Snapshot the host's DEBUGCTL after disabling IRQs [ Upstream commit 189ecdb3e112da703ac0699f4ec76aa78122f911 ] Snapshot the host's DEBUGCTL after disabling IRQs, as perf can toggle debugctl bits from IRQ context, e.g. when enabling/disabling events via smp_call_function_single(). Taking the snapshot (long) before IRQs are disabled could result in KVM effectively clobbering DEBUGCTL due to using a stale snapshot. Cc: stable@vger.kernel.org Reviewed-and-tested-by: Ravi Bangoria Link: https://lore.kernel.org/r/20250227222411.3490595-6-seanjc@google.com Signed-off-by: Sean Christopherson Signed-off-by: Sasha Levin --- diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index ba24bb50af573..b0ae61ba9b994 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4742,7 +4742,6 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu) /* Save host pkru register if supported */ vcpu->arch.host_pkru = read_pkru(); - vcpu->arch.host_debugctl = get_debugctlmsr(); /* Apply any externally detected TSC adjustments (due to suspend) */ if (unlikely(vcpu->arch.tsc_offset_adjustment)) { @@ -10851,6 +10850,8 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) set_debugreg(0, 7); } + vcpu->arch.host_debugctl = get_debugctlmsr(); + guest_timing_enter_irqoff(); for (;;) {