Commit 189ecdb3 authored by Sean Christopherson's avatar Sean Christopherson
Browse files

KVM: x86: Snapshot the host's DEBUGCTL after disabling IRQs 



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: default avatarRavi Bangoria <ravi.bangoria@amd.com>
Link: https://lore.kernel.org/r/20250227222411.3490595-6-seanjc@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent 43326587

arch/x86/kvm/x86.c

+2 −1
Original line number Diff line number Diff line
@@ -4968,7 +4968,6 @@ 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)) {
@@ -10969,6 +10968,8 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) 
		set_debugreg(0, 7);

	}



	vcpu->arch.host_debugctl = get_debugctlmsr();



	guest_timing_enter_irqoff();



	for (;;) {