diff mbox series

[v3,5/6] KVM: x86: Snapshot the host's DEBUGCTL after disabling IRQs

Message ID 20250227222411.3490595-6-seanjc@google.com (mailing list archive)
State New
Headers show
Series KVM: SVM: Fix DEBUGCTL bugs | expand

Commit Message

Sean Christopherson Feb. 27, 2025, 10:24 p.m. UTC 
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
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/kvm/x86.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 09c3d27cc01a..a2cd734beef5 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4991,7 +4991,6 @@  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)) {
@@ -10984,6 +10983,8 @@  static int vcpu_enter_guest(struct kvm_vcpu *vcpu)
 		set_debugreg(0, 7);
 	}
 
+	vcpu->arch.host_debugctl = get_debugctlmsr();
+
 	guest_timing_enter_irqoff();
 
 	for (;;) {