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@xxxxxxxxxxxxxxx
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
arch/x86/kvm/x86.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
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 (;;) {
--
2.48.1.658.g4767266eb4-goog
