kvm_vcpu_check_block() is called while not in TASK_RUNNING, and therefore
it cannot sleep. Writing to guest memory is therefore forbidden, but it
can happen on AMD processors if kvm_check_nested_events() causes a vmexit.
Fortunately, all events that are caught by kvm_check_nested_events() are
also recognized by kvm_vcpu_has_events() through vendor callbacks such as
kvm_x86_interrupt_allowed() or kvm_x86_ops.nested_ops->has_events(), so
remove the call and postpone the actual processing to vcpu_block().
Reported-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>
Reviewed-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
arch/x86/kvm/x86.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 5c5341110876..f901cd872b6d 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10637,6 +10637,15 @@ static inline int vcpu_block(struct kvm_vcpu *vcpu)
return 1;
}
+ /*
+ * Evaluate nested events before exiting the halted state. This allows
+ * the halt state to be recorded properly in the VMCS12's activity
+ * state field (AMD does not have a similar field and a VM-Exit always
+ * causes a spurious wakeup from HLT).
+ */
+ if (is_guest_mode(vcpu))
+ kvm_check_nested_events(vcpu);
+
if (kvm_apic_accept_events(vcpu) < 0)
return 0;
switch(vcpu->arch.mp_state) {
@@ -10660,9 +10669,6 @@ static inline int vcpu_block(struct kvm_vcpu *vcpu)
static inline bool kvm_vcpu_running(struct kvm_vcpu *vcpu)
{
- if (is_guest_mode(vcpu))
- kvm_check_nested_events(vcpu);
-
return (vcpu->arch.mp_state == KVM_MP_STATE_RUNNABLE &&
!vcpu->arch.apf.halted);
}
--
2.31.1
