Re: [PATCH 2/2] KVM: x86: Prevent set vCPU into INIT/SIPI_RECEIVED state when INIT are latched

[Paolo Bonzini <pbonzini@redhat.com>]

On 11/11/19 10:16, Liran Alon wrote:
> -	/* INITs are latched while in SMM */
> -	if ((is_smm(vcpu) || vcpu->arch.smi_pending) &&
> +	/* INITs are latched while CPU is in specific states */
> +	if ((kvm_vcpu_latch_init(vcpu) || vcpu->arch.smi_pending) &&
>  	    (mp_state->mp_state == KVM_MP_STATE_SIPI_RECEIVED ||
>  	     mp_state->mp_state == KVM_MP_STATE_INIT_RECEIVED))
>  		goto out;

Just a small doc clarification:

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 318046647fda..cacfe14717d6 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -2707,7 +2707,8 @@ void kvm_apic_accept_events(struct kvm_vcpu *vcpu)
 		return;
 
 	/*
-	 * INITs are latched while CPU is in specific states.
+	 * INITs are latched while CPU is in specific states
+	 * (SMM, VMX non-root mode, SVM with GIF=0).
 	 * Because a CPU cannot be in these states immediately
 	 * after it has processed an INIT signal (and thus in
 	 * KVM_MP_STATE_INIT_RECEIVED state), just eat SIPIs
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 681544f8db31..11746534e209 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8706,7 +8706,11 @@ int kvm_arch_vcpu_ioctl_set_mpstate(struct kvm_vcpu *vcpu,
 	    mp_state->mp_state != KVM_MP_STATE_RUNNABLE)
 		goto out;
 
-	/* INITs are latched while CPU is in specific states */
+	/*
+	 * KVM_MP_STATE_INIT_RECEIVED means the processor is in
+	 * INIT state; latched init should be reported using
+	 * KVM_SET_VCPU_EVENTS, so reject it here.
+	 */
 	if ((kvm_vcpu_latch_init(vcpu) || vcpu->arch.smi_pending) &&
 	    (mp_state->mp_state == KVM_MP_STATE_SIPI_RECEIVED ||
 	     mp_state->mp_state == KVM_MP_STATE_INIT_RECEIVED))


I'm not sure why you're removing the first hunk, it's just meant to
explain why it needs to be a kvm_x86_ops in case the reader is not
thinking about nested virtualization.

Paolo