Commit 57cb3bb0 authored by Paolo Bonzini's avatar Paolo Bonzini
Browse files

KVM: x86: do not deliver asynchronous page faults if CR0.PG=0 



Enabling async page faults is nonsensical if paging is disabled, but
it is allowed because CR0.PG=0 does not clear the async page fault
MSR.  Just ignore them and only use the artificial halt state,
similar to what happens in guest mode if async #PF vmexits are disabled.

Given the increasingly complex logic, and the nicer code if the new
"if" is placed last, opportunistically change the "||" into a chain
of "if (...) return false" statements.

Reviewed-by: default avatarSean Christopherson <seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent d6174299

arch/x86/kvm/x86.c

+18 −4
Original line number Diff line number Diff line
@@ -12287,14 +12287,28 @@ static inline bool apf_pageready_slot_free(struct kvm_vcpu *vcpu) 


static bool kvm_can_deliver_async_pf(struct kvm_vcpu *vcpu)

{

	if (!vcpu->arch.apf.delivery_as_pf_vmexit && is_guest_mode(vcpu))



	if (!kvm_pv_async_pf_enabled(vcpu))

		return false;



	if (!kvm_pv_async_pf_enabled(vcpu) ||

	    (vcpu->arch.apf.send_user_only && static_call(kvm_x86_get_cpl)(vcpu) == 0))

	if (vcpu->arch.apf.send_user_only &&

	    static_call(kvm_x86_get_cpl)(vcpu) == 0)

		return false;



	return true;

	if (is_guest_mode(vcpu)) {

		/*

		 * L1 needs to opt into the special #PF vmexits that are

		 * used to deliver async page faults.

		 */

		return vcpu->arch.apf.delivery_as_pf_vmexit;

	} else {

		/*

		 * Play it safe in case the guest temporarily disables paging.

		 * The real mode IDT in particular is unlikely to have a #PF

		 * exception setup.

		 */

		return is_paging(vcpu);

	}

}



bool kvm_can_do_async_pf(struct kvm_vcpu *vcpu)