Commit ac9b305c authored by Liran Alon's avatar Liran Alon Committed by Paolo Bonzini
Browse files

KVM: nVMX/nSVM: Don't intercept #UD when running L2 



When running L2, #UD should be intercepted by L1 or just forwarded
directly to L2. It should not reach L0 x86 emulator.
Therefore, set intercept for #UD only based on L1 exception-bitmap.

Also add WARN_ON_ONCE() on L0 #UD intercept handlers to make sure
it is never reached while running L2.

This improves commit ae1f5767 ("KVM: nVMX: Do not emulate #UD while
in guest mode") by removing an unnecessary exit from L2 to L0 on #UD
when L1 doesn't intercept it.

In addition, SVM L0 #UD intercept handler doesn't handle correctly the
case it is raised from L2. In this case, it should forward the #UD to
guest instead of x86 emulator. As done in VMX #UD intercept handler.
This commit fixes this issue as-well.

Signed-off-by: default avatarLiran Alon <liran.alon@oracle.com>
Reviewed-by: default avatarNikita Leshenko <nikita.leshchenko@oracle.com>
Reviewed-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: default avatarKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reviewed-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: default avatarWanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: default avatarRadim Krčmář <rkrcmar@redhat.com>
parent 51c4b8bb

arch/x86/kvm/svm.c

+8 −1
Original line number Diff line number Diff line
@@ -361,6 +361,7 @@ static void recalc_intercepts(struct vcpu_svm *svm) 
{

	struct vmcb_control_area *c, *h;

	struct nested_state *g;

	u32 h_intercept_exceptions;



	mark_dirty(svm->vmcb, VMCB_INTERCEPTS);
@@ -371,9 +372,14 @@ static void recalc_intercepts(struct vcpu_svm *svm) 
	h = &svm->nested.hsave->control;

	g = &svm->nested;



	/* No need to intercept #UD if L1 doesn't intercept it */

	h_intercept_exceptions =

		h->intercept_exceptions & ~(1U << UD_VECTOR);



	c->intercept_cr = h->intercept_cr | g->intercept_cr;

	c->intercept_dr = h->intercept_dr | g->intercept_dr;

	c->intercept_exceptions = h->intercept_exceptions | g->intercept_exceptions;

	c->intercept_exceptions =

		h_intercept_exceptions | g->intercept_exceptions;

	c->intercept = h->intercept | g->intercept;

}
@@ -2196,6 +2202,7 @@ static int ud_interception(struct vcpu_svm *svm) 
{

	int er;



	WARN_ON_ONCE(is_guest_mode(&svm->vcpu));

	er = emulate_instruction(&svm->vcpu, EMULTYPE_TRAP_UD);

	if (er != EMULATE_DONE)

		kvm_queue_exception(&svm->vcpu, UD_VECTOR);

arch/x86/kvm/vmx.c

+4 −5
Original line number Diff line number Diff line
@@ -1887,7 +1887,7 @@ static void update_exception_bitmap(struct kvm_vcpu *vcpu) 
{

	u32 eb;



	eb = (1u << PF_VECTOR) | (1u << UD_VECTOR) | (1u << MC_VECTOR) |

	eb = (1u << PF_VECTOR) | (1u << MC_VECTOR) |

	     (1u << DB_VECTOR) | (1u << AC_VECTOR);

	if ((vcpu->guest_debug &

	     (KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_USE_SW_BP)) ==
@@ -1905,6 +1905,8 @@ static void update_exception_bitmap(struct kvm_vcpu *vcpu) 
	 */

	if (is_guest_mode(vcpu))

		eb |= get_vmcs12(vcpu)->exception_bitmap;

	else

		eb |= 1u << UD_VECTOR;



	vmcs_write32(EXCEPTION_BITMAP, eb);

}
@@ -5915,10 +5917,7 @@ static int handle_exception(struct kvm_vcpu *vcpu) 
		return 1;  /* already handled by vmx_vcpu_run() */



	if (is_invalid_opcode(intr_info)) {

		if (is_guest_mode(vcpu)) {

			kvm_queue_exception(vcpu, UD_VECTOR);

			return 1;

		}

		WARN_ON_ONCE(is_guest_mode(vcpu));

		er = emulate_instruction(vcpu, EMULTYPE_TRAP_UD);

		if (er != EMULATE_DONE)

			kvm_queue_exception(vcpu, UD_VECTOR);

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