[PATCH 1/2] KVM: VMX: report internal error for the unhandleable event

[PATCH 1/2] KVM: VMX: report internal error for the unhandleable event

[Xiao Guangrong]

VM exits during Event Delivery is really unexpected if it is not caused
by Exceptions/EPT-VIOLATION/TASK_SWITCH, we'd better to report an internal
and freeze the guest, the VMM has the chance to check the guest

Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
---
 arch/x86/kvm/vmx.c  |   19 +++++++++++++++----
 include/linux/kvm.h |    8 ++++++--
 2 files changed, 21 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index ad6b1dd..b8a0841 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -5979,13 +5979,24 @@ static int vmx_handle_exit(struct kvm_vcpu *vcpu)
 		return 0;
 	}

+	/*
+	 * Note:
+	 * Do not try to fix EXIT_REASON_EPT_MISCONFIG if it caused by
+	 * delivery event since it indicates guest is accessing MMIO.
+	 * The vm-exit can be triggered again after return to guest that
+	 * will cause infinite loop.
+	 */
 	if ((vectoring_info & VECTORING_INFO_VALID_MASK) &&
 			(exit_reason != EXIT_REASON_EXCEPTION_NMI &&
 			exit_reason != EXIT_REASON_EPT_VIOLATION &&
-			exit_reason != EXIT_REASON_TASK_SWITCH))
-		printk(KERN_WARNING "%s: unexpected, valid vectoring info "
-		       "(0x%x) and exit reason is 0x%x\n",
-		       __func__, vectoring_info, exit_reason);
+			exit_reason != EXIT_REASON_TASK_SWITCH)) {
+		vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
+		vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_DELIVERY_EV;
+		vcpu->run->internal.ndata = 2;
+		vcpu->run->internal.data[0] = vectoring_info;
+		vcpu->run->internal.data[1] = exit_reason;
+		return 0;
+	}

 	if (unlikely(!cpu_has_virtual_nmis() && vmx->soft_vnmi_blocked &&
 	    !(is_guest_mode(vcpu) && nested_cpu_has_virtual_nmis(
diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index 65ad5c6..494a84c 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -170,8 +170,12 @@ struct kvm_pit_config {
 #define KVM_EXIT_WATCHDOG         21

 /* For KVM_EXIT_INTERNAL_ERROR */
-#define KVM_INTERNAL_ERROR_EMULATION 1
-#define KVM_INTERNAL_ERROR_SIMUL_EX 2
+/* Emulate instruction failed. */
+#define KVM_INTERNAL_ERROR_EMULATION	1
+/* Encounter unexpected simultaneous exceptions. */
+#define KVM_INTERNAL_ERROR_SIMUL_EX	2
+/* Encounter unexpected vm-exit due to delivery event. */
+#define KVM_INTERNAL_ERROR_DELIVERY_EV	3

 /* for KVM_RUN, returned by mmap(vcpu_fd, offset=0) */
 struct kvm_run {
-- 
1.7.7.6

[PATCH 2/2] KVM: VMX: report internal error for MMIO #PF due to delivery event

[Xiao Guangrong]

The #PF with PFEC.RSV = 1 indicates that the guest is accessing MMIO, we
can not fix it if it is caused by delivery event. Reporting internal error
for this case

Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
---
 arch/x86/kvm/vmx.c |   26 ++++++++++++++++----------
 1 files changed, 16 insertions(+), 10 deletions(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index b8a0841..6599e45 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -4287,16 +4287,6 @@ static int handle_exception(struct kvm_vcpu *vcpu)
 	if (is_machine_check(intr_info))
 		return handle_machine_check(vcpu);

-	if ((vect_info & VECTORING_INFO_VALID_MASK) &&
-	    !is_page_fault(intr_info)) {
-		vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
-		vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_SIMUL_EX;
-		vcpu->run->internal.ndata = 2;
-		vcpu->run->internal.data[0] = vect_info;
-		vcpu->run->internal.data[1] = intr_info;
-		return 0;
-	}
-
 	if ((intr_info & INTR_INFO_INTR_TYPE_MASK) == INTR_TYPE_NMI_INTR)
 		return 1;  /* already handled by vmx_vcpu_run() */

@@ -4315,6 +4305,22 @@ static int handle_exception(struct kvm_vcpu *vcpu)
 	error_code = 0;
 	if (intr_info & INTR_INFO_DELIVER_CODE_MASK)
 		error_code = vmcs_read32(VM_EXIT_INTR_ERROR_CODE);
+
+	/*
+	 * The #PF with PFEC.RSVD = 1 indicates the guest is accessing
+	 * MMIO, it is better to report an internal error.
+	 * See the comments in vmx_handle_exit.
+	 */
+	if ((vect_info & VECTORING_INFO_VALID_MASK) &&
+	    !(is_page_fault(intr_info) && !(error_code & PFERR_RSVD_MASK))) {
+		vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
+		vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_SIMUL_EX;
+		vcpu->run->internal.ndata = 2;
+		vcpu->run->internal.data[0] = vect_info;
+		vcpu->run->internal.data[1] = intr_info;
+		return 0;
+	}
+
 	if (is_page_fault(intr_info)) {
 		/* EPT won't cause page fault directly */
 		BUG_ON(enable_ept);
-- 
1.7.7.6

Re: [PATCH 2/2] KVM: VMX: report internal error for MMIO #PF due to delivery event

[Avi Kivity]

On 10/17/2012 07:48 AM, Xiao Guangrong wrote:
> The #PF with PFEC.RSV = 1 indicates that the guest is accessing MMIO, we
> can not fix it if it is caused by delivery event. Reporting internal error
> for this case

Applied, thanks.


-- 
error compiling committee.c: too many arguments to function