[PATCH 01/47] KVM: Return to userspace on emulation failure

[Avi Kivity]

Instead of mindlessly retrying to execute the instruction, report the
failure to userspace.

Signed-off-by: Avi Kivity <avi@xxxxxxxxxx>
---
 arch/x86/kvm/mmu.c  |    5 +++--
 include/linux/kvm.h |    7 +++++++
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 5f97dbd..b6e4cda 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -2673,8 +2673,9 @@ int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gva_t cr2, u32 error_code)
 		++vcpu->stat.mmio_exits;
 		return 0;
 	case EMULATE_FAIL:
-		kvm_report_emulation_failure(vcpu, "pagetable");
-		return 1;
+		vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
+		vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_EMULATION;
+		return 0;
 	default:
 		BUG();
 	}
diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index 5037e17..6710518 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -95,6 +95,10 @@ struct kvm_pit_config {
 #define KVM_EXIT_S390_RESET       14
 #define KVM_EXIT_DCR              15
 #define KVM_EXIT_NMI              16
+#define KVM_EXIT_INTERNAL_ERROR   17
+
+/* For KVM_EXIT_INTERNAL_ERROR */
+#define KVM_INTERNAL_ERROR_EMULATION 1
 
 /* for KVM_RUN, returned by mmap(vcpu_fd, offset=0) */
 struct kvm_run {
@@ -181,6 +185,9 @@ struct kvm_run {
 			__u32 data;
 			__u8  is_write;
 		} dcr;
+		struct {
+			__u32 suberror;
+		} internal;
 		/* Fix the size of the union. */
 		char padding[256];
 	};
-- 
1.6.3.3

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