From 4513d9232badcc5039d69dae946054ba2682c258 Mon Sep 17 00:00:00 2001
From: Gleb Natapov <gleb@redhat.com>
Date: Mon, 10 May 2010 11:21:34 +0300
Subject: [PATCH] Do not stop VM if emulation failed in userspace.

Continue vcpu execution in case emulation failure happened while vcpu
was in userspace. In this case #UD will be injected into the guest
allowing guest OS to kill offending process and continue.

Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
---
 kvm-all.c          | 2 ++
 kvm.h              | 2 ++
 target-i386/kvm.c  | 7 +++++++
 target-ppc/kvm.c   | 5 +++++
 target-s390x/kvm.c | 5 +++++
 5 files changed, 21 insertions(+)

diff --git a/kvm-all.c b/kvm-all.c
index d06980c000..c238f5421c 100644
--- a/kvm-all.c
+++ b/kvm-all.c
@@ -764,6 +764,8 @@ static void kvm_handle_internal_error(CPUState *env, struct kvm_run *run)
     cpu_dump_state(env, stderr, fprintf, 0);
     if (run->internal.suberror == KVM_INTERNAL_ERROR_EMULATION) {
         fprintf(stderr, "emulation failure\n");
+        if (!kvm_arch_stop_on_emulation_error(env))
+		return;
     }
     /* FIXME: Should trigger a qmp message to let management know
      * something went wrong.
diff --git a/kvm.h b/kvm.h
index 5071a31dec..a28e7aab53 100644
--- a/kvm.h
+++ b/kvm.h
@@ -140,6 +140,8 @@ void kvm_arch_remove_all_hw_breakpoints(void);
 
 void kvm_arch_update_guest_debug(CPUState *env, struct kvm_guest_debug *dbg);
 
+bool kvm_arch_stop_on_emulation_error(CPUState *env);
+
 int kvm_check_extension(KVMState *s, unsigned int extension);
 
 uint32_t kvm_arch_get_supported_cpuid(CPUState *env, uint32_t function,
diff --git a/target-i386/kvm.c b/target-i386/kvm.c
index bd7a190678..676aa60791 100644
--- a/target-i386/kvm.c
+++ b/target-i386/kvm.c
@@ -1289,3 +1289,10 @@ void kvm_arch_update_guest_debug(CPUState *env, struct kvm_guest_debug *dbg)
     }
 }
 #endif /* KVM_CAP_SET_GUEST_DEBUG */
+
+bool kvm_arch_stop_on_emulation_error(CPUState *env)
+{
+      return !(env->cr[0] & CR0_PE_MASK) ||
+              ((env->segs[R_CS].selector  & 3) != 3);
+}
+
diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c
index 91c0963f88..2625cb8bd9 100644
--- a/target-ppc/kvm.c
+++ b/target-ppc/kvm.c
@@ -326,3 +326,8 @@ uint32_t kvmppc_get_tbfreq(void)
     retval = atoi(ns);
     return retval;
 }
+
+bool kvm_arch_stop_on_emulation_error(CPUState *env)
+{
+    return true;
+}
diff --git a/target-s390x/kvm.c b/target-s390x/kvm.c
index a2c00acf0f..a2d77419bd 100644
--- a/target-s390x/kvm.c
+++ b/target-s390x/kvm.c
@@ -485,3 +485,8 @@ int kvm_arch_handle_exit(CPUState *env, struct kvm_run *run)
 
     return ret;
 }
+
+bool kvm_arch_stop_on_emulation_error(CPUState *env)
+{
+    return true;
+}