[Xen-changelog] [xen-unstable] nestedsvm: fix error path when VMRUN emulation fails

[Xen patchbot-unstable <patchbot@xxxxxxx>]

# HG changeset patch
# User Christoph Egger <Christoph.Egger@xxxxxxx>
# Date 1305187082 -3600
# Node ID b6e8e916ed2827fb1329de0de2e23ee5b6b78662
# Parent  8489494ee490cdf25e4d5132b871216e85c92836
nestedsvm: fix error path when VMRUN emulation fails

With this, l1 guest keeps alive rather crashing the host.

Signed-off-by: Christoph Egger <Christoph.Egger@xxxxxxx>
Acked-by: Tim Deegan <Tim.Deegan@xxxxxxxxxx>
---


diff -r 8489494ee490 -r b6e8e916ed28 xen/arch/x86/hvm/svm/nestedsvm.c
--- a/xen/arch/x86/hvm/svm/nestedsvm.c  Thu May 12 08:57:08 2011 +0100
+++ b/xen/arch/x86/hvm/svm/nestedsvm.c  Thu May 12 08:58:02 2011 +0100
@@ -656,17 +656,21 @@
 
     /* save host state */
     ret = nsvm_vcpu_vmentry(v, regs, inst_len);
+
+    /* Switch vcpu to guest mode. In the error case
+     * this ensures the host mode is restored correctly
+     * and l1 guest keeps alive. */
+    nestedhvm_vcpu_enter_guestmode(v);
+
     if (ret) {
         gdprintk(XENLOG_ERR,
             "nsvm_vcpu_vmentry failed, injecting #UD\n");
         hvm_inject_exception(TRAP_invalid_op, HVM_DELIVER_NO_ERROR_CODE, 0);
+        /* Must happen after hvm_inject_exception or it doesn't work right. */
         nv->nv_vmswitch_in_progress = 0;
         return 1;
     }
 
-    /* Switch vcpu to guest mode
-     */
-    nestedhvm_vcpu_enter_guestmode(v);
     nv->nv_vmswitch_in_progress = 0;
     return 0;
 }
@@ -1329,7 +1333,7 @@
         int ret;
         ASSERT(!nv->nv_vmexit_pending);
         ret = nsvm_vcpu_vmrun(v, regs);
-        if (ret < 0)
+        if (ret)
             goto vmexit;
 
         ASSERT(nestedhvm_vcpu_in_guestmode(v));

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