[Xen-changelog] [xen-unstable] x86: Do not #GP when guest writes unexpected values to CR4. Just

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User kfraser@xxxxxxxxxxxxxxxxxxxxx
# Date 1188395654 -3600
# Node ID 747b71c8c4a8d0a7e72c2bbadba23d974ba5d10b
# Parent  79053138b35c8e77ef828f920ce0c68543c6a932
x86: Do not #GP when guest writes unexpected values to CR4. Just
ignore them.
Signed-off-by: Keir Fraser <keir@xxxxxxxxxxxxx>
---
 xen/arch/x86/traps.c |    9 ++++-----
 1 files changed, 4 insertions(+), 5 deletions(-)

diff -r 79053138b35c -r 747b71c8c4a8 xen/arch/x86/traps.c
--- a/xen/arch/x86/traps.c      Wed Aug 29 14:40:00 2007 +0100
+++ b/xen/arch/x86/traps.c      Wed Aug 29 14:54:14 2007 +0100
@@ -1673,12 +1673,11 @@ static int emulate_privileged_op(struct 
                 goto fail;
             break;
 
-        case 4:
+        case 4: /* Write CR4 */
             if ( *reg != (read_cr4() & ~(X86_CR4_PGE|X86_CR4_PSE)) )
-            {
-                gdprintk(XENLOG_WARNING, "Attempt to change CR4 flags.\n");
-                goto fail;
-            }
+                gdprintk(XENLOG_WARNING,
+                         "Attempt to change CR4 flags %08lx -> %08lx\n",
+                         read_cr4() & ~(X86_CR4_PGE|X86_CR4_PSE), *reg);
             break;
 
         default:

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