From: kfraser@localhost.localdomain <kfraser@localhost.localdomain>
Date: Wed, 29 Aug 2007 13:54:14 +0000 (+0100)
Subject: x86: Do not #GP when guest writes unexpected values to CR4. Just
X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~14987^2~54
X-Git-Url: https://dgit.raspbian.org/%22http:/www.example.com/cgi/%22https:/%22bookmarks://%22Dat/%22http:/www.example.com/cgi/%22https:/%22bookmarks:/%22Dat?a=commitdiff_plain;h=17af24e1892dc45e2cca26a9bed9d8a09d715c67;p=xen.git

x86: Do not #GP when guest writes unexpected values to CR4. Just
ignore them.
Signed-off-by: Keir Fraser <keir@xensource.com>
---

diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c
index f89e169108..459077a822 100644
--- a/xen/arch/x86/traps.c
+++ b/xen/arch/x86/traps.c
@@ -1673,12 +1673,11 @@ static int emulate_privileged_op(struct cpu_user_regs *regs)
                 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: