[Xen-changelog] [xen-unstable] Hide RDTSCP feature flag from PV guests.

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

# HG changeset patch
# User kfraser@xxxxxxxxxxxxxxxxxxxxx
# Date 1170432433 0
# Node ID 01ec7dba9ff805a5c74a0318997b747d3e3e3327
# Parent  1e56ac73b9b9d2a23d8d9b7b3382c372b38bc7b8
Hide RDTSCP feature flag from PV guests.

Linux 2.6.19 (x86-64) makes use of this feature if available, but Xen
(validly) fails the attempt to write the respective MSR. Hence the
feature must be hidden from PV guests.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>
---
 xen/arch/x86/traps.c             |    5 +++++
 xen/include/asm-x86/cpufeature.h |    1 +
 2 files changed, 6 insertions(+)

diff -r 1e56ac73b9b9 -r 01ec7dba9ff8 xen/arch/x86/traps.c
--- a/xen/arch/x86/traps.c      Fri Feb 02 16:04:11 2007 +0000
+++ b/xen/arch/x86/traps.c      Fri Feb 02 16:07:13 2007 +0000
@@ -596,6 +596,11 @@ static int emulate_forced_invalid_op(str
             clear_bit(X86_FEATURE_SEP, &d);
         if ( !IS_PRIV(current->domain) )
             clear_bit(X86_FEATURE_MTRR, &d);
+    }
+    else if ( regs->eax == 0x80000001 )
+    {
+        /* Modify Feature Information. */
+        clear_bit(X86_FEATURE_RDTSCP % 32, &d);
     }
     else
     {
diff -r 1e56ac73b9b9 -r 01ec7dba9ff8 xen/include/asm-x86/cpufeature.h
--- a/xen/include/asm-x86/cpufeature.h  Fri Feb 02 16:04:11 2007 +0000
+++ b/xen/include/asm-x86/cpufeature.h  Fri Feb 02 16:07:13 2007 +0000
@@ -49,6 +49,7 @@
 #define X86_FEATURE_MP         (1*32+19) /* MP Capable. */
 #define X86_FEATURE_NX         (1*32+20) /* Execute Disable */
 #define X86_FEATURE_MMXEXT     (1*32+22) /* AMD MMX extensions */
+#define X86_FEATURE_RDTSCP     (1*32+27) /* RDTSCP */
 #define X86_FEATURE_LM         (1*32+29) /* Long Mode (x86-64) */
 #define X86_FEATURE_3DNOWEXT   (1*32+30) /* AMD 3DNow! extensions */
 #define X86_FEATURE_3DNOW      (1*32+31) /* 3DNow! */

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