[Xen-changelog] [xen-unstable] xen/libxc: set CPUID topology leaf as unsupported for PV guests

[Xen patchbot-unstable <patchbot@xxxxxxx>]

# HG changeset patch
# User David Vrabel <david.vrabel@xxxxxxxxxx>
# Date 1310803545 -3600
# Node ID 867bb675b57b54e81013b2f2aa2665fb0e882af8
# Parent  6fe9f26bb9aefa948ee6d3a26582d26465aca770
xen/libxc: set CPUID topology leaf as unsupported for PV guests

The result of a CPUID Extended Topology Enumeration leaf for PV guests
is invalid as the level in ECX is ignored.  This can cause some guests
to loop endlessly when trying to enumerate the topology.

Since the physical topology isn't useful to PV guests set the topology
leaf as unsupported.

Guests affected include Linux kernels prior 2.6.32 where a workaround
was applied ("xen: mask extended topology info in cpu",
82d6469916c6fcfa345636a49004c9d1753905d1).

Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>
---


diff -r 6fe9f26bb9ae -r 867bb675b57b tools/libxc/xc_cpuid_x86.c
--- a/tools/libxc/xc_cpuid_x86.c        Fri Jul 15 18:22:03 2011 +0100
+++ b/tools/libxc/xc_cpuid_x86.c        Sat Jul 16 09:05:45 2011 +0100
@@ -518,6 +518,7 @@
 
     case 5: /* MONITOR/MWAIT */
     case 0xa: /* Architectural Performance Monitor Features */
+    case 0x0000000b: /* Extended Topology Enumeration */
     case 0x8000000a: /* SVM revision and features */
     case 0x8000001b: /* Instruction Based Sampling */
     case 0x8000001c: /* Light Weight Profiling */
diff -r 6fe9f26bb9ae -r 867bb675b57b xen/arch/x86/traps.c
--- a/xen/arch/x86/traps.c      Fri Jul 15 18:22:03 2011 +0100
+++ b/xen/arch/x86/traps.c      Sat Jul 16 09:05:45 2011 +0100
@@ -861,6 +861,7 @@
         /* fall through */
     case 5: /* MONITOR/MWAIT */
     case 0xa: /* Architectural Performance Monitor Features */
+    case 0x0000000b: /* Extended Topology Enumeration */
     case 0x8000000a: /* SVM revision and features */
     case 0x8000001b: /* Instruction Based Sampling */
     case 0x8000001c: /* Light Weight Profiling */

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