[Xen-changelog] [xen-3.4-testing] xen/libxc: set CPUID topology leaf as unsupported for PV guests

[Xen patchbot-3.4-testing <patchbot@xxxxxxx>]

# HG changeset patch
# User Keith Coleman <keith.coleman@xxxxxxxxxxxxx>
# Date 1325657708 18000
# Node ID 606abc216dbb9cbdb8af02b50fc135e9c4e60786
# Parent  7b68af1f52e749084bfd03eac97191d8ae8a7a90
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>
xen-unstable changeset: 23700:867bb675b57b
xen-unstable date: Sat Jul 16 09:05:45 2011 +0100
---


diff -r 7b68af1f52e7 -r 606abc216dbb tools/libxc/xc_cpuid_x86.c
--- a/tools/libxc/xc_cpuid_x86.c        Wed Jan 04 01:07:02 2012 -0500
+++ b/tools/libxc/xc_cpuid_x86.c        Wed Jan 04 01:15:08 2012 -0500
@@ -334,6 +334,7 @@
         break;
     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 */
         regs[0] = regs[1] = regs[2] = regs[3] = 0;
diff -r 7b68af1f52e7 -r 606abc216dbb xen/arch/x86/traps.c
--- a/xen/arch/x86/traps.c      Wed Jan 04 01:07:02 2012 -0500
+++ b/xen/arch/x86/traps.c      Wed Jan 04 01:15:08 2012 -0500
@@ -784,6 +784,7 @@
         break;
     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 */
         a = b = c = d = 0;

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