diff options
| author | Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> | 2009-10-22 16:41:15 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2009-11-09 16:22:41 -0800 |
| commit | 9416d12bcaa77126bd55f7df2cb4e78b711f97bd (patch) | |
| tree | 7b56ae0c17fe2e3f4b21b66fca6f01a8a4634354 /arch | |
| parent | b318606e41620d2fee78444ae54533a323108e2b (diff) | |
| download | lwn-9416d12bcaa77126bd55f7df2cb4e78b711f97bd.tar.gz lwn-9416d12bcaa77126bd55f7df2cb4e78b711f97bd.zip | |
xen: mask extended topology info in cpuid
commit 82d6469916c6fcfa345636a49004c9d1753905d1 upstream.
A Xen guest never needs to know about extended topology, and knowing
would just confuse it.
This patch just zeros ebx in leaf 0xb which indicates no topology info,
preventing a crash under Xen on cpus which support this leaf.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/xen/enlighten.c | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c index 3839a0fd3f4c..a11a115d82d3 100644 --- a/arch/x86/xen/enlighten.c +++ b/arch/x86/xen/enlighten.c @@ -178,6 +178,7 @@ static __read_mostly unsigned int cpuid_leaf1_ecx_mask = ~0; static void xen_cpuid(unsigned int *ax, unsigned int *bx, unsigned int *cx, unsigned int *dx) { + unsigned maskebx = ~0; unsigned maskecx = ~0; unsigned maskedx = ~0; @@ -185,9 +186,16 @@ static void xen_cpuid(unsigned int *ax, unsigned int *bx, * Mask out inconvenient features, to try and disable as many * unsupported kernel subsystems as possible. */ - if (*ax == 1) { + switch (*ax) { + case 1: maskecx = cpuid_leaf1_ecx_mask; maskedx = cpuid_leaf1_edx_mask; + break; + + case 0xb: + /* Suppress extended topology stuff */ + maskebx = 0; + break; } asm(XEN_EMULATE_PREFIX "cpuid" @@ -197,6 +205,7 @@ static void xen_cpuid(unsigned int *ax, unsigned int *bx, "=d" (*dx) : "0" (*ax), "2" (*cx)); + *bx &= maskebx; *cx &= maskecx; *dx &= maskedx; } |