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authorJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>2009-10-22 19:41:15 -0400
committerJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>2009-11-03 14:09:12 -0500
commit82d6469916c6fcfa345636a49004c9d1753905d1 (patch)
treef4d95a9159234b66d26e4e8ebe661e105929234b /arch
parent7825cf10e31c64ece3cac66fb01a742f1094da51 (diff)
xen: mask extended topology info in cpuid
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> Cc: Stable Kernel <stable@kernel.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/xen/enlighten.c11
1 files changed, 10 insertions, 1 deletions
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 23a4d80fb39e..dfbf70e65860 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;
178static void xen_cpuid(unsigned int *ax, unsigned int *bx, 178static void xen_cpuid(unsigned int *ax, unsigned int *bx,
179 unsigned int *cx, unsigned int *dx) 179 unsigned int *cx, unsigned int *dx)
180{ 180{
181 unsigned maskebx = ~0;
181 unsigned maskecx = ~0; 182 unsigned maskecx = ~0;
182 unsigned maskedx = ~0; 183 unsigned maskedx = ~0;
183 184
@@ -185,9 +186,16 @@ static void xen_cpuid(unsigned int *ax, unsigned int *bx,
185 * Mask out inconvenient features, to try and disable as many 186 * Mask out inconvenient features, to try and disable as many
186 * unsupported kernel subsystems as possible. 187 * unsupported kernel subsystems as possible.
187 */ 188 */
188 if (*ax == 1) { 189 switch (*ax) {
190 case 1:
189 maskecx = cpuid_leaf1_ecx_mask; 191 maskecx = cpuid_leaf1_ecx_mask;
190 maskedx = cpuid_leaf1_edx_mask; 192 maskedx = cpuid_leaf1_edx_mask;
193 break;
194
195 case 0xb:
196 /* Suppress extended topology stuff */
197 maskebx = 0;
198 break;
191 } 199 }
192 200
193 asm(XEN_EMULATE_PREFIX "cpuid" 201 asm(XEN_EMULATE_PREFIX "cpuid"
@@ -197,6 +205,7 @@ static void xen_cpuid(unsigned int *ax, unsigned int *bx,
197 "=d" (*dx) 205 "=d" (*dx)
198 : "0" (*ax), "2" (*cx)); 206 : "0" (*ax), "2" (*cx));
199 207
208 *bx &= maskebx;
200 *cx &= maskecx; 209 *cx &= maskecx;
201 *dx &= maskedx; 210 *dx &= maskedx;
202} 211}