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Subject[tip:x86/fpu] x86, xsave: Disable xsave in i387 emulation mode
Commit-ID:  1f999ab5a1360afc388868cc0ef9afe8edeef3be
Gitweb: http://git.kernel.org/tip/1f999ab5a1360afc388868cc0ef9afe8edeef3be
Author: Robert Richter <robert.richter@amd.com>
AuthorDate: Wed, 21 Jul 2010 19:03:57 +0200
Committer: H. Peter Anvin <hpa@linux.intel.com>
CommitDate: Thu, 12 Aug 2010 14:16:54 -0700

x86, xsave: Disable xsave in i387 emulation mode

xsave is broken for (!HAVE_HWFP). This is the case if config
MATH_EMULATION is enabled, 'no387' kernel parameter is set and xsave
exists. xsave will not work because x86/math-emu and xsave share the
same memory. As this case can be treated as corner case we simply
disable xsave then.

Signed-off-by: Robert Richter <robert.richter@amd.com>
LKML-Reference: <1279731838-1522-7-git-send-email-robert.richter@amd.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
---
arch/x86/kernel/i387.c | 6 ++++++
1 files changed, 6 insertions(+), 0 deletions(-)
diff --git a/arch/x86/kernel/i387.c b/arch/x86/kernel/i387.c
index 1f11f5c..2605c50 100644
--- a/arch/x86/kernel/i387.c
+++ b/arch/x86/kernel/i387.c
@@ -67,6 +67,12 @@ static void __cpuinit init_thread_xstate(void)
*/

if (!HAVE_HWFP) {
+ /*
+ * Disable xsave as we do not support it if i387
+ * emulation is enabled.
+ */
+ setup_clear_cpu_cap(X86_FEATURE_XSAVE);
+ setup_clear_cpu_cap(X86_FEATURE_XSAVEOPT);
xstate_size = sizeof(struct i387_soft_struct);
return;
}

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