[PATCH v2 9/9] x86/xsaves: Re-enable XSAVES
From: Yu-cheng Yu
Date: Thu Feb 25 2016 - 15:31:35 EST
We did not handle XSAVES* instructions correctly. There were issues in
converting between standard and compacted format when interfacing with
user-space. These issues have been corrected.
Signed-off-by: Yu-cheng Yu <yu-cheng.yu@xxxxxxxxx>
arch/x86/kernel/fpu/init.c | 16 ++++------------
1 file changed, 4 insertions(+), 12 deletions(-)
diff --git a/arch/x86/kernel/fpu/init.c b/arch/x86/kernel/fpu/init.c
index b5952d5..21e0d52 100644
@@ -228,19 +228,11 @@ static void __init fpu__init_system_xstate_size_legacy(void)
user_xstate_size = kernel_xstate_size;
- * Quirk: we don't yet handle the XSAVES* instructions
- * correctly, as we don't correctly convert between
- * standard and compacted format when interfacing
- * with user-space - so disable it for now.
- * The difference is small: with recent CPUs the
- * compacted format is only marginally smaller than
- * the standard FPU state format.
- * ( This is easy to backport while we are fixing
- * XSAVES* support. )
+ * Most recent CPUs supporting XSAVES can run 64-bit mode.
+ * Enable XSAVES for 64-bit.
+ if (!config_enabled(CONFIG_X86_64))