[PATCH 10/10] x86/xsaves: Re-enable XSAVES

From: Yu-cheng Yu
Date: Mon Feb 22 2016 - 14:03:56 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 | 15 ---------------
1 file changed, 15 deletions(-)

diff --git a/arch/x86/kernel/fpu/init.c b/arch/x86/kernel/fpu/init.c
index b5952d5..6bfa059 100644
--- a/arch/x86/kernel/fpu/init.c
+++ b/arch/x86/kernel/fpu/init.c
@@ -226,21 +226,6 @@ 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. )
- */
- setup_clear_cpu_cap(X86_FEATURE_XSAVES);
}

/*
--
1.9.1