x86/fpu: Add FPU state copying quirk to handle XRSTOR failure on Intel Skylake CPUs
authorRik van Riel <riel@redhat.com>
Sat, 23 Sep 2017 13:00:04 +0000 (15:00 +0200)
committerIngo Molnar <mingo@kernel.org>
Sun, 24 Sep 2017 11:04:34 +0000 (13:04 +0200)
commit0852b374173bb57f870d78e6c6839c77b339be5f
tree5dc1a0236423ee5b4708d534a7cbb7fd898d2bbc
parent99dc26bda233ee722bbd370bddf20beece3ffb93
x86/fpu: Add FPU state copying quirk to handle XRSTOR failure on Intel Skylake CPUs

On Skylake CPUs I noticed that XRSTOR is unable to deal with states
created by copyout_from_xsaves() if the xstate has only SSE/YMM state, and
no FP state. That is, xfeatures had XFEATURE_MASK_SSE set, but not
XFEATURE_MASK_FP.

The reason is that part of the SSE/YMM state lives in the MXCSR and
MXCSR_FLAGS fields of the FP state.

Ensure that whenever we copy SSE or YMM state around, the MXCSR and
MXCSR_FLAGS fields are also copied around.

Signed-off-by: Rik van Riel <riel@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Borislav Petkov <bp@suse.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Eric Biggers <ebiggers3@gmail.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Link: http://lkml.kernel.org/r/20170210085445.0f1cc708@annuminas.surriel.com
Link: http://lkml.kernel.org/r/20170923130016.21448-22-mingo@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
arch/x86/include/asm/fpu/types.h
arch/x86/kernel/fpu/xstate.c