Commit-ID: b8be15d588060a03569ac85dc4a0247460988f5b Gitweb: http://git.kernel.org/tip/b8be15d588060a03569ac85dc4a0247460988f5b Author: Yu-cheng Yu <yu-cheng...@intel.com> AuthorDate: Mon, 11 Jul 2016 09:18:57 -0700 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Mon, 11 Jul 2016 16:44:01 +0200
x86/fpu/xstate: Re-enable XSAVES 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. Add a WARN_ONCE() to make it clear that XSAVES supervisor states are not yet implemented. Signed-off-by: Yu-cheng Yu <yu-cheng...@intel.com> Signed-off-by: Fenghua Yu <fenghua...@intel.com> Reviewed-by: Dave Hansen <dave.han...@intel.com> Cc: H. Peter Anvin <h.peter.an...@intel.com> Cc: Linus Torvalds <torva...@linux-foundation.org> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Ravi V Shankar <ravi.v.shan...@intel.com> Cc: Thomas Gleixner <t...@linutronix.de> Link: http://lkml.kernel.org/r/1468253937-40008-5-git-send-email-fenghua...@intel.com Signed-off-by: Ingo Molnar <mi...@kernel.org> --- arch/x86/kernel/fpu/init.c | 15 --------------- arch/x86/kernel/fpu/xstate.c | 9 +++++++++ 2 files changed, 9 insertions(+), 15 deletions(-) diff --git a/arch/x86/kernel/fpu/init.c b/arch/x86/kernel/fpu/init.c index 60f3839..93982ae 100644 --- a/arch/x86/kernel/fpu/init.c +++ b/arch/x86/kernel/fpu/init.c @@ -230,21 +230,6 @@ static void __init fpu__init_system_xstate_size_legacy(void) } fpu_user_xstate_size = fpu_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); } /* diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index 4fb8dd7..3169bca 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -221,6 +221,15 @@ void fpu__init_cpu_xstate(void) { if (!boot_cpu_has(X86_FEATURE_XSAVE) || !xfeatures_mask) return; + /* + * Make it clear that XSAVES supervisor states are not yet + * implemented should anyone expect it to work by changing + * bits in XFEATURE_MASK_* macros and XCR0. + */ + WARN_ONCE((xfeatures_mask & XFEATURE_MASK_SUPERVISOR), + "x86/fpu: XSAVES supervisor states are not yet implemented.\n"); + + xfeatures_mask &= ~XFEATURE_MASK_SUPERVISOR; cr4_set_bits(X86_CR4_OSXSAVE); xsetbv(XCR_XFEATURE_ENABLED_MASK, xfeatures_mask);
