Messages in this thread Patch in this message | | | From | Yu-cheng Yu <> | Subject | [PATCH v6 13/13] x86/xsaves: Re-enable XSAVES | Date | Tue, 10 May 2016 16:30:05 -0700 |
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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.yu@intel.com> Reviewed-by: Dave Hansen <dave.hansen@intel.com> --- arch/x86/kernel/fpu/init.c | 15 --------------- arch/x86/kernel/fpu/xstate.c | 10 ++++++++++ 2 files changed, 10 insertions(+), 15 deletions(-)
diff --git a/arch/x86/kernel/fpu/init.c b/arch/x86/kernel/fpu/init.c index eccc36b..2b4f871 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 7c2cdc4..fed95f5 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -222,6 +222,16 @@ void fpu__init_cpu_xstate(void) if (!cpu_has_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); } -- 1.9.1
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