The following commit has been merged into the x86/fpu branch of tip: Commit-ID: c351101678ce54492b6e09810ec02efc0df036a9 Gitweb: https://git.kernel.org/tip/c351101678ce54492b6e09810ec02efc0df036a9 Author: Chang S. Bae <chang.seok.bae@xxxxxxxxx> AuthorDate: Thu, 21 Oct 2021 15:55:16 -07:00 Committer: Borislav Petkov <bp@xxxxxxx> CommitterDate: Tue, 26 Oct 2021 10:18:09 +02:00 x86/cpufeatures: Add eXtended Feature Disabling (XFD) feature bit Intel's eXtended Feature Disable (XFD) feature is an extension of the XSAVE architecture. XFD allows the kernel to enable a feature state in XCR0 and to receive a #NM trap when a task uses instructions accessing that state. This is going to be used to postpone the allocation of a larger XSTATE buffer for a task to the point where it is actually using a related instruction after the permission to use that facility has been granted. XFD is not used by the kernel, but only applied to userspace. This is a matter of policy as the kernel knows how a fpstate is reallocated and the XFD state. The compacted XSAVE format is adjustable for dynamic features. Make XFD depend on XSAVES. Signed-off-by: Chang S. Bae <chang.seok.bae@xxxxxxxxx> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Signed-off-by: Chang S. Bae <chang.seok.bae@xxxxxxxxx> Signed-off-by: Borislav Petkov <bp@xxxxxxx> Link: https://lkml.kernel.org/r/20211021225527.10184-13-chang.seok.bae@xxxxxxxxx --- arch/x86/include/asm/cpufeatures.h | 1 + arch/x86/kernel/cpu/cpuid-deps.c | 1 + 2 files changed, 2 insertions(+) diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h index d0ce5cf..ab7b3a2 100644 --- a/arch/x86/include/asm/cpufeatures.h +++ b/arch/x86/include/asm/cpufeatures.h @@ -277,6 +277,7 @@ #define X86_FEATURE_XSAVEC (10*32+ 1) /* XSAVEC instruction */ #define X86_FEATURE_XGETBV1 (10*32+ 2) /* XGETBV with ECX = 1 instruction */ #define X86_FEATURE_XSAVES (10*32+ 3) /* XSAVES/XRSTORS instructions */ +#define X86_FEATURE_XFD (10*32+ 4) /* "" eXtended Feature Disabling */ /* * Extended auxiliary flags: Linux defined - for features scattered in various diff --git a/arch/x86/kernel/cpu/cpuid-deps.c b/arch/x86/kernel/cpu/cpuid-deps.c index defda61..d9ead9c 100644 --- a/arch/x86/kernel/cpu/cpuid-deps.c +++ b/arch/x86/kernel/cpu/cpuid-deps.c @@ -75,6 +75,7 @@ static const struct cpuid_dep cpuid_deps[] = { { X86_FEATURE_SGX_LC, X86_FEATURE_SGX }, { X86_FEATURE_SGX1, X86_FEATURE_SGX }, { X86_FEATURE_SGX2, X86_FEATURE_SGX1 }, + { X86_FEATURE_XFD, X86_FEATURE_XSAVES }, {} };
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