diff mbox series

x86/cpufeatures: Fix dependencies for GFNI, VAES, and VPCLMULQDQ

Message ID 20240417060434.47101-1-ebiggers@kernel.org (mailing list archive)
State Not Applicable
Delegated to: Herbert Xu
Headers show
Series x86/cpufeatures: Fix dependencies for GFNI, VAES, and VPCLMULQDQ | expand

Commit Message

Eric Biggers April 17, 2024, 6:04 a.m. UTC 
From: Eric Biggers <ebiggers@google.com>

Fix cpuid_deps[] to list the correct dependencies for GFNI, VAES, and
VPCLMULQDQ.  These features don't depend on AVX512, and there exist CPUs
that support these features but not AVX512.  GFNI actually doesn't even
depend on AVX.

This prevents GFNI from being unnecessarily disabled if AVX is disabled
to mitigate the GDS vulnerability.

This also prevents all three features from being unnecessarily disabled
if AVX512VL (or its dependency AVX512F) were to be disabled, but it
looks like there isn't any case where this happens anyway.

Fixes: c128dbfa0f87 ("x86/cpufeatures: Enable new SSE/AVX/AVX512 CPU features")
Signed-off-by: Eric Biggers <ebiggers@google.com>
---
 arch/x86/kernel/cpu/cpuid-deps.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)


base-commit: 20cb38a7af88dc40095da7c2c9094da3873fea23

Comments

Dave Hansen April 18, 2024, 2:24 p.m. UTC | #1 
On 4/16/24 23:04, Eric Biggers wrote:
> Fix cpuid_deps[] to list the correct dependencies for GFNI, VAES, and
> VPCLMULQDQ.  These features don't depend on AVX512, and there exist CPUs
> that support these features but not AVX512.  GFNI actually doesn't even
> depend on AVX.
> 
> This prevents GFNI from being unnecessarily disabled if AVX is disabled
> to mitigate the GDS vulnerability.

Looks like the original commit was quite confused.  Thanks for finding this.

Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
diff mbox series

Patch

diff --git a/arch/x86/kernel/cpu/cpuid-deps.c b/arch/x86/kernel/cpu/cpuid-deps.c
index b7174209d855..946813d816bf 100644
--- a/arch/x86/kernel/cpu/cpuid-deps.c
+++ b/arch/x86/kernel/cpu/cpuid-deps.c
@@ -42,11 +42,14 @@  static const struct cpuid_dep cpuid_deps[] = {
 	{ X86_FEATURE_PCLMULQDQ,		X86_FEATURE_XMM2      },
 	{ X86_FEATURE_SSSE3,			X86_FEATURE_XMM2,     },
 	{ X86_FEATURE_F16C,			X86_FEATURE_XMM2,     },
 	{ X86_FEATURE_AES,			X86_FEATURE_XMM2      },
 	{ X86_FEATURE_SHA_NI,			X86_FEATURE_XMM2      },
+	{ X86_FEATURE_GFNI,			X86_FEATURE_XMM2      },
 	{ X86_FEATURE_FMA,			X86_FEATURE_AVX       },
+	{ X86_FEATURE_VAES,			X86_FEATURE_AVX       },
+	{ X86_FEATURE_VPCLMULQDQ,		X86_FEATURE_AVX       },
 	{ X86_FEATURE_AVX2,			X86_FEATURE_AVX,      },
 	{ X86_FEATURE_AVX512F,			X86_FEATURE_AVX,      },
 	{ X86_FEATURE_AVX512IFMA,		X86_FEATURE_AVX512F   },
 	{ X86_FEATURE_AVX512PF,			X86_FEATURE_AVX512F   },
 	{ X86_FEATURE_AVX512ER,			X86_FEATURE_AVX512F   },
@@ -54,13 +57,10 @@  static const struct cpuid_dep cpuid_deps[] = {
 	{ X86_FEATURE_AVX512DQ,			X86_FEATURE_AVX512F   },
 	{ X86_FEATURE_AVX512BW,			X86_FEATURE_AVX512F   },
 	{ X86_FEATURE_AVX512VL,			X86_FEATURE_AVX512F   },
 	{ X86_FEATURE_AVX512VBMI,		X86_FEATURE_AVX512F   },
 	{ X86_FEATURE_AVX512_VBMI2,		X86_FEATURE_AVX512VL  },
-	{ X86_FEATURE_GFNI,			X86_FEATURE_AVX512VL  },
-	{ X86_FEATURE_VAES,			X86_FEATURE_AVX512VL  },
-	{ X86_FEATURE_VPCLMULQDQ,		X86_FEATURE_AVX512VL  },
 	{ X86_FEATURE_AVX512_VNNI,		X86_FEATURE_AVX512VL  },
 	{ X86_FEATURE_AVX512_BITALG,		X86_FEATURE_AVX512VL  },
 	{ X86_FEATURE_AVX512_4VNNIW,		X86_FEATURE_AVX512F   },
 	{ X86_FEATURE_AVX512_4FMAPS,		X86_FEATURE_AVX512F   },
 	{ X86_FEATURE_AVX512_VPOPCNTDQ,		X86_FEATURE_AVX512F   },