[PATCH v2 17/22] x86/cpufeatures/amx: Enumerate Advanced Matrix Extension (AMX) feature bits

From: Chang S. Bae
Date: Thu Nov 19 2020 - 18:37:23 EST


Intel's Advanced Matrix Extension (AMX) is a new 64-bit extended feature
consisting of two-dimensional registers and an accelerator unit. The first
implementation of the latter is the tile matrix multiply unit (TMUL). TMUL
performs SIMD dot-products on four bytes (INT8) or two bfloat16
floating-point (BF16) elements.

Here we add AMX to the kernel/user ABI, by enumerating the capability.
E.g., /proc/cpuinfo: amx_tile, amx_bf16, amx_int8

Signed-off-by: Chang S. Bae <chang.seok.bae@xxxxxxxxx>
Reviewed-by: Len Brown <len.brown@xxxxxxxxx>
Cc: x86@xxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
---
arch/x86/include/asm/cpufeatures.h | 3 +++
arch/x86/kernel/cpu/cpuid-deps.c | 3 +++
2 files changed, 6 insertions(+)

diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index 5b6496ee3703..a1839b6a1929 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -375,6 +375,9 @@
#define X86_FEATURE_TSXLDTRK (18*32+16) /* TSX Suspend Load Address Tracking */
#define X86_FEATURE_PCONFIG (18*32+18) /* Intel PCONFIG */
#define X86_FEATURE_ARCH_LBR (18*32+19) /* Intel ARCH LBR */
+#define X86_FEATURE_AMX_BF16 (18*32+22) /* AMX BF16 Support */
+#define X86_FEATURE_AMX_TILE (18*32+24) /* AMX tile Support */
+#define X86_FEATURE_AMX_INT8 (18*32+25) /* AMX INT8 Support */
#define X86_FEATURE_SPEC_CTRL (18*32+26) /* "" Speculation Control (IBRS + IBPB) */
#define X86_FEATURE_INTEL_STIBP (18*32+27) /* "" Single Thread Indirect Branch Predictors */
#define X86_FEATURE_FLUSH_L1D (18*32+28) /* Flush L1D cache */
diff --git a/arch/x86/kernel/cpu/cpuid-deps.c b/arch/x86/kernel/cpu/cpuid-deps.c
index d502241995a3..aed150626ea0 100644
--- a/arch/x86/kernel/cpu/cpuid-deps.c
+++ b/arch/x86/kernel/cpu/cpuid-deps.c
@@ -71,6 +71,9 @@ static const struct cpuid_dep cpuid_deps[] = {
{ X86_FEATURE_AVX512_BF16, X86_FEATURE_AVX512VL },
{ X86_FEATURE_ENQCMD, X86_FEATURE_XSAVES },
{ X86_FEATURE_PER_THREAD_MBA, X86_FEATURE_MBA },
+ { X86_FEATURE_AMX_TILE, X86_FEATURE_XSAVE },
+ { X86_FEATURE_AMX_INT8, X86_FEATURE_AMX_TILE },
+ { X86_FEATURE_AMX_BF16, X86_FEATURE_AMX_TILE },
{}
};

--
2.17.1