On November 2, 2022 7:27:52 AM PDT, "Elliott, Robert (Servers)" <elliott@xxxxxxx> wrote: > >> From: Paolo Bonzini <pbonzini@xxxxxxxxxx> >... >> (2) in particular holds even on bare metal. The kernel bug here is that >> X86_FEATURE_AVX only tells you if the instructions are _present_, not if >> they are _usable_. Indeed, the XCR0 check is present for all other >> files in arch/x86/crypto, either instead or in addition to >> boot_cpu_has(X86_FEATURE_AVX). >> >> Maxim had sent a patch about a year ago to do it in aesni-intel-glue.c >> but Dave told him to fix the dependencies instead >> (https://lore.kernel.org/all/20211103124614.499580-1- >> mlevitsk@xxxxxxxxxx/). >> What do you think of applying that patch instead? > >Most of the x86 crypto modules using X86_FEATURE_AVX do check > cpu_has_xfeatures(XFEATURE_MASK_YMM, ... > >so it's probably prudent to add it to the rest (or remove it everywhere >if it is not needed). > >1. Currently checking XSAVE YMM: > aria_aesni_avx_glue > blake2s-glue > camellia_aesni_avx2_glue camellia_aesni_avx_glue > cast5_avx_glue cast6_avx_glue > chacha_glue > poly1305_glue > serpent_avx2_glue serpent_avx_glue > sha1_ssse3_glue sha256_ssse3_glue sha512_ssse3_glue > sm3_avx_glue > sm4_aesni_avx2_glue sm4_aesni_avx_glue > twofish_avx_glue > >Currently not checking XSAVE YMM: > aesni-intel_glue > curve25519-x86_64 > nhpoly1305-avx2-glue > polyval-clmulni_glue > >2. Similarly, modules using X86_FEATURE_AVX512F, X86_FEATURE_AVXX512VL >and/or X86_FEATURE_AVX512BW probably need to check XFEATURE_MASK_AVX512: > >Currently checking XSAVE AVX512: > blake2s-glue > poly1305_glue > >Currently not checking XSAVE AVX512: > chacha_glue > >3. Similarly, modules using X86_FEATURE_XMM2 probably need to >check XFEATURE_MASK_SSE: > >Currently checking XSAVE SSE: > aegis128-aesni-glue > >Current not checking XSAVE SSE: > nhpoly1305-sse2_glue > serpent_sse2_glue > > > We have a dependency system for CPUID features. If you are going to do this (as opposed to "fixing" this in Qemu or just saying "don't do that, it isn't a valid hardware configuration."
