[PATCH v2 0/5] x86: cpuid: improve support for broken CPUID configurations

Maxim Levitsky
2022-07-18T14:11:39Z

This patch series aims to harden the cpuid code against the case when
the hypervisor exposes a broken CPUID configuration to the guest,
in the form of having a feature disabled but not features that depend on it.

This is the more generic way to fix kernel panic in aes-ni kernel driver,
which was triggered by CPUID configuration in which AVX is disabled but
not AVX2.

https://lore.kernel.org/all/20211103145231.GA4485@gondor.apana.org.au/T/

This was tested by booting a guest with AVX disabled and not AVX2,
and observing that both a warning is now printed in dmesg, and
that avx2 is gone from /proc/cpuinfo.

V2:

I hopefully addressed all the (very good) review feedback.

Best regards,
Maxim Levitsky

Maxim Levitsky (5):
perf/x86/intel/lbr: use setup_clear_cpu_cap instead of clear_cpu_cap
x86/cpuid: refactor setup_clear_cpu_cap()/clear_cpu_cap()
x86/cpuid: move filter_cpuid_features to cpuid-deps.c
x86/cpuid: remove 'warn' parameter from filter_cpuid_features
x86/cpuid: check for dependencies violations in CPUID and attempt to
fix them

arch/x86/events/intel/lbr.c | 2 +-
arch/x86/include/asm/cpufeature.h | 1 +
arch/x86/kernel/cpu/common.c | 51 +-------------------
arch/x86/kernel/cpu/cpuid-deps.c | 80 +++++++++++++++++++++++++++----
4 files changed, 74 insertions(+), 60 deletions(-)

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2.34.3