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h=Date:Subject:From:To:Cc:References:In-Reply-To:From; b=P+XOR+ascBKH5UlIhU7GbgsYk9tqHVI5mzNuSvPKVMajt16J0Ms5atBT63dnIuPht vQOP024oaeRIMKFie4ObxLtGREKd53fIGnrwUluDPng5CxqxlfoNL5MNQgChgCdby8 r5V6EtURoK7zChkfHZraJw9x9NIWneCvHWwSLX1OsSMTCINOT94/mtGdK7lXJOlgPW IVkgslx0yQxCkm8H8te349d2lpWG8kijRZG+uqS83tI7EvWjHxrguZZ3ZS7OEHAlfX P/qJs57bDniajMOJlxqBklCP9ShvFe/pjWQKqmFP1pvz1qMJyjDry+JPsS9lllPSik SsWuvrn6SQ0/A== Message-ID: <4b44eaec-2c45-4a68-80c5-6a8c0905b1ab@zytor.com> Date: Fri, 7 Mar 2025 10:28:56 -0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v7 0/4] x86/cpufeatures: Automatically generate required and disabled feature masks From: Xin Li To: linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org Cc: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, will@kernel.org, peterz@infradead.org, yury.norov@gmail.com, akpm@linux-foundation.org, acme@kernel.org, namhyung@kernel.org, brgerst@gmail.com, andrew.cooper3@citrix.com, nik.borisov@suse.com, sraithal@amd.com, philip.li@intel.com References: <20250305184725.3341760-1-xin@zytor.com> Content-Language: en-US Autocrypt: addr=xin@zytor.com; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 3/5/2025 10:47 AM, Xin Li (Intel) wrote: > The x86 build process first generates required and disabled feature > masks based on current build config, and then uses these generated > masks to compile the source code. When a CPU feature is not enabled > in a build config, e.g., when CONFIG_X86_FRED=n, its feature disable > flag, i.e., DISABLE_FRED, needs to be properly defined and added to > a specific disabled CPU features mask in , > as the following patch does: > https://lore.kernel.org/all/20231205105030.8698-8-xin3.li@intel.com/. > As a result, the FRED feature bit is surely cleared in the generated > kernel binary when CONFIG_X86_FRED=n. > > Recently there is another case to repeat the same exercise for the > AMD SEV-SNP CPU feature: > https://lore.kernel.org/all/20240126041126.1927228-2-michael.roth@amd.com/. > https://lore.kernel.org/all/20240126041126.1927228-23-michael.roth@amd.com/. > > It was one thing when there were four of CPU feature masks, but with > over 20 it is going to cause mistakes, e.g., > https://lore.kernel.org/lkml/aaed79d5-d683-d1bc-7ba1-b33c8d6db618@suse.com/. > > We want to eliminate the stupidly repeated exercise to manually assign > features to CPU feature words through introducing an AWK script to > automatically generate a header with required and disabled CPU feature > masks based on current build config, and this patch set does that. > > Link to v6: > https://lore.kernel.org/lkml/20250228082338.73859-1-xin@zytor.com/ > > Changes in v7: > * Fix build error with "make distclean; make headers" (Aithal, Srikanth) > * Collect reviewed-bys. > This version v7 can be cleanly applied on tip/x86/cpu but NOT the latest tip/master. I guess I don't have to rebase on the latest tip/master and resend it? Thanks! Xin > > H. Peter Anvin (Intel) (2): > x86/cpufeatures: Add {required,disabled} feature configs > x86/cpufeatures: Generate a feature mask header based on build config > > Xin Li (Intel) (2): > x86/cpufeatures: Remove {disabled,required}-features.h > x86/cpufeatures: Use AWK to generate {REQUIRED|DISABLED}_MASK_BIT_SET > > arch/x86/Kconfig | 2 + > arch/x86/Kconfig.cpufeatures | 197 ++++++++++++++++++ > arch/x86/Makefile | 15 ++ > arch/x86/boot/cpucheck.c | 3 +- > arch/x86/boot/cpuflags.c | 1 - > arch/x86/boot/mkcpustr.c | 3 +- > arch/x86/include/asm/Kbuild | 1 + > arch/x86/include/asm/cpufeature.h | 70 +------ > arch/x86/include/asm/cpufeatures.h | 8 - > arch/x86/include/asm/disabled-features.h | 161 -------------- > arch/x86/include/asm/required-features.h | 105 ---------- > arch/x86/kernel/verify_cpu.S | 4 + > arch/x86/tools/featuremasks.awk | 88 ++++++++ > tools/arch/x86/include/asm/cpufeatures.h | 8 - > .../arch/x86/include/asm/disabled-features.h | 161 -------------- > .../arch/x86/include/asm/required-features.h | 105 ---------- > tools/perf/check-headers.sh | 2 - > 17 files changed, 311 insertions(+), 623 deletions(-) > create mode 100644 arch/x86/Kconfig.cpufeatures > delete mode 100644 arch/x86/include/asm/disabled-features.h > delete mode 100644 arch/x86/include/asm/required-features.h > create mode 100755 arch/x86/tools/featuremasks.awk > delete mode 100644 tools/arch/x86/include/asm/disabled-features.h > delete mode 100644 tools/arch/x86/include/asm/required-features.h > > > base-commit: 32dc26a2f55f71907af0874468298c6ab8a8f7f9