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Mon, 16 Dec 2024 19:05:13 +0000 Message-ID: Date: Mon, 16 Dec 2024 11:05:10 -0800 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 09/10] x86/fpu: Remove unnecessary CPUID level check To: Dave Hansen , CC: , , , , , , , References: <20241213205026.25B1D283@davehans-spike.ostc.intel.com> <20241213205038.6E71F9A4@davehans-spike.ostc.intel.com> Content-Language: en-US From: "Chang S. 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> } > > - if (boot_cpu_data.cpuid_level < XSTATE_CPUID) { > - WARN_ON_FPU(1); > - return; > - } > - I think this change effectively reverts commit ee813d53a8e9 ("x86, xsave: Check cpuid level for XSTATE_CPUID (0x0d)"). At the time of its introduction, commit b38b06659055 ("x86: filter CPU features dependent on unavailable CPUID levels") was already there. The cpu_has_xsave flag (now boot_cpu_has(X86_FEATURE_XSAVE)) should be false for CPUs with a lower CPUID level in this: void __cpuinit xsave_init(void) { if (!cpu_has_xsave) return; ... xstate_enable_boot_cpu(); } Then, the sanity check introduced in this code path appears redundant: xsave_init() -> xstate_enable_boot_cpu() -> setup_xstate_init() -> setup_xstate_features() Reviewed-by: Chang S. Bae Thanks, Chang