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Wed, 26 Mar 2025 18:44:00 +0000 Message-ID: <97d77c5f-eb99-4c82-9b58-9783060c2810@intel.com> Date: Wed, 26 Mar 2025 11:43:58 -0700 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2a 3/6] x86/microcode/intel: Establish staging control logic To: Chao Gao CC: , , , , , , References: <20250320234104.8288-4-chang.seok.bae@intel.com> <20250321211853.13909-1-chang.seok.bae@intel.com> Content-Language: en-US From: "Chang S. 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Yes, it looks equivalent but shorter. > So, how about: > > if (cpu != cpumask_first(topology_core_cpumask(cpu))) > continue; > > and dropping the pkg_id? No, the pkg_id check is intentional to prevent duplicate staging within a package. As noted in the comment: "The MMIO address is unique per package." >> + rdmsrl_on_cpu(cpu, MSR_IA32_MCU_STAGING_MBOX_ADDR, &mmio_pa); > > Note rdmsrl_on_cpu() may return an error. please consider adding > error-handling. Is it possible that somehow one package doesn't support > this staging feature while others do? rdmsrl_on_cpu() -> smp_call_function_single() -> generic_exec_single(): if ((unsigned)cpu >= nr_cpu_ids || !cpu_online(cpu)) { csd_unlock(csd); return -ENXIO; } This error condition applies to an invalid cpu, but since the function is guarded by cpu_online_mask, it should not occur. That said though, ignoring the return value may appear to be incorrect. Perhaps, err = rdmsrl_on_cpu(cpu, MSR_IA32_MCU_STAGING_MBOX_ADDR, &mmio_pa); if (WARN_ON_ONCE(err)) return; > Shall we print a message somewhere showing "Continuing updates without > staging"? > > It could be confusing for users to see a success message following an error > message that states "Error: staging failed ..." This function already prints either a success or failure message based on staging results which are variable. But this behavior follows the established policy that loading should continue even if staging fails, which is a known and invariant behavior at runtime. So, explicitly stating that updates will proceed without staging seems redundant and could be considered noise. Thanks, Chang