linux-kernel - Re: [PATCH v2 4/5] x86/mce: Define mce_prep_record() helpers for common and per-CPU fields

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Date: Tue, 25 Jun 2024 16:19:40 +0300
From: Nikolay Borisov <nik.borisov@...e.com>
To: Yazen Ghannam <yazen.ghannam@....com>, linux-edac@...r.kernel.org
Cc: linux-kernel@...r.kernel.org, tony.luck@...el.com, x86@...nel.org,
 avadhut.naik@....com, john.allen@....com
Subject: Re: [PATCH v2 4/5] x86/mce: Define mce_prep_record() helpers for
 common and per-CPU fields



On 25.06.24 г. 0:20 ч., Yazen Ghannam wrote:
> Generally, MCA information for an error is gathered on the CPU that
> reported the error. In this case, CPU-specific information from the
> running CPU will be correct.
> 
> However, this will be incorrect if the MCA information is gathered while
> running on a CPU that didn't report the error. One example is creating
> an MCA record using mce_prep_record() for errors reported from ACPI.
> 
> Split mce_prep_record() so that there is a helper function to gather
> common, i.e. not CPU-specific, information and another helper for
> CPU-specific information.
> 
> Leave mce_prep_record() defined as-is for the common case when running
> on the reporting CPU.
> 
> Get MCG_CAP in the global helper even though the register is per-CPU.
> This value is not already cached per-CPU like other values. And it does
> not assist with any per-CPU decoding or handling.
> 
> Signed-off-by: Yazen Ghannam <yazen.ghannam@....com>
> ---
> Link:
> https://lkml.kernel.org/r/20240521125434.1555845-3-yazen.ghannam@amd.com
> 
> v1->v2:
> * No change.
> 
>   arch/x86/kernel/cpu/mce/core.c     | 34 ++++++++++++++++++++----------
>   arch/x86/kernel/cpu/mce/internal.h |  2 ++
>   2 files changed, 25 insertions(+), 11 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c
> index dd5192ef52e0..0133f88dfffb 100644
> --- a/arch/x86/kernel/cpu/mce/core.c
> +++ b/arch/x86/kernel/cpu/mce/core.c
> @@ -117,20 +117,32 @@ static struct irq_work mce_irq_work;
>    */
>   BLOCKING_NOTIFIER_HEAD(x86_mce_decoder_chain);
>   
> -/* Do initial initialization of a struct mce */
> -void mce_prep_record(struct mce *m)
> +void mce_prep_record_common(struct mce *m)
>   {
>   	memset(m, 0, sizeof(struct mce));
> -	m->cpu = m->extcpu = smp_processor_id();
> +
> +	m->cpuid	= cpuid_eax(1);
> +	m->cpuvendor	= boot_cpu_data.x86_vendor;
> +	m->mcgcap	= __rdmsr(MSR_IA32_MCG_CAP);
>   	/* need the internal __ version to avoid deadlocks */
> -	m->time = __ktime_get_real_seconds();
> -	m->cpuvendor = boot_cpu_data.x86_vendor;
> -	m->cpuid = cpuid_eax(1);
> -	m->socketid = cpu_data(m->extcpu).topo.pkg_id;
> -	m->apicid = cpu_data(m->extcpu).topo.initial_apicid;
> -	m->mcgcap = __rdmsr(MSR_IA32_MCG_CAP);
> -	m->ppin = cpu_data(m->extcpu).ppin;
> -	m->microcode = boot_cpu_data.microcode;
> +	m->time		= __ktime_get_real_seconds();
> +}
> +
> +void mce_prep_record_per_cpu(unsigned int cpu, struct mce *m)
> +{
> +	m->cpu		= cpu;
> +	m->extcpu	= cpu;
> +	m->apicid	= cpu_data(m->extcpu).topo.initial_apicid;
> +	m->microcode	= cpu_data(m->extcpu).microcode;
> +	m->ppin		= cpu_data(m->extcpu).ppin;

nit: Similar to tglx's feedback for patch 2 you could use topology_ppin()

> +	m->socketid	= cpu_data(m->extcpu).topo.pkg_id;
nit: topology_physical_package_id()


> +}
> +


<snip>