linux-kernel - Re: [PATCH] x86/mce: Schedule mce_setup() on correct CPU for CPER decoding

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <471df10c-782d-f251-f8ff-59b01ed097b2@amd.com>
Date:   Fri, 16 Jun 2023 10:16:51 -0400
From:   Yazen Ghannam <yazen.ghannam@....com>
To:     "Luck, Tony" <tony.luck@...el.com>, Borislav Petkov <bp@...en8.de>
Cc:     yazen.ghannam@....com,
        "linux-edac@...r.kernel.org" <linux-edac@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "x86@...nel.org" <x86@...nel.org>
Subject: Re: [PATCH] x86/mce: Schedule mce_setup() on correct CPU for CPER
 decoding

On 6/15/2023 1:54 PM, Luck, Tony wrote:
>>          for_each_possible_cpu(cpu) {
>>                  if (cpu_data(cpu).initial_apicid == lapic_id) {
>>                          m.extcpu = cpu;
> 
> Are there any other places in the kernel where we need to find the
> Linux CPU number starting from the apic id?
> 
> I briefly looked a while back when I needed this for some
> debug use case and didn't find it then. But Linux changes
> and maybe there are some now.
> 
> Which is a long way to say I'd like to see boot code initialize an array so the above
> could just be:
> 
> 	m.extcpu = lapic_to_cpu[lapic_id];
>

So functionally the inverse of "x86_cpu_to_apicid", right? Though not 
per_cpu, of course.

I'll try and write this up if I don't find anything like it.

> But we'd need at least a couple of use cases to justify.
> 

Can you describe your original use case?

Thanks,
Yazen