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From: Yazen Ghannam <yazen.ghannam@amd.com>
To: Borislav Petkov <bp@alien8.de>
Cc: linux-edac@vger.kernel.org, linux-kernel@vger.kernel.org,
	tony.luck@intel.com, x86@kernel.org,
	Smita.KoralahalliChannabasappa@amd.com
Subject: Re: [PATCH v2 1/8] x86/CPU/AMD: Save NodeId on AMD-based systems
Date: Thu, 17 Sep 2020 14:44:25 -0500
Message-ID: <20200917194425.GB504453@yaz-nikka.amd.com> (raw)
In-Reply-To: <20200917164048.GM31960@zn.tnic>

On Thu, Sep 17, 2020 at 06:40:48PM +0200, Borislav Petkov wrote:
> On Thu, Sep 17, 2020 at 11:20:53AM -0500, Yazen Ghannam wrote:
> > But newer systems support CPUID Leaf 0xB, so cpu_die_id will get
> > explicitly set by detect_extended_topology(). The value set is
> > different from the AMD NodeId. And at that point I shied away from
> > doing any override or fixup.
> 
> Well, different how? Can you extract the node_id you need
> from CPUID(0xb)? If yes, we can do an AMD-specific branch in
> detect_extended_topology() but that better be future proof.
> 
> IOW, is information from CPUID(0xb) ever going to be needed in the
> kernel?
> 
> Also, and independently, if its definition do not give you the
> node_id you need, then you can just as well overwrite ->cpu_die_id in
> detect_extended_topology() because that value - whatever that is, could
> be garbage, just as well - is wrong on AMD anyway.
> 
> So it would be a fix for the leaf parsing, regardless of whether you
> need it or not.
> 
> Makes sense?
>

Yes, I think so. "Die" is not defined in CPUID(0xb), only SMT and Core,
so the cpu_die_id value is not valid. In which case, we can overwrite
it. CPUID(0xb) doesn't have anything equivalent to AMD NodeId. So on
systems with CPUID < 0x1F, we should be okay with using cpu_die_id equal
to AMD NodeId.

I have an idea on what to do, so I'll send another rev if that's okay.
Do you have any comments on the other patches in the set?

Thanks,
Yazen

  reply index

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-03 20:01 [PATCH v2 0/8] AMD MCA Address Translation Updates Yazen Ghannam
2020-09-03 20:01 ` [PATCH v2 1/8] x86/CPU/AMD: Save NodeId on AMD-based systems Yazen Ghannam
2020-09-09 18:06   ` Borislav Petkov
2020-09-09 20:17     ` Yazen Ghannam
2020-09-10 10:14       ` Borislav Petkov
2020-09-14 19:20         ` Yazen Ghannam
2020-09-15  8:35           ` Borislav Petkov
2020-09-16 19:51             ` Yazen Ghannam
2020-09-17 10:37               ` Borislav Petkov
2020-09-17 16:20                 ` Yazen Ghannam
2020-09-17 16:40                   ` Borislav Petkov
2020-09-17 19:44                     ` Yazen Ghannam [this message]
2020-09-17 20:10                       ` Borislav Petkov
2020-09-03 20:01 ` [PATCH v2 2/8] x86/CPU/AMD: Remove amd_get_nb_id() Yazen Ghannam
2020-09-03 20:01 ` [PATCH v2 3/8] EDAC/mce_amd: Use struct cpuinfo_x86.node_id for NodeId Yazen Ghannam
2020-09-03 20:01 ` [PATCH v2 4/8] x86/MCE/AMD: Use defines for register addresses in translation code Yazen Ghannam
2020-09-03 20:01 ` [PATCH v2 5/8] x86/MCE/AMD: Use macros to get bitfields " Yazen Ghannam
2020-09-21 13:58   ` Borislav Petkov
2020-09-03 20:01 ` [PATCH v2 6/8] x86/MCE/AMD: Drop tmp variable " Yazen Ghannam
2020-09-23  8:05   ` Borislav Petkov
2020-09-23 16:05     ` Yazen Ghannam
2020-09-03 20:01 ` [PATCH v2 7/8] x86/MCE/AMD: Group register reads " Yazen Ghannam
2020-09-03 20:01 ` [PATCH v2 8/8] x86/MCE/AMD Support new memory interleaving modes during address translation Yazen Ghannam
2020-09-23  8:20   ` Borislav Petkov
2020-09-23 16:25     ` Yazen Ghannam
2020-09-25  7:22       ` Borislav Petkov
2020-09-25 19:51         ` Yazen Ghannam
2020-09-28  9:47           ` Borislav Petkov
2020-09-28 15:53             ` Yazen Ghannam
2020-09-28 18:14               ` Borislav Petkov
2020-09-29 13:21                 ` Yazen Ghannam

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