linux-kernel - Re: [PATCH RESEND V2 1/2] x86/mce: Fix missing address mask in recovery for errors in TDX/SEAM non-root mode

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Message-ID: <20250821132521.GDaKceQXfEWHVwrlxV@fat_crate.local>
Date: Thu, 21 Aug 2025 15:25:21 +0200
From: Borislav Petkov <bp@...en8.de>
To: Adrian Hunter <adrian.hunter@...el.com>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>,
	Tony Luck <tony.luck@...el.com>, pbonzini@...hat.com,
	seanjc@...gle.com, vannapurve@...gle.com,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, x86@...nel.org,
	H Peter Anvin <hpa@...or.com>, linux-edac@...r.kernel.org,
	linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
	rick.p.edgecombe@...el.com, kai.huang@...el.com,
	reinette.chatre@...el.com, xiaoyao.li@...el.com,
	tony.lindgren@...ux.intel.com, binbin.wu@...ux.intel.com,
	ira.weiny@...el.com, isaku.yamahata@...el.com,
	Fan Du <fan.du@...el.com>, Yazen Ghannam <yazen.ghannam@....com>,
	yan.y.zhao@...el.com, chao.gao@...el.com
Subject: Re: [PATCH RESEND V2 1/2] x86/mce: Fix missing address mask in
 recovery for errors in TDX/SEAM non-root mode

On Thu, Aug 21, 2025 at 10:24:22AM +0300, Adrian Hunter wrote:
> Something like below would work, but doesn't answer Dave's question
> of why not do it in mce_read_aux()

So, let me see what I understand from all this bla: you want to zap the KeyID
from mci_addr because it is completely useless there. So zap it.

You can't make any other changes to mci_addr because that goes to luserspace.

So far so good.

Now, all that other bla leads me to believe that there might be some need to
dump the raw mci_addr value after all.

If so, your patch is not needed.

Which makes me think, all yall folks need to make up your mind here.

And you need to get rid of all that extraneous information in your commit
message:

"Investigation of user space expectations has concluded it..."

No investigation needed - this is exported to userspace so you can't touch it.

The one and only question you need to answer is, do you really need KeyID in
it or not. And whatever you do, once you do it, we're stuck with it because it
goes out to userspace.

Especially if you want this backported to stable.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette