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: <20250820175610.GA936971@yaz-khff2.amd.com>
Date: Wed, 20 Aug 2025 13:56:10 -0400
From: Yazen Ghannam <yazen.ghannam@....com>
To: "Luck, Tony" <tony.luck@...el.com>
Cc: "Hunter, Adrian" <adrian.hunter@...el.com>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	"pbonzini@...hat.com" <pbonzini@...hat.com>,
	"seanjc@...gle.com" <seanjc@...gle.com>,
	"Annapurve, Vishal" <vannapurve@...gle.com>,
	Borislav Petkov <bp@...en8.de>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, "x86@...nel.org" <x86@...nel.org>,
	H Peter Anvin <hpa@...or.com>,
	"linux-edac@...r.kernel.org" <linux-edac@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"kvm@...r.kernel.org" <kvm@...r.kernel.org>,
	"Edgecombe, Rick P" <rick.p.edgecombe@...el.com>,
	"Huang, Kai" <kai.huang@...el.com>,
	"Chatre, Reinette" <reinette.chatre@...el.com>,
	"Li, Xiaoyao" <xiaoyao.li@...el.com>,
	"tony.lindgren@...ux.intel.com" <tony.lindgren@...ux.intel.com>,
	"binbin.wu@...ux.intel.com" <binbin.wu@...ux.intel.com>,
	"Weiny, Ira" <ira.weiny@...el.com>,
	"Yamahata, Isaku" <isaku.yamahata@...el.com>,
	"Du, Fan" <fan.du@...el.com>, "Zhao, Yan Y" <yan.y.zhao@...el.com>,
	"Gao, Chao" <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 Wed, Aug 20, 2025 at 04:12:28PM +0000, Luck, Tony wrote:
> > >> For struct mce?  Maybe that should be 2 new fields:
> > >>
> > >>    __u64 addr;             /* Deprecated */
> > >>    ...
> > >>    __u64 mci_addr;         /* Bank's MCi_ADDR MSR */
> > >>    __u64 phys_addr;        /* Physical address */
> > >
> > > Would "addr" keep the current (low bits masked, high bits preserved) value?
> >
> > Yeah, it wouldn't make much sense if phys_addr was the same as addr anyway.
> > Not really thinking
> 
> The other option (but a bad one) would be:
> 
>         __u64 deprecated;       /* was "addr" */
>         ...
>         __u64 mci_addr;         /* Bank's MCi_ADDR MSR */
>         __u64 phys_addr;        /* Physical address */
> 
> which would be good to force cleanup in the kernel, but bad for preserving
> ABI (since "struct mce" is visible to user space via /dev/mcelog).
> 

/dev/mcelog has been deprecated for a while.

Is the mcelog app still in active development? Could it be updated to
use trace events for MCE info?

You could also just fix up the address value in the mcelog notifier's
copy. I believe it has its own cache separate from the MCE genpool.

Thanks,
Yazen