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

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Message-ID: <SJ1PR11MB6083B94467DD85C8C2DF33D9FC45A@SJ1PR11MB6083.namprd11.prod.outlook.com>
Date: Fri, 27 Jun 2025 16:28:42 +0000
From: "Luck, Tony" <tony.luck@...el.com>
To: "Hunter, Adrian" <adrian.hunter@...el.com>, "Hansen, Dave"
	<dave.hansen@...el.com>
CC: "Annapurve, Vishal" <vannapurve@...gle.com>, Borislav Petkov
	<bp@...en8.de>, Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar
	<mingo@...hat.com>, Dave Hansen <dave.hansen@...ux.intel.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>, "kirill.shutemov@...ux.intel.com"
	<kirill.shutemov@...ux.intel.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>, "Yamahata, Isaku" <isaku.yamahata@...el.com>,
	"Zhao, Yan Y" <yan.y.zhao@...el.com>, "Gao, Chao" <chao.gao@...el.com>,
	"pbonzini@...hat.com" <pbonzini@...hat.com>, "seanjc@...gle.com"
	<seanjc@...gle.com>
Subject: RE: [PATCH 1/2] x86/mce: Fix missing address mask in recovery for
 errors in TDX/SEAM non-root mode

> >> If ->addr isn't really an address that software can do much with,
> >> shouldn't we mask MCI_ADDR_PHYSADDR off up front, like in mce_read_aux()?
> >
> > Would that mean no one would know if the mce addr had KeyID bits or not?
>
> Current design, to keep the bits in mce addr, is from Tony's patch:
>
>       x86/mce: Mask out non-address bits from machine check bank
>       https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=8a01ec97dc066009dd89e43bfcf55644f2dd6d19
>
> Assuming that is not altered, a tidy-up is still possible like:
>
> diff --git a/arch/x86/include/asm/mce.h b/arch/x86/include/asm/mce.h
> index 6c77c03139f7..b469b7a7ecfa 100644
> --- a/arch/x86/include/asm/mce.h
> +++ b/arch/x86/include/asm/mce.h
> @@ -386,4 +386,14 @@ static inline void mce_amd_feature_init(struct cpuinfo_x86 *c)           { }
>
>  unsigned long copy_mc_fragile_handle_tail(char *to, char *from, unsigned len);
>
> +static inline unsigned long mce_addr_to_phys(u64 mce_addr)
> +{
> +     return mce_addr & MCI_ADDR_PHYSADDR;
> +}
> +
> +static inline unsigned long mce_addr_to_pfn(u64 mce_addr)
> +{
> +     return mce_addr_to_phys(mce_addr) >> PAGE_SHIFT;
> +}
> +
>  #endif /* _ASM_X86_MCE_H */

I like this. Can you write up a patch with a commit message please?

-Tony