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: <9a4752a4-e783-4f03-babf-23c31cee4ff9@intel.com>
Date: Fri, 27 Jun 2025 08:25:59 -0700
From: Dave Hansen <dave.hansen@...el.com>
To: Adrian Hunter <adrian.hunter@...el.com>, Tony Luck <tony.luck@...el.com>
Cc: 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,
 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, kirill.shutemov@...ux.intel.com,
 kai.huang@...el.com, reinette.chatre@...el.com, xiaoyao.li@...el.com,
 tony.lindgren@...ux.intel.com, binbin.wu@...ux.intel.com,
 isaku.yamahata@...el.com, yan.y.zhao@...el.com, chao.gao@...el.com,
 pbonzini@...hat.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

On 6/27/25 08:23, Adrian Hunter wrote:
> On 19/06/2025 14:57, Adrian Hunter wrote:
>> On 18/06/2025 17:55, Dave Hansen wrote:
>>> On 6/18/25 05:08, Adrian Hunter wrote:
>>>> --- a/arch/x86/kernel/cpu/mce/core.c
>>>> +++ b/arch/x86/kernel/cpu/mce/core.c
>>>> @@ -1665,7 +1665,8 @@ noinstr void do_machine_check(struct pt_regs *regs)
>>>>  		 * be added to free list when the guest is terminated.
>>>>  		 */
>>>>  		if (mce_usable_address(m)) {
>>>> -			struct page *p = pfn_to_online_page(m->addr >> PAGE_SHIFT);
>>>> +			unsigned long pfn = (m->addr & MCI_ADDR_PHYSADDR) >> PAGE_SHIFT;
>>>> +			struct page *p = pfn_to_online_page(pfn);
>>> 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?

Uhhh, just store the KeyID separately. Have

	mce->addr
and
	mce->keyid

Problem solved.