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Date:   Fri, 29 Jul 2022 16:07:36 -0700
From:   Tony Luck <tony.luck@intel.com>
To:     Dave Hansen <dave.hansen@intel.com>
Cc:     Pawan Gupta <pawan.kumar.gupta@linux.intel.com>,
        Borislav Petkov <bp@alien8.de>,
        Jonathan Corbet <corbet@lwn.net>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>,
        Dave Hansen <dave.hansen@linux.intel.com>, x86@kernel.org,
        "H. Peter Anvin" <hpa@zytor.com>, linux-doc@vger.kernel.org,
        linux-kernel@vger.kernel.org, stable@vger.kernel.org,
        antonio.gomez.iglesias@linux.intel.com,
        Daniel Sneddon <daniel.sneddon@linux.intel.com>,
        andrew.cooper3@citrix.com, Josh Poimboeuf <jpoimboe@kernel.org>
Subject: Re: [RESEND RFC PATCH] x86/bugs: Add "unknown" reporting for MMIO
 Stale Data
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On Fri, Jul 29, 2022 at 03:54:58PM -0700, Dave Hansen wrote:
> On 7/29/22 14:46, Pawan Gupta wrote:
> > Let me see if there is a way to distinguish between 4. and 5. below:
> > 
> >    CPU category				  X86_BUG_MMIO_STALE_DATA	X86_BUG_MMIO_UNKNOWN
> > -----------------------------------------------------------------------------------------------
> > 1. Known affected (in cpu list)			1				0
> > 2. CPUs with HW immunity (MMIO_NO=1)		0				0
> > 3. Other vendors				0				0
> > 4. Older Intel CPUs				0				1
> > 5. Not affected current CPUs (but MMIO_NO=0)	0				?
> 
> This seems like something we would need to go back to our colleagues to
> figure out.  Basically, at the time of publishing the
> X86_BUG_MMIO_STALE_DATA papers, what was considered "older"?
> 
> In other words, we need the folks at Intel that did this good work to
> _show_ their work (at least part of it).

https://www.intel.com/content/www/us/en/developer/topic-technology/software-security-guidance/processors-affected-consolidated-product-cpu-model.html

Click to the 2022 tab. The MMIO affected/not-affected status is there
(you'll need to use the horizontal scroll to shift over to see those
columns).

This table lists all the CPUs that were not "older".

Any CPU not on that list is out of servicing period.

-Tony