Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <1bcf0b54-6ddf-b343-87c5-f7fd7538759c@intel.com>
Date:   Fri, 29 Jul 2022 15:54:58 -0700
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101
 Thunderbird/91.11.0
Subject: Re: [RESEND RFC PATCH] x86/bugs: Add "unknown" reporting for MMIO
 Stale Data
Content-Language: en-US
To:     Pawan Gupta <pawan.kumar.gupta@linux.intel.com>,
        Borislav Petkov <bp@alien8.de>
Cc:     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,
        tony.luck@intel.com, antonio.gomez.iglesias@linux.intel.com,
        Daniel Sneddon <daniel.sneddon@linux.intel.com>,
        andrew.cooper3@citrix.com, Josh Poimboeuf <jpoimboe@kernel.org>
References: <a932c154772f2121794a5f2eded1a11013114711.1657846269.git.pawan.kumar.gupta@linux.intel.com>
 <YuJ6TQpSTIeXLNfB@zn.tnic> <20220729022851.mdj3wuevkztspodh@desk>
 <YuPpKa6OsG9e9nTj@zn.tnic> <20220729173609.45o7lllpvsgjttqt@desk>
 <YuRDbuQPYiYBZghm@zn.tnic> <20220729214627.wowu5sny226c5pe4@desk>
From:   Dave Hansen <dave.hansen@intel.com>
In-Reply-To: <20220729214627.wowu5sny226c5pe4@desk>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit
Precedence: bulk

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).