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;
Date:   Fri, 29 Jul 2022 19:31:51 -0700
From:   Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
To:     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>
Subject: Re: [RESEND RFC PATCH] x86/bugs: Add "unknown" reporting for MMIO
 Stale Data
Message-ID: <20220730023151.kogebjrhsvhitklj@desk>
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>
 <YuRY+rKaocoV8ECn@zn.tnic>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <YuRY+rKaocoV8ECn@zn.tnic>
Precedence: bulk

On Sat, Jul 30, 2022 at 12:02:34AM +0200, Borislav Petkov wrote:
> On Fri, Jul 29, 2022 at 02:46:27PM -0700, 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				?
> 
> Not affected current CPUs should be arch_cap_mmio_immune() == true, no?

That would be true in most cases, with some exceptions like systems
that did not update the microcode.