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;
Received-SPF: Pass (protection.outlook.com: domain of nvidia.com designates
 216.228.117.160 as permitted sender) receiver=protection.outlook.com;
 client-ip=216.228.117.160; helo=mail.nvidia.com; pr=C
Date:   Wed, 12 Apr 2023 00:47:21 -0700
From:   Nicolin Chen <nicolinc@nvidia.com>
To:     Robin Murphy <robin.murphy@arm.com>
CC:     <jgg@nvidia.com>, <will@kernel.org>, <eric.auger@redhat.com>,
        <kevin.tian@intel.com>, <baolu.lu@linux.intel.com>,
        <joro@8bytes.org>, <shameerali.kolothum.thodi@huawei.com>,
        <jean-philippe@linaro.org>, <linux-arm-kernel@lists.infradead.org>,
        <iommu@lists.linux.dev>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v1 04/14] iommu/arm-smmu-v3: Add arm_smmu_hw_info
Message-ID: <ZDZiCUY25pix/NIX@Asurada-Nvidia>
References: <cover.1678348754.git.nicolinc@nvidia.com>
 <494e36cbb77d49e11427b308868dbc1b0e19fe18.1678348754.git.nicolinc@nvidia.com>
 <bfa43614-c052-4bed-b87e-691141f41909@arm.com>
 <ZAqFFolbw5xoJDfb@Asurada-Nvidia>
 <5cc56149-965a-bb47-f23f-6aa9d0ecce4e@arm.com>
 <ZBJfJUjbAUId68s1@Asurada-Nvidia>
 <1d4ff93d-a97e-85bb-4259-9da259bc2ab7@arm.com>
 <ZBN2tmWoRURvjarc@Asurada-Nvidia>
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Disposition: inline
In-Reply-To: <ZBN2tmWoRURvjarc@Asurada-Nvidia>
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 12 Apr 2023 07:47:33.8487
 (UTC)
X-MS-Exchange-CrossTenant-Network-Message-Id: 3f83c3d8-7b41-4e59-05e0-08db3b2a2d69
X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a
X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.117.160];Helo=[mail.nvidia.com]
X-MS-Exchange-CrossTenant-AuthSource: CO1PEPF00001A63.namprd05.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Anonymous
X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem
X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH8PR12MB7025
X-Spam-Status: No, score=-1.1 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,
        DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FORGED_SPF_HELO,
        RCVD_IN_DNSWL_NONE,RCVD_IN_MSPIKE_H2,SPF_HELO_PASS,SPF_NONE,
        URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
        lindbergh.monkeyblade.net
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

Hi Robin,

On Thu, Mar 16, 2023 at 01:06:17PM -0700, Nicolin Chen wrote:
> On Thu, Mar 16, 2023 at 03:19:27PM +0000, Robin Murphy wrote:
> 
> > > > Note that until now it has been extremely fortunate that in pretty much
> > > > every case Linux either hasn't supported the affected feature at all, or
> > > > has happened to avoid meeting the conditions. Once we do introduce
> > > > nesting support that all goes out the window (and I'll have to think
> > > > more when reviewing new errata in future...)
> > > > 
> > > > I've been putting off revisiting all the existing errata to figure out
> > > > what we'd need to do until new nesting patches appeared, so I'll try to
> > > > get to that soon now. I think in many cases it's likely to be best to
> > > > just disallowing nesting entirely on affected implementations.
> > > 
> > > Do we have already a list of "affected implementations"? Or,
> > > we would need to make such a list now? In a latter case, can
> > > these affected implementations be detected from their IRD0-5
> > > registers, so that we can simply do something in hw_info()?
> > 
> > Somewhere I have a patch that adds all the IIDR stuff needed for this,
> > but I never sent it upstream since the erratum itself was an early
> > MMU-600 one which in practice doesn't matter. I'll dig that out and
> > update it with what I have in mind.
> 
> Nice!
> 
> Perhaps we should merge that first, or include in this series
> if you don't mind, so that we would be less worried about any
> affected platform when releasing the new Linux version having
> this nesting feature.

I just want to see if there's a possibility of adding the
patch that you mentioned above in the near term?

I'd like to send a v2 of this series for another round of
review before the next -rc1, so it'd be nicer to include
that.

Thanks
Nic