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Thu, 7 May 2020 06:37:06 +0000 (UTC) Date: Thu, 7 May 2020 08:37:04 +0200 From: Cornelia Huck To: Kirti Wankhede Subject: Re: [PATCH v16 QEMU 08/16] vfio: Register SaveVMHandlers for VFIO device Message-ID: <20200507083704.7b2553b1.cohuck@redhat.com> In-Reply-To: References: <1585084154-29461-1-git-send-email-kwankhede@nvidia.com> <1585084154-29461-9-git-send-email-kwankhede@nvidia.com> <20200325150248.6661e1bd@w520.home> <20200504223726.5d4bb9ce@x1.home> <20200506063846.GB19334@joy-OptiPlex-7040> <20200506115856.012c88d8.cohuck@redhat.com> <20200506165305.GP2743@work-vm> Organization: Red Hat GmbH MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=207.211.31.81; envelope-from=cohuck@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/05/07 00:55:34 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "Tian, Kevin" , "Liu, Yi L" , "cjia@nvidia.com" , "eskultet@redhat.com" , "Yang, Ziye" , "qemu-devel@nongnu.org" , "Zhengxiao.zx@Alibaba-inc.com" , "shuangtai.tst@alibaba-inc.com" , "Dr. David Alan Gilbert" , "Wang, Zhi A" , "mlevitsk@redhat.com" , "pasic@linux.ibm.com" , "aik@ozlabs.ru" , Alex Williamson , "eauger@redhat.com" , "felipe@nutanix.com" , "jonathan.davies@nutanix.com" , Yan Zhao , "Liu, Changpeng" , "Ken.Xue@amd.com" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Thu, 7 May 2020 01:00:05 +0530 Kirti Wankhede wrote: > On 5/6/2020 10:23 PM, Dr. David Alan Gilbert wrote: > > * Cornelia Huck (cohuck@redhat.com) wrote: > >> On Wed, 6 May 2020 02:38:46 -0400 > >> Yan Zhao wrote: > >> > >>> On Tue, May 05, 2020 at 12:37:26PM +0800, Alex Williamson wrote: > >>>> It's been a long time, but that doesn't seem like what I was asking. > >>>> The sysfs version checking is used to select a target that is likely to > >>>> succeed, but the migration stream is still generated by a user and the > >>>> vendor driver is still ultimately responsible for validating that > >>>> stream. I would hope that a vendor migration stream therefore starts > >>>> with information similar to that found in the sysfs interface, allowing > >>>> the receiving vendor driver to validate the source device and vendor > >>>> software version, such that we can fail an incoming migration that the > >>>> vendor driver deems incompatible. Ideally the vendor driver might also > >>>> include consistency and sequence checking throughout the stream to > >>>> prevent a malicious user from exploiting the internal operation of the > >>>> vendor driver. Thanks, > >> > >> Some kind of somewhat standardized marker for driver/version seems like > >> a good idea. Further checking is also a good idea, but I think the > >> details of that need to be left to the individual drivers. > > > > Standardised markers like that would be useful; although the rules of > > how to compare them might be a bit vendor specific; but still - it would > > be good for us to be able to dump something out when it all goes wrong. > > > > Such checking should already there in vendor driver. Vendor driver might > also support across version migration. I think checking in QEMU again > would be redundant. Let vendor driver handle version checks. Of course the actual rules of what is supported and what not are vendor driver specific -- but we can still benefit from some standardization. It ensures that this checking is not forgotten, and it can help with figuring out what went wrong.