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Wed, 01 Jul 2020 05:16:28 -0700 (PDT) Date: Wed, 1 Jul 2020 08:16:26 -0400 From: Peter Xu To: Jason Wang Subject: Re: [RFC v2 1/1] memory: Delete assertion in memory_region_unregister_iommu_notifier Message-ID: <20200701121626.GD40675@xz-x1> References: <8cf25190-53e6-8cbb-372b-e3d4ec714dc5@redhat.com> <20200628144746.GA239443@xz-x1> <54d2cdfd-97b8-9e1d-a607-d7a5e96be3a1@redhat.com> <20200629133403.GA266532@xz-x1> <2589d0e9-cc5b-a4df-8790-189b49f1a40e@redhat.com> <1b4eaaaf-c2ab-0da8-afb4-1b7b4221e6cf@redhat.com> <20200630052148-mutt-send-email-mst@kernel.org> <49f547e1-dd87-7abe-1075-9dcece75b641@redhat.com> <20200630152050.GC3138@xz-x1> MIME-Version: 1.0 In-Reply-To: Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=peterx@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Content-Disposition: inline Received-SPF: pass client-ip=207.211.31.120; envelope-from=peterx@redhat.com; helo=us-smtp-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/07/01 01:29:47 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, 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=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-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: Peter Maydell , Yan Zhao , "Michael S. Tsirkin" , Juan Quintela , qemu-devel@nongnu.org, Eugenio =?utf-8?B?UMOpcmV6?= , Eric Auger , Paolo Bonzini Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, Jul 01, 2020 at 04:11:49PM +0800, Jason Wang wrote: > > On 2020/6/30 下午11:20, Peter Xu wrote: > > On Tue, Jun 30, 2020 at 05:23:31PM +0800, Jason Wang wrote: > > > > > Ok, we had a dedicated mr for interrupt: > > > > > > > > > > memory_region_add_subregion_overlap(MEMORY_REGION(&vtd_dev_as->iommu), > > > > > VTD_INTERRUPT_ADDR_FIRST, > > > > > &vtd_dev_as->iommu_ir, 1); > > > > > > > > > > So it should be fine. I guess the reason that I'm asking is that I thought > > > > > "IR" means "Interrupt remapping" but in fact it means "Interrupt Region"? > > I was meaning "interrupt remapping", and of course it's the interrupt region > > too when IR enabled... > > > Right. > > > > > > > > > But I'm still not clear about the invalidation part for interrupt region, > > > > > maybe you can elaborate a little more on this. > > > > > > > > > > Btw, I think guest can trigger the assert in vtd_do_iommu_translate() if we > > > > > teach vhost to DMA to that region: > > > > Why would we want to? > > > > > > I meant a buggy(malicious) guest driver. > > Yes seems possible. Do you want to post a patch? Let me know if you want me > > to... Thanks, > > > Yes please. Oh wait... Actually the comment above explains... /* * We have standalone memory region for interrupt addresses, we * should never receive translation requests in this region. */ assert(!vtd_is_interrupt_addr(addr)); I overlooked myself that the IR region will be there even if ir=off. So I think the assert should stand. -- Peter Xu