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[213.175.37.10]) by smtp.gmail.com with ESMTPSA id b7-20020a170906660700b009935aba3a9dsm3363095ejp.48.2023.07.04.04.38.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 04 Jul 2023 04:38:02 -0700 (PDT) Date: Tue, 4 Jul 2023 13:38:01 +0200 From: Igor Mammedov To: Akihiko Odaki Cc: "Michael S. Tsirkin" , Ani Sinha , qemu-devel , Marcel Apfelbaum , Julia Suvorova Subject: Re: [PATCH v6 5/5] hw/pci: ensure PCIE devices are plugged into only slot 0 of PCIE port Message-ID: <20230704133801.0423b554@imammedo.users.ipa.redhat.com> In-Reply-To: <0879ed66-766c-1d3f-dcce-31e1285a7972@daynix.com> References: <9DDBE75A-C72C-4238-9166-3CBDBEA68188@redhat.com> <167eea06-b917-8783-5cd6-8fda56e41331@daynix.com> <20230630041937-mutt-send-email-mst@kernel.org> <4618EAD1-2862-4288-A881-CA860D04ADB0@redhat.com> <20230630043734-mutt-send-email-mst@kernel.org> <49B901C6-4819-4A00-8225-39FAA6678F3E@redhat.com> <20230630055717-mutt-send-email-mst@kernel.org> <20230630112611-mutt-send-email-mst@kernel.org> <0879ed66-766c-1d3f-dcce-31e1285a7972@daynix.com> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=170.10.129.124; envelope-from=imammedo@redhat.com; helo=us-smtp-delivery-124.mimecast.com 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_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Sat, 1 Jul 2023 16:28:30 +0900 Akihiko Odaki wrote: > On 2023/07/01 0:29, Michael S. Tsirkin wrote: > > On Fri, Jun 30, 2023 at 08:36:38PM +0900, Akihiko Odaki wrote: =20 > >> On 2023/06/30 19:37, Ani Sinha wrote: =20 > >>> > >>> =20 > >>>> On 30-Jun-2023, at 3:30 PM, Michael S. Tsirkin wrot= e: > >>>> > >>>> On Fri, Jun 30, 2023 at 02:52:52PM +0530, Ani Sinha wrote: =20 > >>>>> > >>>>> =20 > >>>>>> On 30-Jun-2023, at 2:13 PM, Michael S. Tsirkin wr= ote: > >>>>>> > >>>>>> On Fri, Jun 30, 2023 at 02:06:59PM +0530, Ani Sinha wrote: =20 > >>>>>>> > >>>>>>> =20 > >>>>>>>> On 30-Jun-2023, at 2:02 PM, Michael S. Tsirkin = wrote: > >>>>>>>> > >>>>>>>> On Fri, Jun 30, 2023 at 01:11:33PM +0530, Ani Sinha wrote: =20 > >>>>>>>>>> > >>>>>>>>>> Thus the check for unoccupied function 0 needs to use pci_is_v= f() instead of checking ARI capability, and that can happen in do_pci_regis= ter_device(). > >>>>>>>>>> =20 > >>>>>>>>>>> Also where do you propose we move the check? =20 > >>>>>>>>>> > >>>>>>>>>> In pci_qdev_realize(), somewhere after pc->realize() and befor= e option ROM loading. =20 > >>>>>>>>> > >>>>>>>>> Hmm, I tried this. The issue here is something like this would = be now allowed since the PF has ARI capability: > >>>>>>>>> > >>>>>>>>> -device pcie-root-port,id=3Dp -device igb,bus=3Dp,addr=3D0x2.0x0 > >>>>>>>>> > >>>>>>>>> The above should not be allowed and when used, we do not see th= e igb ethernet device from the guest OS. =20 > >>>>>>>> > >>>>>>>> I think it's allowed because it expects you to hotplug function = 0 later, =20 > >>>>>>> > >>>>>>> This is about the igb device being plugged into the non-zero slot= of the pci-root-port. The guest OS ignores it. =20 > >>>>>> > >>>>>> yes but if you later add a device with ARI and with next field poi= nting > >>>>>> slot 2 guest will suddently find both. =20 > >>>>> > >>>>> Hmm, I tried this: > >>>>> > >>>>> -device pcie-root-port,id=3Dp \ > >>>>> -device igb,bus=3Dp,addr=3D0x2.0x0 \ > >>>>> -device igb,bus=3Dp,addr=3D0x0.0x0 \ > >>>>> > >>>>> The guest only found the second igb device not the first. You can t= ry too. =20 > >>>> > >>>> Because next parameter in pcie_ari_init does not match. =20 > >>> > >>> OK send me a command line that I can test it with. I can=E2=80=99t co= me up with a case that actually works in practice. =20 > >> > >> I don't think there is one because the code for PCI multifunction does= not > >> care ARI. In my opinion, we need yet another check to make non-SR-IOV > >> multifunction and ARI capability mutually exclusive; if a function has= the > >> ARI capability and it is not a VF, an attempt to assign non-zero funct= ion > >> number for it should fail. =20 is it stated somewhere in spec(s) that ARI and !SR-IOV are mutually exclusi= ve? > >=20 > > Why is that? My understanding is that ARI capable devices should also > > set the multifunction bit in the header. It's not terribly clear from > > the spec though. =20 >=20 > Something like the following will not work properly with ARI-capable=20 > device (think of a as an ARI-capable device): > -device a,addr=3D0x1.0x0,multifunction=3Don -device a,addr=3D0x1.0x1 (I had a crazy idea, to use it like that so we could put more devices on port without resorting to adding extra bridges) Can you elaborate some more why it won't work? > This is because the next function numbers advertised with ARI are not=20 > updated with the multifunction configuration, but they are hardcoded in=20 > the device implementation. In this sense, the traditional (non-SR/IOV)=20 > multifunction mechanism QEMU has will not work with ARI-capable devices. >=20 > > =20 > >> But it should be a distinct check as it will need to check the function > >> number bits. > >> =20 > >>> =20 > >>>> > >>>> =20 > >>>>>> =20 > >>>>>>>> no? > >>>>>>>> > >>>>>>>> I am quite worried about all this work going into blocking > >>>>>>>> what we think is disallowed configurations. We should have > >>>>>>>> maybe blocked them originally, but now that we didn't > >>>>>>>> there's a non zero chance of regressions, =20 > >>>>>>> > >>>>>>> Sigh, =20 > >>>>>> > >>>>>> There's value in patches 1-4 I think - the last patch helped you f= ind > >>>>>> these. so there's value in this work. > >>>>>> =20 > >>>>>>> no medals here for being brave :-) =20 > >>>>>> > >>>>>> Try removing support for a 3.5mm jack next. Oh wait ... =20 > >>>>> > >>>>> Indeed. Everyone uses bluetooth these days. I for one is happy that= the jack is gone (and they were bold enough to do it while Samsung and oth= ers still carry the useless port ) :-) =20 > >> > >> Hello from a guy using a shiny M2 Macbook Air carrying the legacy jack= with > >> a 100-yen earphone. Even people who ported Linux to this machine spent > >> efforts to get the jack to work on Linux ;) > >> =20 > >>>>> =20 > >>>>>> =20 > >>>>>>>> and the benefit > >>>>>>>> is not guaranteed. > >>>>>>>> > >>>>>>>> --=20 > >>>>>>>> MST =20 > >>> =20 > > =20 >=20