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[109.64.41.91]) by smtp.gmail.com with ESMTPSA id c65sm22564342wme.8.2020.06.08.02.31.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 08 Jun 2020 02:31:51 -0700 (PDT) Date: Mon, 8 Jun 2020 05:31:48 -0400 From: "Michael S. Tsirkin" To: Jason Wang Cc: kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, rob.miller@broadcom.com, lingshan.zhu@intel.com, eperezma@redhat.com, lulu@redhat.com, shahafs@mellanox.com, hanand@xilinx.com, mhabets@solarflare.com, gdawar@xilinx.com, saugatm@xilinx.com, vmireyno@marvell.com, zhangweining@ruijie.com.cn, eli@mellanox.com Subject: Re: [PATCH 5/6] vdpa: introduce virtio pci driver Message-ID: <20200608052041-mutt-send-email-mst@kernel.org> References: <20200529080303.15449-1-jasowang@redhat.com> <20200529080303.15449-6-jasowang@redhat.com> <20200602010332-mutt-send-email-mst@kernel.org> <5dbb0386-beeb-5bf4-d12e-fb5427486bb8@redhat.com> <6b1d1ef3-d65e-08c2-5b65-32969bb5ecbc@redhat.com> <20200607095012-mutt-send-email-mst@kernel.org> <9b1abd2b-232c-aa0f-d8bb-03e65fd47de2@redhat.com> <20200608021438-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Mon, Jun 08, 2020 at 05:18:44PM +0800, Jason Wang wrote: > > On 2020/6/8 下午2:32, Michael S. Tsirkin wrote: > > On Mon, Jun 08, 2020 at 11:32:31AM +0800, Jason Wang wrote: > > > On 2020/6/7 下午9:51, Michael S. Tsirkin wrote: > > > > On Fri, Jun 05, 2020 at 04:54:17PM +0800, Jason Wang wrote: > > > > > On 2020/6/2 下午3:08, Jason Wang wrote: > > > > > > > > +static const struct pci_device_id vp_vdpa_id_table[] = { > > > > > > > > +    { PCI_DEVICE(PCI_VENDOR_ID_REDHAT_QUMRANET, PCI_ANY_ID) }, > > > > > > > > +    { 0 } > > > > > > > > +}; > > > > > > > This looks like it'll create a mess with either virtio pci > > > > > > > or vdpa being loaded at random. Maybe just don't specify > > > > > > > any IDs for now. Down the road we could get a > > > > > > > distinct vendor ID or a range of device IDs for this. > > > > > > Right, will do. > > > > > > > > > > > > Thanks > > > > > Rethink about this. If we don't specify any ID, the binding won't work. > > > > We can bind manually. It's not really for production anyway, so > > > > not a big deal imho. > > > > > > I think you mean doing it via "new_id", right. > > I really meant driver_override. This is what people have been using > > with pci-stub for years now. > > > Do you want me to implement "driver_overrid" in this series, or a NULL > id_table is sufficient? Doesn't the pci subsystem create driver_override for all devices on the pci bus? > > > > > > > > How about using a dedicated subsystem vendor id for this? > > > > > > > > > > Thanks > > > > If virtio vendor id is used then standard driver is expected > > > > to bind, right? Maybe use a dedicated vendor id? > > > > > > I meant something like: > > > > > > static const struct pci_device_id vp_vdpa_id_table[] = { > > >     { PCI_DEVICE_SUB(PCI_VENDOR_ID_REDHAT_QUMRANET, PCI_ANY_ID, > > > VP_TEST_VENDOR_ID, VP_TEST_DEVICE_ID) }, > > >     { 0 } > > > }; > > > > > > Thanks > > > > > Then regular virtio will still bind to it. It has > > > > drivers/virtio/virtio_pci_common.c: { PCI_DEVICE(PCI_VENDOR_ID_REDHAT_QUMRANET, PCI_ANY_ID) }, > > > > > > IFCVF use this to avoid the binding to regular virtio device. Ow. Indeed: #define IFCVF_VENDOR_ID 0x1AF4 Which is of course not an IFCVF vendor id, it's the Red Hat vendor ID. I missed that. Does it actually work if you bind a virtio driver to it? I'm guessing no otherwise they wouldn't need IFC driver, right? > Looking at > pci_match_one_device() it checks both subvendor and subdevice there. > > Thanks But IIUC there is no guarantee that driver with a specific subvendor matches in presence of a generic one. So either IFC or virtio pci can win, whichever binds first. I guess we need to blacklist IFC in virtio pci probe code. Ugh. -- MST