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To: Stefan Hajnoczi , lagarcia@linux.ibm.com References: <20210127111938.GH299797@stefanha-x1.localdomain> From: Laszlo Ersek Message-ID: <6e8d0352-8418-ebb4-2562-13d3920093b5@redhat.com> Date: Wed, 27 Jan 2021 17:49:14 +0100 MIME-Version: 1.0 In-Reply-To: <20210127111938.GH299797@stefanha-x1.localdomain> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=lersek@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=windows-1252 Content-Language: en-US Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=lersek@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -23 X-Spam_score: -2.4 X-Spam_bar: -- X-Spam_report: (-2.4 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.308, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no 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: Leonardo Garcia , qemu-devel@nongnu.org, dgilbert@redhat.com, "Michael S. Tsirkin" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 01/27/21 12:19, Stefan Hajnoczi wrote: > On Tue, Jan 26, 2021 at 03:23:38PM -0300, lagarcia@linux.ibm.com wrote: >> From: Leonardo Garcia >> >> Currently, as IOMMU and ATS are not supported, if a user mistakenly set >> any of them and tries to mount the vhost-user filesystem inside the >> guest, whenever the user tries to access the mount point, the system >> will hang forever. >> >> Signed-off-by: Leonardo Garcia >> --- >> hw/virtio/vhost-user-fs-pci.c | 7 +++++++ >> hw/virtio/vhost-user-fs.c | 5 +++++ >> 2 files changed, 12 insertions(+) >> >> diff --git a/hw/virtio/vhost-user-fs-pci.c b/hw/virtio/vhost-user-fs-pci.c >> index 2ed8492b3f..564d1fd108 100644 >> --- a/hw/virtio/vhost-user-fs-pci.c >> +++ b/hw/virtio/vhost-user-fs-pci.c >> @@ -11,6 +11,8 @@ >> * top-level directory. >> */ >> >> +#include "qemu/osdep.h" >> +#include "qapi/error.h" >> #include "qemu/osdep.h" >> #include "hw/qdev-properties.h" >> #include "hw/virtio/vhost-user-fs.h" >> @@ -45,6 +47,11 @@ static void vhost_user_fs_pci_realize(VirtIOPCIProxy *vpci_dev, Error **errp) >> vpci_dev->nvectors = dev->vdev.conf.num_request_queues + 2; >> } >> >> + if (vpci_dev->flags & VIRTIO_PCI_FLAG_ATS) { >> + error_setg(errp, "ATS is currently not supported with vhost-user-fs-pci"); >> + return; >> + } > > Why is this check needed in addition to VIRTIO_F_IOMMU_PLATFORM? > > What needs to be added to support ATS? > >> + >> qdev_realize(vdev, BUS(&vpci_dev->bus), errp); >> } >> >> diff --git a/hw/virtio/vhost-user-fs.c b/hw/virtio/vhost-user-fs.c >> index ac4fc34b36..914d68b3ee 100644 >> --- a/hw/virtio/vhost-user-fs.c >> +++ b/hw/virtio/vhost-user-fs.c >> @@ -203,6 +203,11 @@ static void vuf_device_realize(DeviceState *dev, Error **errp) >> return; >> } >> >> + if (virtio_host_has_feature(vdev, VIRTIO_F_IOMMU_PLATFORM)) { >> + error_setg(errp, "IOMMU is currently not supported with vhost-user-fs"); >> + return; >> + } >> + >> if (!vhost_user_init(&fs->vhost_user, &fs->conf.chardev, errp)) { > > I thought IOMMU support depends on the vhost-user device backend (e.g. > virtiofsd), so the vhost-user backend should participate in advertising > this feature. ... I had the same thought when a few weeks earlier I tried to use virtio-fs with an SEV guest (just OVMF), and virtiofsd crashed, apparently :) (I didn't report it because, well, SEV wants to prevent sharing between host and guest, and virtio-fs works precisely in the opposite direction; so the use case may not have much merit.) Thanks Laszlo > > Perhaps the check should be: > > ret = vhost_dev_init(&fs->vhost_dev, &fs->vhost_user, > VHOST_BACKEND_TYPE_USER, 0); > if (ret < 0) { > error_setg_errno(errp, -ret, "vhost_dev_init failed"); > goto err_virtio; > } > + > + if (virtio_host_has_feature(vdev, VIRTIO_F_IOMMU_PLATFORM) && > + !(fs->vhost_dev.hdev_features & (1ull << VIRTIO_F_IOMMU_PLATFORM))) { > + error_setg(errp, "IOMMU is not supported by the vhost-user device backend"); > + goto err_iommu_needed; > + } > > Also, can this logic be made generic for all vhost-user devices? It's > not really specific to vhost-user-fs. > > Stefan >