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To: "Dr. David Alan Gilbert" References: <20210127111938.GH299797@stefanha-x1.localdomain> <20210127163423.GI3052@work-vm> From: =?UTF-8?Q?Leonardo_Augusto_Guimar=c3=a3es_Garcia?= Organization: IBM Message-ID: <3b31eb9a-1737-e681-73a1-e4a96313a819@br.ibm.com> Date: Wed, 27 Jan 2021 16:32:33 -0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <20210127163423.GI3052@work-vm> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.343, 18.0.737 definitions=2021-01-27_06:2021-01-27, 2021-01-27 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 impostorscore=0 clxscore=1015 mlxscore=0 phishscore=0 malwarescore=0 mlxlogscore=999 lowpriorityscore=0 spamscore=0 bulkscore=0 adultscore=0 priorityscore=1501 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2101270093 Received-SPF: pass client-ip=148.163.156.1; envelope-from=lagarcia@br.ibm.com; helo=mx0a-001b2d01.pphosted.com X-Spam_score_int: -26 X-Spam_score: -2.7 X-Spam_bar: -- X-Spam_report: (-2.7 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, 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: maxime.coquelin@redhat.com, qemu-devel@nongnu.org, Stefan Hajnoczi , "Michael S. Tsirkin" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 1/27/21 1:34 PM, Dr. David Alan Gilbert wrote: > * Leonardo Augusto Guimarães Garcia (lagarcia@linux.ibm.com) wrote: >> On 1/27/21 8:19 AM, 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. >>> >>> 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. >> Further analyzing this, on vhost-user.c, I see: >> >>         if (virtio_has_feature(features, VIRTIO_F_IOMMU_PLATFORM) && >>                 !(virtio_has_feature(dev->protocol_features, >>                     VHOST_USER_PROTOCOL_F_SLAVE_REQ) && >>                  virtio_has_feature(dev->protocol_features, >>                     VHOST_USER_PROTOCOL_F_REPLY_ACK))) { >>             error_report("IOMMU support requires reply-ack and " >>                          "slave-req protocol features."); >>             return -1; >>         } >> >> This code was included by commit 6dcdd06. It included support for >> VIRTIO_F_IOMMU_PLATFORM with vhost_net devices. So, the restriction is not >> generic for all vhost-user devices. > That test is a slightly different test; that's checking that the > vhost-user device has two underlying features that are needed to make > iommu work; it's not a full test though; it doesn't actually check the > vhost-user device also wants to do iommu. Right... but Stefan was suggesting to move the check I proposed to avoid VIRTIO_F_IOMMU_PLATFORM on vhost-user-fs up to vhost-user. What I understand from the above code excerpt and the rest of commit 6dcdd06 is that IOMMU support has been added into vhost-user already. However, it seems vhost-user-fs (maybe all other devices on top of vhost-user) doesn't support it yet. If I move the check up to vhost-user, does it make sense to still have all the IOMMU code support there? Leo > > Dave > >> Cheers, >> >> Leo >> >>> Stefan