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[109.43.177.66]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3675a0d9286sm10382944f8f.35.2024.07.01.09.06.43 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 01 Jul 2024 09:06:44 -0700 (PDT) Message-ID: <1ce5bce5-2659-4da8-81ac-34838768f04d@redhat.com> Date: Mon, 1 Jul 2024 18:06:42 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] hw/virtio: Fix the de-initialization of vhost-user devices To: "Michael S. Tsirkin" Cc: qemu-devel@nongnu.org, =?UTF-8?Q?Alex_Benn=C3=A9e?= , qemu-stable@nongnu.org, =?UTF-8?Q?C=C3=A9dric_Le_Goater?= , Stefan Hajnoczi References: <20240618121958.88673-1-thuth@redhat.com> <3f96e237-d367-4f8e-b96d-f51d4ba33ab1@redhat.com> <20240701110607-mutt-send-email-mst@kernel.org> Content-Language: en-US From: Thomas Huth Autocrypt: addr=thuth@redhat.com; keydata= xsFNBFH7eUwBEACzyOXKU+5Pcs6wNpKzrlJwzRl3VGZt95VCdb+FgoU9g11m7FWcOafrVRwU yYkTm9+7zBUc0sW5AuPGR/dp3pSLX/yFWsA/UB4nJsHqgDvDU7BImSeiTrnpMOTXb7Arw2a2 4CflIyFqjCpfDM4MuTmzTjXq4Uov1giGE9X6viNo1pxyEpd7PanlKNnf4PqEQp06X4IgUacW tSGj6Gcns1bCuHV8OPWLkf4hkRnu8hdL6i60Yxz4E6TqlrpxsfYwLXgEeswPHOA6Mn4Cso9O 0lewVYfFfsmokfAVMKWzOl1Sr0KGI5T9CpmRfAiSHpthhHWnECcJFwl72NTi6kUcUzG4se81 O6n9d/kTj7pzTmBdfwuOZ0YUSqcqs0W+l1NcASSYZQaDoD3/SLk+nqVeCBB4OnYOGhgmIHNW 0CwMRO/GK+20alxzk//V9GmIM2ACElbfF8+Uug3pqiHkVnKqM7W9/S1NH2qmxB6zMiJUHlTH gnVeZX0dgH27mzstcF786uPcdEqS0KJuxh2kk5IvUSL3Qn3ZgmgdxBMyCPciD/1cb7/Ahazr 3ThHQXSHXkH/aDXdfLsKVuwDzHLVSkdSnZdt5HHh75/NFHxwaTlydgfHmFFwodK8y/TjyiGZ zg2Kje38xnz8zKn9iesFBCcONXS7txENTzX0z80WKBhK+XSFJwARAQABzR5UaG9tYXMgSHV0 aCA8dGh1dGhAcmVkaGF0LmNvbT7CwXgEEwECACIFAlVgX6oCGwMGCwkIBwMCBhUIAgkKCwQW AgMBAh4BAheAAAoJEC7Z13T+cC21EbIP/ii9cvT2HHGbFRl8HqGT6+7Wkb+XLMqJBMAIGiQK QIP3xk1HPTsLfVG0ao4hy/oYkGNOP8+ubLnZen6Yq3zAFiMhQ44lvgigDYJo3Ve59gfe99KX EbtB+X95ODARkq0McR6OAsPNJ7gpEUzfkQUUJTXRDQXfG/FX303Gvk+YU0spm2tsIKPl6AmV 1CegDljzjycyfJbk418MQmMu2T82kjrkEofUO2a24ed3VGC0/Uz//XCR2ZTo+vBoBUQl41BD eFFtoCSrzo3yPFS+w5fkH9NT8ChdpSlbNS32NhYQhJtr9zjWyFRf0Zk+T/1P7ECn6gTEkp5k ofFIA4MFBc/fXbaDRtBmPB0N9pqTFApIUI4vuFPPO0JDrII9dLwZ6lO9EKiwuVlvr1wwzsgq zJTPBU3qHaUO4d/8G+gD7AL/6T4zi8Jo/GmjBsnYaTzbm94lf0CjXjsOX3seMhaE6WAZOQQG tZHAO1kAPWpaxne+wtgMKthyPLNwelLf+xzGvrIKvLX6QuLoWMnWldu22z2ICVnLQChlR9d6 WW8QFEpo/FK7omuS8KvvopFcOOdlbFMM8Y/8vBgVMSsK6fsYUhruny/PahprPbYGiNIhKqz7 UvgyZVl4pBFjTaz/SbimTk210vIlkDyy1WuS8Zsn0htv4+jQPgo9rqFE4mipJjy/iboDzsFN BFH7eUwBEAC2nzfUeeI8dv0C4qrfCPze6NkryUflEut9WwHhfXCLjtvCjnoGqFelH/PE9NF4 4VPSCdvD1SSmFVzu6T9qWdcwMSaC+e7G/z0/AhBfqTeosAF5XvKQlAb9ZPkdDr7YN0a1XDfa +NgA+JZB4ROyBZFFAwNHT+HCnyzy0v9Sh3BgJJwfpXHH2l3LfncvV8rgFv0bvdr70U+On2XH 5bApOyW1WpIG5KPJlDdzcQTyptOJ1dnEHfwnABEfzI3dNf63rlxsGouX/NFRRRNqkdClQR3K gCwciaXfZ7ir7fF0u1N2UuLsWA8Ei1JrNypk+MRxhbvdQC4tyZCZ8mVDk+QOK6pyK2f4rMf/ WmqxNTtAVmNuZIwnJdjRMMSs4W4w6N/bRvpqtykSqx7VXcgqtv6eqoDZrNuhGbekQA0sAnCJ VPArerAZGArm63o39me/bRUQeQVSxEBmg66yshF9HkcUPGVeC4B0TPwz+HFcVhheo6hoJjLq knFOPLRj+0h+ZL+D0GenyqD3CyuyeTT5dGcNU9qT74bdSr20k/CklvI7S9yoQje8BeQAHtdV cvO8XCLrpGuw9SgOS7OP5oI26a0548M4KldAY+kqX6XVphEw3/6U1KTf7WxW5zYLTtadjISB X9xsRWSU+Yqs3C7oN5TIPSoj9tXMoxZkCIHWvnqGwZ7JhwARAQABwsFfBBgBAgAJBQJR+3lM AhsMAAoJEC7Z13T+cC21hPAQAIsBL9MdGpdEpvXs9CYrBkd6tS9mbaSWj6XBDfA1AEdQkBOn ZH1Qt7HJesk+qNSnLv6+jP4VwqK5AFMrKJ6IjE7jqgzGxtcZnvSjeDGPF1h2CKZQPpTw890k fy18AvgFHkVk2Oylyexw3aOBsXg6ukN44vIFqPoc+YSU0+0QIdYJp/XFsgWxnFIMYwDpxSHS 5fdDxUjsk3UBHZx+IhFjs2siVZi5wnHIqM7eK9abr2cK2weInTBwXwqVWjsXZ4tq5+jQrwDK cvxIcwXdUTLGxc4/Z/VRH1PZSvfQxdxMGmNTGaXVNfdFZjm4fz0mz+OUi6AHC4CZpwnsliGV ODqwX8Y1zic9viSTbKS01ZNp175POyWViUk9qisPZB7ypfSIVSEULrL347qY/hm9ahhqmn17 Ng255syASv3ehvX7iwWDfzXbA0/TVaqwa1YIkec+/8miicV0zMP9siRcYQkyTqSzaTFBBmqD oiT+z+/E59qj/EKfyce3sbC9XLjXv3mHMrq1tKX4G7IJGnS989E/fg6crv6NHae9Ckm7+lSs IQu4bBP2GxiRQ+NV3iV/KU3ebMRzqIC//DCOxzQNFNJAKldPe/bKZMCxEqtVoRkuJtNdp/5a yXFZ6TfE1hGKrDBYAm4vrnZ4CXFSBDllL59cFFOJCkn4Xboj/aVxxJxF30bn In-Reply-To: <20240701110607-mutt-send-email-mst@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=thuth@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 autolearn=unavailable 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 01/07/2024 17.06, Michael S. Tsirkin wrote: > On Mon, Jul 01, 2024 at 04:07:56PM +0200, Thomas Huth wrote: >> On 18/06/2024 14.19, Thomas Huth wrote: >>> The unrealize functions of the various vhost-user devices are >>> calling the corresponding vhost_*_set_status() functions with a >>> status of 0 to shut down the device correctly. >>> >>> Now these vhost_*_set_status() functions all follow this scheme: >>> >>> bool should_start = virtio_device_should_start(vdev, status); >>> >>> if (vhost_dev_is_started(&vvc->vhost_dev) == should_start) { >>> return; >>> } >>> >>> if (should_start) { >>> /* ... do the initialization stuff ... */ >>> } else { >>> /* ... do the cleanup stuff ... */ >>> } >>> >>> The problem here is virtio_device_should_start(vdev, 0) currently >>> always returns "true" since it internally only looks at vdev->started >>> instead of looking at the "status" parameter. Thus once the device >>> got started once, virtio_device_should_start() always returns true >>> and thus the vhost_*_set_status() functions return early, without >>> ever doing any clean-up when being called with status == 0. This >>> causes e.g. problems when trying to hot-plug and hot-unplug a vhost >>> user devices multiple times since the de-initialization step is >>> completely skipped during the unplug operation. >>> >>> This bug has been introduced in commit 9f6bcfd99f ("hw/virtio: move >>> vm_running check to virtio_device_started") which replaced >>> >>> should_start = status & VIRTIO_CONFIG_S_DRIVER_OK; >>> >>> with >>> >>> should_start = virtio_device_started(vdev, status); >>> >>> which later got replaced by virtio_device_should_start(). This blocked >>> the possibility to set should_start to false in case the status flag >>> VIRTIO_CONFIG_S_DRIVER_OK was not set. >>> >>> Fix it by adjusting the virtio_device_should_start() function to >>> only consider the status flag instead of vdev->started. Since this >>> function is only used in the various vhost_*_set_status() functions >>> for exactly the same purpose, it should be fine to fix it in this >>> central place there without any risk to change the behavior of other >>> code. >>> >>> Fixes: 9f6bcfd99f ("hw/virtio: move vm_running check to virtio_device_started") >>> Buglink: https://issues.redhat.com/browse/RHEL-40708 >>> Signed-off-by: Thomas Huth >>> --- >>> include/hw/virtio/virtio.h | 8 ++++---- >>> 1 file changed, 4 insertions(+), 4 deletions(-) >>> >>> diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h >>> index 7d5ffdc145..2eafad17b8 100644 >>> --- a/include/hw/virtio/virtio.h >>> +++ b/include/hw/virtio/virtio.h >>> @@ -470,9 +470,9 @@ static inline bool virtio_device_started(VirtIODevice *vdev, uint8_t status) >>> * @vdev - the VirtIO device >>> * @status - the devices status bits >>> * >>> - * This is similar to virtio_device_started() but also encapsulates a >>> - * check on the VM status which would prevent a device starting >>> - * anyway. >>> + * This is similar to virtio_device_started() but ignores vdev->started >>> + * and also encapsulates a check on the VM status which would prevent a >>> + * device from starting anyway. >>> */ >>> static inline bool virtio_device_should_start(VirtIODevice *vdev, uint8_t status) >>> { >>> @@ -480,7 +480,7 @@ static inline bool virtio_device_should_start(VirtIODevice *vdev, uint8_t status >>> return false; >>> } >>> - return virtio_device_started(vdev, status); >>> + return status & VIRTIO_CONFIG_S_DRIVER_OK; >>> } >> >> Michael, any concerns or comments about this patch? >> >> If not, I could also take it via my s390x tree since this fixes vhost-ccw >> devices on s390x. >> >> Thomas > > I'm working on a pull request with this today. > I can drop it if you prefer ... Ah, perfect, please include it in your PR then! Thanks, Thomas