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Tsirkin" To: Philippe =?iso-8859-1?Q?Mathieu-Daud=E9?= Cc: qemu-devel@nongnu.org, Cindy Lu , qemu-stable@nongnu.org, Lei Yang , Jason Wang Subject: Re: [PATCH v7] virtio-pci: Fix the crash that the vector was used after released. Message-ID: <20240415052513-mutt-send-email-mst@kernel.org> References: <133af310-c3ea-4b2f-b4d9-846cc0684710@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <133af310-c3ea-4b2f-b4d9-846cc0684710@linaro.org> Received-SPF: pass client-ip=170.10.133.124; envelope-from=mst@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -41 X-Spam_score: -4.2 X-Spam_bar: ---- X-Spam_report: (-4.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-2.127, 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=-0.01, RCVD_IN_MSPIKE_WL=-0.01, 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 Mon, Apr 15, 2024 at 11:23:46AM +0200, Philippe Mathieu-Daudé wrote: > On 15/4/24 11:19, Michael S. Tsirkin wrote: > > From: Cindy Lu > > > > During the booting process of the non-standard image, the behavior of the > > called function in qemu is as follows: > > > > 1. vhost_net_stop() was triggered by guest image. This will call the function > > virtio_pci_set_guest_notifiers() with assgin= false, > > virtio_pci_set_guest_notifiers(） will release the irqfd for vector 0 > > > > 2. virtio_reset() was triggered, this will set configure vector to VIRTIO_NO_VECTOR > > > > 3.vhost_net_start() was called (at this time, the configure vector is > > still VIRTIO_NO_VECTOR) and then call virtio_pci_set_guest_notifiers() with > > assgin=true, so the irqfd for vector 0 is still not "init" during this process > > > > 4. The system continues to boot and sets the vector back to 0. After that > > msix_fire_vector_notifier() was triggered to unmask the vector 0 and meet the crash > > > > To fix the issue, we need to support changing the vector after VIRTIO_CONFIG_S_DRIVER_OK is set. > > > > MST: coding style and typo fixups > > > > Fixes: f9a09ca3ea ("vhost: add support for configure interrupt") > > Cc: qemu-stable@nongnu.org > > Signed-off-by: Cindy Lu > > Message-Id: <20240412062750.475180-1-lulu@redhat.com> > > Reviewed-by: Michael S. Tsirkin > > Signed-off-by: Michael S. Tsirkin > > Signed-off-by: Michael S. Tsirkin > > --- > > > > To expedite fixed lots of style issues myself. > > Completely untested - guys can you pls test and ack? > > > > > > hw/virtio/virtio-pci.c | 41 +++++++++++++++++++++++++++++++++++++++-- > > 1 file changed, 39 insertions(+), 2 deletions(-) > > > > diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c > > index cb6940fc0e..e9edd57339 100644 > > --- a/hw/virtio/virtio-pci.c > > +++ b/hw/virtio/virtio-pci.c > > @@ -1424,6 +1424,34 @@ static int virtio_pci_add_mem_cap(VirtIOPCIProxy *proxy, > > return offset; > > } > > +static void virtio_pci_set_and_change_vector(VirtIODevice *vdev, > > + VirtIOPCIProxy *proxy, > > + int queue_no, uint16_t old_vector, > > + uint16_t new_vector) > > +{ > > Alternatively: > > if (new_vector == old_vector) { > return; > } True. And in fact callers do not need check this. Let me do v8. > > + bool kvm_irqfd = (vdev->status & VIRTIO_CONFIG_S_DRIVER_OK) && > > + msix_enabled(&proxy->pci_dev) && kvm_msi_via_irqfd_enabled(); > > + > > + /* > > + * If the device uses irqfd and the vector changes after DRIVER_OK is > > + * set, we need to release the old vector and set up the new one. > > + * Otherwise just need to set the new vector on the device. > > + */ > > + if (kvm_irqfd && old_vector != VIRTIO_NO_VECTOR) { > > + kvm_virtio_pci_vector_release_one(proxy, queue_no); > > + } > > + /* Set the new vector on the device. */ > > + if (queue_no == VIRTIO_CONFIG_IRQ_IDX) { > > + vdev->config_vector = new_vector; > > + } else { > > + virtio_queue_set_vector(vdev, queue_no, new_vector); > > + } > > + /* If the new vector changed need to set it up. */ > > + if (kvm_irqfd && new_vector != VIRTIO_NO_VECTOR) { > > + kvm_virtio_pci_vector_use_one(proxy, queue_no); > > + } > > +} > > + > > int virtio_pci_add_shm_cap(VirtIOPCIProxy *proxy, > > uint8_t bar, uint64_t offset, uint64_t length, > > uint8_t id) > > @@ -1570,7 +1598,12 @@ static void virtio_pci_common_write(void *opaque, hwaddr addr, > > } else { > > val = VIRTIO_NO_VECTOR; > > } > > - vdev->config_vector = val; > > + vector = vdev->config_vector; > > + /* Check if we need to change the vector. */ > > + if (val != vector) { > > + virtio_pci_set_and_change_vector(vdev, proxy, VIRTIO_CONFIG_IRQ_IDX, > > + vector, val); > > + } > > break;