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Tsirkin" To: Yishai Hadas Cc: alex.williamson@redhat.com, jasowang@redhat.com, jgg@nvidia.com, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, parav@nvidia.com, feliu@nvidia.com, jiri@nvidia.com, kevin.tian@intel.com, joao.m.martins@oracle.com, si-wei.liu@oracle.com, leonro@nvidia.com, maorg@nvidia.com Subject: Re: [PATCH V2 vfio 3/9] virtio-pci: Introduce admin command sending function Message-ID: <20231029162255-mutt-send-email-mst@kernel.org> References: <20231029155952.67686-1-yishaih@nvidia.com> <20231029155952.67686-4-yishaih@nvidia.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20231029155952.67686-4-yishaih@nvidia.com> On Sun, Oct 29, 2023 at 05:59:46PM +0200, Yishai Hadas wrote: > From: Feng Liu > > Add support for sending admin command through admin virtqueue interface. > Abort any inflight admin commands once device reset completes. > > To enforce the below statement from the specification [1], the admin > queue is activated for the upper layer users only post of setting status > to DRIVER_OK. > > [1] The driver MUST NOT send any buffer available notifications to the > device before setting DRIVER_OK. > > Signed-off-by: Feng Liu > Reviewed-by: Parav Pandit > Signed-off-by: Yishai Hadas > --- > drivers/virtio/virtio_pci_common.h | 3 + > drivers/virtio/virtio_pci_modern.c | 174 +++++++++++++++++++++++++++++ > include/linux/virtio.h | 8 ++ > include/uapi/linux/virtio_pci.h | 22 ++++ > 4 files changed, 207 insertions(+) > > diff --git a/drivers/virtio/virtio_pci_common.h b/drivers/virtio/virtio_pci_common.h > index e03af0966a4b..a21b9ba01a60 100644 > --- a/drivers/virtio/virtio_pci_common.h > +++ b/drivers/virtio/virtio_pci_common.h > @@ -44,9 +44,12 @@ struct virtio_pci_vq_info { > struct virtio_pci_admin_vq { > /* Virtqueue info associated with this admin queue. */ > struct virtio_pci_vq_info info; > + struct completion flush_done; > + refcount_t refcount; what exactly does this count? > /* Name of the admin queue: avq.$index. */ > char name[10]; > u16 vq_index; > + bool abort; > }; > > /* Our device structure */ > diff --git a/drivers/virtio/virtio_pci_modern.c b/drivers/virtio/virtio_pci_modern.c > index 01c5ba346471..ccd7a4d9f57f 100644 > --- a/drivers/virtio/virtio_pci_modern.c > +++ b/drivers/virtio/virtio_pci_modern.c > @@ -36,6 +36,58 @@ static bool vp_is_avq(struct virtio_device *vdev, unsigned int index) > return index == vp_dev->admin_vq.vq_index; > } > > +static bool vp_modern_avq_get(struct virtio_pci_admin_vq *admin_vq) > +{ > + return refcount_inc_not_zero(&admin_vq->refcount); > +} > + > +static void vp_modern_avq_put(struct virtio_pci_admin_vq *admin_vq) > +{ > + if (refcount_dec_and_test(&admin_vq->refcount)) > + complete(&admin_vq->flush_done); > +} > + > +static bool vp_modern_avq_is_abort(const struct virtio_pci_admin_vq *admin_vq) > +{ > + return READ_ONCE(admin_vq->abort); > +} > + > +static void > +vp_modern_avq_set_abort(struct virtio_pci_admin_vq *admin_vq, bool abort) > +{ > + /* Mark the AVQ to abort, so that inflight commands can be aborted. */ > + WRITE_ONCE(admin_vq->abort, abort); > +} > + > +static void vp_modern_avq_activate(struct virtio_device *vdev) > +{ > + struct virtio_pci_device *vp_dev = to_vp_device(vdev); > + struct virtio_pci_admin_vq *admin_vq = &vp_dev->admin_vq; > + > + if (!virtio_has_feature(vdev, VIRTIO_F_ADMIN_VQ)) > + return; > + > + init_completion(&admin_vq->flush_done); > + refcount_set(&admin_vq->refcount, 1); > + vp_modern_avq_set_abort(admin_vq, false); > +} > + > +static void vp_modern_avq_deactivate(struct virtio_device *vdev) > +{ > + struct virtio_pci_device *vp_dev = to_vp_device(vdev); > + struct virtio_pci_admin_vq *admin_vq = &vp_dev->admin_vq; > + > + if (!virtio_has_feature(vdev, VIRTIO_F_ADMIN_VQ)) > + return; > + > + vp_modern_avq_set_abort(admin_vq, true); > + /* Balance with refcount_set() during vp_modern_avq_activate */ > + vp_modern_avq_put(admin_vq); > + > + /* Wait for all the inflight admin commands to be aborted */ > + wait_for_completion(&vp_dev->admin_vq.flush_done); > +} > + > static void vp_transport_features(struct virtio_device *vdev, u64 features) > { > struct virtio_pci_device *vp_dev = to_vp_device(vdev); > @@ -172,6 +224,8 @@ static void vp_set_status(struct virtio_device *vdev, u8 status) > /* We should never be setting status to 0. */ > BUG_ON(status == 0); > vp_modern_set_status(&vp_dev->mdev, status); > + if (status & VIRTIO_CONFIG_S_DRIVER_OK) > + vp_modern_avq_activate(vdev); > } > > static void vp_reset(struct virtio_device *vdev) > @@ -188,6 +242,9 @@ static void vp_reset(struct virtio_device *vdev) > */ > while (vp_modern_get_status(mdev)) > msleep(1); > + > + vp_modern_avq_deactivate(vdev); > + > /* Flush pending VQ/configuration callbacks. */ > vp_synchronize_vectors(vdev); > } > @@ -505,6 +562,121 @@ static bool vp_get_shm_region(struct virtio_device *vdev, > return true; > } > > +static int virtqueue_exec_admin_cmd(struct virtio_pci_admin_vq *admin_vq, > + struct scatterlist **sgs, > + unsigned int out_num, > + unsigned int in_num, > + void *data, > + gfp_t gfp) > +{ > + struct virtqueue *vq; > + int ret, len; > + > + if (!vp_modern_avq_get(admin_vq)) > + return -EIO; > + > + vq = admin_vq->info.vq; > + > + ret = virtqueue_add_sgs(vq, sgs, out_num, in_num, data, gfp); > + if (ret < 0) > + goto out; > + virtqueue_add_sgs requires locking, it is not atomic. Add some kind of mutex? Will also help prevent vq overruns. > + if (unlikely(!virtqueue_kick(vq))) { > + ret = -EIO; > + goto out; > + } > + > + while (!virtqueue_get_buf(vq, &len) && > + !virtqueue_is_broken(vq) && > + !vp_modern_avq_is_abort(admin_vq)) > + cpu_relax(); > + > + if (vp_modern_avq_is_abort(admin_vq) || virtqueue_is_broken(vq)) { > + ret = -EIO; > + goto out; > + } > +out: > + vp_modern_avq_put(admin_vq); > + return ret; > +} > + > +#define VIRTIO_AVQ_SGS_MAX 4 > + > +static int vp_modern_admin_cmd_exec(struct virtio_device *vdev, > + struct virtio_admin_cmd *cmd) > +{ > + struct scatterlist *sgs[VIRTIO_AVQ_SGS_MAX], hdr, stat; > + struct virtio_pci_device *vp_dev = to_vp_device(vdev); > + struct virtio_admin_cmd_status *va_status; > + unsigned int out_num = 0, in_num = 0; > + struct virtio_admin_cmd_hdr *va_hdr; > + struct virtqueue *avq; > + u16 status; > + int ret; > + > + avq = virtio_has_feature(vdev, VIRTIO_F_ADMIN_VQ) ? > + vp_dev->admin_vq.info.vq : NULL; > + if (!avq) > + return -EOPNOTSUPP; > + > + va_status = kzalloc(sizeof(*va_status), GFP_KERNEL); > + if (!va_status) > + return -ENOMEM; > + > + va_hdr = kzalloc(sizeof(*va_hdr), GFP_KERNEL); > + if (!va_hdr) { > + ret = -ENOMEM; > + goto err_alloc; > + } > + > + va_hdr->opcode = cmd->opcode; > + va_hdr->group_type = cmd->group_type; > + va_hdr->group_member_id = cmd->group_member_id; > + > + /* Add header */ > + sg_init_one(&hdr, va_hdr, sizeof(*va_hdr)); > + sgs[out_num] = &hdr; > + out_num++; > + > + if (cmd->data_sg) { > + sgs[out_num] = cmd->data_sg; > + out_num++; > + } > + > + /* Add return status */ > + sg_init_one(&stat, va_status, sizeof(*va_status)); > + sgs[out_num + in_num] = &stat; > + in_num++; > + > + if (cmd->result_sg) { > + sgs[out_num + in_num] = cmd->result_sg; > + in_num++; > + } BUG_ON here to check we did not overrun sgs? > + > + ret = virtqueue_exec_admin_cmd(&vp_dev->admin_vq, sgs, > + out_num, in_num, > + sgs, GFP_KERNEL); > + if (ret) { > + dev_err(&vdev->dev, > + "Failed to execute command on admin vq: %d\n.", ret); > + goto err_cmd_exec; > + } > + > + status = le16_to_cpu(va_status->status); > + if (status != VIRTIO_ADMIN_STATUS_OK) { > + dev_err(&vdev->dev, > + "admin command error: status(%#x) qualifier(%#x)\n", > + status, le16_to_cpu(va_status->status_qualifier)); > + ret = -status; > + } > + > +err_cmd_exec: > + kfree(va_hdr); > +err_alloc: > + kfree(va_status); > + return ret; > +} > + > static int vp_modern_create_avq(struct virtio_device *vdev) > { > struct virtio_pci_device *vp_dev = to_vp_device(vdev); > @@ -530,6 +702,7 @@ static int vp_modern_create_avq(struct virtio_device *vdev) > return PTR_ERR(vq); > } > > + refcount_set(&vp_dev->admin_vq.refcount, 0); > vp_dev->admin_vq.info.vq = vq; > vp_modern_set_queue_enable(&vp_dev->mdev, avq->info.vq->index, true); > return 0; > @@ -542,6 +715,7 @@ static void vp_modern_destroy_avq(struct virtio_device *vdev) > if (!virtio_has_feature(vdev, VIRTIO_F_ADMIN_VQ)) > return; > > + WARN_ON(refcount_read(&vp_dev->admin_vq.refcount)); > vp_dev->del_vq(&vp_dev->admin_vq.info); > } > > diff --git a/include/linux/virtio.h b/include/linux/virtio.h > index 4cc614a38376..b0201747a263 100644 > --- a/include/linux/virtio.h > +++ b/include/linux/virtio.h > @@ -103,6 +103,14 @@ int virtqueue_resize(struct virtqueue *vq, u32 num, > int virtqueue_reset(struct virtqueue *vq, > void (*recycle)(struct virtqueue *vq, void *buf)); > > +struct virtio_admin_cmd { > + __le16 opcode; > + __le16 group_type; > + __le64 group_member_id; > + struct scatterlist *data_sg; > + struct scatterlist *result_sg; > +}; > + > /** > * struct virtio_device - representation of a device using virtio > * @index: unique position on the virtio bus > diff --git a/include/uapi/linux/virtio_pci.h b/include/uapi/linux/virtio_pci.h > index f703afc7ad31..68eacc9676dc 100644 > --- a/include/uapi/linux/virtio_pci.h > +++ b/include/uapi/linux/virtio_pci.h > @@ -207,4 +207,26 @@ struct virtio_pci_cfg_cap { > > #endif /* VIRTIO_PCI_NO_MODERN */ > > +/* Admin command status. */ > +#define VIRTIO_ADMIN_STATUS_OK 0 > + > +struct __packed virtio_admin_cmd_hdr { > + __le16 opcode; > + /* > + * 1 - SR-IOV > + * 2-65535 - reserved > + */ > + __le16 group_type; > + /* Unused, reserved for future extensions. */ > + __u8 reserved1[12]; > + __le64 group_member_id; > +}; > + > +struct __packed virtio_admin_cmd_status { > + __le16 status; > + __le16 status_qualifier; > + /* Unused, reserved for future extensions. */ > + __u8 reserved2[4]; > +}; > + > #endif > -- > 2.27.0