[PATCH V1 vfio 4/9] virtio-pci: Introduce admin command sending function

Yishai Hadas
2023-10-17T13:43:22Z

From: Feng Liu <feliu@nvidia.com>

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 <feliu@nvidia.com>
Reviewed-by: Parav Pandit <parav@nvidia.com>
Signed-off-by: Yishai Hadas <yishaih@nvidia.com>
---
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;
/* 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..cc159a8e6c70 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;
+
+ 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)) {
+ 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++;
+ }
+
+ 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