[PATCH V7 vfio 3/9] virtio-pci: Introduce admin command sending function

Yishai Hadas
2023-12-07T10:29:24Z

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. Activate
admin queue when device becomes ready; deactivate on device reset.

To comply to the below specification statement [1], the admin virtqueue
is activated for upper layer users only after setting DRIVER_OK status.

[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>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Yishai Hadas <yishaih@nvidia.com>
---
drivers/virtio/virtio_pci_common.h | 3 +
drivers/virtio/virtio_pci_modern.c | 143 ++++++++++++++++++++++++++++-
include/linux/virtio.h | 8 ++
include/uapi/linux/virtio_pci.h | 22 +++++
4 files changed, 174 insertions(+), 2 deletions(-)

diff --git a/drivers/virtio/virtio_pci_common.h b/drivers/virtio/virtio_pci_common.h
index 7306128e63e9..a50a58014c9f 100644
--- a/drivers/virtio/virtio_pci_common.h
+++ b/drivers/virtio/virtio_pci_common.h
@@ -29,6 +29,7 @@
#include <linux/virtio_pci_modern.h>
#include <linux/highmem.h>
#include <linux/spinlock.h>
+#include <linux/mutex.h>

struct virtio_pci_vq_info {
/* the actual virtqueue */
@@ -44,6 +45,8 @@ struct virtio_pci_vq_info {
struct virtio_pci_admin_vq {
/* Virtqueue info associated with this admin queue. */
struct virtio_pci_vq_info info;
+ /* serializing admin commands execution and virtqueue deletion */
+ struct mutex cmd_lock;
/* Name of the admin queue: avq.$vq_index. */
char name[10];
u16 vq_index;
diff --git a/drivers/virtio/virtio_pci_modern.c b/drivers/virtio/virtio_pci_modern.c
index ce915018b5b0..18366a82408c 100644
--- a/drivers/virtio/virtio_pci_modern.c
+++ b/drivers/virtio/virtio_pci_modern.c
@@ -38,6 +38,132 @@ static bool vp_is_avq(struct virtio_device *vdev, unsigned int index)
return index == vp_dev->admin_vq.vq_index;
}

+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)
+{
+ struct virtqueue *vq;
+ int ret, len;
+
+ vq = admin_vq->info.vq;
+ if (!vq)
+ return -EIO;
+
+ ret = virtqueue_add_sgs(vq, sgs, out_num, in_num, data, GFP_KERNEL);
+ if (ret < 0)
+ return -EIO;
+
+ if (unlikely(!virtqueue_kick(vq)))
+ return -EIO;
+
+ while (!virtqueue_get_buf(vq, &len) &&
+ !virtqueue_is_broken(vq))
+ cpu_relax();
+
+ if (virtqueue_is_broken(vq))
+ return -EIO;
+
+ return 0;
+}
+
+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;
+ u16 status;
+ int ret;
+
+ if (!virtio_has_feature(vdev, VIRTIO_F_ADMIN_VQ))
+ 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++;
+ }
+
+ mutex_lock(&vp_dev->admin_vq.cmd_lock);
+ ret = virtqueue_exec_admin_cmd(&vp_dev->admin_vq, sgs,
+ out_num, in_num, sgs);
+ mutex_unlock(&vp_dev->admin_vq.cmd_lock);
+
+ 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 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;
+
+ __virtqueue_unbreak(admin_vq->info.vq);
+}
+
+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;
+
+ __virtqueue_break(admin_vq->info.vq);
+}
+
static void vp_transport_features(struct virtio_device *vdev, u64 features)
{
struct virtio_pci_device *vp_dev = to_vp_device(vdev);
@@ -213,6 +339,8 @@ 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)
@@ -229,6 +357,9 @@ 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);
}
@@ -404,8 +535,11 @@ static struct virtqueue *setup_vq(struct virtio_pci_device *vp_dev,
goto err;
}

- if (is_avq)
+ if (is_avq) {
+ mutex_lock(&vp_dev->admin_vq.cmd_lock);
vp_dev->admin_vq.info.vq = vq;
+ mutex_unlock(&vp_dev->admin_vq.cmd_lock);
+ }

return vq;

@@ -442,8 +576,11 @@ static void del_vq(struct virtio_pci_vq_info *info)
struct virtio_pci_device *vp_dev = to_vp_device(vq->vdev);
struct virtio_pci_modern_device *mdev = &vp_dev->mdev;

- if (vp_is_avq(&vp_dev->vdev, vq->index))
+ if (vp_is_avq(&vp_dev->vdev, vq->index)) {
+ mutex_lock(&vp_dev->admin_vq.cmd_lock);
vp_dev->admin_vq.info.vq = NULL;
+ mutex_unlock(&vp_dev->admin_vq.cmd_lock);
+ }

if (vp_dev->msix_enabled)
vp_modern_queue_vector(mdev, vq->index,
@@ -662,6 +799,7 @@ int virtio_pci_modern_probe(struct virtio_pci_device *vp_dev)
vp_dev->isr = mdev->isr;
vp_dev->vdev.id = mdev->id;

+ mutex_init(&vp_dev->admin_vq.cmd_lock);
return 0;
}

@@ -669,5 +807,6 @@ void virtio_pci_modern_remove(struct virtio_pci_device *vp_dev)
{
struct virtio_pci_modern_device *mdev = &vp_dev->mdev;

+ mutex_destroy(&vp_dev->admin_vq.cmd_lock);
vp_modern_remove(mdev);
}
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 240ddeef7eae..187fd9e34a30 100644
--- a/include/uapi/linux/virtio_pci.h
+++ b/include/uapi/linux/virtio_pci.h
@@ -223,4 +223,26 @@ 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