From: Jiri Pirko <jiri@xxxxxxxxxx>
Currently, the code waits in a busy loop on every admin virtqueue issued
command to get a reply. That prevents callers from issuing multiple
commands in parallel.
To overcome this limitation, introduce a virtqueue event callback for
admin virtqueue. For every issued command, use completion mechanism
to wait on a reply. In the event callback, trigger the completion
is done for every incoming reply.
Alongside with that, introduce a spin lock to protect the admin
virtqueue operations.
Signed-off-by: Jiri Pirko <jiri@xxxxxxxxxx>
---
drivers/virtio/virtio_pci_common.c | 10 +++---
drivers/virtio/virtio_pci_common.h | 3 ++
drivers/virtio/virtio_pci_modern.c | 52 +++++++++++++++++++++++-------
include/linux/virtio.h | 2 ++
4 files changed, 51 insertions(+), 16 deletions(-)
diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c
index 07c0511f170a..5ff7304c7a2a 100644
--- a/drivers/virtio/virtio_pci_common.c
+++ b/drivers/virtio/virtio_pci_common.c
@@ -346,6 +346,8 @@ static int vp_find_vqs_msix(struct virtio_device *vdev, unsigned int nvqs,
for (i = 0; i < nvqs; ++i)
if (names[i] && callbacks[i])
++nvectors;
+ if (avq_num)
+ ++nvectors;
} else {
/* Second best: one for change, shared for all vqs. */
nvectors = 2;
@@ -375,8 +377,8 @@ static int vp_find_vqs_msix(struct virtio_device *vdev, unsigned int nvqs,
if (!avq_num)
return 0;
sprintf(avq->name, "avq.%u", avq->vq_index);
- vqs[i] = vp_find_one_vq_msix(vdev, avq->vq_index, NULL, avq->name,
- false, &allocated_vectors);
+ vqs[i] = vp_find_one_vq_msix(vdev, avq->vq_index, vp_modern_avq_done,
+ avq->name, false, &allocated_vectors);
if (IS_ERR(vqs[i])) {
err = PTR_ERR(vqs[i]);
goto error_find;
@@ -432,8 +434,8 @@ static int vp_find_vqs_intx(struct virtio_device *vdev, unsigned int nvqs,
if (!avq_num)
return 0;
sprintf(avq->name, "avq.%u", avq->vq_index);
- vqs[i] = vp_setup_vq(vdev, queue_idx++, NULL, avq->name,
- false, VIRTIO_MSI_NO_VECTOR);
+ vqs[i] = vp_setup_vq(vdev, queue_idx++, vp_modern_avq_done,
+ avq->name, false, VIRTIO_MSI_NO_VECTOR);
if (IS_ERR(vqs[i])) {
err = PTR_ERR(vqs[i]);
goto out_del_vqs;
diff --git a/drivers/virtio/virtio_pci_common.h b/drivers/virtio/virtio_pci_common.h
index b3ef76287b43..38a0b6df0844 100644
--- a/drivers/virtio/virtio_pci_common.h
+++ b/drivers/virtio/virtio_pci_common.h
@@ -45,6 +45,8 @@ struct virtio_pci_vq_info {
struct virtio_pci_admin_vq {
/* serializing admin commands execution. */
struct mutex cmd_lock;
+ /* Protects virtqueue access. */
+ spinlock_t lock;
u64 supported_cmds;
/* Name of the admin queue: avq.$vq_index. */
char name[10];
@@ -174,6 +176,7 @@ struct virtio_device *virtio_pci_vf_get_pf_dev(struct pci_dev *pdev);
#define VIRTIO_ADMIN_CMD_BITMAP 0
#endif
+void vp_modern_avq_done(struct virtqueue *vq);
int vp_modern_admin_cmd_exec(struct virtio_device *vdev,
struct virtio_admin_cmd *cmd);
diff --git a/drivers/virtio/virtio_pci_modern.c b/drivers/virtio/virtio_pci_modern.c
index b4041e541fc3..b9937e4b8a69 100644
--- a/drivers/virtio/virtio_pci_modern.c
+++ b/drivers/virtio/virtio_pci_modern.c
@@ -53,6 +53,23 @@ static bool vp_is_avq(struct virtio_device *vdev, unsigned int index)
return index == vp_dev->admin_vq.vq_index;
}
+void vp_modern_avq_done(struct virtqueue *vq)
+{
+ struct virtio_pci_device *vp_dev = to_vp_device(vq->vdev);
+ struct virtio_pci_admin_vq *admin_vq = &vp_dev->admin_vq;
+ struct virtio_admin_cmd *cmd;
+ unsigned long flags;
+ unsigned int len;
+
+ spin_lock_irqsave(&admin_vq->lock, flags);
+ do {
+ virtqueue_disable_cb(vq);
+ while ((cmd = virtqueue_get_buf(vq, &len)))
+ complete(&cmd->completion);
+ } while (!virtqueue_enable_cb(vq));
+ spin_unlock_irqrestore(&admin_vq->lock, flags);
+}
+
static int virtqueue_exec_admin_cmd(struct virtio_pci_device *vp_dev,
struct virtio_pci_admin_vq *admin_vq,
u16 opcode,
@@ -62,7 +79,8 @@ static int virtqueue_exec_admin_cmd(struct virtio_pci_device *vp_dev,
struct virtio_admin_cmd *cmd)
{
struct virtqueue *vq;
- int ret, len;
+ unsigned long flags;
+ int ret;
vq = vp_dev->vqs[admin_vq->vq_index]->vq;
if (!vq)
@@ -73,21 +91,30 @@ static int virtqueue_exec_admin_cmd(struct virtio_pci_device *vp_dev,
!((1ULL << opcode) & admin_vq->supported_cmds))
return -EOPNOTSUPP;
- ret = virtqueue_add_sgs(vq, sgs, out_num, in_num, cmd, GFP_KERNEL);
- if (ret < 0)
- return -EIO;
-
- if (unlikely(!virtqueue_kick(vq)))
- return -EIO;
+ init_completion(&cmd->completion);
- while (!virtqueue_get_buf(vq, &len) &&
- !virtqueue_is_broken(vq))
- cpu_relax();
+again:
+ spin_lock_irqsave(&admin_vq->lock, flags);
+ ret = virtqueue_add_sgs(vq, sgs, out_num, in_num, cmd, GFP_KERNEL);
+ if (ret < 0) {
+ if (ret == -ENOSPC) {
+ spin_unlock_irqrestore(&admin_vq->lock, flags);
+ cpu_relax();
+ goto again;
+ }
+ goto unlock_err;
+ }
+ if (WARN_ON_ONCE(!virtqueue_kick(vq)))
+ goto unlock_err;
+ spin_unlock_irqrestore(&admin_vq->lock, flags);
- if (virtqueue_is_broken(vq))
- return -EIO;
+ wait_for_completion(&cmd->completion);
return 0;
+
+unlock_err:
+ spin_unlock_irqrestore(&admin_vq->lock, flags);
+ return -EIO;
}
int vp_modern_admin_cmd_exec(struct virtio_device *vdev,
@@ -787,6 +814,7 @@ int virtio_pci_modern_probe(struct virtio_pci_device *vp_dev)
vp_dev->isr = mdev->isr;
vp_dev->vdev.id = mdev->id;
+ spin_lock_init(&vp_dev->admin_vq.lock);
mutex_init(&vp_dev->admin_vq.cmd_lock);
return 0;
}
diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index 26c4325aa373..5db8ee175e71 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -10,6 +10,7 @@
#include <linux/mod_devicetable.h>
#include <linux/gfp.h>
#include <linux/dma-mapping.h>
+#include <linux/completion.h>
/**
* struct virtqueue - a queue to register buffers for sending or receiving.
@@ -109,6 +110,7 @@ struct virtio_admin_cmd {
__le64 group_member_id;
struct scatterlist *data_sg;
struct scatterlist *result_sg;
+ struct completion completion;
};
/**
--
2.45.1
