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>
---
v1->v2:
- rebased on top of newly added patches
- rebased on top of changes in previous patches (vq info, vqs[])
- removed WARN_ON_ONCE() when calling virtqueue_kick()
- added virtqueue_is_broken check in virtqueue_exec_admin_cmd() loop
- added vp_modern_avq_cleanup() implementation to handle surprise
removal case
---
drivers/virtio/virtio_pci_common.c | 13 ++++--
drivers/virtio/virtio_pci_common.h | 3 ++
drivers/virtio/virtio_pci_modern.c | 74 +++++++++++++++++++++++++-----
include/linux/virtio.h | 3 ++
4 files changed, 77 insertions(+), 16 deletions(-)
diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c
index 267643bb1cd5..c44d8ba00c02 100644
--- a/drivers/virtio/virtio_pci_common.c
+++ b/drivers/virtio/virtio_pci_common.c
@@ -395,6 +395,8 @@ static int vp_find_vqs_msix(struct virtio_device *vdev, unsigned int nvqs,
if (vqi->name && vqi->callback)
++nvectors;
}
+ if (avq_num && vector_policy == VP_VQ_VECTOR_POLICY_EACH)
+ ++nvectors;
} else {
/* Second best: one for change, shared for all vqs. */
nvectors = 2;
@@ -425,9 +427,9 @@ 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);
- vq = vp_find_one_vq_msix(vdev, avq->vq_index, NULL, avq->name, false,
- true, &allocated_vectors, vector_policy,
- &vp_dev->admin_vq.info);
+ vq = vp_find_one_vq_msix(vdev, avq->vq_index, vp_modern_avq_done,
+ avq->name, false, true, &allocated_vectors,
+ vector_policy, &vp_dev->admin_vq.info);
if (IS_ERR(vq)) {
err = PTR_ERR(vq);
goto error_find;
@@ -486,8 +488,9 @@ 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);
- vq = vp_setup_vq(vdev, queue_idx++, NULL, avq->name, false,
- VIRTIO_MSI_NO_VECTOR, &vp_dev->admin_vq.info);
+ vq = vp_setup_vq(vdev, queue_idx++, vp_modern_avq_done, avq->name,
+ false, VIRTIO_MSI_NO_VECTOR,
+ &vp_dev->admin_vq.info);
if (IS_ERR(vq)) {
err = PTR_ERR(vq);
goto out_del_vqs;
diff --git a/drivers/virtio/virtio_pci_common.h b/drivers/virtio/virtio_pci_common.h
index de59bb06ec3c..90df381fbbcf 100644
--- a/drivers/virtio/virtio_pci_common.h
+++ b/drivers/virtio/virtio_pci_common.h
@@ -47,6 +47,8 @@ struct virtio_pci_admin_vq {
struct virtio_pci_vq_info *info;
/* 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];
@@ -178,6 +180,7 @@ 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 0fd344d1eaf9..608df3263df1 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_admin_vq *admin_vq,
u16 opcode,
struct scatterlist **sgs,
@@ -61,7 +78,8 @@ static int virtqueue_exec_admin_cmd(struct virtio_pci_admin_vq *admin_vq,
struct virtio_admin_cmd *cmd)
{
struct virtqueue *vq;
- int ret, len;
+ unsigned long flags;
+ int ret;
vq = admin_vq->info->vq;
if (!vq)
@@ -72,21 +90,33 @@ static int virtqueue_exec_admin_cmd(struct virtio_pci_admin_vq *admin_vq,
!((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;
+ init_completion(&cmd->completion);
- if (unlikely(!virtqueue_kick(vq)))
+again:
+ if (virtqueue_is_broken(vq))
return -EIO;
- while (!virtqueue_get_buf(vq, &len) &&
- !virtqueue_is_broken(vq))
- cpu_relax();
+ 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 (!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;
+ return cmd->ret;
+
+unlock_err:
+ spin_unlock_irqrestore(&admin_vq->lock, flags);
+ return -EIO;
}
int vp_modern_admin_cmd_exec(struct virtio_device *vdev,
@@ -209,6 +239,25 @@ static void vp_modern_avq_activate(struct virtio_device *vdev)
virtio_pci_admin_cmd_list_init(vdev);
}
+static void vp_modern_avq_cleanup(struct virtio_device *vdev)
+{
+ struct virtio_pci_device *vp_dev = to_vp_device(vdev);
+ struct virtio_admin_cmd *cmd;
+ struct virtqueue *vq;
+
+ if (!virtio_has_feature(vdev, VIRTIO_F_ADMIN_VQ))
+ return;
+
+ vq = vp_dev->vqs[vp_dev->admin_vq.vq_index]->vq;
+ if (!vq)
+ return;
+
+ while ((cmd = virtqueue_detach_unused_buf(vq))) {
+ cmd->ret = -EIO;
+ complete(&cmd->completion);
+ }
+}
+
static void vp_transport_features(struct virtio_device *vdev, u64 features)
{
struct virtio_pci_device *vp_dev = to_vp_device(vdev);
@@ -403,6 +452,8 @@ static void vp_reset(struct virtio_device *vdev)
while (vp_modern_get_status(mdev))
msleep(1);
+ vp_modern_avq_cleanup(vdev);
+
/* Flush pending VQ/configuration callbacks. */
vp_synchronize_vectors(vdev);
}
@@ -785,6 +836,7 @@ 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 96fea920873b..999ff5934392 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 +110,8 @@ struct virtio_admin_cmd {
__le64 group_member_id;
struct scatterlist *data_sg;
struct scatterlist *result_sg;
+ struct completion completion;
+ int ret;
};
/**
--
2.45.2
