Mike Christie
2022-Jul-08 03:05 UTC
[PATCH 0/2] vhost-scsi: IO virtqueue creation fixes/features
The following patches were made over Linus's tree but apply over mst's next/vhost branches. They fix an issue where userspace calculates the number of virtqueues differently than the kernel and allows userspace to control the max number of queues.
Qemu takes it's num_queues limit then adds the fixed queues (control and
event) to the total it will request from the kernel. So when a user
requests 128 (or qemu does it's num_queues calculation based on vCPUS
and other system limits), we hit errors due to userspace trying to setup
130 queues when vhost-scsi has a hard coded limit of 128.
This has vhost-scsi adjust it's max so we can do a total of 130 virtqueues
(128 IO and 2 fixed). For the case where the user has 128 vCPUs the guest
OS can then nicely map each IO virtqueue to a vCPU and not have the odd case
where 2 vCPUs share a virtqueue.
Signed-off-by: Mike Christie <michael.christie at oracle.com>
---
drivers/vhost/scsi.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
index ffd9e6c2ffc1..8d6b4eef554d 100644
--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c
@@ -159,7 +159,7 @@ enum {
};
#define VHOST_SCSI_MAX_TARGET 256
-#define VHOST_SCSI_MAX_VQ 128
+#define VHOST_SCSI_MAX_VQ 128 + VHOST_SCSI_VQ_IO
#define VHOST_SCSI_MAX_EVENT 128
struct vhost_scsi_virtqueue {
--
2.25.1
Mike Christie
2022-Jul-08 03:05 UTC
[PATCH 2/2] vhost scsi: Allow user to control num virtqueues
We are currently hard coded to always create 128 IO virtqueues, so this
adds a modparam to control it. For large systems where we are ok with
using memory for virtqueues it allows us to add up to 1024. This limit
was just selected becuase that's qemu's limit.
Signed-off-by: Mike Christie <michael.christie at oracle.com>
---
drivers/vhost/scsi.c | 85 +++++++++++++++++++++++++++++++-------------
1 file changed, 61 insertions(+), 24 deletions(-)
diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
index 8d6b4eef554d..d9861ab2c300 100644
--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c
@@ -159,9 +159,13 @@ enum {
};
#define VHOST_SCSI_MAX_TARGET 256
-#define VHOST_SCSI_MAX_VQ 128 + VHOST_SCSI_VQ_IO
+#define VHOST_SCSI_MAX_IO_VQ 1024
#define VHOST_SCSI_MAX_EVENT 128
+static unsigned vhost_scsi_max_io_vqs = 128;
+module_param_named(max_io_vqs, vhost_scsi_max_io_vqs, uint, 0644);
+MODULE_PARM_DESC(max_io_vqs, "Set the max number of IO virtqueues a vhost
scsi device can support. The default is 128. The max is 1024.");
+
struct vhost_scsi_virtqueue {
struct vhost_virtqueue vq;
/*
@@ -186,7 +190,9 @@ struct vhost_scsi {
char vs_vhost_wwpn[TRANSPORT_IQN_LEN];
struct vhost_dev dev;
- struct vhost_scsi_virtqueue vqs[VHOST_SCSI_MAX_VQ];
+ struct vhost_scsi_virtqueue *vqs;
+ unsigned long *compl_bitmap;
+ struct vhost_scsi_inflight **old_inflight;
struct vhost_work vs_completion_work; /* cmd completion work item */
struct llist_head vs_completion_list; /* cmd completion queue */
@@ -245,7 +251,7 @@ static void vhost_scsi_init_inflight(struct vhost_scsi *vs,
struct vhost_virtqueue *vq;
int idx, i;
- for (i = 0; i < VHOST_SCSI_MAX_VQ; i++) {
+ for (i = 0; i < vs->dev.nvqs; i++) {
vq = &vs->vqs[i].vq;
mutex_lock(&vq->mutex);
@@ -533,7 +539,6 @@ static void vhost_scsi_complete_cmd_work(struct vhost_work
*work)
{
struct vhost_scsi *vs = container_of(work, struct vhost_scsi,
vs_completion_work);
- DECLARE_BITMAP(signal, VHOST_SCSI_MAX_VQ);
struct virtio_scsi_cmd_resp v_rsp;
struct vhost_scsi_cmd *cmd, *t;
struct llist_node *llnode;
@@ -541,7 +546,7 @@ static void vhost_scsi_complete_cmd_work(struct vhost_work
*work)
struct iov_iter iov_iter;
int ret, vq;
- bitmap_zero(signal, VHOST_SCSI_MAX_VQ);
+ bitmap_zero(vs->compl_bitmap, vs->dev.nvqs);
llnode = llist_del_all(&vs->vs_completion_list);
llist_for_each_entry_safe(cmd, t, llnode, tvc_completion_list) {
se_cmd = &cmd->tvc_se_cmd;
@@ -566,7 +571,7 @@ static void vhost_scsi_complete_cmd_work(struct vhost_work
*work)
vhost_add_used(cmd->tvc_vq, cmd->tvc_vq_desc, 0);
q = container_of(cmd->tvc_vq, struct vhost_scsi_virtqueue, vq);
vq = q - vs->vqs;
- __set_bit(vq, signal);
+ __set_bit(vq, vs->compl_bitmap);
} else
pr_err("Faulted on virtio_scsi_cmd_resp\n");
@@ -574,8 +579,8 @@ static void vhost_scsi_complete_cmd_work(struct vhost_work
*work)
}
vq = -1;
- while ((vq = find_next_bit(signal, VHOST_SCSI_MAX_VQ, vq + 1))
- < VHOST_SCSI_MAX_VQ)
+ while ((vq = find_next_bit(vs->compl_bitmap, vs->dev.nvqs, vq + 1))
+ < vs->dev.nvqs)
vhost_signal(&vs->dev, &vs->vqs[vq].vq);
}
@@ -1421,26 +1426,25 @@ static void vhost_scsi_handle_kick(struct vhost_work
*work)
/* Callers must hold dev mutex */
static void vhost_scsi_flush(struct vhost_scsi *vs)
{
- struct vhost_scsi_inflight *old_inflight[VHOST_SCSI_MAX_VQ];
int i;
/* Init new inflight and remember the old inflight */
- vhost_scsi_init_inflight(vs, old_inflight);
+ vhost_scsi_init_inflight(vs, vs->old_inflight);
/*
* The inflight->kref was initialized to 1. We decrement it here to
* indicate the start of the flush operation so that it will reach 0
* when all the reqs are finished.
*/
- for (i = 0; i < VHOST_SCSI_MAX_VQ; i++)
- kref_put(&old_inflight[i]->kref, vhost_scsi_done_inflight);
+ for (i = 0; i < vs->dev.nvqs; i++)
+ kref_put(&vs->old_inflight[i]->kref, vhost_scsi_done_inflight);
/* Flush both the vhost poll and vhost work */
vhost_dev_flush(&vs->dev);
/* Wait for all reqs issued before the flush to be finished */
- for (i = 0; i < VHOST_SCSI_MAX_VQ; i++)
- wait_for_completion(&old_inflight[i]->comp);
+ for (i = 0; i < vs->dev.nvqs; i++)
+ wait_for_completion(&vs->old_inflight[i]->comp);
}
static void vhost_scsi_destroy_vq_cmds(struct vhost_virtqueue *vq)
@@ -1603,7 +1607,7 @@ vhost_scsi_set_endpoint(struct vhost_scsi *vs,
memcpy(vs->vs_vhost_wwpn, t->vhost_wwpn,
sizeof(vs->vs_vhost_wwpn));
- for (i = VHOST_SCSI_VQ_IO; i < VHOST_SCSI_MAX_VQ; i++) {
+ for (i = VHOST_SCSI_VQ_IO; i < vs->dev.nvqs; i++) {
vq = &vs->vqs[i].vq;
if (!vhost_vq_is_setup(vq))
continue;
@@ -1613,7 +1617,7 @@ vhost_scsi_set_endpoint(struct vhost_scsi *vs,
goto destroy_vq_cmds;
}
- for (i = 0; i < VHOST_SCSI_MAX_VQ; i++) {
+ for (i = 0; i < vs->dev.nvqs; i++) {
vq = &vs->vqs[i].vq;
mutex_lock(&vq->mutex);
vhost_vq_set_backend(vq, vs_tpg);
@@ -1715,7 +1719,7 @@ vhost_scsi_clear_endpoint(struct vhost_scsi *vs,
target_undepend_item(&se_tpg->tpg_group.cg_item);
}
if (match) {
- for (i = 0; i < VHOST_SCSI_MAX_VQ; i++) {
+ for (i = 0; i < vs->dev.nvqs; i++) {
vq = &vs->vqs[i].vq;
mutex_lock(&vq->mutex);
vhost_vq_set_backend(vq, NULL);
@@ -1724,7 +1728,7 @@ vhost_scsi_clear_endpoint(struct vhost_scsi *vs,
/* Make sure cmds are not running before tearing them down. */
vhost_scsi_flush(vs);
- for (i = 0; i < VHOST_SCSI_MAX_VQ; i++) {
+ for (i = 0; i < vs->dev.nvqs; i++) {
vq = &vs->vqs[i].vq;
vhost_scsi_destroy_vq_cmds(vq);
}
@@ -1764,7 +1768,7 @@ static int vhost_scsi_set_features(struct vhost_scsi *vs,
u64 features)
return -EFAULT;
}
- for (i = 0; i < VHOST_SCSI_MAX_VQ; i++) {
+ for (i = 0; i < vs->dev.nvqs; i++) {
vq = &vs->vqs[i].vq;
mutex_lock(&vq->mutex);
vq->acked_features = features;
@@ -1778,16 +1782,40 @@ static int vhost_scsi_open(struct inode *inode, struct
file *f)
{
struct vhost_scsi *vs;
struct vhost_virtqueue **vqs;
- int r = -ENOMEM, i;
+ int r = -ENOMEM, i, nvqs = vhost_scsi_max_io_vqs;
vs = kvzalloc(sizeof(*vs), GFP_KERNEL);
if (!vs)
goto err_vs;
- vqs = kmalloc_array(VHOST_SCSI_MAX_VQ, sizeof(*vqs), GFP_KERNEL);
- if (!vqs)
+ if (nvqs > VHOST_SCSI_MAX_IO_VQ) {
+ pr_err("Invalid max_io_vqs of %d. Using %d.\n", nvqs,
+ VHOST_SCSI_MAX_IO_VQ);
+ nvqs = VHOST_SCSI_MAX_IO_VQ;
+ } else if (nvqs == 0) {
+ pr_err("Invalid max_io_vqs of %d. Using 1.\n", nvqs);
+ nvqs = 1;
+ }
+ nvqs += VHOST_SCSI_VQ_IO;
+
+ vs->compl_bitmap = bitmap_alloc(nvqs, GFP_KERNEL);
+ if (!vs->compl_bitmap)
+ goto err_compl_bitmap;
+
+ vs->old_inflight = kmalloc_array(nvqs, sizeof(*vs->old_inflight),
+ GFP_KERNEL | __GFP_ZERO);
+ if (!vs->old_inflight)
+ goto err_inflight;
+
+ vs->vqs = kmalloc_array(nvqs, sizeof(*vs->vqs),
+ GFP_KERNEL | __GFP_ZERO);
+ if (!vs->vqs)
goto err_vqs;
+ vqs = kmalloc_array(nvqs, sizeof(*vqs), GFP_KERNEL);
+ if (!vqs)
+ goto err_local_vqs;
+
vhost_work_init(&vs->vs_completion_work, vhost_scsi_complete_cmd_work);
vhost_work_init(&vs->vs_event_work, vhost_scsi_evt_work);
@@ -1798,11 +1826,11 @@ static int vhost_scsi_open(struct inode *inode, struct
file *f)
vqs[VHOST_SCSI_VQ_EVT] = &vs->vqs[VHOST_SCSI_VQ_EVT].vq;
vs->vqs[VHOST_SCSI_VQ_CTL].vq.handle_kick = vhost_scsi_ctl_handle_kick;
vs->vqs[VHOST_SCSI_VQ_EVT].vq.handle_kick = vhost_scsi_evt_handle_kick;
- for (i = VHOST_SCSI_VQ_IO; i < VHOST_SCSI_MAX_VQ; i++) {
+ for (i = VHOST_SCSI_VQ_IO; i < nvqs; i++) {
vqs[i] = &vs->vqs[i].vq;
vs->vqs[i].vq.handle_kick = vhost_scsi_handle_kick;
}
- vhost_dev_init(&vs->dev, vqs, VHOST_SCSI_MAX_VQ, UIO_MAXIOV,
+ vhost_dev_init(&vs->dev, vqs, nvqs, UIO_MAXIOV,
VHOST_SCSI_WEIGHT, 0, true, NULL);
vhost_scsi_init_inflight(vs, NULL);
@@ -1810,7 +1838,13 @@ static int vhost_scsi_open(struct inode *inode, struct
file *f)
f->private_data = vs;
return 0;
+err_local_vqs:
+ kfree(vs->vqs);
err_vqs:
+ kfree(vs->old_inflight);
+err_inflight:
+ bitmap_free(vs->compl_bitmap);
+err_compl_bitmap:
kvfree(vs);
err_vs:
return r;
@@ -1828,6 +1862,9 @@ static int vhost_scsi_release(struct inode *inode, struct
file *f)
vhost_dev_stop(&vs->dev);
vhost_dev_cleanup(&vs->dev);
kfree(vs->dev.vqs);
+ kfree(vs->vqs);
+ kfree(vs->old_inflight);
+ bitmap_free(vs->compl_bitmap);
kvfree(vs);
return 0;
}
--
2.25.1