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vdpa_sim: add support for user VA

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The new "use_va" module parameter (default: true) is used in
vdpa_alloc_device() to inform the vDPA framework that the device
supports VA.

vringh is initialized to use VA only when "use_va" is true and the
user's mm has been bound. So, only when the bus supports user VA
(e.g. vhost-vdpa).

vdpasim_mm_work_fn work is used to serialize the binding to a new
address space when the .bind_mm callback is invoked, and unbinding
when the .unbind_mm callback is invoked.

Call mmget_not_zero()/kthread_use_mm() inside the worker function
to pin the address space only as long as needed, following the
documentation of mmget() in include/linux/sched/mm.h:

  * Never use this function to pin this address space for an
  * unbounded/indefinite amount of time.

Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Message-Id: <20230404131734.45943-1-sgarzare@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Stefano Garzarella 2023-04-04 15:17:34 +02:00 committed by Michael S. Tsirkin
parent d7621c28fc
commit 4bb94d2de2
2 changed files with 89 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

95
drivers/vdpa/vdpa_sim/vdpa_sim.c
View File

@ -35,10 +35,44 @@ module_param(max_iotlb_entries, int, 0444);
MODULE_PARM_DESC(max_iotlb_entries,
"Maximum number of iotlb entries for each address space. 0 means unlimited. (default: 2048)");
static bool use_va = true;
module_param(use_va, bool, 0444);
MODULE_PARM_DESC(use_va, "Enable/disable the device's ability to use VA");
#define VDPASIM_QUEUE_ALIGN PAGE_SIZE
#define VDPASIM_QUEUE_MAX 256
#define VDPASIM_VENDOR_ID 0
struct vdpasim_mm_work {
struct kthread_work work;
struct vdpasim *vdpasim;
struct mm_struct *mm_to_bind;
int ret;
};
static void vdpasim_mm_work_fn(struct kthread_work *work)
{
struct vdpasim_mm_work *mm_work =
container_of(work, struct vdpasim_mm_work, work);
struct vdpasim *vdpasim = mm_work->vdpasim;
mm_work->ret = 0;
//TODO: should we attach the cgroup of the mm owner?
vdpasim->mm_bound = mm_work->mm_to_bind;
}
static void vdpasim_worker_change_mm_sync(struct vdpasim *vdpasim,
struct vdpasim_mm_work *mm_work)
{
struct kthread_work *work = &mm_work->work;
kthread_init_work(work, vdpasim_mm_work_fn);
kthread_queue_work(vdpasim->worker, work);
kthread_flush_work(work);
}
static struct vdpasim *vdpa_to_sim(struct vdpa_device *vdpa)
{
return container_of(vdpa, struct vdpasim, vdpa);
@ -59,13 +93,20 @@ static void vdpasim_queue_ready(struct vdpasim *vdpasim, unsigned int idx)
{
struct vdpasim_virtqueue *vq = &vdpasim->vqs[idx];
uint16_t last_avail_idx = vq->vring.last_avail_idx;
struct vring_desc *desc = (struct vring_desc *)
(uintptr_t)vq->desc_addr;
struct vring_avail *avail = (struct vring_avail *)
(uintptr_t)vq->driver_addr;
struct vring_used *used = (struct vring_used *)
(uintptr_t)vq->device_addr;
vringh_init_iotlb(&vq->vring, vdpasim->features, vq->num, true,
(struct vring_desc *)(uintptr_t)vq->desc_addr,
(struct vring_avail *)
(uintptr_t)vq->driver_addr,
(struct vring_used *)
(uintptr_t)vq->device_addr);
if (use_va && vdpasim->mm_bound) {
vringh_init_iotlb_va(&vq->vring, vdpasim->features, vq->num,
true, desc, avail, used);
} else {
vringh_init_iotlb(&vq->vring, vdpasim->features, vq->num,
true, desc, avail, used);
}
vq->vring.last_avail_idx = last_avail_idx;
@ -130,8 +171,20 @@ static const struct vdpa_config_ops vdpasim_batch_config_ops;
static void vdpasim_work_fn(struct kthread_work *work)
{
struct vdpasim *vdpasim = container_of(work, struct vdpasim, work);
struct mm_struct *mm = vdpasim->mm_bound;
if (use_va && mm) {
if (!mmget_not_zero(mm))
return;
kthread_use_mm(mm);
}
vdpasim->dev_attr.work_fn(vdpasim);
if (use_va && mm) {
kthread_unuse_mm(mm);
mmput(mm);
}
}
struct vdpasim *vdpasim_create(struct vdpasim_dev_attr *dev_attr,
@ -162,7 +215,7 @@ struct vdpasim *vdpasim_create(struct vdpasim_dev_attr *dev_attr,
vdpa = __vdpa_alloc_device(NULL, ops,
dev_attr->ngroups, dev_attr->nas,
dev_attr->alloc_size,
dev_attr->name, false);
dev_attr->name, use_va);
if (IS_ERR(vdpa)) {
ret = PTR_ERR(vdpa);
goto err_alloc;
@ -582,6 +635,30 @@ err:
return ret;
}
static int vdpasim_bind_mm(struct vdpa_device *vdpa, struct mm_struct *mm)
{
struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
struct vdpasim_mm_work mm_work;
mm_work.vdpasim = vdpasim;
mm_work.mm_to_bind = mm;
vdpasim_worker_change_mm_sync(vdpasim, &mm_work);
return mm_work.ret;
}
static void vdpasim_unbind_mm(struct vdpa_device *vdpa)
{
struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
struct vdpasim_mm_work mm_work;
mm_work.vdpasim = vdpasim;
mm_work.mm_to_bind = NULL;
vdpasim_worker_change_mm_sync(vdpasim, &mm_work);
}
static int vdpasim_dma_map(struct vdpa_device *vdpa, unsigned int asid,
u64 iova, u64 size,
u64 pa, u32 perm, void *opaque)
@ -678,6 +755,8 @@ static const struct vdpa_config_ops vdpasim_config_ops = {
.set_group_asid = vdpasim_set_group_asid,
.dma_map = vdpasim_dma_map,
.dma_unmap = vdpasim_dma_unmap,
.bind_mm = vdpasim_bind_mm,
.unbind_mm = vdpasim_unbind_mm,
.free = vdpasim_free,
};
@ -712,6 +791,8 @@ static const struct vdpa_config_ops vdpasim_batch_config_ops = {
.get_iova_range = vdpasim_get_iova_range,
.set_group_asid = vdpasim_set_group_asid,
.set_map = vdpasim_set_map,
.bind_mm = vdpasim_bind_mm,
.unbind_mm = vdpasim_unbind_mm,
.free = vdpasim_free,
};

1
drivers/vdpa/vdpa_sim/vdpa_sim.h
View File

@ -59,6 +59,7 @@ struct vdpasim {
struct vdpasim_virtqueue *vqs;
struct kthread_worker *worker;
struct kthread_work work;
struct mm_struct *mm_bound;
struct vdpasim_dev_attr dev_attr;
/* mutex to synchronize virtqueue state */
struct mutex mutex;