Messages in this thread | ![/](/images/icornerl.gif) | | Date | Fri, 24 Mar 2023 15:46:57 +0100 | From | Stefano Garzarella <> | Subject | Re: [PATCH v3 8/8] vdpa_sim: add support for user VA |
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On Fri, Mar 24, 2023 at 11:49:32AM +0800, Jason Wang wrote: > >在 2023/3/21 23:48, Stefano Garzarella 写道: >>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. >> >>Signed-off-by: Stefano Garzarella <sgarzare@redhat.com> >>--- >> >>Notes: >> v3: >> - called mmget_not_zero() before kthread_use_mm() [Jason] >> As the documentation of mmget() in include/linux/sched/mm.h says: >> * Never use this function to pin this address space for an >> * unbounded/indefinite amount of time. >> I moved mmget_not_zero/kthread_use_mm inside the worker function, >> this way we pin the address space only as long as needed. >> This is similar to what vfio_iommu_type1_dma_rw_chunk() does in >> drivers/vfio/vfio_iommu_type1.c >> - simplified the mm bind/unbind [Jason] >> - renamed vdpasim_worker_change_mm_sync() [Jason] >> - fix commit message (s/default: false/default: true) >> v2: >> - `use_va` set to true by default [Eugenio] >> - supported the new unbind_mm callback [Jason] >> - removed the unbind_mm call in vdpasim_do_reset() [Jason] >> - avoided to release the lock while call kthread_flush_work() since we >> are now using a mutex to protect the device state >> >> drivers/vdpa/vdpa_sim/vdpa_sim.h | 1 + >> drivers/vdpa/vdpa_sim/vdpa_sim.c | 80 +++++++++++++++++++++++++++++++- >> 2 files changed, 79 insertions(+), 2 deletions(-) >> >>diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.h b/drivers/vdpa/vdpa_sim/vdpa_sim.h >>index 4774292fba8c..3a42887d05d9 100644 >>--- a/drivers/vdpa/vdpa_sim/vdpa_sim.h >>+++ b/drivers/vdpa/vdpa_sim/vdpa_sim.h >>@@ -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; >>diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.c b/drivers/vdpa/vdpa_sim/vdpa_sim.c >>index ab4cfb82c237..23c891cdcd54 100644 >>--- a/drivers/vdpa/vdpa_sim/vdpa_sim.c >>+++ b/drivers/vdpa/vdpa_sim/vdpa_sim.c >>@@ -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); >>@@ -59,8 +93,10 @@ 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; >>+ bool va_enabled = use_va && vdpasim->mm_bound; >>- vringh_init_iotlb(&vq->vring, vdpasim->features, vq->num, true, false, >>+ vringh_init_iotlb(&vq->vring, vdpasim->features, vq->num, true, >>+ va_enabled, >> (struct vring_desc *)(uintptr_t)vq->desc_addr, >> (struct vring_avail *) >> (uintptr_t)vq->driver_addr, >>@@ -130,8 +166,20 @@ 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 (mm) { >>+ if (!mmget_not_zero(mm)) >>+ return; > > >Do we need to check use_va here.
Yep, right!
> >Other than this > >Acked-by: Jason Wang <jasowang@redhat.com>
Thanks for the reviews, Stefano
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