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[82.57.51.170]) by smtp.gmail.com with ESMTPSA id z15-20020a5d44cf000000b002ce9f0e4a8fsm11692694wrr.84.2023.03.21.08.48.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 21 Mar 2023 08:48:12 -0700 (PDT) From: Stefano Garzarella To: virtualization@lists.linux-foundation.org Cc: Jason Wang , kvm@vger.kernel.org, stefanha@redhat.com, linux-kernel@vger.kernel.org, eperezma@redhat.com, "Michael S. Tsirkin" , Andrey Zhadchenko , netdev@vger.kernel.org, Stefano Garzarella Subject: [PATCH v3 8/8] vdpa_sim: add support for user VA Date: Tue, 21 Mar 2023 16:48:04 +0100 Message-Id: <20230321154804.184577-4-sgarzare@redhat.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230321154804.184577-1-sgarzare@redhat.com> References: <20230321154228.182769-1-sgarzare@redhat.com> <20230321154804.184577-1-sgarzare@redhat.com> MIME-Version: 1.0 Content-type: text/plain Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org 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 Acked-by: Jason Wang --- 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; + kthread_use_mm(mm); + } vdpasim->dev_attr.work_fn(vdpasim); + + if (mm) { + kthread_unuse_mm(mm); + mmput(mm); + } } struct vdpasim *vdpasim_create(struct vdpasim_dev_attr *dev_attr, @@ -162,7 +210,7 @@ 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 +630,30 @@ static int vdpasim_set_map(struct vdpa_device *vdpa, unsigned int asid, 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 +750,8 @@ 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 +786,8 @@ 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, };