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Message-ID: <e2232e4a-d74a-63c9-1e75-b61e4a7aefed@nextfour.com>
Date: Wed, 3 Mar 2021 12:52:48 +0200
From: Mika Penttilä <mika.penttila@...tfour.com>
To: Xie Yongji <xieyongji@...edance.com>, mst@...hat.com,
jasowang@...hat.com, stefanha@...hat.com, sgarzare@...hat.com,
parav@...dia.com, bob.liu@...cle.com, hch@...radead.org,
rdunlap@...radead.org, willy@...radead.org,
viro@...iv.linux.org.uk, axboe@...nel.dk, bcrl@...ck.org,
corbet@....net
Cc: virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
kvm@...r.kernel.org, linux-aio@...ck.org,
linux-fsdevel@...r.kernel.org
Subject: Re: [RFC v4 05/11] vdpa: Support transferring virtual addressing
during DMA mapping
On 23.2.2021 13.50, Xie Yongji wrote:
> This patch introduces an attribute for vDPA device to indicate
> whether virtual address can be used. If vDPA device driver set
> it, vhost-vdpa bus driver will not pin user page and transfer
> userspace virtual address instead of physical address during
> DMA mapping. And corresponding vma->vm_file and offset will be
> also passed as an opaque pointer.
In the virtual addressing case, who is then responsible for the pinning
or even mapping physical pages to the vaddr?
> Suggested-by: Jason Wang <jasowang@...hat.com>
> Signed-off-by: Xie Yongji <xieyongji@...edance.com>
> ---
> drivers/vdpa/ifcvf/ifcvf_main.c | 2 +-
> drivers/vdpa/mlx5/net/mlx5_vnet.c | 2 +-
> drivers/vdpa/vdpa.c | 9 +++-
> drivers/vdpa/vdpa_sim/vdpa_sim.c | 2 +-
> drivers/vhost/vdpa.c | 104 +++++++++++++++++++++++++++++++-------
> include/linux/vdpa.h | 20 ++++++--
> 6 files changed, 113 insertions(+), 26 deletions(-)
>
> diff --git a/drivers/vdpa/ifcvf/ifcvf_main.c b/drivers/vdpa/ifcvf/ifcvf_main.c
> index 7c8bbfcf6c3e..228b9f920fea 100644
> --- a/drivers/vdpa/ifcvf/ifcvf_main.c
> +++ b/drivers/vdpa/ifcvf/ifcvf_main.c
> @@ -432,7 +432,7 @@ static int ifcvf_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>
> adapter = vdpa_alloc_device(struct ifcvf_adapter, vdpa,
> dev, &ifc_vdpa_ops,
> - IFCVF_MAX_QUEUE_PAIRS * 2, NULL);
> + IFCVF_MAX_QUEUE_PAIRS * 2, NULL, false);
> if (adapter == NULL) {
> IFCVF_ERR(pdev, "Failed to allocate vDPA structure");
> return -ENOMEM;
> diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> index 029822060017..54290438da28 100644
> --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
> +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> @@ -1964,7 +1964,7 @@ static int mlx5v_probe(struct auxiliary_device *adev,
> max_vqs = min_t(u32, max_vqs, MLX5_MAX_SUPPORTED_VQS);
>
> ndev = vdpa_alloc_device(struct mlx5_vdpa_net, mvdev.vdev, mdev->device, &mlx5_vdpa_ops,
> - 2 * mlx5_vdpa_max_qps(max_vqs), NULL);
> + 2 * mlx5_vdpa_max_qps(max_vqs), NULL, false);
> if (IS_ERR(ndev))
> return PTR_ERR(ndev);
>
> diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c
> index 9700a0adcca0..fafc0ee5eb05 100644
> --- a/drivers/vdpa/vdpa.c
> +++ b/drivers/vdpa/vdpa.c
> @@ -72,6 +72,7 @@ static void vdpa_release_dev(struct device *d)
> * @nvqs: number of virtqueues supported by this device
> * @size: size of the parent structure that contains private data
> * @name: name of the vdpa device; optional.
> + * @use_va: indicate whether virtual address can be used by this device
> *
> * Driver should use vdpa_alloc_device() wrapper macro instead of
> * using this directly.
> @@ -81,7 +82,8 @@ static void vdpa_release_dev(struct device *d)
> */
> struct vdpa_device *__vdpa_alloc_device(struct device *parent,
> const struct vdpa_config_ops *config,
> - int nvqs, size_t size, const char *name)
> + int nvqs, size_t size, const char *name,
> + bool use_va)
> {
> struct vdpa_device *vdev;
> int err = -EINVAL;
> @@ -92,6 +94,10 @@ struct vdpa_device *__vdpa_alloc_device(struct device *parent,
> if (!!config->dma_map != !!config->dma_unmap)
> goto err;
>
> + /* It should only work for the device that use on-chip IOMMU */
> + if (use_va && !(config->dma_map || config->set_map))
> + goto err;
> +
> err = -ENOMEM;
> vdev = kzalloc(size, GFP_KERNEL);
> if (!vdev)
> @@ -108,6 +114,7 @@ struct vdpa_device *__vdpa_alloc_device(struct device *parent,
> vdev->config = config;
> vdev->features_valid = false;
> vdev->nvqs = nvqs;
> + vdev->use_va = use_va;
>
> if (name)
> err = dev_set_name(&vdev->dev, "%s", name);
> diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.c b/drivers/vdpa/vdpa_sim/vdpa_sim.c
> index 5cfc262ce055..3a9a2dd4e987 100644
> --- a/drivers/vdpa/vdpa_sim/vdpa_sim.c
> +++ b/drivers/vdpa/vdpa_sim/vdpa_sim.c
> @@ -235,7 +235,7 @@ struct vdpasim *vdpasim_create(struct vdpasim_dev_attr *dev_attr)
> ops = &vdpasim_config_ops;
>
> vdpasim = vdpa_alloc_device(struct vdpasim, vdpa, NULL, ops,
> - dev_attr->nvqs, dev_attr->name);
> + dev_attr->nvqs, dev_attr->name, false);
> if (!vdpasim)
> goto err_alloc;
>
> diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
> index 70857fe3263c..93769ace34df 100644
> --- a/drivers/vhost/vdpa.c
> +++ b/drivers/vhost/vdpa.c
> @@ -480,21 +480,31 @@ static long vhost_vdpa_unlocked_ioctl(struct file *filep,
> static void vhost_vdpa_iotlb_unmap(struct vhost_vdpa *v, u64 start, u64 last)
> {
> struct vhost_dev *dev = &v->vdev;
> + struct vdpa_device *vdpa = v->vdpa;
> struct vhost_iotlb *iotlb = dev->iotlb;
> struct vhost_iotlb_map *map;
> + struct vdpa_map_file *map_file;
> struct page *page;
> unsigned long pfn, pinned;
>
> while ((map = vhost_iotlb_itree_first(iotlb, start, last)) != NULL) {
> - pinned = map->size >> PAGE_SHIFT;
> - for (pfn = map->addr >> PAGE_SHIFT;
> - pinned > 0; pfn++, pinned--) {
> - page = pfn_to_page(pfn);
> - if (map->perm & VHOST_ACCESS_WO)
> - set_page_dirty_lock(page);
> - unpin_user_page(page);
> + if (!vdpa->use_va) {
> + pinned = map->size >> PAGE_SHIFT;
> + for (pfn = map->addr >> PAGE_SHIFT;
> + pinned > 0; pfn++, pinned--) {
> + page = pfn_to_page(pfn);
> + if (map->perm & VHOST_ACCESS_WO)
> + set_page_dirty_lock(page);
> + unpin_user_page(page);
> + }
> + atomic64_sub(map->size >> PAGE_SHIFT,
> + &dev->mm->pinned_vm);
> + } else {
> + map_file = (struct vdpa_map_file *)map->opaque;
> + if (map_file->file)
> + fput(map_file->file);
> + kfree(map_file);
> }
> - atomic64_sub(map->size >> PAGE_SHIFT, &dev->mm->pinned_vm);
> vhost_iotlb_map_free(iotlb, map);
> }
> }
> @@ -530,21 +540,21 @@ static int perm_to_iommu_flags(u32 perm)
> return flags | IOMMU_CACHE;
> }
>
> -static int vhost_vdpa_map(struct vhost_vdpa *v,
> - u64 iova, u64 size, u64 pa, u32 perm)
> +static int vhost_vdpa_map(struct vhost_vdpa *v, u64 iova,
> + u64 size, u64 pa, u32 perm, void *opaque)
> {
> struct vhost_dev *dev = &v->vdev;
> struct vdpa_device *vdpa = v->vdpa;
> const struct vdpa_config_ops *ops = vdpa->config;
> int r = 0;
>
> - r = vhost_iotlb_add_range(dev->iotlb, iova, iova + size - 1,
> - pa, perm);
> + r = vhost_iotlb_add_range_ctx(dev->iotlb, iova, iova + size - 1,
> + pa, perm, opaque);
> if (r)
> return r;
>
> if (ops->dma_map) {
> - r = ops->dma_map(vdpa, iova, size, pa, perm, NULL);
> + r = ops->dma_map(vdpa, iova, size, pa, perm, opaque);
> } else if (ops->set_map) {
> if (!v->in_batch)
> r = ops->set_map(vdpa, dev->iotlb);
> @@ -552,13 +562,15 @@ static int vhost_vdpa_map(struct vhost_vdpa *v,
> r = iommu_map(v->domain, iova, pa, size,
> perm_to_iommu_flags(perm));
> }
> -
> - if (r)
> + if (r) {
> vhost_iotlb_del_range(dev->iotlb, iova, iova + size - 1);
> - else
> + return r;
> + }
> +
> + if (!vdpa->use_va)
> atomic64_add(size >> PAGE_SHIFT, &dev->mm->pinned_vm);
>
> - return r;
> + return 0;
> }
>
> static void vhost_vdpa_unmap(struct vhost_vdpa *v, u64 iova, u64 size)
> @@ -579,10 +591,60 @@ static void vhost_vdpa_unmap(struct vhost_vdpa *v, u64 iova, u64 size)
> }
> }
>
> +static int vhost_vdpa_va_map(struct vhost_vdpa *v,
> + u64 iova, u64 size, u64 uaddr, u32 perm)
> +{
> + struct vhost_dev *dev = &v->vdev;
> + u64 offset, map_size, map_iova = iova;
> + struct vdpa_map_file *map_file;
> + struct vm_area_struct *vma;
> + int ret;
> +
> + mmap_read_lock(dev->mm);
> +
> + while (size) {
> + vma = find_vma(dev->mm, uaddr);
> + if (!vma) {
> + ret = -EINVAL;
> + goto err;
> + }
> + map_size = min(size, vma->vm_end - uaddr);
> + offset = (vma->vm_pgoff << PAGE_SHIFT) + uaddr - vma->vm_start;
> + map_file = kzalloc(sizeof(*map_file), GFP_KERNEL);
> + if (!map_file) {
> + ret = -ENOMEM;
> + goto err;
> + }
> + if (vma->vm_file && (vma->vm_flags & VM_SHARED) &&
> + !(vma->vm_flags & (VM_IO | VM_PFNMAP))) {
> + map_file->file = get_file(vma->vm_file);
> + map_file->offset = offset;
> + }
> + ret = vhost_vdpa_map(v, map_iova, map_size, uaddr,
> + perm, map_file);
> + if (ret) {
> + if (map_file->file)
> + fput(map_file->file);
> + kfree(map_file);
> + goto err;
> + }
> + size -= map_size;
> + uaddr += map_size;
> + map_iova += map_size;
> + }
> + mmap_read_unlock(dev->mm);
> +
> + return 0;
> +err:
> + vhost_vdpa_unmap(v, iova, map_iova - iova);
> + return ret;
> +}
> +
> static int vhost_vdpa_process_iotlb_update(struct vhost_vdpa *v,
> struct vhost_iotlb_msg *msg)
> {
> struct vhost_dev *dev = &v->vdev;
> + struct vdpa_device *vdpa = v->vdpa;
> struct vhost_iotlb *iotlb = dev->iotlb;
> struct page **page_list;
> unsigned long list_size = PAGE_SIZE / sizeof(struct page *);
> @@ -601,6 +663,10 @@ static int vhost_vdpa_process_iotlb_update(struct vhost_vdpa *v,
> msg->iova + msg->size - 1))
> return -EEXIST;
>
> + if (vdpa->use_va)
> + return vhost_vdpa_va_map(v, msg->iova, msg->size,
> + msg->uaddr, msg->perm);
> +
> /* Limit the use of memory for bookkeeping */
> page_list = (struct page **) __get_free_page(GFP_KERNEL);
> if (!page_list)
> @@ -654,7 +720,7 @@ static int vhost_vdpa_process_iotlb_update(struct vhost_vdpa *v,
> csize = (last_pfn - map_pfn + 1) << PAGE_SHIFT;
> ret = vhost_vdpa_map(v, iova, csize,
> map_pfn << PAGE_SHIFT,
> - msg->perm);
> + msg->perm, NULL);
> if (ret) {
> /*
> * Unpin the pages that are left unmapped
> @@ -683,7 +749,7 @@ static int vhost_vdpa_process_iotlb_update(struct vhost_vdpa *v,
>
> /* Pin the rest chunk */
> ret = vhost_vdpa_map(v, iova, (last_pfn - map_pfn + 1) << PAGE_SHIFT,
> - map_pfn << PAGE_SHIFT, msg->perm);
> + map_pfn << PAGE_SHIFT, msg->perm, NULL);
> out:
> if (ret) {
> if (nchunks) {
> diff --git a/include/linux/vdpa.h b/include/linux/vdpa.h
> index 93dca2c328ae..bfae6d780c38 100644
> --- a/include/linux/vdpa.h
> +++ b/include/linux/vdpa.h
> @@ -44,6 +44,7 @@ struct vdpa_mgmt_dev;
> * @config: the configuration ops for this device.
> * @index: device index
> * @features_valid: were features initialized? for legacy guests
> + * @use_va: indicate whether virtual address can be used by this device
> * @nvqs: maximum number of supported virtqueues
> * @mdev: management device pointer; caller must setup when registering device as part
> * of dev_add() mgmtdev ops callback before invoking _vdpa_register_device().
> @@ -54,6 +55,7 @@ struct vdpa_device {
> const struct vdpa_config_ops *config;
> unsigned int index;
> bool features_valid;
> + bool use_va;
> int nvqs;
> struct vdpa_mgmt_dev *mdev;
> };
> @@ -69,6 +71,16 @@ struct vdpa_iova_range {
> };
>
> /**
> + * Corresponding file area for device memory mapping
> + * @file: vma->vm_file for the mapping
> + * @offset: mapping offset in the vm_file
> + */
> +struct vdpa_map_file {
> + struct file *file;
> + u64 offset;
> +};
> +
> +/**
> * vDPA_config_ops - operations for configuring a vDPA device.
> * Note: vDPA device drivers are required to implement all of the
> * operations unless it is mentioned to be optional in the following
> @@ -250,14 +262,16 @@ struct vdpa_config_ops {
>
> struct vdpa_device *__vdpa_alloc_device(struct device *parent,
> const struct vdpa_config_ops *config,
> - int nvqs, size_t size, const char *name);
> + int nvqs, size_t size,
> + const char *name, bool use_va);
>
> -#define vdpa_alloc_device(dev_struct, member, parent, config, nvqs, name) \
> +#define vdpa_alloc_device(dev_struct, member, parent, config, \
> + nvqs, name, use_va) \
> container_of(__vdpa_alloc_device( \
> parent, config, nvqs, \
> sizeof(dev_struct) + \
> BUILD_BUG_ON_ZERO(offsetof( \
> - dev_struct, member)), name), \
> + dev_struct, member)), name, use_va), \
> dev_struct, member)
>
> int vdpa_register_device(struct vdpa_device *vdev);
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