Re: [PATCH v3 4/8] vringh: support VA with iotlb

From: Eugenio Perez Martin
Date: Thu Mar 23 2023 - 04:10:48 EST

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On Tue, Mar 21, 2023 at 4:43 PM Stefano Garzarella <sgarzare@xxxxxxxxxx> wrote:
>
> vDPA supports the possibility to use user VA in the iotlb messages.
> So, let's add support for user VA in vringh to use it in the vDPA
> simulators.
>
> Signed-off-by: Stefano Garzarella <sgarzare@xxxxxxxxxx>
> ---
>
> Notes:
> v3:
> - refactored avoiding code duplication [Eugenio]
> v2:
> - replace kmap_atomic() with kmap_local_page() [see previous patch]
> - fix cast warnings when build with W=1 C=1
>
> include/linux/vringh.h | 5 +-
> drivers/vdpa/mlx5/net/mlx5_vnet.c | 2 +-
> drivers/vdpa/vdpa_sim/vdpa_sim.c | 4 +-
> drivers/vhost/vringh.c | 153 +++++++++++++++++++++++-------
> 4 files changed, 127 insertions(+), 37 deletions(-)
>
> diff --git a/include/linux/vringh.h b/include/linux/vringh.h
> index 1991a02c6431..d39b9f2dcba0 100644
> --- a/include/linux/vringh.h
> +++ b/include/linux/vringh.h
> @@ -32,6 +32,9 @@ struct vringh {
> /* Can we get away with weak barriers? */
> bool weak_barriers;
>
> + /* Use user's VA */
> + bool use_va;
> +
> /* Last available index we saw (ie. where we're up to). */
> u16 last_avail_idx;
>
> @@ -279,7 +282,7 @@ void vringh_set_iotlb(struct vringh *vrh, struct vhost_iotlb *iotlb,
> spinlock_t *iotlb_lock);
>
> int vringh_init_iotlb(struct vringh *vrh, u64 features,
> - unsigned int num, bool weak_barriers,
> + unsigned int num, bool weak_barriers, bool use_va,
> struct vring_desc *desc,
> struct vring_avail *avail,
> struct vring_used *used);
> diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> index 520646ae7fa0..dfd0e000217b 100644
> --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
> +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
> @@ -2537,7 +2537,7 @@ static int setup_cvq_vring(struct mlx5_vdpa_dev *mvdev)
>
> if (mvdev->actual_features & BIT_ULL(VIRTIO_NET_F_CTRL_VQ))
> err = vringh_init_iotlb(&cvq->vring, mvdev->actual_features,
> - MLX5_CVQ_MAX_ENT, false,
> + MLX5_CVQ_MAX_ENT, false, false,
> (struct vring_desc *)(uintptr_t)cvq->desc_addr,
> (struct vring_avail *)(uintptr_t)cvq->driver_addr,
> (struct vring_used *)(uintptr_t)cvq->device_addr);
> diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.c b/drivers/vdpa/vdpa_sim/vdpa_sim.c
> index eea23c630f7c..47cdf2a1f5b8 100644
> --- a/drivers/vdpa/vdpa_sim/vdpa_sim.c
> +++ b/drivers/vdpa/vdpa_sim/vdpa_sim.c
> @@ -60,7 +60,7 @@ 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;
>
> - vringh_init_iotlb(&vq->vring, vdpasim->features, vq->num, true,
> + vringh_init_iotlb(&vq->vring, vdpasim->features, vq->num, true, false,
> (struct vring_desc *)(uintptr_t)vq->desc_addr,
> (struct vring_avail *)
> (uintptr_t)vq->driver_addr,
> @@ -92,7 +92,7 @@ static void vdpasim_vq_reset(struct vdpasim *vdpasim,
> vq->cb = NULL;
> vq->private = NULL;
> vringh_init_iotlb(&vq->vring, vdpasim->dev_attr.supported_features,
> - VDPASIM_QUEUE_MAX, false, NULL, NULL, NULL);
> + VDPASIM_QUEUE_MAX, false, false, NULL, NULL, NULL);
>
> vq->vring.notify = NULL;
> }
> diff --git a/drivers/vhost/vringh.c b/drivers/vhost/vringh.c
> index 0ba3ef809e48..72c88519329a 100644
> --- a/drivers/vhost/vringh.c
> +++ b/drivers/vhost/vringh.c
> @@ -1094,10 +1094,18 @@ EXPORT_SYMBOL(vringh_need_notify_kern);
>
> #if IS_REACHABLE(CONFIG_VHOST_IOTLB)
>
> +struct iotlb_vec {
> + union {
> + struct iovec *iovec;
> + struct bio_vec *bvec;
> + } iov;
> + size_t count;
> + bool is_iovec;
> +};
> +
> static int iotlb_translate(const struct vringh *vrh,
> u64 addr, u64 len, u64 *translated,
> - struct bio_vec iov[],
> - int iov_size, u32 perm)
> + struct iotlb_vec *ivec, u32 perm)
> {
> struct vhost_iotlb_map *map;
> struct vhost_iotlb *iotlb = vrh->iotlb;
> @@ -1107,9 +1115,9 @@ static int iotlb_translate(const struct vringh *vrh,
> spin_lock(vrh->iotlb_lock);
>
> while (len > s) {
> - u64 size, pa, pfn;
> + u64 size;
>
> - if (unlikely(ret >= iov_size)) {
> + if (unlikely(ret >= ivec->count)) {
> ret = -ENOBUFS;
> break;
> }
> @@ -1124,10 +1132,22 @@ static int iotlb_translate(const struct vringh *vrh,
> }
>
> size = map->size - addr + map->start;
> - pa = map->addr + addr - map->start;
> - pfn = pa >> PAGE_SHIFT;
> - bvec_set_page(&iov[ret], pfn_to_page(pfn), min(len - s, size),
> - pa & (PAGE_SIZE - 1));
> + if (ivec->is_iovec) {
> + struct iovec *iovec = ivec->iov.iovec;
> +
> + iovec[ret].iov_len = min(len - s, size);
> + iovec[ret].iov_base = (void __user *)(unsigned long)

s/unsigned long/uintptr_t ?

> + (map->addr + addr - map->start);
> + } else {
> + u64 pa = map->addr + addr - map->start;
> + u64 pfn = pa >> PAGE_SHIFT;
> + struct bio_vec *bvec = ivec->iov.bvec;
> +
> + bvec_set_page(&bvec[ret], pfn_to_page(pfn),
> + min(len - s, size),
> + pa & (PAGE_SIZE - 1));
> + }
> +
> s += size;
> addr += size;
> ++ret;
> @@ -1141,26 +1161,42 @@ static int iotlb_translate(const struct vringh *vrh,
> return ret;
> }
>
> +#define IOTLB_IOV_SIZE 16

I'm fine with defining here, but maybe it is better to isolate the
change in a previous patch or reuse another well known macro?

Other looks good, and I agree with Jason's comments so even if the
macro declaration is not moved:

Acked-by: Eugenio Pérez <eperezma@xxxxxxxxxx>

> +
> static inline int copy_from_iotlb(const struct vringh *vrh, void *dst,
> void *src, size_t len)
> {
> + struct iotlb_vec ivec;
> + union {
> + struct iovec iovec[IOTLB_IOV_SIZE];
> + struct bio_vec bvec[IOTLB_IOV_SIZE];
> + } iov;
> u64 total_translated = 0;
>
> + ivec.iov.iovec = iov.iovec;
> + ivec.count = IOTLB_IOV_SIZE;
> + ivec.is_iovec = vrh->use_va;
> +
> while (total_translated < len) {
> - struct bio_vec iov[16];
> struct iov_iter iter;
> u64 translated;
> int ret;
>
> ret = iotlb_translate(vrh, (u64)(uintptr_t)src,
> len - total_translated, &translated,
> - iov, ARRAY_SIZE(iov), VHOST_MAP_RO);
> + &ivec, VHOST_MAP_RO);
> if (ret == -ENOBUFS)
> - ret = ARRAY_SIZE(iov);
> + ret = IOTLB_IOV_SIZE;
> else if (ret < 0)
> return ret;
>
> - iov_iter_bvec(&iter, ITER_SOURCE, iov, ret, translated);
> + if (ivec.is_iovec) {
> + iov_iter_init(&iter, ITER_SOURCE, ivec.iov.iovec, ret,
> + translated);
> + } else {
> + iov_iter_bvec(&iter, ITER_SOURCE, ivec.iov.bvec, ret,
> + translated);
> + }
>
> ret = copy_from_iter(dst, translated, &iter);
> if (ret < 0)
> @@ -1177,23 +1213,37 @@ static inline int copy_from_iotlb(const struct vringh *vrh, void *dst,
> static inline int copy_to_iotlb(const struct vringh *vrh, void *dst,
> void *src, size_t len)
> {
> + struct iotlb_vec ivec;
> + union {
> + struct iovec iovec[IOTLB_IOV_SIZE];
> + struct bio_vec bvec[IOTLB_IOV_SIZE];
> + } iov;
> u64 total_translated = 0;
>
> + ivec.iov.iovec = iov.iovec;
> + ivec.count = IOTLB_IOV_SIZE;
> + ivec.is_iovec = vrh->use_va;
> +
> while (total_translated < len) {
> - struct bio_vec iov[16];
> struct iov_iter iter;
> u64 translated;
> int ret;
>
> ret = iotlb_translate(vrh, (u64)(uintptr_t)dst,
> len - total_translated, &translated,
> - iov, ARRAY_SIZE(iov), VHOST_MAP_WO);
> + &ivec, VHOST_MAP_WO);
> if (ret == -ENOBUFS)
> - ret = ARRAY_SIZE(iov);
> + ret = IOTLB_IOV_SIZE;
> else if (ret < 0)
> return ret;
>
> - iov_iter_bvec(&iter, ITER_DEST, iov, ret, translated);
> + if (ivec.is_iovec) {
> + iov_iter_init(&iter, ITER_DEST, ivec.iov.iovec, ret,
> + translated);
> + } else {
> + iov_iter_bvec(&iter, ITER_DEST, ivec.iov.bvec, ret,
> + translated);
> + }
>
> ret = copy_to_iter(src, translated, &iter);
> if (ret < 0)
> @@ -1210,20 +1260,37 @@ static inline int copy_to_iotlb(const struct vringh *vrh, void *dst,
> static inline int getu16_iotlb(const struct vringh *vrh,
> u16 *val, const __virtio16 *p)
> {
> - struct bio_vec iov;
> - void *kaddr, *from;
> + struct iotlb_vec ivec;
> + union {
> + struct iovec iovec[1];
> + struct bio_vec bvec[1];
> + } iov;
> + __virtio16 tmp;
> int ret;
>
> + ivec.iov.iovec = iov.iovec;
> + ivec.count = 1;
> + ivec.is_iovec = vrh->use_va;
> +
> /* Atomic read is needed for getu16 */
> - ret = iotlb_translate(vrh, (u64)(uintptr_t)p, sizeof(*p), NULL,
> - &iov, 1, VHOST_MAP_RO);
> + ret = iotlb_translate(vrh, (u64)(uintptr_t)p, sizeof(*p),
> + NULL, &ivec, VHOST_MAP_RO);
> if (ret < 0)
> return ret;
>
> - kaddr = kmap_local_page(iov.bv_page);
> - from = kaddr + iov.bv_offset;
> - *val = vringh16_to_cpu(vrh, READ_ONCE(*(__virtio16 *)from));
> - kunmap_local(kaddr);
> + if (ivec.is_iovec) {
> + ret = __get_user(tmp, (__virtio16 __user *)ivec.iov.iovec[0].iov_base);
> + if (ret)
> + return ret;
> + } else {
> + void *kaddr = kmap_local_page(ivec.iov.bvec[0].bv_page);
> + void *from = kaddr + ivec.iov.bvec[0].bv_offset;
> +
> + tmp = READ_ONCE(*(__virtio16 *)from);
> + kunmap_local(kaddr);
> + }
> +
> + *val = vringh16_to_cpu(vrh, tmp);
>
> return 0;
> }
> @@ -1231,20 +1298,37 @@ static inline int getu16_iotlb(const struct vringh *vrh,
> static inline int putu16_iotlb(const struct vringh *vrh,
> __virtio16 *p, u16 val)
> {
> - struct bio_vec iov;
> - void *kaddr, *to;
> + struct iotlb_vec ivec;
> + union {
> + struct iovec iovec;
> + struct bio_vec bvec;
> + } iov;
> + __virtio16 tmp;
> int ret;
>
> + ivec.iov.iovec = &iov.iovec;
> + ivec.count = 1;
> + ivec.is_iovec = vrh->use_va;
> +
> /* Atomic write is needed for putu16 */
> - ret = iotlb_translate(vrh, (u64)(uintptr_t)p, sizeof(*p), NULL,
> - &iov, 1, VHOST_MAP_WO);
> + ret = iotlb_translate(vrh, (u64)(uintptr_t)p, sizeof(*p),
> + NULL, &ivec, VHOST_MAP_RO);
> if (ret < 0)
> return ret;
>
> - kaddr = kmap_local_page(iov.bv_page);
> - to = kaddr + iov.bv_offset;
> - WRITE_ONCE(*(__virtio16 *)to, cpu_to_vringh16(vrh, val));
> - kunmap_local(kaddr);
> + tmp = cpu_to_vringh16(vrh, val);
> +
> + if (ivec.is_iovec) {
> + ret = __put_user(tmp, (__virtio16 __user *)ivec.iov.iovec[0].iov_base);
> + if (ret)
> + return ret;
> + } else {
> + void *kaddr = kmap_local_page(ivec.iov.bvec[0].bv_page);
> + void *to = kaddr + ivec.iov.bvec[0].bv_offset;
> +
> + WRITE_ONCE(*(__virtio16 *)to, tmp);
> + kunmap_local(kaddr);
> + }
>
> return 0;
> }
> @@ -1306,6 +1390,7 @@ static inline int putused_iotlb(const struct vringh *vrh,
> * @features: the feature bits for this ring.
> * @num: the number of elements.
> * @weak_barriers: true if we only need memory barriers, not I/O.
> + * @use_va: true if IOTLB contains user VA
> * @desc: the userpace descriptor pointer.
> * @avail: the userpace avail pointer.
> * @used: the userpace used pointer.
> @@ -1313,11 +1398,13 @@ static inline int putused_iotlb(const struct vringh *vrh,
> * Returns an error if num is invalid.
> */
> int vringh_init_iotlb(struct vringh *vrh, u64 features,
> - unsigned int num, bool weak_barriers,
> + unsigned int num, bool weak_barriers, bool use_va,
> struct vring_desc *desc,
> struct vring_avail *avail,
> struct vring_used *used)
> {
> + vrh->use_va = use_va;
> +
> return vringh_init_kern(vrh, features, num, weak_barriers,
> desc, avail, used);
> }
> --
> 2.39.2
>

Next message: Liu, Yi L: "RE: [PATCH 06/12] iommufd: IOMMU_HWPT_ALLOC allocation with user data"
Previous message: Janne Grunau: "[PATCH v3] PCI: apple: Set only available ports up"
In reply to: Stefano Garzarella: "Re: [PATCH v3 4/8] vringh: support VA with iotlb"
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