-----Original Message-----
From: Jason Wang <jasowang@xxxxxxxxxx>
Sent: Friday, April 1, 2022 9:55 AM
To: Gautam Dawar <gdawar@xxxxxxxxxx>
Cc: Michael S. Tsirkin <mst@xxxxxxxxxx>; kvm <kvm@xxxxxxxxxxxxxxx>; virtualization <virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx>; netdev <netdev@xxxxxxxxxxxxxxx>; linux-kernel <linux-kernel@xxxxxxxxxxxxxxx>; Martin Petrus Hubertus Habets <martinh@xxxxxxxxxx>; Harpreet Singh Anand <hanand@xxxxxxxxxx>; Martin Porter <martinpo@xxxxxxxxxx>; Pablo Cascon <pabloc@xxxxxxxxxx>; Dinan Gunawardena <dinang@xxxxxxxxxx>; tanuj.kamde@xxxxxxx; habetsm.xilinx@xxxxxxxxx; ecree.xilinx@xxxxxxxxx; eperezma <eperezma@xxxxxxxxxx>; Gautam Dawar <gdawar@xxxxxxxxxx>; Wu Zongyong <wuzongyong@xxxxxxxxxxxxxxxxx>; Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>; Eli Cohen <elic@xxxxxxxxxx>; Zhu Lingshan <lingshan.zhu@xxxxxxxxx>; Stefano Garzarella <sgarzare@xxxxxxxxxx>; Xie Yongji <xieyongji@xxxxxxxxxxxxx>; Si-Wei Liu <si-wei.liu@xxxxxxxxxx>; Parav Pandit <parav@xxxxxxxxxx>; Longpeng <longpeng2@xxxxxxxxxx>; Dan Carpenter <dan.carpenter@xxxxxxxxxx>; Zhang Min <zhang.min9@xxxxxxxxxx>
Subject: Re: [PATCH v2 15/19] vhost-vdpa: support ASID based IOTLB API
On Thu, Mar 31, 2022 at 2:17 AM Gautam Dawar <gautam.dawar@xxxxxxxxxx> wrote:
>
> This patch extends the vhost-vdpa to support ASID based IOTLB API. The
> vhost-vdpa device will allocated multiple IOTLBs for vDPA device that
> supports multiple address spaces. The IOTLBs and vDPA device memory
> mappings is determined and maintained through ASID.
>
> Note that we still don't support vDPA device with more than one
> address spaces that depends on platform IOMMU. This work will be done
> by moving the IOMMU logic from vhost-vDPA to vDPA device driver.
>
> Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
> Signed-off-by: Gautam Dawar <gdawar@xxxxxxxxxx>
> ---
> drivers/vhost/vdpa.c | 109 ++++++++++++++++++++++++++++++++++--------
> drivers/vhost/vhost.c | 2 +-
> 2 files changed, 91 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c index
> 6c7ee0f18892..1f1d1c425573 100644
> --- a/drivers/vhost/vdpa.c
> +++ b/drivers/vhost/vdpa.c
> @@ -28,7 +28,8 @@
> enum {
> VHOST_VDPA_BACKEND_FEATURES =
> (1ULL << VHOST_BACKEND_F_IOTLB_MSG_V2) |
> - (1ULL << VHOST_BACKEND_F_IOTLB_BATCH),
> + (1ULL << VHOST_BACKEND_F_IOTLB_BATCH) |
> + (1ULL << VHOST_BACKEND_F_IOTLB_ASID),
> };
>
> #define VHOST_VDPA_DEV_MAX (1U << MINORBITS) @@ -57,12 +58,20 @@
> struct vhost_vdpa {
> struct eventfd_ctx *config_ctx;
> int in_batch;
> struct vdpa_iova_range range;
> + u32 batch_asid;
> };
>
> static DEFINE_IDA(vhost_vdpa_ida);
>
> static dev_t vhost_vdpa_major;
>
> +static inline u32 iotlb_to_asid(struct vhost_iotlb *iotlb) {
> + struct vhost_vdpa_as *as = container_of(iotlb, struct
> + vhost_vdpa_as, iotlb);
> + return as->id;
> +}
> +
> static struct vhost_vdpa_as *asid_to_as(struct vhost_vdpa *v, u32
> asid) {
> struct hlist_head *head = &v->as[asid %
> VHOST_VDPA_IOTLB_BUCKETS]; @@ -75,6 +84,16 @@ static struct vhost_vdpa_as *asid_to_as(struct vhost_vdpa *v, u32 asid)
> return NULL;
> }
>
> +static struct vhost_iotlb *asid_to_iotlb(struct vhost_vdpa *v, u32
> +asid) {
> + struct vhost_vdpa_as *as = asid_to_as(v, asid);
> +
> + if (!as)
> + return NULL;
> +
> + return &as->iotlb;
> +}
> +
> static struct vhost_vdpa_as *vhost_vdpa_alloc_as(struct vhost_vdpa
> *v, u32 asid) {
> struct hlist_head *head = &v->as[asid %
> VHOST_VDPA_IOTLB_BUCKETS]; @@ -83,6 +102,9 @@ static struct vhost_vdpa_as *vhost_vdpa_alloc_as(struct vhost_vdpa *v, u32 asid)
> if (asid_to_as(v, asid))
> return NULL;
>
> + if (asid >= v->vdpa->nas)
> + return NULL;
> +
> as = kmalloc(sizeof(*as), GFP_KERNEL);
> if (!as)
> return NULL;
> @@ -94,6 +116,17 @@ static struct vhost_vdpa_as *vhost_vdpa_alloc_as(struct vhost_vdpa *v, u32 asid)
> return as;
> }
>
> +static struct vhost_vdpa_as *vhost_vdpa_find_alloc_as(struct vhost_vdpa *v,
> + u32 asid) {
> + struct vhost_vdpa_as *as = asid_to_as(v, asid);
> +
> + if (as)
> + return as;
> +
> + return vhost_vdpa_alloc_as(v, asid); }
> +
> static int vhost_vdpa_remove_as(struct vhost_vdpa *v, u32 asid) {
> struct vhost_vdpa_as *as = asid_to_as(v, asid); @@ -692,6
> +725,7 @@ static int vhost_vdpa_map(struct vhost_vdpa *v, struct vhost_iotlb *iotlb,
> struct vhost_dev *dev = &v->vdev;
> struct vdpa_device *vdpa = v->vdpa;
> const struct vdpa_config_ops *ops = vdpa->config;
> + u32 asid = iotlb_to_asid(iotlb);
> int r = 0;
>
> r = vhost_iotlb_add_range_ctx(iotlb, iova, iova + size - 1, @@
> -700,10 +734,10 @@ static int vhost_vdpa_map(struct vhost_vdpa *v, struct vhost_iotlb *iotlb,
> return r;
>
> if (ops->dma_map) {
> - r = ops->dma_map(vdpa, 0, iova, size, pa, perm, opaque);
> + r = ops->dma_map(vdpa, asid, iova, size, pa, perm,
> + opaque);
> } else if (ops->set_map) {
> if (!v->in_batch)
> - r = ops->set_map(vdpa, 0, iotlb);
> + r = ops->set_map(vdpa, asid, iotlb);
> } else {
> r = iommu_map(v->domain, iova, pa, size,
> perm_to_iommu_flags(perm)); @@ -725,17
> +759,24 @@ static void vhost_vdpa_unmap(struct vhost_vdpa *v, {
> struct vdpa_device *vdpa = v->vdpa;
> const struct vdpa_config_ops *ops = vdpa->config;
> + u32 asid = iotlb_to_asid(iotlb);
>
> vhost_vdpa_iotlb_unmap(v, iotlb, iova, iova + size - 1);
>
> if (ops->dma_map) {
> - ops->dma_unmap(vdpa, 0, iova, size);
> + ops->dma_unmap(vdpa, asid, iova, size);
> } else if (ops->set_map) {
> if (!v->in_batch)
> - ops->set_map(vdpa, 0, iotlb);
> + ops->set_map(vdpa, asid, iotlb);
> } else {
> iommu_unmap(v->domain, iova, size);
> }
> +
> + /* If we are in the middle of batch processing, delay the free
> + * of AS until BATCH_END.
> + */
> + if (!v->in_batch && !iotlb->nmaps)
> + vhost_vdpa_remove_as(v, asid);
> }
>
> static int vhost_vdpa_va_map(struct vhost_vdpa *v, @@ -943,19 +984,38
> @@ static int vhost_vdpa_process_iotlb_msg(struct vhost_dev *dev, u32 asid,
> struct vhost_vdpa *v = container_of(dev, struct vhost_vdpa, vdev);
> struct vdpa_device *vdpa = v->vdpa;
> const struct vdpa_config_ops *ops = vdpa->config;
> - struct vhost_vdpa_as *as = asid_to_as(v, 0);
> - struct vhost_iotlb *iotlb = &as->iotlb;
> + struct vhost_iotlb *iotlb = NULL;
> + struct vhost_vdpa_as *as = NULL;
> int r = 0;
>
> - if (asid != 0)
> - return -EINVAL;
> -
> mutex_lock(&dev->mutex);
>
> r = vhost_dev_check_owner(dev);
> if (r)
> goto unlock;
>
> + if (msg->type == VHOST_IOTLB_UPDATE ||
> + msg->type == VHOST_IOTLB_BATCH_BEGIN) {
> + as = vhost_vdpa_find_alloc_as(v, asid);
I wonder if it's better to mandate the ASID to [0, dev->nas), otherwise user space is free to use arbitrary IDs which may exceeds the #address spaces that is supported by the device.
[GD>>] Isn’t the following check in vhost_vdpa_alloc_as () sufficient to ensure ASID's value in the range [0, dev->nas):
if (asid >= v->vdpa->nas)
return NULL;
Thanks
> + if (!as) {
> + dev_err(&v->dev, "can't find and alloc asid %d\n",
> + asid);
> + return -EINVAL;
> + }
> + iotlb = &as->iotlb;
> + } else
> + iotlb = asid_to_iotlb(v, asid);
> +
> + if ((v->in_batch && v->batch_asid != asid) || !iotlb) {
> + if (v->in_batch && v->batch_asid != asid) {
> + dev_info(&v->dev, "batch id %d asid %d\n",
> + v->batch_asid, asid);
> + }
> + if (!iotlb)
> + dev_err(&v->dev, "no iotlb for asid %d\n", asid);
> + return -EINVAL;
> + }
> +
> switch (msg->type) {
> case VHOST_IOTLB_UPDATE:
> r = vhost_vdpa_process_iotlb_update(v, iotlb, msg); @@
> -964,12 +1024,15 @@ static int vhost_vdpa_process_iotlb_msg(struct vhost_dev *dev, u32 asid,
> vhost_vdpa_unmap(v, iotlb, msg->iova, msg->size);
> break;
> case VHOST_IOTLB_BATCH_BEGIN:
> + v->batch_asid = asid;
> v->in_batch = true;
> break;
> case VHOST_IOTLB_BATCH_END:
> if (v->in_batch && ops->set_map)
> - ops->set_map(vdpa, 0, iotlb);
> + ops->set_map(vdpa, asid, iotlb);
> v->in_batch = false;
> + if (!iotlb->nmaps)
> + vhost_vdpa_remove_as(v, asid);
> break;
> default:
> r = -EINVAL;
> @@ -1057,9 +1120,17 @@ static void vhost_vdpa_set_iova_range(struct
> vhost_vdpa *v)
>
> static void vhost_vdpa_cleanup(struct vhost_vdpa *v) {
> + struct vhost_vdpa_as *as;
> + u32 asid;
> +
> vhost_dev_cleanup(&v->vdev);
> kfree(v->vdev.vqs);
> - vhost_vdpa_remove_as(v, 0);
> +
> + for (asid = 0; asid < v->vdpa->nas; asid++) {
> + as = asid_to_as(v, asid);
> + if (as)
> + vhost_vdpa_remove_as(v, asid);
> + }
> }
>
> static int vhost_vdpa_open(struct inode *inode, struct file *filep)
> @@ -1095,12 +1166,9 @@ static int vhost_vdpa_open(struct inode *inode, struct file *filep)
> vhost_dev_init(dev, vqs, nvqs, 0, 0, 0, false,
> vhost_vdpa_process_iotlb_msg);
>
> - if (!vhost_vdpa_alloc_as(v, 0))
> - goto err_alloc_as;
> -
> r = vhost_vdpa_alloc_domain(v);
> if (r)
> - goto err_alloc_as;
> + goto err_alloc_domain;
>
> vhost_vdpa_set_iova_range(v);
>
> @@ -1108,7 +1176,7 @@ static int vhost_vdpa_open(struct inode *inode,
> struct file *filep)
>
> return 0;
>
> -err_alloc_as:
> +err_alloc_domain:
> vhost_vdpa_cleanup(v);
> err:
> atomic_dec(&v->opened);
> @@ -1233,8 +1301,11 @@ static int vhost_vdpa_probe(struct vdpa_device *vdpa)
> int minor;
> int i, r;
>
> - /* Only support 1 address space and 1 groups */
> - if (vdpa->ngroups != 1 || vdpa->nas != 1)
> + /* We can't support platform IOMMU device with more than 1
> + * group or as
> + */
> + if (!ops->set_map && !ops->dma_map &&
> + (vdpa->ngroups > 1 || vdpa->nas > 1))
> return -EOPNOTSUPP;
>
> v = kzalloc(sizeof(*v), GFP_KERNEL | __GFP_RETRY_MAYFAIL);
> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index
> d1e58f976f6e..5022c648d9c0 100644
> --- a/drivers/vhost/vhost.c
> +++ b/drivers/vhost/vhost.c
> @@ -1167,7 +1167,7 @@ ssize_t vhost_chr_write_iter(struct vhost_dev *dev,
> ret = -EINVAL;
> goto done;
> }
> - offset = sizeof(__u16);
> + offset = 0;
> } else
> offset = sizeof(__u32);
> break;
> --
> 2.30.1
>
