Re: [RFC PATCH V2 2/2] vhost: device IOTLB API
From: Michael S. Tsirkin
Date: Wed Apr 27 2016 - 07:46:05 EST
On Fri, Mar 25, 2016 at 10:34:34AM +0800, Jason Wang wrote:
> This patch tries to implement an device IOTLB for vhost. This could be
> used with for co-operation with userspace(qemu) implementation of DMA
> remapping.
>
> The idea is simple. When vhost meets an IOTLB miss, it will request
> the assistance of userspace to do the translation, this is done
> through:
>
> - Fill the translation request in a preset userspace address (This
> address is set through ioctl VHOST_SET_IOTLB_REQUEST_ENTRY).
> - Notify userspace through eventfd (This eventfd was set through ioctl
> VHOST_SET_IOTLB_FD).
Why use an eventfd for this? We use them for interrupts because
that happens to be what kvm wants, but here - why don't we
just add a generic support for reading out events
on the vhost fd itself?
> - device IOTLB were started and stopped through VHOST_RUN_IOTLB ioctl
>
> When userspace finishes the translation, it will update the vhost
> IOTLB through VHOST_UPDATE_IOTLB ioctl. Userspace is also in charge of
> snooping the IOTLB invalidation of IOMMU IOTLB and use
> VHOST_UPDATE_IOTLB to invalidate the possible entry in vhost.
There's one problem here, and that is that VQs still do not undergo
translation. In theory VQ could be mapped in such a way
that it's not contigious in userspace memory.
> Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
What limits amount of entries that kernel keeps around?
Do we want at least a mod parameter for this?
> ---
> drivers/vhost/net.c | 6 +-
> drivers/vhost/vhost.c | 301 +++++++++++++++++++++++++++++++++++++++------
> drivers/vhost/vhost.h | 17 ++-
> fs/eventfd.c | 3 +-
> include/uapi/linux/vhost.h | 35 ++++++
> 5 files changed, 320 insertions(+), 42 deletions(-)
>
> diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
> index 481db96..7cbdeed 100644
> --- a/drivers/vhost/net.c
> +++ b/drivers/vhost/net.c
> @@ -334,7 +334,7 @@ static void handle_tx(struct vhost_net *net)
> head = vhost_get_vq_desc(vq, vq->iov,
> ARRAY_SIZE(vq->iov),
> &out, &in,
> - NULL, NULL);
> + NULL, NULL, VHOST_ACCESS_RO);
> /* On error, stop handling until the next kick. */
> if (unlikely(head < 0))
> break;
> @@ -470,7 +470,7 @@ static int get_rx_bufs(struct vhost_virtqueue *vq,
> }
> r = vhost_get_vq_desc(vq, vq->iov + seg,
> ARRAY_SIZE(vq->iov) - seg, &out,
> - &in, log, log_num);
> + &in, log, log_num, VHOST_ACCESS_WO);
> if (unlikely(r < 0))
> goto err;
>
> @@ -1083,7 +1083,7 @@ static long vhost_net_ioctl(struct file *f, unsigned int ioctl,
> r = vhost_dev_ioctl(&n->dev, ioctl, argp);
> if (r == -ENOIOCTLCMD)
> r = vhost_vring_ioctl(&n->dev, ioctl, argp);
> - else
> + else if (ioctl != VHOST_UPDATE_IOTLB)
> vhost_net_flush(n);
> mutex_unlock(&n->dev.mutex);
> return r;
> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> index 32c35a9..1dd43e8 100644
> --- a/drivers/vhost/vhost.c
> +++ b/drivers/vhost/vhost.c
> @@ -280,6 +280,10 @@ static void vhost_vq_reset(struct vhost_dev *dev,
> vq->call_ctx = NULL;
> vq->call = NULL;
> vq->log_ctx = NULL;
> + vq->iotlb_call = NULL;
> + vq->iotlb_call_ctx = NULL;
> + vq->iotlb_request = NULL;
> + vq->pending_request.flags.type = VHOST_IOTLB_INVALIDATE;
> vq->umem = NULL;
> vq->is_le = virtio_legacy_is_little_endian();
> vhost_vq_reset_user_be(vq);
> @@ -387,8 +391,10 @@ void vhost_dev_init(struct vhost_dev *dev,
> dev->log_ctx = NULL;
> dev->log_file = NULL;
> dev->umem = NULL;
> + dev->iotlb = NULL;
> dev->mm = NULL;
> spin_lock_init(&dev->work_lock);
> + spin_lock_init(&dev->iotlb_lock);
> INIT_LIST_HEAD(&dev->work_list);
> dev->worker = NULL;
>
> @@ -537,6 +543,15 @@ void vhost_dev_stop(struct vhost_dev *dev)
> }
> EXPORT_SYMBOL_GPL(vhost_dev_stop);
>
> +static void vhost_umem_free(struct vhost_umem *umem,
> + struct vhost_umem_node *node)
> +{
> + vhost_umem_interval_tree_remove(node, &umem->umem_tree);
> + list_del(&node->link);
> + kfree(node);
> + umem->numem--;
> +}
> +
> static void vhost_umem_clean(struct vhost_umem *umem)
> {
> struct vhost_umem_node *node, *tmp;
> @@ -544,11 +559,9 @@ static void vhost_umem_clean(struct vhost_umem *umem)
> if (!umem)
> return;
>
> - list_for_each_entry_safe(node, tmp, &umem->umem_list, link) {
> - vhost_umem_interval_tree_remove(node, &umem->umem_tree);
> - list_del(&node->link);
> - kvfree(node);
> - }
> + list_for_each_entry_safe(node, tmp, &umem->umem_list, link)
> + vhost_umem_free(umem, node);
> +
> kvfree(umem);
> }
>
> @@ -580,6 +593,8 @@ void vhost_dev_cleanup(struct vhost_dev *dev, bool locked)
> /* No one will access memory at this point */
> vhost_umem_clean(dev->umem);
> dev->umem = NULL;
> + vhost_umem_clean(dev->iotlb);
> + dev->iotlb = NULL;
> WARN_ON(!list_empty(&dev->work_list));
> if (dev->worker) {
> kthread_stop(dev->worker);
> @@ -699,11 +714,61 @@ int vhost_vq_access_ok(struct vhost_virtqueue *vq)
> }
> EXPORT_SYMBOL_GPL(vhost_vq_access_ok);
>
> +static int vhost_new_umem_range(struct vhost_umem *umem,
> + u64 start, u64 size, u64 end,
> + u64 userspace_addr, int perm)
> +{
> + struct vhost_umem_node *tmp, *node = kmalloc(sizeof(*node), GFP_ATOMIC);
> +
> + if (!node)
> + return -ENOMEM;
> +
> + if (umem->numem == VHOST_IOTLB_SIZE) {
> + tmp = list_last_entry(&umem->umem_list, typeof(*tmp), link);
> + vhost_umem_free(umem, tmp);
> + }
> +
> + node->start = start;
> + node->size = size;
> + node->last = end;
> + node->userspace_addr = userspace_addr;
> + node->perm = perm;
> + INIT_LIST_HEAD(&node->link);
> + list_add_tail(&node->link, &umem->umem_list);
> + vhost_umem_interval_tree_insert(node, &umem->umem_tree);
> + umem->numem++;
> +
> + return 0;
> +}
> +
> +static void vhost_del_umem_range(struct vhost_umem *umem,
> + u64 start, u64 end)
> +{
> + struct vhost_umem_node *node;
> +
> + while ((node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
> + start, end)))
> + vhost_umem_free(umem, node);
> +}
> +
> +static struct vhost_umem *vhost_umem_alloc(void)
> +{
> + struct vhost_umem *umem = vhost_kvzalloc(sizeof(*umem));
> +
> + if (!umem)
> + return NULL;
> +
> + umem->umem_tree = RB_ROOT;
> + umem->numem = 0;
> + INIT_LIST_HEAD(&umem->umem_list);
> +
> + return umem;
> +}
> +
> static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
> {
> struct vhost_memory mem, *newmem;
> struct vhost_memory_region *region;
> - struct vhost_umem_node *node;
> struct vhost_umem *newumem, *oldumem;
> unsigned long size = offsetof(struct vhost_memory, regions);
> int i;
> @@ -725,28 +790,23 @@ static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
> return -EFAULT;
> }
>
> - newumem = vhost_kvzalloc(sizeof(*newumem));
> + newumem = vhost_umem_alloc();
> if (!newumem) {
> kvfree(newmem);
> return -ENOMEM;
> }
>
> - newumem->umem_tree = RB_ROOT;
> - INIT_LIST_HEAD(&newumem->umem_list);
> -
> for (region = newmem->regions;
> region < newmem->regions + mem.nregions;
> region++) {
> - node = vhost_kvzalloc(sizeof(*node));
> - if (!node)
> + if (vhost_new_umem_range(newumem,
> + region->guest_phys_addr,
> + region->memory_size,
> + region->guest_phys_addr +
> + region->memory_size - 1,
> + region->userspace_addr,
> + VHOST_ACCESS_RW))
> goto err;
> - node->start = region->guest_phys_addr;
> - node->size = region->memory_size;
> - node->last = node->start + node->size - 1;
> - node->userspace_addr = region->userspace_addr;
> - INIT_LIST_HEAD(&node->link);
> - list_add_tail(&node->link, &newumem->umem_list);
> - vhost_umem_interval_tree_insert(node, &newumem->umem_tree);
> }
>
> if (!memory_access_ok(d, newumem, 0))
> @@ -782,6 +842,7 @@ long vhost_vring_ioctl(struct vhost_dev *d, int ioctl, void __user *argp)
> struct vhost_vring_state s;
> struct vhost_vring_file f;
> struct vhost_vring_addr a;
> + struct vhost_vring_iotlb_entry e;
> u32 idx;
> long r;
>
> @@ -910,6 +971,35 @@ long vhost_vring_ioctl(struct vhost_dev *d, int ioctl, void __user *argp)
> } else
> filep = eventfp;
> break;
> + case VHOST_SET_VRING_IOTLB_REQUEST:
> + r = -EFAULT;
> + if (copy_from_user(&e, argp, sizeof e))
> + break;
> + if (!access_ok(VERIFY_WRITE, e.userspace_addr,
> + sizeof(*vq->iotlb_request)))
> + break;
> + r = 0;
> + vq->iotlb_request = (struct vhost_iotlb_entry __user *)e.userspace_addr;
> + break;
> + case VHOST_SET_VRING_IOTLB_CALL:
> + if (copy_from_user(&f, argp, sizeof f)) {
> + r = -EFAULT;
> + break;
> + }
> + eventfp = f.fd == -1 ? NULL : eventfd_fget(f.fd);
> + if (IS_ERR(eventfp)) {
> + r = PTR_ERR(eventfp);
> + break;
> + }
> + if (eventfp != vq->iotlb_call) {
> + filep = vq->iotlb_call;
> + ctx = vq->iotlb_call_ctx;
> + vq->iotlb_call = eventfp;
> + vq->iotlb_call_ctx = eventfp ?
> + eventfd_ctx_fileget(eventfp) : NULL;
> + } else
> + filep = eventfp;
> + break;
> case VHOST_SET_VRING_CALL:
> if (copy_from_user(&f, argp, sizeof f)) {
> r = -EFAULT;
> @@ -977,11 +1067,55 @@ long vhost_vring_ioctl(struct vhost_dev *d, int ioctl, void __user *argp)
> }
> EXPORT_SYMBOL_GPL(vhost_vring_ioctl);
>
> +static int vhost_init_device_iotlb(struct vhost_dev *d, bool enabled)
> +{
> + struct vhost_umem *niotlb, *oiotlb;
> +
> + if (enabled) {
> + niotlb = vhost_umem_alloc();
> + if (!niotlb)
> + return -ENOMEM;
> + } else
> + niotlb = NULL;
> +
> + spin_lock(&d->iotlb_lock);
> + oiotlb = d->iotlb;
> + d->iotlb = niotlb;
> + spin_unlock(&d->iotlb_lock);
> +
> + vhost_umem_clean(oiotlb);
> +
> + return 0;
> +}
> +
> +static void vhost_complete_iotlb_update(struct vhost_dev *d,
> + struct vhost_iotlb_entry *entry)
> +{
> + struct vhost_iotlb_entry *req;
> + struct vhost_virtqueue *vq;
> + int i;
> +
> +
> + for (i = 0; i < d->nvqs; i++) {
> + vq = d->vqs[i];
> + mutex_lock(&vq->mutex);
> + req = &vq->pending_request;
> + if (entry->iova <= req->iova &&
> + entry->iova + entry->size - 1 > req->iova &&
> + req->flags.type == VHOST_IOTLB_MISS) {
> + *req = *entry;
> + vhost_poll_queue(&vq->poll);
> + }
> + mutex_unlock(&vq->mutex);
> + }
> +}
> +
> /* Caller must have device mutex */
> long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
> {
> struct file *eventfp, *filep = NULL;
> struct eventfd_ctx *ctx = NULL;
> + struct vhost_iotlb_entry entry;
> u64 p;
> long r;
> int i, fd;
> @@ -1050,6 +1184,52 @@ long vhost_dev_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *argp)
> if (filep)
> fput(filep);
> break;
> + case VHOST_RUN_IOTLB:
> + /* FIXME: enable and disabled */
> + vhost_init_device_iotlb(d, true);
> + break;
> + case VHOST_UPDATE_IOTLB:
> + r = copy_from_user(&entry, argp, sizeof(entry));
> + if (r < 0) {
> + r = -EFAULT;
> + goto done;
> + }
> +
> + spin_lock(&d->iotlb_lock);
> + if (!d->iotlb) {
> + spin_unlock(&d->iotlb_lock);
> + r = -EFAULT;
> + goto done;
> + }
> + switch (entry.flags.type) {
> + case VHOST_IOTLB_UPDATE:
> + if (entry.flags.valid != VHOST_IOTLB_VALID) {
> + break;
> + }
> + if (vhost_new_umem_range(d->iotlb,
> + entry.iova,
> + entry.size,
> + entry.iova + entry.size - 1,
> + entry.userspace_addr,
> + entry.flags.perm)) {
> + r = -ENOMEM;
> + break;
> + }
> + break;
> + case VHOST_IOTLB_INVALIDATE:
> + vhost_del_umem_range(d->iotlb,
> + entry.iova,
> + entry.iova + entry.size - 1);
> + break;
> + default:
> + r = -EINVAL;
> + }
> + spin_unlock(&d->iotlb_lock);
> +
> + if (!r && entry.flags.type != VHOST_IOTLB_INVALIDATE)
> + vhost_complete_iotlb_update(d, &entry);
> +
> + break;
> default:
> r = -ENOIOCTLCMD;
> break;
> @@ -1197,27 +1377,69 @@ int vhost_init_used(struct vhost_virtqueue *vq)
> }
> EXPORT_SYMBOL_GPL(vhost_init_used);
>
> +static int vhost_iotlb_miss(struct vhost_virtqueue *vq, u64 iova)
> +{
> + struct vhost_iotlb_entry *pending = &vq->pending_request;
> + int ret;
> +
> + if (!vq->iotlb_call_ctx)
> + return -EOPNOTSUPP;
> +
> + if (!vq->iotlb_request)
> + return -EOPNOTSUPP;
> +
> + if (pending->flags.type == VHOST_IOTLB_MISS) {
> + return -EEXIST;
> + }
> +
> + pending->iova = iova;
> + pending->flags.type = VHOST_IOTLB_MISS;
> +
> + ret = __copy_to_user(vq->iotlb_request, pending,
> + sizeof(struct vhost_iotlb_entry));
> + if (ret) {
> + goto err;
> + }
> +
> + if (vq->iotlb_call_ctx)
> + eventfd_signal(vq->iotlb_call_ctx, 1);
> +err:
> + return ret;
> +}
> +
> static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
> - struct iovec iov[], int iov_size)
> + struct iovec iov[], int iov_size, int access)
> {
> const struct vhost_umem_node *node;
> - struct vhost_umem *umem = vq->umem;
> + struct vhost_dev *dev = vq->dev;
> + struct vhost_umem *umem = dev->iotlb ? dev->iotlb : dev->umem;
> struct iovec *_iov;
> u64 s = 0;
> int ret = 0;
>
> + spin_lock(&dev->iotlb_lock);
> +
> while ((u64)len > s) {
> u64 size;
> if (unlikely(ret >= iov_size)) {
> ret = -ENOBUFS;
> break;
> }
> +
> node = vhost_umem_interval_tree_iter_first(&umem->umem_tree,
> addr, addr + len - 1);
> if (node == NULL || node->start > addr) {
> - ret = -EFAULT;
> + if (umem != dev->iotlb) {
> + ret = -EFAULT;
> + break;
> + }
> + ret = -EAGAIN;
> + break;
> + } else if (!(node->perm & access)) {
> + ret = -EPERM;
> break;
> }
> +
> _iov = iov + ret;
> size = node->size - addr + node->start;
> _iov->iov_len = min((u64)len - s, size);
> @@ -1228,6 +1450,10 @@ static int translate_desc(struct vhost_virtqueue *vq, u64 addr, u32 len,
> ++ret;
> }
>
> + spin_unlock(&dev->iotlb_lock);
> +
> + if (ret == -EAGAIN)
> + vhost_iotlb_miss(vq, addr);
> return ret;
> }
>
> @@ -1256,7 +1482,7 @@ static int get_indirect(struct vhost_virtqueue *vq,
> struct iovec iov[], unsigned int iov_size,
> unsigned int *out_num, unsigned int *in_num,
> struct vhost_log *log, unsigned int *log_num,
> - struct vring_desc *indirect)
> + struct vring_desc *indirect, int access)
> {
> struct vring_desc desc;
> unsigned int i = 0, count, found = 0;
> @@ -1274,9 +1500,10 @@ static int get_indirect(struct vhost_virtqueue *vq,
> }
>
> ret = translate_desc(vq, vhost64_to_cpu(vq, indirect->addr), len, vq->indirect,
> - UIO_MAXIOV);
> + UIO_MAXIOV, access);
> if (unlikely(ret < 0)) {
> - vq_err(vq, "Translation failure %d in indirect.\n", ret);
> + if (ret != -EAGAIN)
> + vq_err(vq, "Translation failure %d in indirect.\n", ret);
> return ret;
> }
> iov_iter_init(&from, READ, vq->indirect, ret, len);
> @@ -1316,10 +1543,11 @@ static int get_indirect(struct vhost_virtqueue *vq,
>
> ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
> vhost32_to_cpu(vq, desc.len), iov + iov_count,
> - iov_size - iov_count);
> + iov_size - iov_count, access);
> if (unlikely(ret < 0)) {
> - vq_err(vq, "Translation failure %d indirect idx %d\n",
> - ret, i);
> + if (ret != -EAGAIN)
> + vq_err(vq, "Translation failure %d indirect idx %d\n",
> + ret, i);
> return ret;
> }
> /* If this is an input descriptor, increment that count. */
> @@ -1355,7 +1583,8 @@ static int get_indirect(struct vhost_virtqueue *vq,
> int vhost_get_vq_desc(struct vhost_virtqueue *vq,
> struct iovec iov[], unsigned int iov_size,
> unsigned int *out_num, unsigned int *in_num,
> - struct vhost_log *log, unsigned int *log_num)
> + struct vhost_log *log, unsigned int *log_num,
> + int access)
> {
> struct vring_desc desc;
> unsigned int i, head, found = 0;
> @@ -1433,10 +1662,11 @@ int vhost_get_vq_desc(struct vhost_virtqueue *vq,
> if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_INDIRECT)) {
> ret = get_indirect(vq, iov, iov_size,
> out_num, in_num,
> - log, log_num, &desc);
> + log, log_num, &desc, access);
> if (unlikely(ret < 0)) {
> - vq_err(vq, "Failure detected "
> - "in indirect descriptor at idx %d\n", i);
> + if (ret != -EAGAIN)
> + vq_err(vq, "Failure detected "
> + "in indirect descriptor at idx %d\n", i);
> return ret;
> }
> continue;
> @@ -1444,10 +1674,11 @@ int vhost_get_vq_desc(struct vhost_virtqueue *vq,
>
> ret = translate_desc(vq, vhost64_to_cpu(vq, desc.addr),
> vhost32_to_cpu(vq, desc.len), iov + iov_count,
> - iov_size - iov_count);
> + iov_size - iov_count, access);
> if (unlikely(ret < 0)) {
> - vq_err(vq, "Translation failure %d descriptor idx %d\n",
> - ret, i);
> + if (ret != -EAGAIN)
> + vq_err(vq, "Translation failure %d descriptor idx %d\n",
> + ret, i);
> return ret;
> }
> if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE)) {
> diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
> index 5d64393..4365104 100644
> --- a/drivers/vhost/vhost.h
> +++ b/drivers/vhost/vhost.h
> @@ -62,13 +62,15 @@ struct vhost_umem_node {
> __u64 last;
> __u64 size;
> __u64 userspace_addr;
> - __u64 flags_padding;
> + __u32 perm;
> + __u32 flags_padding;
> __u64 __subtree_last;
> };
>
> struct vhost_umem {
> struct rb_root umem_tree;
> struct list_head umem_list;
> + int numem;
> };
>
> /* The virtqueue structure describes a queue attached to a device. */
> @@ -84,9 +86,13 @@ struct vhost_virtqueue {
> struct file *kick;
> struct file *call;
> struct file *error;
> + struct file *iotlb_call;
> struct eventfd_ctx *call_ctx;
> struct eventfd_ctx *error_ctx;
> struct eventfd_ctx *log_ctx;
> + struct eventfd_ctx *iotlb_call_ctx;
> + struct vhost_iotlb_entry __user *iotlb_request;
> + struct vhost_iotlb_entry pending_request;
>
> struct vhost_poll poll;
>
> @@ -135,6 +141,8 @@ struct vhost_virtqueue {
> #endif
> };
>
> +#define VHOST_IOTLB_SIZE 2048
> +
> struct vhost_dev {
> struct mm_struct *mm;
> struct mutex mutex;
> @@ -146,6 +154,8 @@ struct vhost_dev {
> struct list_head work_list;
> struct task_struct *worker;
> struct vhost_umem *umem;
> + struct vhost_umem *iotlb;
> + spinlock_t iotlb_lock;
> };
>
> void vhost_dev_init(struct vhost_dev *, struct vhost_virtqueue **vqs, int nvqs);
> @@ -164,7 +174,8 @@ int vhost_log_access_ok(struct vhost_dev *);
> int vhost_get_vq_desc(struct vhost_virtqueue *,
> struct iovec iov[], unsigned int iov_count,
> unsigned int *out_num, unsigned int *in_num,
> - struct vhost_log *log, unsigned int *log_num);
> + struct vhost_log *log, unsigned int *log_num,
> + int access);
> void vhost_discard_vq_desc(struct vhost_virtqueue *, int n);
>
> int vhost_init_used(struct vhost_virtqueue *);
> @@ -183,7 +194,7 @@ int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
> unsigned int log_num, u64 len);
>
> #define vq_err(vq, fmt, ...) do { \
> - pr_debug(pr_fmt(fmt), ##__VA_ARGS__); \
> + printk(pr_fmt(fmt), ##__VA_ARGS__); \
> if ((vq)->error_ctx) \
> eventfd_signal((vq)->error_ctx, 1);\
> } while (0)
> diff --git a/fs/eventfd.c b/fs/eventfd.c
> index 8d0c0df..5c0a22f 100644
> --- a/fs/eventfd.c
> +++ b/fs/eventfd.c
> @@ -59,8 +59,9 @@ __u64 eventfd_signal(struct eventfd_ctx *ctx, __u64 n)
> if (ULLONG_MAX - ctx->count < n)
> n = ULLONG_MAX - ctx->count;
> ctx->count += n;
> - if (waitqueue_active(&ctx->wqh))
> + if (waitqueue_active(&ctx->wqh)) {
> wake_up_locked_poll(&ctx->wqh, POLLIN);
> + }
> spin_unlock_irqrestore(&ctx->wqh.lock, flags);
>
> return n;
> diff --git a/include/uapi/linux/vhost.h b/include/uapi/linux/vhost.h
> index ab373191..5c35ab4 100644
> --- a/include/uapi/linux/vhost.h
> +++ b/include/uapi/linux/vhost.h
> @@ -47,6 +47,32 @@ struct vhost_vring_addr {
> __u64 log_guest_addr;
> };
>
> +struct vhost_iotlb_entry {
> + __u64 iova;
> + __u64 size;
> + __u64 userspace_addr;
Alignment requirements?
> + struct {
> +#define VHOST_ACCESS_RO 0x1
> +#define VHOST_ACCESS_WO 0x2
> +#define VHOST_ACCESS_RW 0x3
> + __u8 perm;
> +#define VHOST_IOTLB_MISS 1
> +#define VHOST_IOTLB_UPDATE 2
> +#define VHOST_IOTLB_INVALIDATE 3
> + __u8 type;
> +#define VHOST_IOTLB_INVALID 0x1
> +#define VHOST_IOTLB_VALID 0x2
> + __u8 valid;
why do we need this flag?
> + __u8 u8_padding;
> + __u32 padding;
> + } flags;
> +};
> +
> +struct vhost_vring_iotlb_entry {
> + unsigned int index;
> + __u64 userspace_addr;
> +};
> +
> struct vhost_memory_region {
> __u64 guest_phys_addr;
> __u64 memory_size; /* bytes */
> @@ -127,6 +153,15 @@ struct vhost_memory {
> /* Set eventfd to signal an error */
> #define VHOST_SET_VRING_ERR _IOW(VHOST_VIRTIO, 0x22, struct vhost_vring_file)
>
> +/* IOTLB */
> +/* Specify an eventfd file descriptor to signle on IOTLB miss */
typo
> +#define VHOST_SET_VRING_IOTLB_CALL _IOW(VHOST_VIRTIO, 0x23, struct \
> + vhost_vring_file)
> +#define VHOST_SET_VRING_IOTLB_REQUEST _IOW(VHOST_VIRTIO, 0x25, struct \
> + vhost_vring_iotlb_entry)
> +#define VHOST_UPDATE_IOTLB _IOW(VHOST_VIRTIO, 0x24, struct vhost_iotlb_entry)
> +#define VHOST_RUN_IOTLB _IOW(VHOST_VIRTIO, 0x26, int)
> +
Is the assumption that userspace must dedicate a thread to running the iotlb?
I dislike this one.
Please support asynchronous APIs at least optionally to make
userspace make its own threading decisions.
> /* VHOST_NET specific defines */
>
> /* Attach virtio net ring to a raw socket, or tap device.
Don't we need a feature bit for this?
Are we short on feature bits? If yes maybe it's time to add
something like PROTOCOL_FEATURES that we have in vhost-user.
> --
> 2.5.0