b9f7ac8c72
When switching everything over to virtio 1.0 memory access APIs, I missed converting vringh. Fortunately, it's straight-forward. Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
1037 lines
28 KiB
C
1037 lines
28 KiB
C
/*
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* Helpers for the host side of a virtio ring.
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*
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* Since these may be in userspace, we use (inline) accessors.
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*/
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#include <linux/module.h>
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#include <linux/vringh.h>
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#include <linux/virtio_ring.h>
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#include <linux/kernel.h>
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#include <linux/ratelimit.h>
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#include <linux/uaccess.h>
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#include <linux/slab.h>
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#include <linux/export.h>
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#include <uapi/linux/virtio_config.h>
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static __printf(1,2) __cold void vringh_bad(const char *fmt, ...)
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{
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static DEFINE_RATELIMIT_STATE(vringh_rs,
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DEFAULT_RATELIMIT_INTERVAL,
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DEFAULT_RATELIMIT_BURST);
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if (__ratelimit(&vringh_rs)) {
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va_list ap;
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va_start(ap, fmt);
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printk(KERN_NOTICE "vringh:");
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vprintk(fmt, ap);
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va_end(ap);
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}
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}
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/* Returns vring->num if empty, -ve on error. */
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static inline int __vringh_get_head(const struct vringh *vrh,
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int (*getu16)(const struct vringh *vrh,
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u16 *val, const __virtio16 *p),
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u16 *last_avail_idx)
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{
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u16 avail_idx, i, head;
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int err;
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err = getu16(vrh, &avail_idx, &vrh->vring.avail->idx);
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if (err) {
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vringh_bad("Failed to access avail idx at %p",
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&vrh->vring.avail->idx);
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return err;
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}
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if (*last_avail_idx == avail_idx)
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return vrh->vring.num;
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/* Only get avail ring entries after they have been exposed by guest. */
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virtio_rmb(vrh->weak_barriers);
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i = *last_avail_idx & (vrh->vring.num - 1);
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err = getu16(vrh, &head, &vrh->vring.avail->ring[i]);
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if (err) {
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vringh_bad("Failed to read head: idx %d address %p",
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*last_avail_idx, &vrh->vring.avail->ring[i]);
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return err;
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}
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if (head >= vrh->vring.num) {
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vringh_bad("Guest says index %u > %u is available",
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head, vrh->vring.num);
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return -EINVAL;
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}
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(*last_avail_idx)++;
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return head;
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}
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/* Copy some bytes to/from the iovec. Returns num copied. */
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static inline ssize_t vringh_iov_xfer(struct vringh_kiov *iov,
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void *ptr, size_t len,
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int (*xfer)(void *addr, void *ptr,
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size_t len))
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{
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int err, done = 0;
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while (len && iov->i < iov->used) {
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size_t partlen;
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partlen = min(iov->iov[iov->i].iov_len, len);
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err = xfer(iov->iov[iov->i].iov_base, ptr, partlen);
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if (err)
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return err;
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done += partlen;
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len -= partlen;
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ptr += partlen;
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iov->consumed += partlen;
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iov->iov[iov->i].iov_len -= partlen;
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iov->iov[iov->i].iov_base += partlen;
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if (!iov->iov[iov->i].iov_len) {
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/* Fix up old iov element then increment. */
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iov->iov[iov->i].iov_len = iov->consumed;
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iov->iov[iov->i].iov_base -= iov->consumed;
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iov->consumed = 0;
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iov->i++;
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}
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}
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return done;
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}
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/* May reduce *len if range is shorter. */
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static inline bool range_check(struct vringh *vrh, u64 addr, size_t *len,
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struct vringh_range *range,
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bool (*getrange)(struct vringh *,
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u64, struct vringh_range *))
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{
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if (addr < range->start || addr > range->end_incl) {
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if (!getrange(vrh, addr, range))
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return false;
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}
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BUG_ON(addr < range->start || addr > range->end_incl);
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/* To end of memory? */
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if (unlikely(addr + *len == 0)) {
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if (range->end_incl == -1ULL)
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return true;
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goto truncate;
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}
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/* Otherwise, don't wrap. */
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if (addr + *len < addr) {
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vringh_bad("Wrapping descriptor %zu@0x%llx",
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*len, (unsigned long long)addr);
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return false;
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}
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if (unlikely(addr + *len - 1 > range->end_incl))
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goto truncate;
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return true;
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truncate:
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*len = range->end_incl + 1 - addr;
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return true;
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}
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static inline bool no_range_check(struct vringh *vrh, u64 addr, size_t *len,
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struct vringh_range *range,
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bool (*getrange)(struct vringh *,
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u64, struct vringh_range *))
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{
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return true;
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}
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/* No reason for this code to be inline. */
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static int move_to_indirect(const struct vringh *vrh,
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int *up_next, u16 *i, void *addr,
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const struct vring_desc *desc,
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struct vring_desc **descs, int *desc_max)
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{
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u32 len;
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/* Indirect tables can't have indirect. */
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if (*up_next != -1) {
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vringh_bad("Multilevel indirect %u->%u", *up_next, *i);
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return -EINVAL;
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}
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len = vringh32_to_cpu(vrh, desc->len);
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if (unlikely(len % sizeof(struct vring_desc))) {
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vringh_bad("Strange indirect len %u", desc->len);
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return -EINVAL;
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}
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/* We will check this when we follow it! */
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if (desc->flags & cpu_to_vringh16(vrh, VRING_DESC_F_NEXT))
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*up_next = vringh16_to_cpu(vrh, desc->next);
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else
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*up_next = -2;
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*descs = addr;
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*desc_max = len / sizeof(struct vring_desc);
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/* Now, start at the first indirect. */
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*i = 0;
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return 0;
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}
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static int resize_iovec(struct vringh_kiov *iov, gfp_t gfp)
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{
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struct kvec *new;
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unsigned int flag, new_num = (iov->max_num & ~VRINGH_IOV_ALLOCATED) * 2;
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if (new_num < 8)
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new_num = 8;
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flag = (iov->max_num & VRINGH_IOV_ALLOCATED);
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if (flag)
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new = krealloc(iov->iov, new_num * sizeof(struct iovec), gfp);
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else {
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new = kmalloc(new_num * sizeof(struct iovec), gfp);
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if (new) {
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memcpy(new, iov->iov,
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iov->max_num * sizeof(struct iovec));
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flag = VRINGH_IOV_ALLOCATED;
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}
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}
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if (!new)
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return -ENOMEM;
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iov->iov = new;
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iov->max_num = (new_num | flag);
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return 0;
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}
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static u16 __cold return_from_indirect(const struct vringh *vrh, int *up_next,
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struct vring_desc **descs, int *desc_max)
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{
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u16 i = *up_next;
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*up_next = -1;
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*descs = vrh->vring.desc;
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*desc_max = vrh->vring.num;
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return i;
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}
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static int slow_copy(struct vringh *vrh, void *dst, const void *src,
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bool (*rcheck)(struct vringh *vrh, u64 addr, size_t *len,
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struct vringh_range *range,
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bool (*getrange)(struct vringh *vrh,
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u64,
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struct vringh_range *)),
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bool (*getrange)(struct vringh *vrh,
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u64 addr,
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struct vringh_range *r),
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struct vringh_range *range,
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int (*copy)(void *dst, const void *src, size_t len))
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{
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size_t part, len = sizeof(struct vring_desc);
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do {
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u64 addr;
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int err;
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part = len;
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addr = (u64)(unsigned long)src - range->offset;
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if (!rcheck(vrh, addr, &part, range, getrange))
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return -EINVAL;
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err = copy(dst, src, part);
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if (err)
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return err;
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dst += part;
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src += part;
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len -= part;
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} while (len);
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return 0;
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}
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static inline int
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__vringh_iov(struct vringh *vrh, u16 i,
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struct vringh_kiov *riov,
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struct vringh_kiov *wiov,
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bool (*rcheck)(struct vringh *vrh, u64 addr, size_t *len,
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struct vringh_range *range,
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bool (*getrange)(struct vringh *, u64,
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struct vringh_range *)),
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bool (*getrange)(struct vringh *, u64, struct vringh_range *),
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gfp_t gfp,
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int (*copy)(void *dst, const void *src, size_t len))
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{
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int err, count = 0, up_next, desc_max;
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struct vring_desc desc, *descs;
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struct vringh_range range = { -1ULL, 0 }, slowrange;
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bool slow = false;
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/* We start traversing vring's descriptor table. */
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descs = vrh->vring.desc;
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desc_max = vrh->vring.num;
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up_next = -1;
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if (riov)
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riov->i = riov->used = 0;
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else if (wiov)
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wiov->i = wiov->used = 0;
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else
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/* You must want something! */
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BUG();
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for (;;) {
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void *addr;
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struct vringh_kiov *iov;
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size_t len;
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if (unlikely(slow))
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err = slow_copy(vrh, &desc, &descs[i], rcheck, getrange,
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&slowrange, copy);
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else
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err = copy(&desc, &descs[i], sizeof(desc));
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if (unlikely(err))
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goto fail;
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if (unlikely(desc.flags &
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cpu_to_vringh16(vrh, VRING_DESC_F_INDIRECT))) {
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u64 a = vringh64_to_cpu(vrh, desc.addr);
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/* Make sure it's OK, and get offset. */
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len = vringh32_to_cpu(vrh, desc.len);
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if (!rcheck(vrh, a, &len, &range, getrange)) {
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err = -EINVAL;
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goto fail;
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}
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if (unlikely(len != vringh32_to_cpu(vrh, desc.len))) {
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slow = true;
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/* We need to save this range to use offset */
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slowrange = range;
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}
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addr = (void *)(long)(a + range.offset);
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err = move_to_indirect(vrh, &up_next, &i, addr, &desc,
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&descs, &desc_max);
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if (err)
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goto fail;
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continue;
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}
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if (count++ == vrh->vring.num) {
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vringh_bad("Descriptor loop in %p", descs);
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err = -ELOOP;
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goto fail;
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}
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if (desc.flags & cpu_to_vringh16(vrh, VRING_DESC_F_WRITE))
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iov = wiov;
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else {
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iov = riov;
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if (unlikely(wiov && wiov->i)) {
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vringh_bad("Readable desc %p after writable",
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&descs[i]);
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err = -EINVAL;
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goto fail;
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}
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}
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if (!iov) {
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vringh_bad("Unexpected %s desc",
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!wiov ? "writable" : "readable");
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err = -EPROTO;
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goto fail;
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}
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again:
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/* Make sure it's OK, and get offset. */
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len = vringh32_to_cpu(vrh, desc.len);
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if (!rcheck(vrh, vringh64_to_cpu(vrh, desc.addr), &len, &range,
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getrange)) {
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err = -EINVAL;
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goto fail;
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}
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addr = (void *)(unsigned long)(vringh64_to_cpu(vrh, desc.addr) +
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range.offset);
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if (unlikely(iov->used == (iov->max_num & ~VRINGH_IOV_ALLOCATED))) {
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err = resize_iovec(iov, gfp);
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if (err)
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goto fail;
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}
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iov->iov[iov->used].iov_base = addr;
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iov->iov[iov->used].iov_len = len;
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iov->used++;
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if (unlikely(len != vringh32_to_cpu(vrh, desc.len))) {
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desc.len = cpu_to_vringh32(vrh,
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vringh32_to_cpu(vrh, desc.len) - len);
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desc.addr = cpu_to_vringh64(vrh,
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vringh64_to_cpu(vrh, desc.addr) + len);
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goto again;
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}
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|
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if (desc.flags & cpu_to_vringh16(vrh, VRING_DESC_F_NEXT)) {
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i = vringh16_to_cpu(vrh, desc.next);
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} else {
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/* Just in case we need to finish traversing above. */
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if (unlikely(up_next > 0)) {
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i = return_from_indirect(vrh, &up_next,
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&descs, &desc_max);
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slow = false;
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} else
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break;
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}
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|
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if (i >= desc_max) {
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vringh_bad("Chained index %u > %u", i, desc_max);
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err = -EINVAL;
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goto fail;
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}
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}
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return 0;
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fail:
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return err;
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}
|
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|
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static inline int __vringh_complete(struct vringh *vrh,
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const struct vring_used_elem *used,
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unsigned int num_used,
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int (*putu16)(const struct vringh *vrh,
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__virtio16 *p, u16 val),
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int (*putused)(struct vring_used_elem *dst,
|
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const struct vring_used_elem
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*src, unsigned num))
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{
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struct vring_used *used_ring;
|
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int err;
|
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u16 used_idx, off;
|
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|
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used_ring = vrh->vring.used;
|
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used_idx = vrh->last_used_idx + vrh->completed;
|
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|
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off = used_idx % vrh->vring.num;
|
|
|
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/* Compiler knows num_used == 1 sometimes, hence extra check */
|
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if (num_used > 1 && unlikely(off + num_used >= vrh->vring.num)) {
|
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u16 part = vrh->vring.num - off;
|
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err = putused(&used_ring->ring[off], used, part);
|
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if (!err)
|
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err = putused(&used_ring->ring[0], used + part,
|
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num_used - part);
|
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} else
|
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err = putused(&used_ring->ring[off], used, num_used);
|
|
|
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if (err) {
|
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vringh_bad("Failed to write %u used entries %u at %p",
|
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num_used, off, &used_ring->ring[off]);
|
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return err;
|
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}
|
|
|
|
/* Make sure buffer is written before we update index. */
|
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virtio_wmb(vrh->weak_barriers);
|
|
|
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err = putu16(vrh, &vrh->vring.used->idx, used_idx + num_used);
|
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if (err) {
|
|
vringh_bad("Failed to update used index at %p",
|
|
&vrh->vring.used->idx);
|
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return err;
|
|
}
|
|
|
|
vrh->completed += num_used;
|
|
return 0;
|
|
}
|
|
|
|
|
|
static inline int __vringh_need_notify(struct vringh *vrh,
|
|
int (*getu16)(const struct vringh *vrh,
|
|
u16 *val,
|
|
const __virtio16 *p))
|
|
{
|
|
bool notify;
|
|
u16 used_event;
|
|
int err;
|
|
|
|
/* Flush out used index update. This is paired with the
|
|
* barrier that the Guest executes when enabling
|
|
* interrupts. */
|
|
virtio_mb(vrh->weak_barriers);
|
|
|
|
/* Old-style, without event indices. */
|
|
if (!vrh->event_indices) {
|
|
u16 flags;
|
|
err = getu16(vrh, &flags, &vrh->vring.avail->flags);
|
|
if (err) {
|
|
vringh_bad("Failed to get flags at %p",
|
|
&vrh->vring.avail->flags);
|
|
return err;
|
|
}
|
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return (!(flags & VRING_AVAIL_F_NO_INTERRUPT));
|
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}
|
|
|
|
/* Modern: we know when other side wants to know. */
|
|
err = getu16(vrh, &used_event, &vring_used_event(&vrh->vring));
|
|
if (err) {
|
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vringh_bad("Failed to get used event idx at %p",
|
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&vring_used_event(&vrh->vring));
|
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return err;
|
|
}
|
|
|
|
/* Just in case we added so many that we wrap. */
|
|
if (unlikely(vrh->completed > 0xffff))
|
|
notify = true;
|
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else
|
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notify = vring_need_event(used_event,
|
|
vrh->last_used_idx + vrh->completed,
|
|
vrh->last_used_idx);
|
|
|
|
vrh->last_used_idx += vrh->completed;
|
|
vrh->completed = 0;
|
|
return notify;
|
|
}
|
|
|
|
static inline bool __vringh_notify_enable(struct vringh *vrh,
|
|
int (*getu16)(const struct vringh *vrh,
|
|
u16 *val, const __virtio16 *p),
|
|
int (*putu16)(const struct vringh *vrh,
|
|
__virtio16 *p, u16 val))
|
|
{
|
|
u16 avail;
|
|
|
|
if (!vrh->event_indices) {
|
|
/* Old-school; update flags. */
|
|
if (putu16(vrh, &vrh->vring.used->flags, 0) != 0) {
|
|
vringh_bad("Clearing used flags %p",
|
|
&vrh->vring.used->flags);
|
|
return true;
|
|
}
|
|
} else {
|
|
if (putu16(vrh, &vring_avail_event(&vrh->vring),
|
|
vrh->last_avail_idx) != 0) {
|
|
vringh_bad("Updating avail event index %p",
|
|
&vring_avail_event(&vrh->vring));
|
|
return true;
|
|
}
|
|
}
|
|
|
|
/* They could have slipped one in as we were doing that: make
|
|
* sure it's written, then check again. */
|
|
virtio_mb(vrh->weak_barriers);
|
|
|
|
if (getu16(vrh, &avail, &vrh->vring.avail->idx) != 0) {
|
|
vringh_bad("Failed to check avail idx at %p",
|
|
&vrh->vring.avail->idx);
|
|
return true;
|
|
}
|
|
|
|
/* This is unlikely, so we just leave notifications enabled
|
|
* (if we're using event_indices, we'll only get one
|
|
* notification anyway). */
|
|
return avail == vrh->last_avail_idx;
|
|
}
|
|
|
|
static inline void __vringh_notify_disable(struct vringh *vrh,
|
|
int (*putu16)(const struct vringh *vrh,
|
|
__virtio16 *p, u16 val))
|
|
{
|
|
if (!vrh->event_indices) {
|
|
/* Old-school; update flags. */
|
|
if (putu16(vrh, &vrh->vring.used->flags,
|
|
VRING_USED_F_NO_NOTIFY)) {
|
|
vringh_bad("Setting used flags %p",
|
|
&vrh->vring.used->flags);
|
|
}
|
|
}
|
|
}
|
|
|
|
/* Userspace access helpers: in this case, addresses are really userspace. */
|
|
static inline int getu16_user(const struct vringh *vrh, u16 *val, const __virtio16 *p)
|
|
{
|
|
__virtio16 v = 0;
|
|
int rc = get_user(v, (__force __virtio16 __user *)p);
|
|
*val = vringh16_to_cpu(vrh, v);
|
|
return rc;
|
|
}
|
|
|
|
static inline int putu16_user(const struct vringh *vrh, __virtio16 *p, u16 val)
|
|
{
|
|
__virtio16 v = cpu_to_vringh16(vrh, val);
|
|
return put_user(v, (__force __virtio16 __user *)p);
|
|
}
|
|
|
|
static inline int copydesc_user(void *dst, const void *src, size_t len)
|
|
{
|
|
return copy_from_user(dst, (__force void __user *)src, len) ?
|
|
-EFAULT : 0;
|
|
}
|
|
|
|
static inline int putused_user(struct vring_used_elem *dst,
|
|
const struct vring_used_elem *src,
|
|
unsigned int num)
|
|
{
|
|
return copy_to_user((__force void __user *)dst, src,
|
|
sizeof(*dst) * num) ? -EFAULT : 0;
|
|
}
|
|
|
|
static inline int xfer_from_user(void *src, void *dst, size_t len)
|
|
{
|
|
return copy_from_user(dst, (__force void __user *)src, len) ?
|
|
-EFAULT : 0;
|
|
}
|
|
|
|
static inline int xfer_to_user(void *dst, void *src, size_t len)
|
|
{
|
|
return copy_to_user((__force void __user *)dst, src, len) ?
|
|
-EFAULT : 0;
|
|
}
|
|
|
|
/**
|
|
* vringh_init_user - initialize a vringh for a userspace vring.
|
|
* @vrh: the vringh to initialize.
|
|
* @features: the feature bits for this ring.
|
|
* @num: the number of elements.
|
|
* @weak_barriers: true if we only need memory barriers, not I/O.
|
|
* @desc: the userpace descriptor pointer.
|
|
* @avail: the userpace avail pointer.
|
|
* @used: the userpace used pointer.
|
|
*
|
|
* Returns an error if num is invalid: you should check pointers
|
|
* yourself!
|
|
*/
|
|
int vringh_init_user(struct vringh *vrh, u64 features,
|
|
unsigned int num, bool weak_barriers,
|
|
struct vring_desc __user *desc,
|
|
struct vring_avail __user *avail,
|
|
struct vring_used __user *used)
|
|
{
|
|
/* Sane power of 2 please! */
|
|
if (!num || num > 0xffff || (num & (num - 1))) {
|
|
vringh_bad("Bad ring size %u", num);
|
|
return -EINVAL;
|
|
}
|
|
|
|
vrh->little_endian = (features & (1ULL << VIRTIO_F_VERSION_1));
|
|
vrh->event_indices = (features & (1 << VIRTIO_RING_F_EVENT_IDX));
|
|
vrh->weak_barriers = weak_barriers;
|
|
vrh->completed = 0;
|
|
vrh->last_avail_idx = 0;
|
|
vrh->last_used_idx = 0;
|
|
vrh->vring.num = num;
|
|
/* vring expects kernel addresses, but only used via accessors. */
|
|
vrh->vring.desc = (__force struct vring_desc *)desc;
|
|
vrh->vring.avail = (__force struct vring_avail *)avail;
|
|
vrh->vring.used = (__force struct vring_used *)used;
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(vringh_init_user);
|
|
|
|
/**
|
|
* vringh_getdesc_user - get next available descriptor from userspace ring.
|
|
* @vrh: the userspace vring.
|
|
* @riov: where to put the readable descriptors (or NULL)
|
|
* @wiov: where to put the writable descriptors (or NULL)
|
|
* @getrange: function to call to check ranges.
|
|
* @head: head index we received, for passing to vringh_complete_user().
|
|
*
|
|
* Returns 0 if there was no descriptor, 1 if there was, or -errno.
|
|
*
|
|
* Note that on error return, you can tell the difference between an
|
|
* invalid ring and a single invalid descriptor: in the former case,
|
|
* *head will be vrh->vring.num. You may be able to ignore an invalid
|
|
* descriptor, but there's not much you can do with an invalid ring.
|
|
*
|
|
* Note that you may need to clean up riov and wiov, even on error!
|
|
*/
|
|
int vringh_getdesc_user(struct vringh *vrh,
|
|
struct vringh_iov *riov,
|
|
struct vringh_iov *wiov,
|
|
bool (*getrange)(struct vringh *vrh,
|
|
u64 addr, struct vringh_range *r),
|
|
u16 *head)
|
|
{
|
|
int err;
|
|
|
|
*head = vrh->vring.num;
|
|
err = __vringh_get_head(vrh, getu16_user, &vrh->last_avail_idx);
|
|
if (err < 0)
|
|
return err;
|
|
|
|
/* Empty... */
|
|
if (err == vrh->vring.num)
|
|
return 0;
|
|
|
|
/* We need the layouts to be the identical for this to work */
|
|
BUILD_BUG_ON(sizeof(struct vringh_kiov) != sizeof(struct vringh_iov));
|
|
BUILD_BUG_ON(offsetof(struct vringh_kiov, iov) !=
|
|
offsetof(struct vringh_iov, iov));
|
|
BUILD_BUG_ON(offsetof(struct vringh_kiov, i) !=
|
|
offsetof(struct vringh_iov, i));
|
|
BUILD_BUG_ON(offsetof(struct vringh_kiov, used) !=
|
|
offsetof(struct vringh_iov, used));
|
|
BUILD_BUG_ON(offsetof(struct vringh_kiov, max_num) !=
|
|
offsetof(struct vringh_iov, max_num));
|
|
BUILD_BUG_ON(sizeof(struct iovec) != sizeof(struct kvec));
|
|
BUILD_BUG_ON(offsetof(struct iovec, iov_base) !=
|
|
offsetof(struct kvec, iov_base));
|
|
BUILD_BUG_ON(offsetof(struct iovec, iov_len) !=
|
|
offsetof(struct kvec, iov_len));
|
|
BUILD_BUG_ON(sizeof(((struct iovec *)NULL)->iov_base)
|
|
!= sizeof(((struct kvec *)NULL)->iov_base));
|
|
BUILD_BUG_ON(sizeof(((struct iovec *)NULL)->iov_len)
|
|
!= sizeof(((struct kvec *)NULL)->iov_len));
|
|
|
|
*head = err;
|
|
err = __vringh_iov(vrh, *head, (struct vringh_kiov *)riov,
|
|
(struct vringh_kiov *)wiov,
|
|
range_check, getrange, GFP_KERNEL, copydesc_user);
|
|
if (err)
|
|
return err;
|
|
|
|
return 1;
|
|
}
|
|
EXPORT_SYMBOL(vringh_getdesc_user);
|
|
|
|
/**
|
|
* vringh_iov_pull_user - copy bytes from vring_iov.
|
|
* @riov: the riov as passed to vringh_getdesc_user() (updated as we consume)
|
|
* @dst: the place to copy.
|
|
* @len: the maximum length to copy.
|
|
*
|
|
* Returns the bytes copied <= len or a negative errno.
|
|
*/
|
|
ssize_t vringh_iov_pull_user(struct vringh_iov *riov, void *dst, size_t len)
|
|
{
|
|
return vringh_iov_xfer((struct vringh_kiov *)riov,
|
|
dst, len, xfer_from_user);
|
|
}
|
|
EXPORT_SYMBOL(vringh_iov_pull_user);
|
|
|
|
/**
|
|
* vringh_iov_push_user - copy bytes into vring_iov.
|
|
* @wiov: the wiov as passed to vringh_getdesc_user() (updated as we consume)
|
|
* @dst: the place to copy.
|
|
* @len: the maximum length to copy.
|
|
*
|
|
* Returns the bytes copied <= len or a negative errno.
|
|
*/
|
|
ssize_t vringh_iov_push_user(struct vringh_iov *wiov,
|
|
const void *src, size_t len)
|
|
{
|
|
return vringh_iov_xfer((struct vringh_kiov *)wiov,
|
|
(void *)src, len, xfer_to_user);
|
|
}
|
|
EXPORT_SYMBOL(vringh_iov_push_user);
|
|
|
|
/**
|
|
* vringh_abandon_user - we've decided not to handle the descriptor(s).
|
|
* @vrh: the vring.
|
|
* @num: the number of descriptors to put back (ie. num
|
|
* vringh_get_user() to undo).
|
|
*
|
|
* The next vringh_get_user() will return the old descriptor(s) again.
|
|
*/
|
|
void vringh_abandon_user(struct vringh *vrh, unsigned int num)
|
|
{
|
|
/* We only update vring_avail_event(vr) when we want to be notified,
|
|
* so we haven't changed that yet. */
|
|
vrh->last_avail_idx -= num;
|
|
}
|
|
EXPORT_SYMBOL(vringh_abandon_user);
|
|
|
|
/**
|
|
* vringh_complete_user - we've finished with descriptor, publish it.
|
|
* @vrh: the vring.
|
|
* @head: the head as filled in by vringh_getdesc_user.
|
|
* @len: the length of data we have written.
|
|
*
|
|
* You should check vringh_need_notify_user() after one or more calls
|
|
* to this function.
|
|
*/
|
|
int vringh_complete_user(struct vringh *vrh, u16 head, u32 len)
|
|
{
|
|
struct vring_used_elem used;
|
|
|
|
used.id = cpu_to_vringh32(vrh, head);
|
|
used.len = cpu_to_vringh32(vrh, len);
|
|
return __vringh_complete(vrh, &used, 1, putu16_user, putused_user);
|
|
}
|
|
EXPORT_SYMBOL(vringh_complete_user);
|
|
|
|
/**
|
|
* vringh_complete_multi_user - we've finished with many descriptors.
|
|
* @vrh: the vring.
|
|
* @used: the head, length pairs.
|
|
* @num_used: the number of used elements.
|
|
*
|
|
* You should check vringh_need_notify_user() after one or more calls
|
|
* to this function.
|
|
*/
|
|
int vringh_complete_multi_user(struct vringh *vrh,
|
|
const struct vring_used_elem used[],
|
|
unsigned num_used)
|
|
{
|
|
return __vringh_complete(vrh, used, num_used,
|
|
putu16_user, putused_user);
|
|
}
|
|
EXPORT_SYMBOL(vringh_complete_multi_user);
|
|
|
|
/**
|
|
* vringh_notify_enable_user - we want to know if something changes.
|
|
* @vrh: the vring.
|
|
*
|
|
* This always enables notifications, but returns false if there are
|
|
* now more buffers available in the vring.
|
|
*/
|
|
bool vringh_notify_enable_user(struct vringh *vrh)
|
|
{
|
|
return __vringh_notify_enable(vrh, getu16_user, putu16_user);
|
|
}
|
|
EXPORT_SYMBOL(vringh_notify_enable_user);
|
|
|
|
/**
|
|
* vringh_notify_disable_user - don't tell us if something changes.
|
|
* @vrh: the vring.
|
|
*
|
|
* This is our normal running state: we disable and then only enable when
|
|
* we're going to sleep.
|
|
*/
|
|
void vringh_notify_disable_user(struct vringh *vrh)
|
|
{
|
|
__vringh_notify_disable(vrh, putu16_user);
|
|
}
|
|
EXPORT_SYMBOL(vringh_notify_disable_user);
|
|
|
|
/**
|
|
* vringh_need_notify_user - must we tell the other side about used buffers?
|
|
* @vrh: the vring we've called vringh_complete_user() on.
|
|
*
|
|
* Returns -errno or 0 if we don't need to tell the other side, 1 if we do.
|
|
*/
|
|
int vringh_need_notify_user(struct vringh *vrh)
|
|
{
|
|
return __vringh_need_notify(vrh, getu16_user);
|
|
}
|
|
EXPORT_SYMBOL(vringh_need_notify_user);
|
|
|
|
/* Kernelspace access helpers. */
|
|
static inline int getu16_kern(const struct vringh *vrh,
|
|
u16 *val, const __virtio16 *p)
|
|
{
|
|
*val = vringh16_to_cpu(vrh, ACCESS_ONCE(*p));
|
|
return 0;
|
|
}
|
|
|
|
static inline int putu16_kern(const struct vringh *vrh, __virtio16 *p, u16 val)
|
|
{
|
|
ACCESS_ONCE(*p) = cpu_to_vringh16(vrh, val);
|
|
return 0;
|
|
}
|
|
|
|
static inline int copydesc_kern(void *dst, const void *src, size_t len)
|
|
{
|
|
memcpy(dst, src, len);
|
|
return 0;
|
|
}
|
|
|
|
static inline int putused_kern(struct vring_used_elem *dst,
|
|
const struct vring_used_elem *src,
|
|
unsigned int num)
|
|
{
|
|
memcpy(dst, src, num * sizeof(*dst));
|
|
return 0;
|
|
}
|
|
|
|
static inline int xfer_kern(void *src, void *dst, size_t len)
|
|
{
|
|
memcpy(dst, src, len);
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* vringh_init_kern - initialize a vringh for a kernelspace vring.
|
|
* @vrh: the vringh to initialize.
|
|
* @features: the feature bits for this ring.
|
|
* @num: the number of elements.
|
|
* @weak_barriers: true if we only need memory barriers, not I/O.
|
|
* @desc: the userpace descriptor pointer.
|
|
* @avail: the userpace avail pointer.
|
|
* @used: the userpace used pointer.
|
|
*
|
|
* Returns an error if num is invalid.
|
|
*/
|
|
int vringh_init_kern(struct vringh *vrh, u64 features,
|
|
unsigned int num, bool weak_barriers,
|
|
struct vring_desc *desc,
|
|
struct vring_avail *avail,
|
|
struct vring_used *used)
|
|
{
|
|
/* Sane power of 2 please! */
|
|
if (!num || num > 0xffff || (num & (num - 1))) {
|
|
vringh_bad("Bad ring size %u", num);
|
|
return -EINVAL;
|
|
}
|
|
|
|
vrh->little_endian = (features & (1ULL << VIRTIO_F_VERSION_1));
|
|
vrh->event_indices = (features & (1 << VIRTIO_RING_F_EVENT_IDX));
|
|
vrh->weak_barriers = weak_barriers;
|
|
vrh->completed = 0;
|
|
vrh->last_avail_idx = 0;
|
|
vrh->last_used_idx = 0;
|
|
vrh->vring.num = num;
|
|
vrh->vring.desc = desc;
|
|
vrh->vring.avail = avail;
|
|
vrh->vring.used = used;
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(vringh_init_kern);
|
|
|
|
/**
|
|
* vringh_getdesc_kern - get next available descriptor from kernelspace ring.
|
|
* @vrh: the kernelspace vring.
|
|
* @riov: where to put the readable descriptors (or NULL)
|
|
* @wiov: where to put the writable descriptors (or NULL)
|
|
* @head: head index we received, for passing to vringh_complete_kern().
|
|
* @gfp: flags for allocating larger riov/wiov.
|
|
*
|
|
* Returns 0 if there was no descriptor, 1 if there was, or -errno.
|
|
*
|
|
* Note that on error return, you can tell the difference between an
|
|
* invalid ring and a single invalid descriptor: in the former case,
|
|
* *head will be vrh->vring.num. You may be able to ignore an invalid
|
|
* descriptor, but there's not much you can do with an invalid ring.
|
|
*
|
|
* Note that you may need to clean up riov and wiov, even on error!
|
|
*/
|
|
int vringh_getdesc_kern(struct vringh *vrh,
|
|
struct vringh_kiov *riov,
|
|
struct vringh_kiov *wiov,
|
|
u16 *head,
|
|
gfp_t gfp)
|
|
{
|
|
int err;
|
|
|
|
err = __vringh_get_head(vrh, getu16_kern, &vrh->last_avail_idx);
|
|
if (err < 0)
|
|
return err;
|
|
|
|
/* Empty... */
|
|
if (err == vrh->vring.num)
|
|
return 0;
|
|
|
|
*head = err;
|
|
err = __vringh_iov(vrh, *head, riov, wiov, no_range_check, NULL,
|
|
gfp, copydesc_kern);
|
|
if (err)
|
|
return err;
|
|
|
|
return 1;
|
|
}
|
|
EXPORT_SYMBOL(vringh_getdesc_kern);
|
|
|
|
/**
|
|
* vringh_iov_pull_kern - copy bytes from vring_iov.
|
|
* @riov: the riov as passed to vringh_getdesc_kern() (updated as we consume)
|
|
* @dst: the place to copy.
|
|
* @len: the maximum length to copy.
|
|
*
|
|
* Returns the bytes copied <= len or a negative errno.
|
|
*/
|
|
ssize_t vringh_iov_pull_kern(struct vringh_kiov *riov, void *dst, size_t len)
|
|
{
|
|
return vringh_iov_xfer(riov, dst, len, xfer_kern);
|
|
}
|
|
EXPORT_SYMBOL(vringh_iov_pull_kern);
|
|
|
|
/**
|
|
* vringh_iov_push_kern - copy bytes into vring_iov.
|
|
* @wiov: the wiov as passed to vringh_getdesc_kern() (updated as we consume)
|
|
* @dst: the place to copy.
|
|
* @len: the maximum length to copy.
|
|
*
|
|
* Returns the bytes copied <= len or a negative errno.
|
|
*/
|
|
ssize_t vringh_iov_push_kern(struct vringh_kiov *wiov,
|
|
const void *src, size_t len)
|
|
{
|
|
return vringh_iov_xfer(wiov, (void *)src, len, xfer_kern);
|
|
}
|
|
EXPORT_SYMBOL(vringh_iov_push_kern);
|
|
|
|
/**
|
|
* vringh_abandon_kern - we've decided not to handle the descriptor(s).
|
|
* @vrh: the vring.
|
|
* @num: the number of descriptors to put back (ie. num
|
|
* vringh_get_kern() to undo).
|
|
*
|
|
* The next vringh_get_kern() will return the old descriptor(s) again.
|
|
*/
|
|
void vringh_abandon_kern(struct vringh *vrh, unsigned int num)
|
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{
|
|
/* We only update vring_avail_event(vr) when we want to be notified,
|
|
* so we haven't changed that yet. */
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|
vrh->last_avail_idx -= num;
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}
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EXPORT_SYMBOL(vringh_abandon_kern);
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|
|
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/**
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* vringh_complete_kern - we've finished with descriptor, publish it.
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* @vrh: the vring.
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* @head: the head as filled in by vringh_getdesc_kern.
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|
* @len: the length of data we have written.
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|
*
|
|
* You should check vringh_need_notify_kern() after one or more calls
|
|
* to this function.
|
|
*/
|
|
int vringh_complete_kern(struct vringh *vrh, u16 head, u32 len)
|
|
{
|
|
struct vring_used_elem used;
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|
|
|
used.id = cpu_to_vringh32(vrh, head);
|
|
used.len = cpu_to_vringh32(vrh, len);
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|
|
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return __vringh_complete(vrh, &used, 1, putu16_kern, putused_kern);
|
|
}
|
|
EXPORT_SYMBOL(vringh_complete_kern);
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|
|
|
/**
|
|
* vringh_notify_enable_kern - we want to know if something changes.
|
|
* @vrh: the vring.
|
|
*
|
|
* This always enables notifications, but returns false if there are
|
|
* now more buffers available in the vring.
|
|
*/
|
|
bool vringh_notify_enable_kern(struct vringh *vrh)
|
|
{
|
|
return __vringh_notify_enable(vrh, getu16_kern, putu16_kern);
|
|
}
|
|
EXPORT_SYMBOL(vringh_notify_enable_kern);
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|
|
|
/**
|
|
* vringh_notify_disable_kern - don't tell us if something changes.
|
|
* @vrh: the vring.
|
|
*
|
|
* This is our normal running state: we disable and then only enable when
|
|
* we're going to sleep.
|
|
*/
|
|
void vringh_notify_disable_kern(struct vringh *vrh)
|
|
{
|
|
__vringh_notify_disable(vrh, putu16_kern);
|
|
}
|
|
EXPORT_SYMBOL(vringh_notify_disable_kern);
|
|
|
|
/**
|
|
* vringh_need_notify_kern - must we tell the other side about used buffers?
|
|
* @vrh: the vring we've called vringh_complete_kern() on.
|
|
*
|
|
* Returns -errno or 0 if we don't need to tell the other side, 1 if we do.
|
|
*/
|
|
int vringh_need_notify_kern(struct vringh *vrh)
|
|
{
|
|
return __vringh_need_notify(vrh, getu16_kern);
|
|
}
|
|
EXPORT_SYMBOL(vringh_need_notify_kern);
|
|
|
|
MODULE_LICENSE("GPL");
|