linux-imx

/*

 * Helpers for the host side of a virtio ring.

 *

 * Since these may be in userspace, we use (inline) accessors.

 */

#include <linux/compiler.h>

#include <linux/module.h>

#include <linux/vringh.h>

#include <linux/virtio_ring.h>

#include <linux/kernel.h>

#include <linux/ratelimit.h>

#include <linux/uaccess.h>

#include <linux/slab.h>

#include <linux/export.h>

#include <uapi/linux/virtio_config.h>

​

static __printf(1,2) __cold void vringh_bad(const char *fmt, ...)

{

    static DEFINE_RATELIMIT_STATE(vringh_rs,

                      DEFAULT_RATELIMIT_INTERVAL,

                      DEFAULT_RATELIMIT_BURST);

    if (__ratelimit(&vringh_rs)) {

        va_list ap;

        va_start(ap, fmt);

        printk(KERN_NOTICE "vringh:");

        vprintk(fmt, ap);

        va_end(ap);

    }

}

​

/* Returns vring->num if empty, -ve on error. */

static inline int __vringh_get_head(const struct vringh *vrh,

                    int (*getu16)(const struct vringh *vrh,

                          u16 *val, const __virtio16 *p),

                    u16 *last_avail_idx)

{

    u16 avail_idx, i, head;

    int err;

​

    err = getu16(vrh, &avail_idx, &vrh->vring.avail->idx);

    if (err) {

        vringh_bad("Failed to access avail idx at %p",

               &vrh->vring.avail->idx);

        return err;

    }

​

    if (*last_avail_idx == avail_idx)

        return vrh->vring.num;

​

    /* Only get avail ring entries after they have been exposed by guest. */

    virtio_rmb(vrh->weak_barriers);

​

    i = *last_avail_idx & (vrh->vring.num - 1);

​

    err = getu16(vrh, &head, &vrh->vring.avail->ring[i]);

    if (err) {

        vringh_bad("Failed to read head: idx %d address %p",

               *last_avail_idx, &vrh->vring.avail->ring[i]);

        return err;

    }

​

    if (head >= vrh->vring.num) {

        vringh_bad("Guest says index %u > %u is available",

               head, vrh->vring.num);

        return -EINVAL;

    }

​

    (*last_avail_idx)++;

    return head;

}

​

/* Copy some bytes to/from the iovec.  Returns num copied. */

static inline ssize_t vringh_iov_xfer(struct vringh_kiov *iov,

                      void *ptr, size_t len,

                      int (*xfer)(void *addr, void *ptr,

                          size_t len))

{

    int err, done = 0;

​

    while (len && iov->i < iov->used) {

        size_t partlen;

​

        partlen = min(iov->iov[iov->i].iov_len, len);

        err = xfer(iov->iov[iov->i].iov_base, ptr, partlen);

        if (err)

            return err;

        done += partlen;

        len -= partlen;

        ptr += partlen;

        iov->consumed += partlen;

        iov->iov[iov->i].iov_len -= partlen;

        iov->iov[iov->i].iov_base += partlen;