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vringh: iterate on iotlb_translate to handle large translations 

iotlb_translate() can return -ENOBUFS if the bio_vec is not big enough
to contain all the ranges for translation.
This can happen for example if the VMM maps a large bounce buffer,
without using hugepages, that requires more than 16 ranges to translate
the addresses.

To handle this case, let's extend iotlb_translate() to also return the
number of bytes successfully translated.
In copy_from_iotlb()/copy_to_iotlb() loops by calling iotlb_translate()
several times until we complete the translation.

Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Message-Id: <20220624075656.13997-1-sgarzare@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Stefano Garzarella 2022-06-24 09:56:56 +02:00 committed by Michael S. Tsirkin
parent 96ef18a24b
commit 309bba39c9
1 changed files with 56 additions and 22 deletions
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60
drivers/vhost/vringh.c
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@ -1095,7 +1095,8 @@ EXPORT_SYMBOL(vringh_need_notify_kern);
#if IS_REACHABLE(CONFIG_VHOST_IOTLB)
static int iotlb_translate(const struct vringh *vrh,
u64 addr, u64 len, struct bio_vec iov[],
u64 addr, u64 len, u64 *translated,
struct bio_vec iov[],
int iov_size, u32 perm)
{
struct vhost_iotlb_map *map;
@ -1136,43 +1137,76 @@ static int iotlb_translate(const struct vringh *vrh,
spin_unlock(vrh->iotlb_lock);
if (translated)
*translated = min(len, s);
return ret;
}
static inline int copy_from_iotlb(const struct vringh *vrh, void *dst,
void *src, size_t len)
{
struct iov_iter iter;
u64 total_translated = 0;
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, iov, 16, VHOST_MAP_RO);
len - total_translated, &translated,
iov, ARRAY_SIZE(iov), VHOST_MAP_RO);
if (ret == -ENOBUFS)
ret = ARRAY_SIZE(iov);
else if (ret < 0)
return ret;
iov_iter_bvec(&iter, READ, iov, ret, translated);
ret = copy_from_iter(dst, translated, &iter);
if (ret < 0)
return ret;
iov_iter_bvec(&iter, READ, iov, ret, len);
src += translated;
dst += translated;
total_translated += translated;
}
ret = copy_from_iter(dst, len, &iter);
return ret;
return total_translated;
}
static inline int copy_to_iotlb(const struct vringh *vrh, void *dst,
void *src, size_t len)
{
struct iov_iter iter;
u64 total_translated = 0;
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, iov, 16, VHOST_MAP_WO);
len - total_translated, &translated,
iov, ARRAY_SIZE(iov), VHOST_MAP_WO);
if (ret == -ENOBUFS)
ret = ARRAY_SIZE(iov);
else if (ret < 0)
return ret;
iov_iter_bvec(&iter, WRITE, iov, ret, translated);
ret = copy_to_iter(src, translated, &iter);
if (ret < 0)
return ret;
iov_iter_bvec(&iter, WRITE, iov, ret, len);
src += translated;
dst += translated;
total_translated += translated;
}
return copy_to_iter(src, len, &iter);
return total_translated;
}
static inline int getu16_iotlb(const struct vringh *vrh,
@ -1183,7 +1217,7 @@ static inline int getu16_iotlb(const struct vringh *vrh,
int ret;
/* Atomic read is needed for getu16 */
ret = iotlb_translate(vrh, (u64)(uintptr_t)p, sizeof(*p),
ret = iotlb_translate(vrh, (u64)(uintptr_t)p, sizeof(*p), NULL,
&iov, 1, VHOST_MAP_RO);
if (ret < 0)
return ret;
@ -1204,7 +1238,7 @@ static inline int putu16_iotlb(const struct vringh *vrh,
int ret;
/* Atomic write is needed for putu16 */
ret = iotlb_translate(vrh, (u64)(uintptr_t)p, sizeof(*p),
ret = iotlb_translate(vrh, (u64)(uintptr_t)p, sizeof(*p), NULL,
&iov, 1, VHOST_MAP_WO);
if (ret < 0)
return ret;