Commit 309bba39 authored by Stefano Garzarella's avatar Stefano Garzarella Committed by Michael S. Tsirkin
Browse files

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: default avatarStefano Garzarella <sgarzare@redhat.com>
Message-Id: <20220624075656.13997-1-sgarzare@redhat.com>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
parent 96ef18a2

drivers/vhost/vringh.c

+56 −22
Original line number Diff line number Diff line
@@ -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);

	if (ret < 0)

				      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, len);



	ret = copy_from_iter(dst, len, &iter);

		iov_iter_bvec(&iter, READ, iov, ret, translated);



		ret = copy_from_iter(dst, translated, &iter);

		if (ret < 0)

			return ret;



		src += translated;

		dst += translated;

		total_translated += translated;

	}



	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;