diff options
Diffstat (limited to 'block/crypto.c')
| -rw-r--r-- | block/crypto.c | 28 |
1 files changed, 15 insertions, 13 deletions
diff --git a/block/crypto.c b/block/crypto.c index 58ef6f2f52..684cabeaf8 100644 --- a/block/crypto.c +++ b/block/crypto.c @@ -379,7 +379,11 @@ static void block_crypto_close(BlockDriverState *bs) } -#define BLOCK_CRYPTO_MAX_SECTORS 32 +/* + * 1 MB bounce buffer gives good performance / memory tradeoff + * when using cache=none|directsync. + */ +#define BLOCK_CRYPTO_MAX_IO_SIZE (1024 * 1024) static coroutine_fn int block_crypto_co_readv(BlockDriverState *bs, int64_t sector_num, @@ -396,12 +400,11 @@ block_crypto_co_readv(BlockDriverState *bs, int64_t sector_num, qemu_iovec_init(&hd_qiov, qiov->niov); - /* Bounce buffer so we have a linear mem region for - * entire sector. XXX optimize so we avoid bounce - * buffer in case that qiov->niov == 1 + /* Bounce buffer because we don't wish to expose cipher text + * in qiov which points to guest memory. */ cipher_data = - qemu_try_blockalign(bs->file->bs, MIN(BLOCK_CRYPTO_MAX_SECTORS * 512, + qemu_try_blockalign(bs->file->bs, MIN(BLOCK_CRYPTO_MAX_IO_SIZE, qiov->size)); if (cipher_data == NULL) { ret = -ENOMEM; @@ -411,8 +414,8 @@ block_crypto_co_readv(BlockDriverState *bs, int64_t sector_num, while (remaining_sectors) { cur_nr_sectors = remaining_sectors; - if (cur_nr_sectors > BLOCK_CRYPTO_MAX_SECTORS) { - cur_nr_sectors = BLOCK_CRYPTO_MAX_SECTORS; + if (cur_nr_sectors > (BLOCK_CRYPTO_MAX_IO_SIZE / 512)) { + cur_nr_sectors = (BLOCK_CRYPTO_MAX_IO_SIZE / 512); } qemu_iovec_reset(&hd_qiov); @@ -464,12 +467,11 @@ block_crypto_co_writev(BlockDriverState *bs, int64_t sector_num, qemu_iovec_init(&hd_qiov, qiov->niov); - /* Bounce buffer so we have a linear mem region for - * entire sector. XXX optimize so we avoid bounce - * buffer in case that qiov->niov == 1 + /* Bounce buffer because we're not permitted to touch + * contents of qiov - it points to guest memory. */ cipher_data = - qemu_try_blockalign(bs->file->bs, MIN(BLOCK_CRYPTO_MAX_SECTORS * 512, + qemu_try_blockalign(bs->file->bs, MIN(BLOCK_CRYPTO_MAX_IO_SIZE, qiov->size)); if (cipher_data == NULL) { ret = -ENOMEM; @@ -479,8 +481,8 @@ block_crypto_co_writev(BlockDriverState *bs, int64_t sector_num, while (remaining_sectors) { cur_nr_sectors = remaining_sectors; - if (cur_nr_sectors > BLOCK_CRYPTO_MAX_SECTORS) { - cur_nr_sectors = BLOCK_CRYPTO_MAX_SECTORS; + if (cur_nr_sectors > (BLOCK_CRYPTO_MAX_IO_SIZE / 512)) { + cur_nr_sectors = (BLOCK_CRYPTO_MAX_IO_SIZE / 512); } qemu_iovec_to_buf(qiov, bytes_done, |