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Commit d0fa28f0 authored by Michael S. Tsirkin's avatar Michael S. Tsirkin Committed by David S. Miller
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virtio_net: fix PAGE_SIZE > 64k 



I don't have any guests with PAGE_SIZE > 64k but the
code seems to be clearly broken in that case
as PAGE_SIZE / MERGEABLE_BUFFER_ALIGN will need
more than 8 bit and so the code in mergeable_ctx_to_buf_address
does not give us the actual true size.

Cc: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 0fb44559

drivers/net/virtio_net.c

+9 −1
Original line number Diff line number Diff line
@@ -48,8 +48,16 @@ module_param(gso, bool, 0444); 
 */

DECLARE_EWMA(pkt_len, 1, 64)



/* With mergeable buffers we align buffer address and use the low bits to

 * encode its true size. Buffer size is up to 1 page so we need to align to

 * square root of page size to ensure we reserve enough bits to encode the true

 * size.

 */

#define MERGEABLE_BUFFER_MIN_ALIGN_SHIFT ((PAGE_SHIFT + 1) / 2)



/* Minimum alignment for mergeable packet buffers. */

#define MERGEABLE_BUFFER_ALIGN max(L1_CACHE_BYTES, 256)

#define MERGEABLE_BUFFER_ALIGN max(L1_CACHE_BYTES, \

				   1 << MERGEABLE_BUFFER_MIN_ALIGN_SHIFT)



#define VIRTNET_DRIVER_VERSION "1.0.0"