Commit 7fdc81f6 authored Jan 23, 2017 by Michael S. Tsirkin Committed by Greg Kroah-Hartman Jul 05, 2017

virtio_net: fix PAGE_SIZE > 64k




[ Upstream commit d0fa28f00052391b5df328f502fbbdd4444938b7 ]

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: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent a6c3e01b

drivers/net/virtio_net.c

+9 −1

Original line number	Diff line number	Diff line
		@@ -47,8 +47,16 @@ 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"