[dpdk-dev] bug: virtio PMD sends malformed packets for 32-bit processes on 64-bit kernel
Frederico.Cadete-ext at oneaccess-net.com
Thu Jun 22 16:58:20 CEST 2017
I believe commit 260aae9a  has introduced a regression for the case
of 32-bit process running on a 64-bit kernel.
The commit is effectively casting mbuf->buf_physaddr to uintptr_t
before dereferencing it. It truncates the physical address to the width
of the process's uint, and in the the aforementioned combination this
loses important bits.
I can confirm this under GDB. When virtqueue_enqueue_xmit is filling in
start_dp, I get this result:
(gdb) p /x cookie->buf_physaddr
$5 = 0x12f94a000
(gdb) p /x start_dp[idx].addr
$6 = 0x2f94a080
On my system, I capture the packet that goes out to the host and I see
it has the correct size but the content is all-zeroes.
I would like to propose a patch that would work for all supported
combinations of user/kernel bitwidth *and* virtio-pci/virtio-user. But
I don't really see how that could work, given virtio-user tries to
store a physical address in rte_mbuf's "void *buf_addr", and this is
not always big enough for a physical address.
Any suggestions on if and how this could be fixed?
Meanwhile, the bug affects dpdk 17.05, 17.02.1 and master. Users not
requiring virtio-user support can avoid it by setting
CONFIG_VIRTIO_USER=n during compilation.
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