Re: [PATCH v2 0/4] virtio: Clean up scatterlists and use the DMA API

Christian Borntraeger
2014-08-28T07:44:53Z

On 27/08/14 23:50, Andy Lutomirski wrote:
> This fixes virtio on Xen guests as well as on any other platform
> that uses virtio_pci on which physical addresses don't match bus
> addresses.
>
> This can be tested with:
>
> virtme-run --xen xen --kimg arch/x86/boot/bzImage --console
>
> using virtme from here:
>
> https://git.kernel.org/cgit/utils/kernel/virtme/virtme.git
>
> Without these patches, the guest hangs forever. With these patches,
> everything works.
>
> This should be safe on all platforms that I'm aware of. That
> doesn't mean that there isn't anything that I missed.
>
> Changes from v1:
> - Using the DMA API is optional now. It would be nice to improve the
> DMA API to the point that it could be used unconditionally, but s390
> proves that we're not there yet.
> - Includes patch 4, which fixes DMA debugging warnings from virtio_net.
>
> Andy Lutomirski (4):
> virtio_ring: Remove sg_next indirection
> virtio_ring: Support DMA APIs if requested
> virtio_pci: Use the DMA API for virtqueues
> virtio_net: Stop doing DMA from the stack
>
> drivers/lguest/lguest_device.c | 3 +-
> drivers/misc/mic/card/mic_virtio.c | 2 +-
> drivers/net/virtio_net.c | 53 +++++---
> drivers/remoteproc/remoteproc_virtio.c | 4 +-
> drivers/s390/kvm/kvm_virtio.c | 2 +-
> drivers/s390/kvm/virtio_ccw.c | 4 +-
> drivers/virtio/virtio_mmio.c | 5 +-
> drivers/virtio/virtio_pci.c | 35 ++++--
> drivers/virtio/virtio_ring.c | 219 ++++++++++++++++++++++++++-------
> include/linux/virtio_ring.h | 1 +
> tools/virtio/linux/virtio.h | 1 +
> tools/virtio/virtio_test.c | 2 +-
> tools/virtio/vringh_test.c | 3 +-
> 13 files changed, 253 insertions(+), 81 deletions(-)
>

Patches were applied on top of 3.16.

block seems to work, with net a simple ping works, iperf causes this:

[ 8.643981] ------------[ cut here ]------------
[ 8.643986] kernel BUG at drivers/virtio/virtio_ring.c:245!
[ 8.644036] illegal operation: 0001 [#1] SMP
[ 8.644039] Modules linked in: virtio_net virtio_blk dm_multipath sunrpc
[ 8.644046] CPU: 0 PID: 1291 Comm: iperf Not tainted 3.16.0+ #130
[ 8.644048] task: 00000000018ee4c0 ti: 0000000022098000 task.ti: 0000000022098000
[ 8.644051] Krnl PSW : 0704d00180000000 0000000000421618 (virtqueue_add_outbuf+0x2e4/0x340)
[ 8.644066] R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:1 PM:0 EA:3
Krnl GPRS: 00000000299f8a80 0000000000000000 0000000000000001 000003d100000000
[ 8.644070] 00000000004214de 0000000000000e2c 0000000000000001 0000000000000002
[ 8.644072] 00000000299f8a40 0000000000000001 00000000299f8a40 0000000000000000
[ 8.644074] 0000000028077608 00000000287ec000 0000000000421548 000000002209b7b0
[ 8.644085] Krnl Code: 000000000042160a: d060a7a90000 trtr 1961(97,%r10),0
0000000000421610: a7f4ff07 brc 15,42141e
#0000000000421614: a7f40001 brc 15,421616
>0000000000421618: a7c8fffb lhi %r12,-5
000000000042161c: a7f4ff46 brc 15,4214a8
0000000000421620: a7f40001 brc 15,421622
0000000000421624: b9040021 lgr %r2,%r1
0000000000421628: c030001c3569 larl %r3,7a80fa
[ 8.644106] Call Trace:
[ 8.644110] ([<00000000004214de>] virtqueue_add_outbuf+0x1aa/0x340)
[ 8.644114] [<000003ff80174466>] start_xmit+0x1e6/0x49c [virtio_net]
[ 8.644119] [<000000000050571a>] dev_hard_start_xmit+0x346/0x600
[ 8.644123] [<000000000052a43c>] sch_direct_xmit+0xe8/0x1e8
[ 8.644126] [<0000000000505be8>] __dev_queue_xmit+0x214/0x4ec
[ 8.644131] [<000000000054a476>] ip_finish_output+0x436/0x90c
[ 8.644134] [<000000000054b7c0>] ip_queue_xmit+0x170/0x3e8
[ 8.644137] [<00000000005636ca>] tcp_transmit_skb+0x462/0x984
[ 8.644140] [<0000000000564870>] tcp_write_xmit+0x220/0xd0c
[ 8.644143] [<00000000005653a2>] tcp_push_one+0x46/0x58
[ 8.644145] [<00000000005568b4>] tcp_sendmsg+0xb7c/0xc9c
[ 8.644148] [<00000000004e7514>] sock_aio_write+0x12c/0x158
[ 8.644153] [<000000000027033c>] do_sync_write+0x80/0xc8
[ 8.644156] [<0000000000271444>] vfs_write+0x144/0x1d8
[ 8.644158] [<000000000027192a>] SyS_write+0x62/0xd0
[ 8.644163] [<000000000062781c>] sysc_tracego+0x14/0x1a
[ 8.644170] [<000003fffd51203c>] 0x3fffd51203c
[ 8.644171] Last Breaking-Event-Address: