tree 09146fc159cc456d79f20f5fb66cbc7bfa8c9871
parent 964fe080d94db82a3268443e9b9ece4c60246414
author Michael S. Tsirkin <mst@redhat.com> 1256216766 +0200
committer Rusty Russell <rusty@rustcorp.com.au> 1256768436 +1030

virtio-pci: fix per-vq MSI-X request logic

Commit f68d24082e22ccee3077d11aeb6dc5354f0ca7f1
in 2.6.32-rc1 broke requesting IRQs for per-VQ MSI-X vectors:
- vector number was used instead of the vector itself
- we try to request an IRQ for VQ which does not
  have a callback handler

This is a regression that causes warnings in kernel log,
potentially lower performance as we need to scan vq list,
and might cause system failure if the interrupt
requested is in fact needed by another system.

This was not noticed earlier because in most cases
we were falling back on shared interrupt for all vqs.

The warnings often look like this:

virtio-pci 0000:00:03.0: irq 26 for MSI/MSI-X
virtio-pci 0000:00:03.0: irq 27 for MSI/MSI-X
virtio-pci 0000:00:03.0: irq 28 for MSI/MSI-X
IRQ handler type mismatch for IRQ 1
current handler: i8042
Pid: 2400, comm: modprobe Tainted: G        W
2.6.32-rc3-11952-gf3ed8d8-dirty #1
Call Trace:
 [<ffffffff81072aed>] ? __setup_irq+0x299/0x304
 [<ffffffff81072ff3>] ? request_threaded_irq+0x144/0x1c1
 [<ffffffff813455af>] ? vring_interrupt+0x0/0x30
 [<ffffffff81346598>] ? vp_try_to_find_vqs+0x583/0x5c7
 [<ffffffffa0015188>] ? skb_recv_done+0x0/0x34 [virtio_net]
 [<ffffffff81346609>] ? vp_find_vqs+0x2d/0x83
 [<ffffffff81345d00>] ? vp_get+0x3c/0x4e
 [<ffffffffa0016373>] ? virtnet_probe+0x2f1/0x428 [virtio_net]
 [<ffffffffa0015188>] ? skb_recv_done+0x0/0x34 [virtio_net]
 [<ffffffffa00150d8>] ? skb_xmit_done+0x0/0x39 [virtio_net]
 [<ffffffff8110ab92>] ? sysfs_do_create_link+0xcb/0x116
 [<ffffffff81345cc2>] ? vp_get_status+0x14/0x16
 [<ffffffff81345464>] ? virtio_dev_probe+0xa9/0xc8
 [<ffffffff8122b11c>] ? driver_probe_device+0x8d/0x128
 [<ffffffff8122b206>] ? __driver_attach+0x4f/0x6f
 [<ffffffff8122b1b7>] ? __driver_attach+0x0/0x6f
 [<ffffffff8122a9f9>] ? bus_for_each_dev+0x43/0x74
 [<ffffffff8122a374>] ? bus_add_driver+0xea/0x22d
 [<ffffffff8122b4a3>] ? driver_register+0xa7/0x111
 [<ffffffffa001a000>] ? init+0x0/0xc [virtio_net]
 [<ffffffff81009051>] ? do_one_initcall+0x50/0x148
 [<ffffffff8106e117>] ? sys_init_module+0xc5/0x21a
 [<ffffffff8100af02>] ? system_call_fastpath+0x16/0x1b
virtio-pci 0000:00:03.0: irq 26 for MSI/MSI-X
virtio-pci 0000:00:03.0: irq 27 for MSI/MSI-X

Reported-by: Marcelo Tosatti <mtosatti@redhat.com>
Reported-by: Shirley Ma <xma@us.ibm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>