linux/drivers/virtio
Angus Chen 71491c54ea virtio_pci: don't try to use intxif pin is zero
The background is that we use dpu in cloud computing,the arch is x86,80
cores. We will have a lots of virtio devices,like 512 or more.
When we probe about 200 virtio_blk devices,it will fail and
the stack is printed as follows:

[25338.485128] virtio-pci 0000:b3:00.0: virtio_pci: leaving for legacy driver
[25338.496174] genirq: Flags mismatch irq 0. 00000080 (virtio418) vs. 00015a00 (timer)
[25338.503822] CPU: 20 PID: 5431 Comm: kworker/20:0 Kdump: loaded Tainted: G           OE    --------- -  - 4.18.0-305.30.1.el8.x86_64
[25338.516403] Hardware name: Inspur NF5280M5/YZMB-00882-10E, BIOS 4.1.21 08/25/2021
[25338.523881] Workqueue: events work_for_cpu_fn
[25338.528235] Call Trace:
[25338.530687]  dump_stack+0x5c/0x80
[25338.534000]  __setup_irq.cold.53+0x7c/0xd3
[25338.538098]  request_threaded_irq+0xf5/0x160
[25338.542371]  vp_find_vqs+0xc7/0x190
[25338.545866]  init_vq+0x17c/0x2e0 [virtio_blk]
[25338.550223]  ? ncpus_cmp_func+0x10/0x10
[25338.554061]  virtblk_probe+0xe6/0x8a0 [virtio_blk]
[25338.558846]  virtio_dev_probe+0x158/0x1f0
[25338.562861]  really_probe+0x255/0x4a0
[25338.566524]  ? __driver_attach_async_helper+0x90/0x90
[25338.571567]  driver_probe_device+0x49/0xc0
[25338.575660]  bus_for_each_drv+0x79/0xc0
[25338.579499]  __device_attach+0xdc/0x160
[25338.583337]  bus_probe_device+0x9d/0xb0
[25338.587167]  device_add+0x418/0x780
[25338.590654]  register_virtio_device+0x9e/0xe0
[25338.595011]  virtio_pci_probe+0xb3/0x140
[25338.598941]  local_pci_probe+0x41/0x90
[25338.602689]  work_for_cpu_fn+0x16/0x20
[25338.606443]  process_one_work+0x1a7/0x360
[25338.610456]  ? create_worker+0x1a0/0x1a0
[25338.614381]  worker_thread+0x1cf/0x390
[25338.618132]  ? create_worker+0x1a0/0x1a0
[25338.622051]  kthread+0x116/0x130
[25338.625283]  ? kthread_flush_work_fn+0x10/0x10
[25338.629731]  ret_from_fork+0x1f/0x40
[25338.633395] virtio_blk: probe of virtio418 failed with error -16

The log :
"genirq: Flags mismatch irq 0. 00000080 (virtio418) vs. 00015a00 (timer)"
was printed because of the irq 0 is used by timer exclusive,and when
vp_find_vqs call vp_find_vqs_msix and returns false twice (for
whatever reason), then it will call vp_find_vqs_intx as a fallback.
Because vp_dev->pci_dev->irq is zero, we request irq 0 with
flag IRQF_SHARED, and get a backtrace like above.

According to PCI spec about "Interrupt Pin" Register (Offset 3Dh):
"The Interrupt Pin register is a read-only register that identifies the
 legacy interrupt Message(s) the Function uses. Valid values are 01h, 02h,
 03h, and 04h that map to legacy interrupt Messages for INTA,
 INTB, INTC, and INTD respectively. A value of 00h indicates that the
 Function uses no legacy interrupt Message(s)."

So if vp_dev->pci_dev->pin is zero, we should not request legacy
interrupt.

Signed-off-by: Angus Chen <angus.chen@jaguarmicro.com>
Suggested-by: Michael S. Tsirkin <mst@redhat.com>
Message-Id: <20220930000915.548-1-angus.chen@jaguarmicro.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2022-10-07 20:00:44 -04:00
..
Kconfig virtio: fatures, fixes 2022-08-12 09:50:34 -07:00
Makefile virtio: replace restricted mem access flag with callback 2022-08-01 07:42:49 +02:00
virtio_anchor.c virtio: replace restricted mem access flag with callback 2022-08-01 07:42:49 +02:00
virtio_balloon.c - The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe 2022-08-05 16:32:45 -07:00
virtio_dma_buf.c dma-buf: move dma-buf symbols into the DMA_BUF module namespace 2021-10-25 14:53:08 +02:00
virtio_input.c virtio: wrap config->reset calls 2022-01-14 18:50:52 -05:00
virtio_mem.c mm: use is_zone_movable_page() helper 2022-07-29 18:07:20 -07:00
virtio_mmio.c virtio: Revert "virtio: find_vqs() add arg sizes" 2022-08-16 01:40:24 -04:00
virtio_pci_common.c virtio_pci: don't try to use intxif pin is zero 2022-10-07 20:00:44 -04:00
virtio_pci_common.h virtio: Revert "virtio: find_vqs() add arg sizes" 2022-08-16 01:40:24 -04:00
virtio_pci_legacy_dev.c virtio/virtio_pci_legacy_dev: ensure the correct return value 2022-01-14 18:50:53 -05:00
virtio_pci_legacy.c virtio_pci: Revert "virtio_pci: support the arg sizes of find_vqs()" 2022-08-16 01:38:29 -04:00
virtio_pci_modern_dev.c virtio_pci: introduce helper to get/set queue reset 2022-08-11 04:06:40 -04:00
virtio_pci_modern.c virtio: Revert "virtio: find_vqs() add arg sizes" 2022-08-16 01:40:24 -04:00
virtio_ring.c virtio_ring: make vring_alloc_queue_packed prettier 2022-10-07 09:32:40 -04:00
virtio_vdpa.c virtio: Revert "virtio: find_vqs() add arg sizes" 2022-08-16 01:40:24 -04:00
virtio.c virtio: fatures, fixes 2022-08-12 09:50:34 -07:00