Hi -- I hope it's okay me reaching out like this. I've been trying to test out the virtio-vhost-user implementation that's been posted to this list a couple of times, but have been unable to get it to boot a kernel following the steps listed either on <https://wiki.qemu.org/Features/VirtioVhostUser> or <https://ndragazis.github.io/dpdk-vhost-vvu-demo.html>.
Specifically, the kernel appears to be unable to write to the virtio-vhost-user device's PCI registers. I've included the full panic output from the kernel at the end of this message. The panic is reproducible with two different kernels I tried (with different configs and versions). I tried both versions of the virtio-vhost-user I was able to find[1][2], and both exhibited the same behaviour. Is this a known issue? Am I doing something wrong? Thanks in advance -- I'm excitedly following the progress of this feature. Alyssa Ross [1]: https://github.com/ndragazis/qemu/commits/virtio-vhost-user [2]: https://github.com/stefanha/qemu/commits/virtio-vhost-user [ 1.287979] BUG: unable to handle page fault for address: ffffb8ca40025014 [ 1.288311] #PF: supervisor write access in kernel mode [ 1.288311] #PF: error_code(0x000b) - reserved bit violation [ 1.288311] PGD 3b128067 P4D 3b128067 PUD 3b129067 PMD 3b12a067 PTE 8000002000000073 [ 1.288311] Oops: 000b [#1] SMP PTI [ 1.288311] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 5.4.28 #1-NixOS [ 1.288311] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.11.0-0-g63451fca13-prebuilt.qemu-project.org 04/01/2014 [ 1.288311] RIP: 0010:iowrite8+0xe/0x30 [ 1.288311] Code: fe ff ff 48 c7 c0 ff ff ff ff c3 48 8b 3f 48 89 f8 c3 66 2e 0f 1f 84 00 00 00 00 00 89 f8 48 89 f7 48 81 fe ff ff 3 [ 1.288311] RSP: 0000:ffffb8ca40013cd8 EFLAGS: 00010292 [ 1.288311] RAX: 0000000000000000 RBX: ffffb8ca40013d60 RCX: 0000000000000000 [ 1.288311] RDX: 000000000000002f RSI: ffffb8ca40025014 RDI: ffffb8ca40025014 [ 1.288311] RBP: ffff9c742ea20400 R08: ffff9c742f0a60af R09: 0000000000000000 [ 1.288311] R10: 0000000000000018 R11: ffff9c742f0a60af R12: 0000000000000000 [ 1.288311] R13: ffff9c742ea20410 R14: 0000000000000000 R15: 0000000000000000 [ 1.288311] FS: 0000000000000000(0000) GS:ffff9c743b700000(0000) knlGS:0000000000000000 [ 1.288311] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 1.288311] CR2: ffffb8ca40025014 CR3: 0000000037a0a001 CR4: 0000000000060ee0 [ 1.288311] Call Trace: [ 1.288311] vp_reset+0x1b/0x50 [ 1.288311] register_virtio_device+0x74/0xe0 [ 1.288311] virtio_pci_probe+0xaf/0x140 [ 1.288311] local_pci_probe+0x42/0x80 [ 1.288311] pci_device_probe+0x104/0x1b0 [ 1.288311] really_probe+0x147/0x3c0 [ 1.288311] driver_probe_device+0xb6/0x100 [ 1.288311] device_driver_attach+0x53/0x60 [ 1.288311] __driver_attach+0x8a/0x150 [ 1.288311] ? device_driver_attach+0x60/0x60 [ 1.288311] bus_for_each_dev+0x78/0xc0 [ 1.288311] bus_add_driver+0x14d/0x1f0 [ 1.288311] driver_register+0x6c/0xc0 [ 1.288311] ? dma_bus_init+0xbf/0xbf [ 1.288311] do_one_initcall+0x46/0x1f4 [ 1.288311] kernel_init_freeable+0x176/0x200 [ 1.288311] ? rest_init+0xab/0xab [ 1.288311] kernel_init+0xa/0x105 [ 1.288311] ret_from_fork+0x35/0x40 [ 1.288311] Modules linked in: [ 1.288311] CR2: ffffb8ca40025014 [ 1.288311] ---[ end trace 5164b2fa531e028f ]--- [ 1.288311] RIP: 0010:iowrite8+0xe/0x30 [ 1.288311] Code: fe ff ff 48 c7 c0 ff ff ff ff c3 48 8b 3f 48 89 f8 c3 66 2e 0f 1f 84 00 00 00 00 00 89 f8 48 89 f7 48 81 fe ff ff 3 [ 1.288311] RSP: 0000:ffffb8ca40013cd8 EFLAGS: 00010292 [ 1.288311] RAX: 0000000000000000 RBX: ffffb8ca40013d60 RCX: 0000000000000000 [ 1.288311] RDX: 000000000000002f RSI: ffffb8ca40025014 RDI: ffffb8ca40025014 [ 1.288311] RBP: ffff9c742ea20400 R08: ffff9c742f0a60af R09: 0000000000000000 [ 1.288311] R10: 0000000000000018 R11: ffff9c742f0a60af R12: 0000000000000000 [ 1.288311] R13: ffff9c742ea20410 R14: 0000000000000000 R15: 0000000000000000 [ 1.288311] FS: 0000000000000000(0000) GS:ffff9c743b700000(0000) knlGS:0000000000000000 [ 1.288311] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 1.288311] CR2: ffffb8ca40025014 CR3: 0000000037a0a001 CR4: 0000000000060ee0 [ 1.288311] Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000009 [ 1.288311] Kernel Offset: 0x21200000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) [ 1.288311] ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000009 ]---
