Re: [PATCH] virtio: use virtio_device_ready() in virtio_device_restore()

[Stefano Garzarella]

On Wed, Mar 23, 2022 at 11:10:27AM +0800, Jason Wang wrote:
> On Tue, Mar 22, 2022 at 10:07 PM Michael S. Tsirkin <mst@xxxxxxxxxx> wrote:
> > On Tue, Mar 22, 2022 at 12:43:13PM +0100, Stefano Garzarella wrote:
> > > After waking up a suspended VM, the kernel prints the following trace
> > > for virtio drivers which do not directly call virtio_device_ready() in
> > > the .restore:
> > >
> > >     PM: suspend exit
> > >     irq 22: nobody cared (try booting with the "irqpoll" option)
> > >     Call Trace:
> > >      <IRQ>
> > >      dump_stack_lvl+0x38/0x49
> > >      dump_stack+0x10/0x12
> > >      __report_bad_irq+0x3a/0xaf
> > >      note_interrupt.cold+0xb/0x60
> > >      handle_irq_event+0x71/0x80
> > >      handle_fasteoi_irq+0x95/0x1e0
> > >      __common_interrupt+0x6b/0x110
> > >      common_interrupt+0x63/0xe0
> > >      asm_common_interrupt+0x1e/0x40
> > >      ? __do_softirq+0x75/0x2f3
> > >      irq_exit_rcu+0x93/0xe0
> > >      sysvec_apic_timer_interrupt+0xac/0xd0
> > >      </IRQ>
> > >      <TASK>
> > >      asm_sysvec_apic_timer_interrupt+0x12/0x20
> > >      arch_cpu_idle+0x12/0x20
> > >      default_idle_call+0x39/0xf0
> > >      do_idle+0x1b5/0x210
> > >      cpu_startup_entry+0x20/0x30
> > >      start_secondary+0xf3/0x100
> > >      secondary_startup_64_no_verify+0xc3/0xcb
> > >      </TASK>
> > >     handlers:
> > >     [<000000008f9bac49>] vp_interrupt
> > >     [<000000008f9bac49>] vp_interrupt
> > >     Disabling IRQ #22
> > >
> > > This happens because we don't invoke .enable_cbs callback in
> > > virtio_device_restore(). That callback is used by some transports
> > > (e.g. virtio-pci) to enable interrupts.
> > >
> > > Let's fix it, by calling virtio_device_ready() as we do in
> > > virtio_dev_probe(). This function calls .enable_cts callback and sets
> > > DRIVER_OK status bit.
> > >
> > > This fix also avoids setting DRIVER_OK twice for those drivers that
> > > call virtio_device_ready() in the .restore.
> > >
> > > Fixes: d50497eb4e55 ("virtio_config: introduce a new .enable_cbs method")
> > > Signed-off-by: Stefano Garzarella <sgarzare@xxxxxxxxxx>
> > > ---
> > >
> > > I'm not sure about the fixes tag. That one is more generic, but the
> > > following one I think introduced the issue.
> > >
> > > Fixes: 9e35276a5344 ("virtio_pci: harden MSI-X interrupts")
> >
> > Jason what should we do about this one BTW? Just revert? We have other
> > issues ...
>
> Let me post a patch to revert it and give it a rework.

Thanks for reverting it.

Should we queue this patch anyway to prevent future issues and avoid 
setting DRIVER_OK twice?

Please, let me know if I have to resend it by removing the call trace 
that after the revert should no longer occur.

Thanks,
Stefano