linux-kernel - Re: [PATCH] virtio: use virtio_device_ready() in virtio_device

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Date:   Wed, 23 Mar 2022 11:10:27 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     "Michael S. Tsirkin" <mst@...hat.com>,
        Parav Pandit <parav@...dia.com>
Cc:     Stefano Garzarella <sgarzare@...hat.com>,
        virtualization <virtualization@...ts.linux-foundation.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] virtio: use virtio_device_ready() in virtio_device_restore()

On Tue, Mar 22, 2022 at 10:07 PM Michael S. Tsirkin <mst@...hat.com> 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@...hat.com>
> > ---
> >
> > 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

>
>
> > Thanks,
> > Stefano
> > ---
> >  drivers/virtio/virtio.c | 5 +++--
> >  1 file changed, 3 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
> > index 22f15f444f75..75c8d560bbd3 100644
> > --- a/drivers/virtio/virtio.c
> > +++ b/drivers/virtio/virtio.c
> > @@ -526,8 +526,9 @@ int virtio_device_restore(struct virtio_device *dev)
> >                       goto err;
> >       }
> >
> > -     /* Finally, tell the device we're all set */
> > -     virtio_add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
> > +     /* If restore didn't do it, mark device DRIVER_OK ourselves. */
> > +     if (!(dev->config->get_status(dev) & VIRTIO_CONFIG_S_DRIVER_OK))
> > +             virtio_device_ready(dev);
> >
> >       virtio_config_enable(dev);
> >
> > --
> > 2.35.1
>