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

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Date:   Wed, 23 Mar 2022 09:04:08 +0100
From:   Stefano Garzarella <sgarzare@...hat.com>
To:     Jason Wang <jasowang@...hat.com>
Cc:     "Michael S. Tsirkin" <mst@...hat.com>,
        Parav Pandit <parav@...dia.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 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@...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 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