linux-kernel - Re: Re: [PATCH V1] vdpa

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Date: Mon, 22 Jan 2024 11:59:29 +0100
From: Stefano Garzarella <sgarzare@...hat.com>
To: Eugenio Perez Martin <eperezma@...hat.com>
Cc: Steve Sistare <steven.sistare@...cle.com>, 
	virtualization@...ts.linux-foundation.org, linux-kernel@...r.kernel.org, 
	"Michael S. Tsirkin" <mst@...hat.com>, Jason Wang <jasowang@...hat.com>, 
	Si-Wei Liu <si-wei.liu@...cle.com>
Subject: Re: Re: [PATCH V1] vdpa_sim: reset must not run

On Mon, Jan 22, 2024 at 11:47:22AM +0100, Eugenio Perez Martin wrote:
>On Mon, Jan 22, 2024 at 11:22 AM Stefano Garzarella <sgarzare@...hat.com> wrote:
>>
>> On Wed, Jan 17, 2024 at 11:23:23AM -0800, Steve Sistare wrote:
>> >vdpasim_do_reset sets running to true, which is wrong, as it allows
>> >vdpasim_kick_vq to post work requests before the device has been
>> >configured.  To fix, do not set running until VIRTIO_CONFIG_S_FEATURES_OK
>> >is set.
>> >
>> >Fixes: 0c89e2a3a9d0 ("vdpa_sim: Implement suspend vdpa op")
>> >Signed-off-by: Steve Sistare <steven.sistare@...cle.com>
>> >Reviewed-by: Eugenio Pérez <eperezma@...hat.com>
>> >---
>> > drivers/vdpa/vdpa_sim/vdpa_sim.c | 3 ++-
>> > 1 file changed, 2 insertions(+), 1 deletion(-)
>> >
>> >diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.c b/drivers/vdpa/vdpa_sim/vdpa_sim.c
>> >index be2925d0d283..6304cb0b4770 100644
>> >--- a/drivers/vdpa/vdpa_sim/vdpa_sim.c
>> >+++ b/drivers/vdpa/vdpa_sim/vdpa_sim.c
>> >@@ -160,7 +160,7 @@ static void vdpasim_do_reset(struct vdpasim *vdpasim, u32 flags)
>> >               }
>> >       }
>> >
>> >-      vdpasim->running = true;
>> >+      vdpasim->running = false;
>> >       spin_unlock(&vdpasim->iommu_lock);
>> >
>> >       vdpasim->features = 0;
>> >@@ -483,6 +483,7 @@ static void vdpasim_set_status(struct vdpa_device *vdpa, u8 status)
>> >
>> >       mutex_lock(&vdpasim->mutex);
>> >       vdpasim->status = status;
>> >+      vdpasim->running = (status & VIRTIO_CONFIG_S_FEATURES_OK) != 0;
>> >       mutex_unlock(&vdpasim->mutex);
>>
>> Should we do something similar also in vdpasim_resume() ?
>>
>> I mean something like this:
>>
>> diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.c b/drivers/vdpa/vdpa_sim/vdpa_sim.c
>> index be2925d0d283..55e4633d5442 100644
>> --- a/drivers/vdpa/vdpa_sim/vdpa_sim.c
>> +++ b/drivers/vdpa/vdpa_sim/vdpa_sim.c
>> @@ -520,7 +520,7 @@ static int vdpasim_resume(struct vdpa_device *vdpa)
>>          int i;
>>
>>          mutex_lock(&vdpasim->mutex);
>> -       vdpasim->running = true;
>> +       vdpasim->running = (vdpasim->status & VIRTIO_CONFIG_S_FEATURES_OK) != 0;
>>
>>          if (vdpasim->pending_kick) {
>>                  /* Process pending descriptors */
>>
>> Thanks,
>> Stefano
>>
>
>The suspend and resume operation should not be called before
>DRIVER_OK, so maybe we should add that protection at
>drivers/vhost/vdpa.c actually?

Yeah, I think so!

Anyway, IMHO we should at least return an error in vdpa_sim if 
vdpasim_suspend/resume are called before DRIVER_OK (in another patch of 
course).

Stefano