Re: [PATCH v6 05/20] vfio: mdev: common lib code for setting up Interrupt Message Store

[Dave Jiang]

On 5/28/2021 5:21 AM, Jason Gunthorpe wrote:
> On Thu, May 27, 2021 at 06:49:59PM -0700, Dave Jiang wrote:
> > > > +static int mdev_msix_enable(struct mdev_irq *mdev_irq, int nvec)
> > > > +{
> > > > +	struct mdev_device *mdev = irq_to_mdev(mdev_irq);
> > > > +	struct device *dev;
> > > > +	int rc;
> > > > +
> > > > +	if (nvec != mdev_irq->num)
> > > > +		return -EINVAL;
> > > > +
> > > > +	if (mdev_irq->ims_num) {
> > > > +		dev = &mdev->dev;
> > > > +		rc = msi_domain_alloc_irqs(dev_get_msi_domain(dev), dev, mdev_irq->ims_num);
> > > Huh? The PCI device should be the only device touching IRQ stuff. I'm
> > > nervous to see you mix in the mdev struct device into this function.
> > As we talked about in the other thread. We have a single IMS domain per
> > device. The domain is set to the mdev 'struct device' and we allocate the
> > vectors to each mdev 'struct device' so we can manage those IMS vectors
> > specifically for that mdev.
> That is not the point, I'm asking if you should be calling
> dev_set_msi_domain(mdev) at all

I'm not familiar with the standard way of doing this. Should I not set 
the domain to the mdev 'struct device' because I can have multiple mdev 
using the same domain? With the domain set, I am able to retrieve it and 
call the msi_domain_alloc_irqs() in common code. Alternatively we can 
pass in the domain during init and not rely on dev->msi_domain.


> Jason