RE: [PATCH v6 1/5] iommu: Return -EMEDIUMTYPE for incompatible domain and device/group

From: Nicolin Chen <redacted>
Sent: Sunday, September 11, 2022 7:36 AM

On Thu, Sep 08, 2022 at 09:08:38AM -0300, Jason Gunthorpe wrote:

quoted

On Thu, Sep 08, 2022 at 09:30:57AM +0000, Tian, Kevin wrote:

quoted

quoted

There are also cases where common kAPIs are called in the attach
path which may return -EINVAL and random errno, e.g.:

omap_iommu_attach_dev()
  omap_iommu_attach()
    iommu_enable()
      pm_runtime_get_sync()
        __pm_runtime_resume()
          rpm_resume()
	if (dev->power.runtime_error) {
		retval = -EINVAL;

quoted

Yes, this is was also on my mind with choosing an unpopular return
code, it has a higher chance of not coming out of some other kernel
API

I wonder if it would be safe to just treat a pm_runtime_get_sync()
failure as -ENODEV, since a PM resume() mostly occurs to the IOMMU
that an IOMMU client/master device is behind, while an iommu_domain
rarely intervenes.

Yes, this is a condition preventing the device from being attached by
a domain hence converting -EINVAL to -ENODEV probably makes sense.
But as replied in another we might want to keep other errno's as is.

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