Alex, is any trick behind checking -ENODEV overlooked here? > From: Jason Gunthorpe <jgg@xxxxxxxxxx> > Sent: Tuesday, November 8, 2022 1:55 AM > > > > > + rc = iommu_get_msi_cookie(hwpt->domain, sw_msi_start); > > > + if (rc && rc != -ENODEV) > > > + return rc; > > > > I know this is copied from VFIO but a comment is appreciated why > > -ENODEV is considered sane to move forward. > > Huh. I actually don't know. It looks like it is here to detect that > the static inline for !CONFIG_IOMMU_DMA returns it. > > However, if we have !CONFIG_IOMMU_DMA then I think we also don't get > interrupts at all. Ie iommu_dma_prepare_msi() becomes a NOP and > nothing will map the ITS page into the iomm_domain. > > So let's drop the ENODEV check, it looks wrong. >
