On Mon, 2021-10-25 at 21:21 +0200, Josef Johansson wrote: > + if (!(pci_msi_ignore_mask || entry->msi_attrib.is_virtual)) Is it just me, or is that a lot easier to read if you write it as the tautologically-identical (!pci_msi_ignore_mask && !entry->…is_virtual)? > @@ -546,7 +548,8 @@ static int msi_capability_init(struct pci_dev *dev, int nvec, > return -ENOMEM; > /* All MSIs are unmasked by default; mask them all * > - pci_msi_mask(entry, msi_multi_mask(entry)) > + if (!pci_msi_ignore_mask) > + pci_msi_mask(entry, msi_multi_mask(entry)); > > list_add_tail(&entry->list, dev_to_msi_list(&dev->dev)); Hm, I thought that older kernels *did* do this part (or at least the later ones in pci_msi*_hutdown). I was watching it when I did the Xen hosting implementation I mentioned before; even a hack to unmask them all when the VM was started, wasn't working because the guest would *mask* all MSI-X, just never unmask them again. I wonder if we should rename 'pci_msi_ignore_mask' to something with Xen in its name because Xen is the only user of this abomination (which fundamentally seems to require that the virtual hardware use MSI entries even while they're masked, so hopefully nobody else would *ever* do such a thing), and the required behaviour is very Xen- specific.
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