On Fri, Aug 21, 2020 at 02:25:02AM +0200, Thomas Gleixner wrote: > +static void ims_mask_irq(struct irq_data *data) > +{ > + struct msi_desc *desc = irq_data_get_msi_desc(data); > + struct ims_array_slot __iomem *slot = desc->device_msi.priv_iomem; > + u32 __iomem *ctrl = &slot->ctrl; > + > + iowrite32(ioread32(ctrl) & ~IMS_VECTOR_CTRL_UNMASK, ctrl); Just to be clear, this is exactly the sort of operation we can't do with non-MSI interrupts. For a real PCI device to execute this it would have to keep the data on die. I saw the idxd driver was doing something like this, I assume it avoids trouble because it is a fake PCI device integrated with the CPU, not on a real PCI bus? It is really nice to see irq_domain used properly in x86! Thanks, Jason