On Wed, Jul 19, 2017 at 08:02:04PM +1000, Alexey Kardashevskiy wrote: > On 11/07/17 05:23, Bjorn Helgaas wrote: > >> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c > >> index cf7ca7e70777..0b5881ddca09 100644 > >> --- a/drivers/iommu/iommu.c > >> +++ b/drivers/iommu/iommu.c > >> @@ -1063,6 +1063,14 @@ static int add_iommu_group(struct device *dev, void *data) > >> const struct iommu_ops *ops = cb->ops; > >> int ret; > >> > >> + /* > >> + * Set PCI_BUS_FLAGS_MSI_REMAP for all PCI buses when IOMMU > >> + * have capability of IRQ remapping. > >> + */ > >> + if (dev_is_pci(dev) && ops->capable && > >> + ops->capable(IOMMU_CAP_INTR_REMAP)) > >> + to_pci_dev(dev)->bus->bus_flags |= PCI_BUS_FLAGS_MSI_REMAP; We avoid bus-specific hacks in generic iommu code. This has to be done in bus-specific iommu-group setup code. > 1. PCI_BUS_FLAGS_MSI_REMAP on a PCI bus - MSIX isolation is not really a > PCI bus property and it is "like a wart". This one is at least debatable. It could be a property of the bus. > 2. Introduce "flags" in iommu_group and define IOMMU_GROUP_MSIX_ISOLATED > and set it when an IOMMU group is created; VFIO-PCI has ways to get to the > group and read the flag. That's the best option I see here. > 3. Create IOMMU_DOMAIN_UNMANAGED IOMMU domains for PPC64/powernv IOMMU > groups and only define capable() hook to report IOMMU_CAP_INTR_REMAP; > others already use these IOMMU domains. VFIO-PCI's mmap() hook could then > check the capability via iommu_capable(bus). The problems is as Robin said: > "iommu_capable() is a fundamentally broken and unworkable interface > anyway"; however it is still not clear to me why it is unworkable in this > particular case of isolation checking. That one is wrong, IRQ remapping is not a property of a domain. A domain is an abstraction for a device address space. Attaching IRQ information there is just wrong. Joerg
