On Fri, Oct 12, 2018 at 02:41:59PM -0500, Bjorn Helgaas wrote: > s/iommu/IOMMU/ in subject > > On Fri, Oct 12, 2018 at 03:59:13PM +0100, Jean-Philippe Brucker wrote: > > Using the iommu-map binding, endpoints in a given PCI domain can be > > managed by different IOMMUs. Some virtual machines may allow a subset of > > endpoints to bypass the IOMMU. In some case the IOMMU itself is presented > > s/case/cases/ > > > as a PCI endpoint (e.g. AMD IOMMU and virtio-iommu). Currently, when a > > PCI root complex has an iommu-map property, the driver requires all > > endpoints to be described by the property. Allow the iommu-map property to > > have gaps. > > I'm not an IOMMU or virtio expert, so it's not obvious to me why it is > safe to allow devices to bypass the IOMMU. Does this mean a typo in > iommu-map could inadvertently allow devices to bypass it? Thinking about this comment, I would like to ask: can't the virtio device indicate the ranges in a portable way? This would minimize the dependency on dt bindings and ACPI, enabling support for systems that have neither but do have virtio e.g. through pci. > Should we > indicate something in dmesg (and/or sysfs) about devices that bypass > it? > > > Relaxing of_pci_map_rid also allows the msi-map property to have gaps, > > s/of_pci_map_rid/of_pci_map_rid()/ > > > which is invalid since MSIs always reach an MSI controller. Thankfully > > Linux will error out later, when attempting to find an MSI domain for the > > device. > > Not clear to me what "error out" means here. In a userspace program, > I would infer that the program exits with an error message, but I > doubt you mean that Linux exits. > > > Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@xxxxxxx> > > --- > > drivers/pci/of.c | 7 ++++--- > > 1 file changed, 4 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/pci/of.c b/drivers/pci/of.c > > index 1836b8ddf292..2f5015bdb256 100644 > > --- a/drivers/pci/of.c > > +++ b/drivers/pci/of.c > > @@ -451,9 +451,10 @@ int of_pci_map_rid(struct device_node *np, u32 rid, > > return 0; > > } > > > > - pr_err("%pOF: Invalid %s translation - no match for rid 0x%x on %pOF\n", > > - np, map_name, rid, target && *target ? *target : NULL); > > - return -EFAULT; > > + /* Bypasses translation */ > > + if (id_out) > > + *id_out = rid; > > + return 0; > > } > > > > #if IS_ENABLED(CONFIG_OF_IRQ) > > -- > > 2.19.1 > > _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization