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? 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
>
