On 31/05/17 18:52, Robin Murphy wrote:
> When a PCI device has DMA quirks, we need to ensure that an upstream
> IOMMU knows about all possible aliases, since the presence of a DMA
> quirk does not preclude the device still also emitting transactions
> (e.g. MSIs) on its 'real' RID. Similarly, the rules for bridge aliasing
> are relatively complex, and some bridges may only take ownership of
> transactions under particular transient circumstances, leading again to
> multiple RIDs potentially being seen at the IOMMU for the given device.
>
> Take all this into account in the OF code by translating every RID
> produced by the alias walk, not just whichever one comes out last.
> Happily, this also makes things tidy enough that we can reduce the
> number of both total lines of code, and confusing levels of indirection,
> by pulling the "iommus"/"iommu-map" parsing helpers back in-line again.
Any comments on this? It should still apply as-is; I don't recall any
conflicts when I rebased a local branch onto 4.13-rc1.
Robin.
> Signed-off-by: Robin Murphy <robin.mur...@arm.com>
> ---
>
> This applies on top of the fix currently queued in the IOMMU tree:
> "iommu/of: Ignore all errors except EPROBE_DEFER"
>
> drivers/iommu/of_iommu.c | 104
> +++++++++++++++++++++--------------------------
> 1 file changed, 47 insertions(+), 57 deletions(-)
>
> diff --git a/drivers/iommu/of_iommu.c b/drivers/iommu/of_iommu.c
> index 19779b88a479..1fbd7a142b30 100644
> --- a/drivers/iommu/of_iommu.c
> +++ b/drivers/iommu/of_iommu.c
> @@ -140,75 +140,39 @@ static const struct iommu_ops
> return ops;
> }
>
> -static int __get_pci_rid(struct pci_dev *pdev, u16 alias, void *data)
> -{
> - struct of_phandle_args *iommu_spec = data;
> +struct of_pci_iommu_alias_info {
> + struct device *dev;
> + struct device_node *np;
> +};
>
> - iommu_spec->args[0] = alias;
> - return iommu_spec->np == pdev->bus->dev.of_node;
> -}
> -
> -static const struct iommu_ops
> -*of_pci_iommu_init(struct pci_dev *pdev, struct device_node *bridge_np)
> +static int of_pci_iommu_init(struct pci_dev *pdev, u16 alias, void *data)
> {
> + struct of_pci_iommu_alias_info *info = data;
> const struct iommu_ops *ops;
> - struct of_phandle_args iommu_spec;
> + struct of_phandle_args iommu_spec = { .args_count = 1 };
> int err;
>
> - /*
> - * Start by tracing the RID alias down the PCI topology as
> - * far as the host bridge whose OF node we have...
> - * (we're not even attempting to handle multi-alias devices yet)
> - */
> - iommu_spec.args_count = 1;
> - iommu_spec.np = bridge_np;
> - pci_for_each_dma_alias(pdev, __get_pci_rid, &iommu_spec);
> - /*
> - * ...then find out what that becomes once it escapes the PCI
> - * bus into the system beyond, and which IOMMU it ends up at.
> - */
> - iommu_spec.np = NULL;
> - err = of_pci_map_rid(bridge_np, iommu_spec.args[0], "iommu-map",
> + err = of_pci_map_rid(info->np, alias, "iommu-map",
> "iommu-map-mask", &iommu_spec.np,
> iommu_spec.args);
> if (err)
> - return err == -ENODEV ? NULL : ERR_PTR(err);
> -
> - ops = of_iommu_xlate(&pdev->dev, &iommu_spec);
> + return err == -ENODEV ? 1 : err;
>
> + ops = of_iommu_xlate(info->dev, &iommu_spec);
> of_node_put(iommu_spec.np);
> - return ops;
> -}
>
> -static const struct iommu_ops
> -*of_platform_iommu_init(struct device *dev, struct device_node *np)
> -{
> - struct of_phandle_args iommu_spec;
> - const struct iommu_ops *ops = NULL;
> - int idx = 0;
> + if (IS_ERR(ops))
> + return PTR_ERR(ops);
>
> - /*
> - * We don't currently walk up the tree looking for a parent IOMMU.
> - * See the `Notes:' section of
> - * Documentation/devicetree/bindings/iommu/iommu.txt
> - */
> - while (!of_parse_phandle_with_args(np, "iommus", "#iommu-cells",
> - idx, &iommu_spec)) {
> - ops = of_iommu_xlate(dev, &iommu_spec);
> - of_node_put(iommu_spec.np);
> - idx++;
> - if (IS_ERR_OR_NULL(ops))
> - break;
> - }
> -
> - return ops;
> + return info->np == pdev->bus->dev.of_node;
> }
>
> const struct iommu_ops *of_iommu_configure(struct device *dev,
> struct device_node *master_np)
> {
> - const struct iommu_ops *ops;
> + const struct iommu_ops *ops = NULL;
> struct iommu_fwspec *fwspec = dev->iommu_fwspec;
> + int err;
>
> if (!master_np)
> return NULL;
> @@ -221,18 +185,44 @@ const struct iommu_ops *of_iommu_configure(struct
> device *dev,
> iommu_fwspec_free(dev);
> }
>
> - if (dev_is_pci(dev))
> - ops = of_pci_iommu_init(to_pci_dev(dev), master_np);
> - else
> - ops = of_platform_iommu_init(dev, master_np);
> + /*
> + * We don't currently walk up the tree looking for a parent IOMMU.
> + * See the `Notes:' section of
> + * Documentation/devicetree/bindings/iommu/iommu.txt
> + */
> + if (dev_is_pci(dev)) {
> + struct of_pci_iommu_alias_info info = {
> + .dev = dev,
> + .np = master_np,
> + };
> +
> + err = pci_for_each_dma_alias(to_pci_dev(dev),
> + of_pci_iommu_init, &info);
> + if (err) /* err > 0 means the walk stopped, but non-fatally */
> + ops = ERR_PTR(min(err, 0));
> + else /* success implies both fwspec and ops are now valid */
> + ops = dev->iommu_fwspec->ops;
> + } else {
> + struct of_phandle_args iommu_spec;
> + int idx = 0;
> +
> + while (!of_parse_phandle_with_args(master_np, "iommus",
> + "#iommu-cells",
> + idx, &iommu_spec)) {
> + ops = of_iommu_xlate(dev, &iommu_spec);
> + of_node_put(iommu_spec.np);
> + idx++;
> + if (IS_ERR_OR_NULL(ops))
> + break;
> + }
> + }
> /*
> * If we have reason to believe the IOMMU driver missed the initial
> * add_device callback for dev, replay it to get things in order.
> */
> if (!IS_ERR_OR_NULL(ops) && ops->add_device &&
> dev->bus && !dev->iommu_group) {
> - int err = ops->add_device(dev);
> -
> + err = ops->add_device(dev);
> if (err)
> ops = ERR_PTR(err);
> }
>
