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SubjectRe: [PATCH] ACPI/IORT: Handle PCI aliases properly
On Wed, May 31, 2017 at 06:52:30PM +0100, 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 IORT code by mapping every RID
> produced by the alias walk, not just whichever one comes out last. Since
> adding any more internal PTR_ERR() juggling would have confused me no
> end, a bit of refactoring happens in the process - we know where to find
> the ops if everything succeeded, so we're free to just pass regular error
> codes around up until then.
>
> Signed-off-by: Robin Murphy <robin.murphy@arm.com>
> ---
>
> This applies on top of the fixes currently queued in the IOMMU tree:
> "ACPI/IORT: Move the check to get iommu_ops from translated fwspec"
> "ACPI/IORT: Ignore all errors except EPROBE_DEFER"
>
> drivers/acpi/arm64/iort.c | 113 ++++++++++++++++++++++++----------------------

It is a bit hard to read (and it is certainly not your fault) but the
patch makes sense to me, I wonder whether it is not better to split it
into two patches, one refactoring the return value and second one
managing the aliases, _properly_ :), anyway:

Reviewed-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>

> 1 file changed, 59 insertions(+), 54 deletions(-)
>
> diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
> index 797b28dc7b34..50e2749eafdc 100644
> --- a/drivers/acpi/arm64/iort.c
> +++ b/drivers/acpi/arm64/iort.c
> @@ -598,14 +598,6 @@ void acpi_configure_pmsi_domain(struct device *dev)
> dev_set_msi_domain(dev, msi_domain);
> }
>
> -static int __get_pci_rid(struct pci_dev *pdev, u16 alias, void *data)
> -{
> - u32 *rid = data;
> -
> - *rid = alias;
> - return 0;
> -}
> -
> static int arm_smmu_iort_xlate(struct device *dev, u32 streamid,
> struct fwnode_handle *fwnode,
> const struct iommu_ops *ops)
> @@ -643,8 +635,7 @@ int iort_add_device_replay(const struct iommu_ops *ops, struct device *dev)
> {
> int err = 0;
>
> - if (!IS_ERR_OR_NULL(ops) && ops->add_device && dev->bus &&
> - !dev->iommu_group)
> + if (ops->add_device && dev->bus && !dev->iommu_group)
> err = ops->add_device(dev);
>
> return err;
> @@ -658,36 +649,49 @@ int iort_add_device_replay(const struct iommu_ops *ops, struct device *dev)
> { return 0; }
> #endif
>
> -static const struct iommu_ops *iort_iommu_xlate(struct device *dev,
> - struct acpi_iort_node *node,
> - u32 streamid)
> +static int iort_iommu_xlate(struct device *dev, struct acpi_iort_node *node,
> + u32 streamid)
> {
> - const struct iommu_ops *ops = NULL;
> - int ret = -ENODEV;
> + const struct iommu_ops *ops;
> struct fwnode_handle *iort_fwnode;
>
> - if (node) {
> - iort_fwnode = iort_get_fwnode(node);
> - if (!iort_fwnode)
> - return NULL;
> + if (!node)
> + return -ENODEV;
>
> - ops = iommu_ops_from_fwnode(iort_fwnode);
> - /*
> - * If the ops look-up fails, this means that either
> - * the SMMU drivers have not been probed yet or that
> - * the SMMU drivers are not built in the kernel;
> - * Depending on whether the SMMU drivers are built-in
> - * in the kernel or not, defer the IOMMU configuration
> - * or just abort it.
> - */
> - if (!ops)
> - return iort_iommu_driver_enabled(node->type) ?
> - ERR_PTR(-EPROBE_DEFER) : NULL;
> + iort_fwnode = iort_get_fwnode(node);
> + if (!iort_fwnode)
> + return -ENODEV;
>
> - ret = arm_smmu_iort_xlate(dev, streamid, iort_fwnode, ops);
> - }
> + ops = iommu_ops_from_fwnode(iort_fwnode);
> + /*
> + * If the ops look-up fails, this means that either
> + * the SMMU drivers have not been probed yet or that
> + * the SMMU drivers are not built in the kernel;
> + * Depending on whether the SMMU drivers are built-in
> + * in the kernel or not, defer the IOMMU configuration
> + * or just abort it.
> + */
> + if (!ops)
> + return iort_iommu_driver_enabled(node->type) ?
> + -EPROBE_DEFER : -ENODEV;
>
> - return ret ? NULL : ops;
> + return arm_smmu_iort_xlate(dev, streamid, iort_fwnode, ops);
> +}
> +
> +struct iort_pci_alias_info {
> + struct device *dev;
> + struct acpi_iort_node *node;
> +};
> +
> +static int iort_pci_iommu_init(struct pci_dev *pdev, u16 alias, void *data)
> +{
> + struct iort_pci_alias_info *info = data;
> + struct acpi_iort_node *parent;
> + u32 streamid;
> +
> + parent = iort_node_map_id(info->node, alias, &streamid,
> + IORT_IOMMU_TYPE);
> + return iort_iommu_xlate(info->dev, parent, streamid);
> }
>
> /**
> @@ -723,7 +727,7 @@ void iort_set_dma_mask(struct device *dev)
> const struct iommu_ops *iort_iommu_configure(struct device *dev)
> {
> struct acpi_iort_node *node, *parent;
> - const struct iommu_ops *ops = NULL;
> + const struct iommu_ops *ops;
> u32 streamid = 0;
> int err;
>
> @@ -737,21 +741,18 @@ const struct iommu_ops *iort_iommu_configure(struct device *dev)
>
> if (dev_is_pci(dev)) {
> struct pci_bus *bus = to_pci_dev(dev)->bus;
> - u32 rid;
> -
> - pci_for_each_dma_alias(to_pci_dev(dev), __get_pci_rid,
> - &rid);
> + struct iort_pci_alias_info info = { .dev = dev };
>
> node = iort_scan_node(ACPI_IORT_NODE_PCI_ROOT_COMPLEX,
> iort_match_node_callback, &bus->dev);
> if (!node)
> return NULL;
>
> - parent = iort_node_map_id(node, rid, &streamid,
> - IORT_IOMMU_TYPE);
> -
> - ops = iort_iommu_xlate(dev, parent, streamid);
> -
> + info.node = node;
> + err = pci_for_each_dma_alias(to_pci_dev(dev),
> + iort_pci_iommu_init, &info);
> + if (err)
> + goto out_err;
> } else {
> int i = 0;
>
> @@ -764,9 +765,9 @@ const struct iommu_ops *iort_iommu_configure(struct device *dev)
> IORT_IOMMU_TYPE, i++);
>
> while (parent) {
> - ops = iort_iommu_xlate(dev, parent, streamid);
> - if (IS_ERR_OR_NULL(ops))
> - return ops;
> + err = iort_iommu_xlate(dev, parent, streamid);
> + if (err)
> + goto out_err;
>
> parent = iort_node_map_platform_id(node, &streamid,
> IORT_IOMMU_TYPE,
> @@ -774,21 +775,25 @@ const struct iommu_ops *iort_iommu_configure(struct device *dev)
> }
> }
>
> + ops = dev->iommu_fwspec->ops;
> +
> /*
> * If we have reason to believe the IOMMU driver missed the initial
> * add_device callback for dev, replay it to get things in order.
> */
> err = iort_add_device_replay(ops, dev);
> if (err)
> - ops = ERR_PTR(err);
> -
> - /* Ignore all other errors apart from EPROBE_DEFER */
> - if (IS_ERR(ops) && (PTR_ERR(ops) != -EPROBE_DEFER)) {
> - dev_dbg(dev, "Adding to IOMMU failed: %ld\n", PTR_ERR(ops));
> - ops = NULL;
> - }
> + goto out_err;
>
> return ops;
> +
> + /* Ignore all other errors apart from EPROBE_DEFER */
> +out_err:
> + if (err == -EPROBE_DEFER)
> + return ERR_PTR(err);
> +
> + dev_dbg(dev, "Adding to IOMMU failed: %d\n", err);
> + return NULL;
> }
>
> static void __init acpi_iort_register_irq(int hwirq, const char *name,
> --
> 2.12.2.dirty
>

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