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Re: [Xen-devel] [RFC 6/6] acpi:arm64: Add support for parsing IORT table



(CC x86 folks)

Hi,

On 09/06/17 12:15, Robin Murphy wrote:
On 08/06/17 20:30, Sameer Goel wrote:
[...]
 /**
- * iort_iommu_configure - Set-up IOMMU configuration for a device.
+ * iort_iommu_configure - Set-up IOMMU configuration for a device. This
+ * function sets up the fwspec as needed for a given device. Only PCI
+ * devices are supported for now.
  *
  * @dev: device to configure
  *
- * Returns: iommu_ops pointer on configuration success
- *          NULL on configuration failure
+ * Returns: Appropriate acpi_status
  */
-const struct iommu_ops *iort_iommu_configure(struct device *dev)
+acpi_status iort_iommu_configure(struct device *dev)
 {
        struct acpi_iort_node *node, *parent;
-       const struct iommu_ops *ops = NULL;
        u32 streamid = 0;
+       acpi_status status = AE_OK;

        if (dev_is_pci(dev)) {
-               struct pci_bus *bus = to_pci_dev(dev)->bus;
+               struct pci_dev *pci_device = to_pci_dev(dev);
                u32 rid;

-               pci_for_each_dma_alias(to_pci_dev(dev), __get_pci_rid,
-                                      &rid);
+               rid = PCI_BDF2(pci_device->bus,pci_device->devfn);

Beware that the Linux code isn't actually correct to begin with[1]. I
don't know how much Xen deals with PCI bridges and quirks, but as it
stands you should be able to trivially expose the flaw here by plugging
in a Marvell 88SE912x-based SATA card and watching either DMA or MSIs
(or even both) kick up stream table faults.

Robin.

[1]:http://www.spinics.net/lists/linux-acpi/msg74844.html

I am not sure how x86 is handling that. The closest I can find would be domain_context_mapping. I have CCed x86 folks to get more feedback here.

Cheers,

--
Julien Grall

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