The current DMA alias implementation requires the aliased device be on the same PCI bus as the requester ID. This introduces an arch-specific mechanism to point to another PCI device when doing mapping and PCI DMA alias search.
Signed-off-by: Jon Derrick <[email protected]> --- arch/x86/pci/common.c | 7 +++++++ drivers/pci/pci.c | 19 ++++++++++++++++++- drivers/pci/search.c | 7 +++++++ include/linux/pci.h | 1 + 4 files changed, 33 insertions(+), 1 deletion(-) diff --git a/arch/x86/pci/common.c b/arch/x86/pci/common.c index 1e59df0..83334a5 100644 --- a/arch/x86/pci/common.c +++ b/arch/x86/pci/common.c @@ -736,3 +736,10 @@ int pci_ext_cfg_avail(void) else return 0; } + +#if IS_ENABLED(CONFIG_VMD) +struct pci_dev *pci_direct_dma_alias(struct pci_dev *dev) +{ + return to_pci_sysdata(dev->bus)->vmd_dev; +} +#endif diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index ad746d9..1362694 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -6034,7 +6034,9 @@ bool pci_devs_are_dma_aliases(struct pci_dev *dev1, struct pci_dev *dev2) return (dev1->dma_alias_mask && test_bit(dev2->devfn, dev1->dma_alias_mask)) || (dev2->dma_alias_mask && - test_bit(dev1->devfn, dev2->dma_alias_mask)); + test_bit(dev1->devfn, dev2->dma_alias_mask)) || + (pci_direct_dma_alias(dev1) == dev2) || + (pci_direct_dma_alias(dev2) == dev1); } bool pci_device_is_present(struct pci_dev *pdev) @@ -6058,6 +6060,21 @@ void pci_ignore_hotplug(struct pci_dev *dev) } EXPORT_SYMBOL_GPL(pci_ignore_hotplug); +/** + * pci_direct_dma_alias - Get PCI DMA alias for PCI device + * @dev: the PCI device that may have a PCI DMA alias + * + * Permits the platform to provide architecture-specific functionality to + * devices needing to alias DMA to another PCI device on another PCI bus. If + * the PCI device is on the same bus, it is recommended to use + * pci_add_dma_alias(). This is the default implementation. Architecture + * implementations can override this. + */ +struct pci_dev __weak *pci_direct_dma_alias(struct pci_dev *dev) +{ + return NULL; +} + resource_size_t __weak pcibios_default_alignment(void) { return 0; diff --git a/drivers/pci/search.c b/drivers/pci/search.c index bade140..12811b3 100644 --- a/drivers/pci/search.c +++ b/drivers/pci/search.c @@ -32,6 +32,13 @@ int pci_for_each_dma_alias(struct pci_dev *pdev, struct pci_bus *bus; int ret; + /* + * The device may have an explicit alias requester ID for DMA where the + * requester is on another PCI bus. + */ + if (unlikely(pci_direct_dma_alias(pdev))) + pdev = pci_direct_dma_alias(pdev); + ret = fn(pdev, pci_dev_id(pdev), data); if (ret) return ret; diff --git a/include/linux/pci.h b/include/linux/pci.h index c393dff..cb6677b 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -1202,6 +1202,7 @@ u32 pcie_bandwidth_available(struct pci_dev *dev, struct pci_dev **limiting_dev, int pci_select_bars(struct pci_dev *dev, unsigned long flags); bool pci_device_is_present(struct pci_dev *pdev); void pci_ignore_hotplug(struct pci_dev *dev); +struct pci_dev *pci_direct_dma_alias(struct pci_dev *dev); int __printf(6, 7) pci_request_irq(struct pci_dev *dev, unsigned int nr, irq_handler_t handler, irq_handler_t thread_fn, void *dev_id, -- 1.8.3.1 _______________________________________________ iommu mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/iommu
