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PCI: Introduce pci_real_dma_dev()

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The current DMA alias implementation requires the aliased device be on the
same PCI bus as the requester ID.  Add an arch-specific mechanism to point
to another PCI device when doing mapping and PCI DMA alias search.  The
default case returns the actual device.

Link: https://lore.kernel.org/r/1579613871-301529-4-git-send-email-jonathan.derrick@intel.com
Signed-off-by: Jon Derrick <jonathan.derrick@intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Jon Derrick 2020-01-21 06:37:47 -07:00 committed by Bjorn Helgaas
parent 34067c56fa
commit 2856ba6020
4 changed files with 35 additions and 1 deletions
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10
arch/x86/pci/common.c
View file

@ -736,3 +736,13 @@ int pci_ext_cfg_avail(void)
else
return 0;
}
#if IS_ENABLED(CONFIG_VMD)
struct pci_dev *pci_real_dma_dev(struct pci_dev *dev)
{
if (is_vmd(dev->bus))
return to_pci_sysdata(dev->bus)->vmd_dev;
return dev;
}
#endif

19
drivers/pci/pci.c
View file

@ -6033,7 +6033,9 @@ 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_real_dma_dev(dev1) == dev2 ||
pci_real_dma_dev(dev2) == dev1;
}
bool pci_device_is_present(struct pci_dev *pdev)
@ -6057,6 +6059,21 @@ void pci_ignore_hotplug(struct pci_dev *dev)
}
EXPORT_SYMBOL_GPL(pci_ignore_hotplug);
/**
* pci_real_dma_dev - Get PCI DMA device 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_real_dma_dev(struct pci_dev *dev)
{
return dev;
}
resource_size_t __weak pcibios_default_alignment(void)
{
return 0;

6
drivers/pci/search.c
View file

@ -32,6 +32,12 @@ 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.
*/
pdev = pci_real_dma_dev(pdev);
ret = fn(pdev, pci_dev_id(pdev), data);
if (ret)
return ret;

1
include/linux/pci.h
View file

@ -1202,6 +1202,7 @@ int __must_check pci_resize_resource(struct pci_dev *dev, int i, int size);
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_real_dma_dev(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,