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PCI/P2PDMA: Factor out __upstream_bridge_distance() 

This is a prep patch to create a second level helper. There are no
functional changes.

The root complex whitelist code will be moved into this function in a
subsequent patch.

Link: https://lore.kernel.org/r/20190730163545.4915-5-logang@deltatee.com
Link: https://lore.kernel.org/r/20190812173048.9186-5-logang@deltatee.com
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Logan Gunthorpe 2019-08-12 11:30:38 -06:00 committed by Bjorn Helgaas
parent 72583084e3
commit c6bfaeb573
1 changed files with 48 additions and 40 deletions
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88
drivers/pci/p2pdma.c
View File

@ -296,47 +296,8 @@ static bool root_complex_whitelist(struct pci_dev *dev)
return false;
}
/*
* Find the distance through the nearest common upstream bridge between
* two PCI devices.
*
* If the two devices are the same device then 0 will be returned.
*
* If there are two virtual functions of the same device behind the same
* bridge port then 2 will be returned (one step down to the PCIe switch,
* then one step back to the same device).
*
* In the case where two devices are connected to the same PCIe switch, the
* value 4 will be returned. This corresponds to the following PCI tree:
*
* -+ Root Port
* \+ Switch Upstream Port
* +-+ Switch Downstream Port
* + \- Device A
* \-+ Switch Downstream Port
* \- Device B
*
* The distance is 4 because we traverse from Device A through the downstream
* port of the switch, to the common upstream port, back up to the second
* downstream port and then to Device B.
*
* Any two devices that cannot communicate using p2pdma will return
* PCI_P2PDMA_MAP_NOT_SUPPORTED.
*
* Any two devices that have a data path that goes through the host bridge
* will consult a whitelist. If the host bridges are on the whitelist,
* this function will return PCI_P2PDMA_MAP_THRU_HOST_BRIDGE.
*
* If either bridge is not on the whitelist this function returns
* PCI_P2PDMA_MAP_NOT_SUPPORTED.
*
* If a bridge which has any ACS redirection bits set is in the path,
* acs_redirects will be set to true. In this case, a list of all infringing
* bridge addresses will be populated in acs_list (assuming it's non-null)
* for printk purposes.
*/
static enum pci_p2pdma_map_type
upstream_bridge_distance(struct pci_dev *provider, struct pci_dev *client,
__upstream_bridge_distance(struct pci_dev *provider, struct pci_dev *client,
int *dist, bool *acs_redirects, struct seq_buf *acs_list)
{
struct pci_dev *a = provider, *b = client, *bb;
@ -416,6 +377,53 @@ check_b_path_acs:
return PCI_P2PDMA_MAP_BUS_ADDR;
}
/*
* Find the distance through the nearest common upstream bridge between
* two PCI devices.
*
* If the two devices are the same device then 0 will be returned.
*
* If there are two virtual functions of the same device behind the same
* bridge port then 2 will be returned (one step down to the PCIe switch,
* then one step back to the same device).
*
* In the case where two devices are connected to the same PCIe switch, the
* value 4 will be returned. This corresponds to the following PCI tree:
*
* -+ Root Port
* \+ Switch Upstream Port
* +-+ Switch Downstream Port
* + \- Device A
* \-+ Switch Downstream Port
* \- Device B
*
* The distance is 4 because we traverse from Device A through the downstream
* port of the switch, to the common upstream port, back up to the second
* downstream port and then to Device B.
*
* Any two devices that cannot communicate using p2pdma will return
* PCI_P2PDMA_MAP_NOT_SUPPORTED.
*
* Any two devices that have a data path that goes through the host bridge
* will consult a whitelist. If the host bridges are on the whitelist,
* this function will return PCI_P2PDMA_MAP_THRU_HOST_BRIDGE.
*
* If either bridge is not on the whitelist this function returns
* PCI_P2PDMA_MAP_NOT_SUPPORTED.
*
* If a bridge which has any ACS redirection bits set is in the path,
* acs_redirects will be set to true. In this case, a list of all infringing
* bridge addresses will be populated in acs_list (assuming it's non-null)
* for printk purposes.
*/
static enum pci_p2pdma_map_type
upstream_bridge_distance(struct pci_dev *provider, struct pci_dev *client,
int *dist, bool *acs_redirects, struct seq_buf *acs_list)
{
return __upstream_bridge_distance(provider, client, dist,
acs_redirects, acs_list);
}
static enum pci_p2pdma_map_type
upstream_bridge_distance_warn(struct pci_dev *provider, struct pci_dev *client,
int *dist)