Commit 1af7c26c authored by Shlomo Pongratz's avatar Shlomo Pongratz Committed by Bjorn Helgaas
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PCI/P2PDMA: Whitelist Intel Skylake-E Root Ports at any devfn 

In 7b94b53d ("PCI/P2PDMA: Add Intel Sky Lake-E Root Ports B, C, D to
the whitelist"), Andrew Maier added Skylake-E 2031, 2032, and 2033 Root
Ports to the pci_p2pdma_whitelist[], so we assume P2PDMA between devices
below these ports works.

Previously we only checked the whitelist for a device at devfn 00.0 on the
root bus, which is often a "host bridge".  But these Skylake Root Ports may
be at any devfn and there may be no "host bridge" device.

Generalize pci_host_bridge_dev() so we check the first device on the root
bus, whether it is devfn 00.0 or a PCIe Root Port, against the whitelist.

[bhelgaas: commit log, comment]
Link: https://lore.kernel.org/r/20220410105213.690-2-shlomop@pliops.com


Tested-by: default avatarMaor Gottlieb <maorg@nvidia.com>
Signed-off-by: default avatarShlomo Pongratz <shlomop@pliops.com>
Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
Cc: Andrew Maier <andrew.maier@eideticom.com>
parent 31231092

drivers/pci/p2pdma.c

+15 −10
Original line number Diff line number Diff line
@@ -326,15 +326,16 @@ static const struct pci_p2pdma_whitelist_entry { 
};



/*

 * This lookup function tries to find the PCI device corresponding to a given

 * host bridge.

 * If the first device on host's root bus is either devfn 00.0 or a PCIe

 * Root Port, return it.  Otherwise return NULL.

 *

 * It assumes the host bridge device is the first PCI device in the

 * bus->devices list and that the devfn is 00.0. These assumptions should hold

 * for all the devices in the whitelist above.

 * We often use a devfn 00.0 "host bridge" in the pci_p2pdma_whitelist[]

 * (though there is no PCI/PCIe requirement for such a device).  On some

 * platforms, e.g., Intel Skylake, there is no such host bridge device, and

 * pci_p2pdma_whitelist[] may contain a Root Port at any devfn.

 *

 * This function is equivalent to pci_get_slot(host->bus, 0), however it does

 * not take the pci_bus_sem lock seeing __host_bridge_whitelist() must not

 * This function is similar to pci_get_slot(host->bus, 0), but it does

 * not take the pci_bus_sem lock since __host_bridge_whitelist() must not

 * sleep.

 *

 * For this to be safe, the caller should hold a reference to a device on the
@@ -350,10 +351,14 @@ static struct pci_dev *pci_host_bridge_dev(struct pci_host_bridge *host) 


	if (!root)

		return NULL;

	if (root->devfn != PCI_DEVFN(0, 0))

		return NULL;



	if (root->devfn == PCI_DEVFN(0, 0))

		return root;



	if (pci_pcie_type(root) == PCI_EXP_TYPE_ROOT_PORT)

		return root;



	return NULL;

}



static bool __host_bridge_whitelist(struct pci_host_bridge *host,