Commit 053497ce authored Apr 19, 2017 by Lorenzo Pieralisi Committed by Bjorn Helgaas Apr 24, 2017

PCI: ECAM: Map config region with pci_remap_cfgspace()

The current ECAM kernel implementation uses ioremap() to map the ECAM
configuration space memory region; this is not safe in that on some
architectures the ioremap interface provides mappings that allow posted
write transactions. This, as highlighted in the PCIe specifications (4.0 -
Rev0.3, "Ordering Considerations for the Enhanced Configuration Address
Mechanism"), can create ordering issues for software because posted writes
transactions on the CPU host bus are non posted in the PCI express fabric.

Update the ioremap() interface to use pci_remap_cfgspace() whose mapping
attributes guarantee that non-posted writes transactions are issued for
memory writes within the ECAM memory mapped address region.

Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: Jayachandran C <jnair@caviumnetworks.com>

parent 490cb6dd

drivers/pci/ecam.c

+4 −2

Original line number	Diff line number	Diff line
		@@ -84,12 +84,14 @@ struct pci_config_window pci_ecam_create(struct device dev,
		if (!cfg->winp)
		goto err_exit_malloc;
		for (i = 0; i < bus_range; i++) {
		cfg->winp[i] = ioremap(cfgres->start + i * bsz, bsz);
		cfg->winp[i] =
		pci_remap_cfgspace(cfgres->start + i * bsz,
		bsz);
		if (!cfg->winp[i])
		goto err_exit_iomap;
		}
		} else {
		cfg->win = ioremap(cfgres->start, bus_range * bsz);
		cfg->win = pci_remap_cfgspace(cfgres->start, bus_range * bsz);
		if (!cfg->win)
		goto err_exit_iomap;
		}

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