| Message ID | 1471279854-11916-6-git-send-email-lorenzo.pieralisi@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Delegated to: | Bjorn Helgaas |
| Headers | show |
On Mon, Aug 15, 2016 at 05:50:45PM +0100, Lorenzo Pieralisi wrote: > On ARM/ARM64 architectures, PCI IO ports are emulated through memory > mapped IO, by reserving a chunk of virtual address space starting at > PCI_IOBASE and by mapping the PCI host bridges memory address space > driving PCI IO cycles to it. > > PCI host bridge drivers that enable downstream PCI IO cycles map the > host bridge memory address responding to PCI IO cycles to the fixed > virtual address space through the pci_remap_iospace() API. > > This means that if the pci_remap_iospace() function fails, the > corresponding host bridge PCI IO resource must be considered invalid, in > that there is no way for the kernel to actually drive PCI IO > transactions if the memory addresses responding to PCI > IO cycles cannot be mapped into the CPU virtual address space. > > The PCI common host bridge driver does not remove the PCI IO > resource from the host bridge resource windows if the > pci_remap_iospace() call fails; this is an actual bug in that the > PCI host bridge would consider the PCI IO resource valid (and possibly > assign it to downstream devices) even if the kernel was not able > to map the PCI host bridge memory address driving IO cycle to the > CPU virtual address space (ie pci_remap_iospace() failures). > > Fix the PCI host bridge driver pci_remap_iospace() failure path, by > destroying the PCI host bridge PCI IO resources retrieved through > firmware when the pci_remap_iospace() function call fails, therefore > preventing the kernel from adding the respective PCI IO resource to the > list of PCI host bridge valid resources, fixing the issue. > > Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> > Fixes: 4e64dbe226e7 ("PCI: generic: Expose pci_host_common_probe() for > use by other drivers") > Cc: Bjorn Helgaas <bhelgaas@google.com> > Cc: Will Deacon <will.deacon@arm.com> > --- > drivers/pci/host/pci-host-common.c | 8 +++++--- > 1 file changed, 5 insertions(+), 3 deletions(-) Looks good to me: Acked-by: Will Deacon <will.deacon@arm.com> Will -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/pci/host/pci-host-common.c b/drivers/pci/host/pci-host-common.c index 9d9d34e..61eb4d4 100644 --- a/drivers/pci/host/pci-host-common.c +++ b/drivers/pci/host/pci-host-common.c @@ -29,7 +29,7 @@ static int gen_pci_parse_request_of_pci_ranges(struct device *dev, int err, res_valid = 0; struct device_node *np = dev->of_node; resource_size_t iobase; - struct resource_entry *win; + struct resource_entry *win, *tmp; err = of_pci_get_host_bridge_resources(np, 0, 0xff, resources, &iobase); if (err) @@ -39,15 +39,17 @@ static int gen_pci_parse_request_of_pci_ranges(struct device *dev, if (err) return err; - resource_list_for_each_entry(win, resources) { + resource_list_for_each_entry_safe(win, tmp, resources) { struct resource *res = win->res; switch (resource_type(res)) { case IORESOURCE_IO: err = pci_remap_iospace(res, iobase); - if (err) + if (err) { dev_warn(dev, "error %d: failed to map resource %pR\n", err, res); + resource_list_destroy_entry(win); + } break; case IORESOURCE_MEM: res_valid |= !(res->flags & IORESOURCE_PREFETCH);
On ARM/ARM64 architectures, PCI IO ports are emulated through memory mapped IO, by reserving a chunk of virtual address space starting at PCI_IOBASE and by mapping the PCI host bridges memory address space driving PCI IO cycles to it. PCI host bridge drivers that enable downstream PCI IO cycles map the host bridge memory address responding to PCI IO cycles to the fixed virtual address space through the pci_remap_iospace() API. This means that if the pci_remap_iospace() function fails, the corresponding host bridge PCI IO resource must be considered invalid, in that there is no way for the kernel to actually drive PCI IO transactions if the memory addresses responding to PCI IO cycles cannot be mapped into the CPU virtual address space. The PCI common host bridge driver does not remove the PCI IO resource from the host bridge resource windows if the pci_remap_iospace() call fails; this is an actual bug in that the PCI host bridge would consider the PCI IO resource valid (and possibly assign it to downstream devices) even if the kernel was not able to map the PCI host bridge memory address driving IO cycle to the CPU virtual address space (ie pci_remap_iospace() failures). Fix the PCI host bridge driver pci_remap_iospace() failure path, by destroying the PCI host bridge PCI IO resources retrieved through firmware when the pci_remap_iospace() function call fails, therefore preventing the kernel from adding the respective PCI IO resource to the list of PCI host bridge valid resources, fixing the issue. Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com> Fixes: 4e64dbe226e7 ("PCI: generic: Expose pci_host_common_probe() for use by other drivers") Cc: Bjorn Helgaas <bhelgaas@google.com> Cc: Will Deacon <will.deacon@arm.com> --- drivers/pci/host/pci-host-common.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)