[+cc Ming, Rusty, Pekka, Sasha] On Wed, Feb 26, 2014 at 12:37:57PM -0700, Bjorn Helgaas wrote: > Don't rely on BAR contents when the command register says the BAR is > disabled. > > If we receive a PCI device from firmware (or a hot-added device that was > just powered up) with the MEMORY or IO enable bits in the PCI command > register cleared, there's no reason to believe the BARs contain valid > addresses. > > In that case, we still know the type and size of the BAR, but this > patch marks the resource as "unset" so we have a chance to reassign it. > > Historically, we often used "BAR == 0" to decide the BAR is invalid. But 0 > is a legal BAR value, especially if the host bridge translates addresses, > so I think it's better to decide based on the PCI command register, and > store the conclusion in the IORESOURCE_UNSET bit. I plan to replace this patch with the following, which only sets IORESOURCE_UNSET when we already have been clearing the bus region start address. (This probably should have been a separate patch to begin with, mea culpa.) This is intended for the v3.15 merge window, so I made the minimal change to reduce risk. Thanks to Ming Lei for prompting me to look at this; I think the issue he reported with the original patch is really a problem somewhere else that the patch just happened to expose, but the original patch was more aggressive than necessary, so this revision tones it down a bit. Bjorn PCI: Mark 64-bit resource as IORESOURCE_UNSET if we only support 32-bit From: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> If we don't support 64-bit addresses, i.e., CONFIG_PHYS_ADDR_T_64BIT is not set, we can't deal with BARs above 4GB. In this case we already pretend the BAR contained zero; this patch also sets IORESOURCE_UNSET so we can try to reallocate it later. I don't think this is exactly correct: what we care about here are *bus* addresses, not CPU addresses, so the tests of sizeof(resource_size_t) probably should be on sizeof(dma_addr_t) instead. But this is what's been in -next, so we'll fix that later. Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> --- drivers/pci/probe.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 6e34498ec9f0..78335efbbb74 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -252,6 +252,7 @@ int __pci_read_base(struct pci_dev *dev, enum pci_bar_type type, /* Address above 32-bit boundary; disable the BAR */ pci_write_config_dword(dev, pos, 0); pci_write_config_dword(dev, pos + 4, 0); + res->flags |= IORESOURCE_UNSET; region.start = 0; region.end = sz64; bar_disabled = true; -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
