From 5b28541552ef5eeffc41d6936105f38c2508e566 Mon Sep 17 00:00:00 2001 From: Yinghai Lu Date: Mon, 19 May 2014 17:01:55 -0600 Subject: PCI: Restrict 64-bit prefetchable bridge windows to 64-bit resources This patch changes the way we handle 64-bit prefetchable bridge windows to make it more likely that we can assign space to all devices. Previously we put all prefetchable resources in the prefetchable bridge window. If any of those resources was 32-bit only, we restricted the window to be below 4GB. After this patch, we only put 64-bit prefetchable resources in a 64-bit prefetchable window. We put all 32-bit prefetchable resources in the non-prefetchable window, even if there are no 64-bit prefetchable resources. With the previous approach, if there was a 32-bit prefetchable resource behind a bridge, we forced the bridge's prefetchable window below 4GB, which meant that even if there was plenty of space above 4GB available, we couldn't use it, and assignment of large 64-bit resources could fail, as in the bugzilla below. The new strategy is: 1) If the prefetchable window is 64 bits wide, we put only 64-bit prefetchable resources in it. Any 32-bit prefetchable resources go in the non-prefetchable window. 2) If the prefetchable window is 32 bits wide, we put both 32- and 64-bit prefetchable resources in it. 3) If there is no prefetchable window, all MMIO resources go in the non-prefetchable window. This reduces performance for 32-bit prefetchable resources below a bridge with a 64-bit prefetchable window. We previously assigned prefetchable space, but now we'll assign non-prefetchable space. This is the case even if there are no 64-bit prefetchable resources, or if they would all fit below 4GB. In those cases, the old strategy would work and would have better performance. [bhelgaas: write changelog, add bugzilla link, fold in mem64_mask removal] Link: https://bugzilla.kernel.org/show_bug.cgi?id=74151 Tested-by: Guo Chao Tested-by: Wei Yang Signed-off-by: Yinghai Lu Signed-off-by: Bjorn Helgaas --- drivers/pci/setup-res.c | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-) (limited to 'drivers/pci/setup-res.c') diff --git a/drivers/pci/setup-res.c b/drivers/pci/setup-res.c index 7eed671d5586..2473f091a9cc 100644 --- a/drivers/pci/setup-res.c +++ b/drivers/pci/setup-res.c @@ -211,15 +211,31 @@ static int __pci_assign_resource(struct pci_bus *bus, struct pci_dev *dev, /* First, try exact prefetching match.. */ ret = pci_bus_alloc_resource(bus, res, size, align, min, - IORESOURCE_PREFETCH, + IORESOURCE_PREFETCH | IORESOURCE_MEM_64, pcibios_align_resource, dev); - if (ret < 0 && (res->flags & IORESOURCE_PREFETCH)) { + if (ret < 0 && + (res->flags & (IORESOURCE_PREFETCH | IORESOURCE_MEM_64)) == + (IORESOURCE_PREFETCH | IORESOURCE_MEM_64)) { + /* + * That failed. + * + * Try 32bit pref + */ + ret = pci_bus_alloc_resource(bus, res, size, align, min, + IORESOURCE_PREFETCH, + pcibios_align_resource, dev); + } + + if (ret < 0 && + (res->flags & (IORESOURCE_PREFETCH | IORESOURCE_MEM_64))) { /* * That failed. * * But a prefetching area can handle a non-prefetching * window (it will just not perform as well). + * + * Also can put 64bit under 32bit range. (below 4g). */ ret = pci_bus_alloc_resource(bus, res, size, align, min, 0, pcibios_align_resource, dev); -- cgit v1.2.3