From 184652eb6f68050af48a2ce3d5cf0537c208bee2 Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Thu, 14 Feb 2008 23:30:20 +0100 Subject: [PATCH] x86: fix gart_iommu_init() When the GART table is unmapped from the kernel direct mappings during early bootup, make sure we have no leftover cachelines in it. Note: the clflush done by set_memory_np() was not enough, because clflush does not work on unmapped pages. Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner --- arch/x86/kernel/pci-gart_64.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/arch/x86/kernel/pci-gart_64.c b/arch/x86/kernel/pci-gart_64.c index 65f6acb025c8..faf3229f8fb3 100644 --- a/arch/x86/kernel/pci-gart_64.c +++ b/arch/x86/kernel/pci-gart_64.c @@ -749,6 +749,15 @@ void __init gart_iommu_init(void) */ set_memory_np((unsigned long)__va(iommu_bus_base), iommu_size >> PAGE_SHIFT); + /* + * Tricky. The GART table remaps the physical memory range, + * so the CPU wont notice potential aliases and if the memory + * is remapped to UC later on, we might surprise the PCI devices + * with a stray writeout of a cacheline. So play it sure and + * do an explicit, full-scale wbinvd() _after_ having marked all + * the pages as Not-Present: + */ + wbinvd(); /* * Try to workaround a bug (thanks to BenH) -- 2.20.1