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Commit 184652eb authored by Ingo Molnar's avatar Ingo Molnar
Browse files

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: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 3223f59f

arch/x86/kernel/pci-gart_64.c

+9 −0
Original line number Diff line number Diff line
@@ -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)