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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 <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Ingo Molnar 2008-02-14 23:30:20 +01:00
parent 3223f59f9c
commit 184652eb6f
1 changed files with 9 additions and 0 deletions
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9
arch/x86/kernel/pci-gart_64.c
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@ -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)