Commit-ID: fe2245c905631a3a353504fc04388ce3dfaf9d9e Gitweb: http://git.kernel.org/tip/fe2245c905631a3a353504fc04388ce3dfaf9d9e Author: Mark Langsdorf <mark.langsdorf@xxxxxxx> AuthorDate: Sun, 5 Jul 2009 15:50:52 -0500 Committer: Ingo Molnar <mingo@xxxxxxx> CommitDate: Sat, 6 Jun 2009 09:42:09 +0200 x86: enable GART-IOMMU only after setting up protection methods The current code to set up the GART as an IOMMU enables GART translations before it removes the aperture from the kernel memory map, sets the GART PTEs to UC, sets up the guard and scratch pages, or does a wbinvd(). This leaves the possibility of cache aliasing open and can cause system crashes. Re-order the code so as to enable the GART translations only after all safeguards are in place and the tlb has been flushed. AMD has tested this patch on both Istanbul systems and 1st generation Opteron systems with APG enabled and seen no adverse effects. Istanbul systems with HT Assist enabled sometimes see MCE errors due to cache artifacts with the unmodified code. Signed-off-by: Mark Langsdorf <mark.langsdorf@xxxxxxx> Cc: <stable@xxxxxxxxxx> Cc: Joerg Roedel <joerg.roedel@xxxxxxx> Cc: akpm@xxxxxxxxxxxxxxxxxxxx Cc: jbarnes@xxxxxxxxxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxx> --- arch/x86/kernel/pci-gart_64.c | 10 ++++++++-- 1 files changed, 8 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/pci-gart_64.c b/arch/x86/kernel/pci-gart_64.c index 1e8920d..cfd9f90 100644 --- a/arch/x86/kernel/pci-gart_64.c +++ b/arch/x86/kernel/pci-gart_64.c @@ -658,8 +658,6 @@ static __init int init_k8_gatt(struct agp_kern_info *info) agp_gatt_table = gatt; - enable_gart_translations(); - error = sysdev_class_register(&gart_sysdev_class); if (!error) error = sysdev_register(&device_gart); @@ -816,6 +814,14 @@ void __init gart_iommu_init(void) * the pages as Not-Present: */ wbinvd(); + + /* + * Now all caches are flushed and we can safely enable + * GART hardware. Doing it early leaves the possibility + * of stale cache entries that can lead to GART PTE + * errors. + */ + enable_gart_translations(); /* * Try to workaround a bug (thanks to BenH): -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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