From 9af88143b277f52fc6ce0d69137f435c73c39c1a Mon Sep 17 00:00:00 2001 From: David Woodhouse Date: Fri, 13 Feb 2009 23:18:03 +0000 Subject: [PATCH] iommu: fix Intel IOMMU write-buffer flushing This is the cause of the DMA faults and disk corruption that people have been seeing. Some chipsets neglect to report the RWBF "capability" -- the flag which says that we need to flush the chipset write-buffer when changing the DMA page tables, to ensure that the change is visible to the IOMMU. Override that bit on the affected chipsets, and everything is happy again. Thanks to Chris and Bhavesh and others for helping to debug. Should resolve: https://bugzilla.redhat.com/show_bug.cgi?id=479996 http://bugzilla.kernel.org/show_bug.cgi?id=12578 Signed-off-by: David Woodhouse Cc: Linus Torvalds Tested-and-acked-by: Chris Wright Reviewed-by: Bhavesh Davda Signed-off-by: Ingo Molnar --- drivers/pci/intel-iommu.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/drivers/pci/intel-iommu.c b/drivers/pci/intel-iommu.c index f4b7c79023ff..f3f686581a90 100644 --- a/drivers/pci/intel-iommu.c +++ b/drivers/pci/intel-iommu.c @@ -61,6 +61,8 @@ /* global iommu list, set NULL for ignored DMAR units */ static struct intel_iommu **g_iommus; +static int rwbf_quirk; + /* * 0: Present * 1-11: Reserved @@ -785,7 +787,7 @@ static void iommu_flush_write_buffer(struct intel_iommu *iommu) u32 val; unsigned long flag; - if (!cap_rwbf(iommu->cap)) + if (!rwbf_quirk && !cap_rwbf(iommu->cap)) return; val = iommu->gcmd | DMA_GCMD_WBF; @@ -3137,3 +3139,15 @@ static struct iommu_ops intel_iommu_ops = { .unmap = intel_iommu_unmap_range, .iova_to_phys = intel_iommu_iova_to_phys, }; + +static void __devinit quirk_iommu_rwbf(struct pci_dev *dev) +{ + /* + * Mobile 4 Series Chipset neglects to set RWBF capability, + * but needs it: + */ + printk(KERN_INFO "DMAR: Forcing write-buffer flush capability\n"); + rwbf_quirk = 1; +} + +DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_INTEL, 0x2a40, quirk_iommu_rwbf); -- 2.20.1