[PATCH] x86_64: Fix swiotlb=force

It was broken before. But having it is important as possible hardware
bug workaround.

And previously there was no way to force swiotlb if there is another IOMMU.
Side effect is that iommu=force won't force swiotlb anymore even if there
isn't another IOMMU.

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/arch/x86_64/kernel/pci-swiotlb.c b/arch/x86_64/kernel/pci-swiotlb.c
index ebdb77fe20573702facc612fd1262ab3e3d93ade..6a55f87ba97f917ed2814bc3c11c3f21a3ad096b 100644 (file)
--- a/arch/x86_64/kernel/pci-swiotlb.c
+++ b/arch/x86_64/kernel/pci-swiotlb.c
@@ -31,9 +31,10 @@ struct dma_mapping_ops swiotlb_dma_ops = {
 void pci_swiotlb_init(void)
 {
        /* don't initialize swiotlb if iommu=off (no_iommu=1) */
-       if (!iommu_detected && !no_iommu &&
-           (end_pfn > MAX_DMA32_PFN || force_iommu))
+       if (!iommu_detected && !no_iommu && end_pfn > MAX_DMA32_PFN)
               swiotlb = 1;
+       if (swiotlb_force)
+               swiotlb = 1;
        if (swiotlb) {
                printk(KERN_INFO "PCI-DMA: Using software bounce buffering for IO (SWIOTLB)\n");
                swiotlb_init();

diff --git a/include/asm-x86_64/swiotlb.h b/include/asm-x86_64/swiotlb.h
index 5f9a0180582187b1b23196955b66dda63951b214..ba94ab3d2673572d6c6eb07a3bd1bb1a840174ef 100644 (file)
--- a/include/asm-x86_64/swiotlb.h
+++ b/include/asm-x86_64/swiotlb.h
@@ -42,6 +42,8 @@ extern void swiotlb_free_coherent (struct device *hwdev, size_t size,
 extern int swiotlb_dma_supported(struct device *hwdev, u64 mask);
 extern void swiotlb_init(void);
 
+extern int swiotlb_force;
+
 #ifdef CONFIG_SWIOTLB
 extern int swiotlb;
 #else