iommu/amd: Build io page-tables with cmpxchg64
This allows to build up the page-tables without holding any
locks. As a consequence it removes the need to pre-populate
dma_ops page-tables.
Signed-off-by: Joerg Roedel <jroedel@suse.de>
diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 4c926da..ecdd3f7 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -1206,11 +1206,21 @@
end_lvl = PAGE_SIZE_LEVEL(page_size);
while (level > end_lvl) {
- if (!IOMMU_PTE_PRESENT(*pte)) {
+ u64 __pte, __npte;
+
+ __pte = *pte;
+
+ if (!IOMMU_PTE_PRESENT(__pte)) {
page = (u64 *)get_zeroed_page(gfp);
if (!page)
return NULL;
- *pte = PM_LEVEL_PDE(level, virt_to_phys(page));
+
+ __npte = PM_LEVEL_PDE(level, virt_to_phys(page));
+
+ if (cmpxchg64(pte, __pte, __npte)) {
+ free_page((unsigned long)page);
+ continue;
+ }
}
/* No level skipping support yet */
@@ -1607,7 +1617,7 @@
address = dma_ops_area_alloc(dev, dom, pages,
align_mask, dma_mask);
- if (address == -1 && alloc_new_range(dom, true, GFP_ATOMIC))
+ if (address == -1 && alloc_new_range(dom, false, GFP_ATOMIC))
break;
}