From: Joerg Roedel <jroedel@suse.de>
Date: Mon, 21 Dec 2015 18:07:50 +0000 (+0100)
Subject: iommu/amd: Build io page-tables with cmpxchg64
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=7bfa5bd2708d096c79fc2c9f32de478ade7a013f;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git

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 4c926dadb281..ecdd3f7dfb89 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -1206,11 +1206,21 @@ static u64 *alloc_pte(struct protection_domain *domain,
 	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 @@ static unsigned long dma_ops_alloc_addresses(struct device *dev,
 		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;
 	}