linux-kernel - [PATCH 6/9] iommu/amd: Optimize iommu_unmap_page for new fetch

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Message-Id: <1427893132-18310-7-git-send-email-joro@8bytes.org>
Date:	Wed,  1 Apr 2015 14:58:49 +0200
From:	Joerg Roedel <joro@...tes.org>
To:	iommu@...ts.linux-foundation.org
Cc:	Suravee.Suthikulpanit@....com, linux-kernel@...r.kernel.org,
	Joerg Roedel <jroedel@...e.de>
Subject: [PATCH 6/9] iommu/amd: Optimize iommu_unmap_page for new fetch_pte interface

From: Joerg Roedel <jroedel@...e.de>

Now that fetch_pte returns the page-size of the pte, this
function can be optimized a lot.

Signed-off-by: Joerg Roedel <jroedel@...e.de>
---
 drivers/iommu/amd_iommu.c | 32 ++++++++------------------------
 1 file changed, 8 insertions(+), 24 deletions(-)

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 24ef9e6..c9ee444 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -1428,8 +1428,8 @@ static unsigned long iommu_unmap_page(struct protection_domain *dom,
 				      unsigned long bus_addr,
 				      unsigned long page_size)
 {
-	unsigned long long unmap_size, unmapped;
-	unsigned long pte_pgsize;
+	unsigned long long unmapped;
+	unsigned long unmap_size;
 	u64 *pte;
 
 	BUG_ON(!is_power_of_2(page_size));
@@ -1438,28 +1438,12 @@ static unsigned long iommu_unmap_page(struct protection_domain *dom,
 
 	while (unmapped < page_size) {
 
-		pte = fetch_pte(dom, bus_addr, &pte_pgsize);
-
-		if (!pte) {
-			/*
-			 * No PTE for this address
-			 * move forward in 4kb steps
-			 */
-			unmap_size = PAGE_SIZE;
-		} else if (PM_PTE_LEVEL(*pte) == 0) {
-			/* 4kb PTE found for this address */
-			unmap_size = PAGE_SIZE;
-			*pte       = 0ULL;
-		} else {
-			int count, i;
-
-			/* Large PTE found which maps this address */
-			unmap_size = PTE_PAGE_SIZE(*pte);
-
-			/* Only unmap from the first pte in the page */
-			if ((unmap_size - 1) & bus_addr)
-				break;
-			count      = PAGE_SIZE_PTE_COUNT(unmap_size);
+		pte = fetch_pte(dom, bus_addr, &unmap_size);
+
+		if (pte) {
+			int i, count;
+
+			count = PAGE_SIZE_PTE_COUNT(unmap_size);
 			for (i = 0; i < count; i++)
 				pte[i] = 0ULL;
 		}
-- 
1.9.1

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