linux-kernel - [PATCH 3.12 098/111] iommu/amd: Optimize iommu_unmap_page for new fetch

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Date:	Wed, 10 Jun 2015 17:27:27 +0200
From:	Jiri Slaby <jslaby@...e.cz>
To:	stable@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, Joerg Roedel <jroedel@...e.de>,
	Jiri Slaby <jslaby@...e.cz>
Subject: [PATCH 3.12 098/111] iommu/amd: Optimize iommu_unmap_page for new fetch_pte interface

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

3.12-stable review patch.  If anyone has any objections, please let me know.

===============

commit 71b390e9bec5121d25c45326ff0b0b96a143f9a8 upstream.

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

Tested-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@....com>
Signed-off-by: Joerg Roedel <jroedel@...e.de>
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
---
 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 976cf15744a9..8f6344df7c49 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -1479,8 +1479,8 @@ 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));
@@ -1489,28 +1489,12 @@ 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;
 		}
-- 
2.4.2

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