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[3.19.y-ckt,stable] Patch "iommu/vt-d: fix range computation when making room for large pages" has been added to staging queue

Message ID 1447370078-30684-1-git-send-email-kamal@canonical.com
State New
Headers show

Commit Message

Kamal Mostafa Nov. 12, 2015, 11:14 p.m. UTC 
This is a note to let you know that I have just added a patch titled

    iommu/vt-d: fix range computation when making room for large pages

to the linux-3.19.y-queue branch of the 3.19.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.19.y-queue

This patch is scheduled to be released in version 3.19.8-ckt10.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.19.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

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From 751bda9959f5893d22b22c3737cd5a81191fbb39 Mon Sep 17 00:00:00 2001
From: Christian Zander <christian@nervanasys.com>
Date: Wed, 10 Jun 2015 09:41:45 -0700
Subject: [PATCH 079/120] iommu/vt-d: fix range computation when making room
 for large pages

commit ba2374fd2bf379f933773811fdb06cb6a5445f41 upstream.

In preparation for the installation of a large page, any small page
tables that may still exist in the target IOV address range are
removed.  However, if a scatter/gather list entry is large enough to
fit more than one large page, the address space for any subsequent
large pages is not cleared of conflicting small page tables.

This can cause legitimate mapping requests to fail with errors of the
form below, potentially followed by a series of IOMMU faults:

ERROR: DMA PTE for vPFN 0xfde00 already set (to 7f83a4003 not 7e9e00083)

In this example, a 4MiB scatter/gather list entry resulted in the
successful installation of a large page @ vPFN 0xfdc00, followed by
a failed attempt to install another large page @ vPFN 0xfde00, due to
the presence of a pointer to a small page table @ 0x7f83a4000.

To address this problem, compute the number of large pages that fit
into a given scatter/gather list entry, and use it to derive the
last vPFN covered by the large page(s).

Signed-off-by: Christian Zander <christian@nervanasys.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
 drivers/iommu/intel-iommu.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

--
1.9.1
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Patch

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 0688303..3583db4 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -2032,15 +2032,19 @@  static int __domain_mapping(struct dmar_domain *domain, unsigned long iov_pfn,
 				return -ENOMEM;
 			/* It is large page*/
 			if (largepage_lvl > 1) {
+				unsigned long nr_superpages, end_pfn;
+
 				pteval |= DMA_PTE_LARGE_PAGE;
 				lvl_pages = lvl_to_nr_pages(largepage_lvl);
+
+				nr_superpages = sg_res / lvl_pages;
+				end_pfn = iov_pfn + nr_superpages * lvl_pages - 1;
+
 				/*
 				 * Ensure that old small page tables are
-				 * removed to make room for superpage,
-				 * if they exist.
+				 * removed to make room for superpage(s).
 				 */
-				dma_pte_free_pagetable(domain, iov_pfn,
-						       iov_pfn + lvl_pages - 1);
+				dma_pte_free_pagetable(domain, iov_pfn, end_pfn);
 			} else {
 				pteval &= ~(uint64_t)DMA_PTE_LARGE_PAGE;
 			}