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[PATCH 3.2 31/60] iommu/vt-d: fix range computation when making room for large pages

From Ben Hutchings <ben@decadent.org.uk>
Newsgroups linux.kernel
Subject [PATCH 3.2 31/60] iommu/vt-d: fix range computation when making room for large pages
Date 2015-11-15 03:10 +0100
Message-ID <quUVt-3GF-49@gated-at.bofh.it> (permalink)
References <quUVr-3GF-3@gated-at.bofh.it>
Organization linux.* mail to news gateway

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3.2.73-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Christian Zander <christian@nervanasys.com>

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>
[bwh: Backported to 3.2:
 - Add the lvl_pages variable, added by an earlier commit upstream
 - Also change arguments to dma_pte_clear_range(), which is called by
   dma_pte_free_pagetable() upstream]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -1798,13 +1798,20 @@ static int __domain_mapping(struct dmar_
 				return -ENOMEM;
 			/* It is large page*/
 			if (largepage_lvl > 1) {
+				unsigned long nr_superpages, end_pfn, lvl_pages;
+
 				pteval |= DMA_PTE_LARGE_PAGE;
-				/* Ensure that old small page tables are removed to make room
-				   for superpage, if they exist. */
-				dma_pte_clear_range(domain, iov_pfn,
-						    iov_pfn + lvl_to_nr_pages(largepage_lvl) - 1);
-				dma_pte_free_pagetable(domain, iov_pfn,
-						       iov_pfn + lvl_to_nr_pages(largepage_lvl) - 1);
+				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(s).
+				 */
+				dma_pte_clear_range(domain, iov_pfn, end_pfn);
+				dma_pte_free_pagetable(domain, iov_pfn, end_pfn);
 			} else {
 				pteval &= ~(uint64_t)DMA_PTE_LARGE_PAGE;
 			}

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[PATCH 3.2 00/60] 3.2.73-rc1 review Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:10 +0100
  [PATCH 3.2 43/60] dm btree remove: fix a bug when rebalancing  nodes after removal Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:10 +0100
  [PATCH 3.2 27/60] 3w-9xxx: don't unmap bounce buffered commands Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:10 +0100
  [PATCH 3.2 12/60] genirq: Fix race in register_irq_proc() Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:10 +0100
  [PATCH 3.2 31/60] iommu/vt-d: fix range computation when making  room for large pages Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:10 +0100
  [PATCH 3.2 28/60] xen-blkfront: check for null drvdata in  blkback_changed (XenbusStateClosing) Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:10 +0100
  [PATCH 3.2 32/60] xhci: don't finish a TD if we get a short  transfer event mid TD Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:10 +0100
  [PATCH 3.2 46/60] md/raid1: don't clear bitmap bit when  bad-block-list write fails. Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:10 +0100
  [PATCH 3.2 24/60] iwlwifi: dvm: fix D3 firmware PN programming Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:10 +0100
  [PATCH 3.2 04/60] regmap: debugfs: Don't bother actually printing  when calculating max length Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:10 +0100
  [PATCH 3.2 55/60] asix: Don't reset PHY on if_up for ASIX 88772 Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:20 +0100
  [PATCH 3.2 08/60] UBI: Validate data_size Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:20 +0100
  [PATCH 3.2 53/60] skbuff: Fix skb checksum partial check. Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:20 +0100
  [PATCH 3.2 38/60] IB/cm: Fix rb-tree duplicate free and  use-after-free Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:20 +0100
  [PATCH 3.2 20/60] usb: Add device quirk for Logitech PTZ cameras Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:20 +0100
  [PATCH 3.2 33/60] xhci: handle no ping response error properly Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:20 +0100
  [PATCH 3.2 19/60] USB: Add reset-resume quirk for two Plantronics  usb headphones. Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:20 +0100
  [PATCH 3.2 44/60] dm btree: fix leak of bufio-backed block in  btree_split_beneath error path Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:20 +0100
  [PATCH 3.2 40/60] powerpc/rtas: Validate rtas.entry before  calling enter_rtas() Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:20 +0100
  [PATCH 3.2 34/60] xhci: Switch Intel Lynx Point LP ports to EHCI  on shutdown. Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:20 +0100
  [PATCH 3.2 07/60] x86/xen: Do not clip xen_e820_map to  xen_e820_map_entries when sanitizing map Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:20 +0100
  [PATCH 3.2 03/60] regmap: debugfs: Ensure we don't underflow when  printing access masks Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:20 +0100
  [PATCH 3.2 51/60] net: add length argument to  skb_copy_and_csum_datagram_iovec Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:20 +0100
  [PATCH 3.2 05/60] ath9k: declare required extra tx headroom Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:20 +0100
  [PATCH 3.2 39/60] drm/nouveau/gem: return only valid domain when  there's only one Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:20 +0100
  [PATCH 3.2 06/60] m68k: Define asmlinkage_protect Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:20 +0100
  [PATCH 3.2 26/60] sched/core: Fix TASK_DEAD race in  finish_task_switch() Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:20 +0100
  [PATCH 3.2 45/60] md/raid1: ensure device failure recorded before  write request returns. Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:20 +0100
  [PATCH 3.2 15/60] md/raid0: update queue parameter in a safer  location. Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:20 +0100
  [PATCH 3.2 59/60] KEYS: Fix race between key destruction and  finding a keyring by name Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:20 +0100
  [PATCH 3.2 23/60] ppp: don't override sk->sk_state in  pppoe_flush_dev() Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:20 +0100
  [PATCH 3.2 49/60] mvsas: Fix NULL pointer dereference in  mvs_slot_task_free Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:20 +0100
  [PATCH 3.2 58/60] KVM: x86: work around infinite loop in  microcode when #AC is delivered Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:20 +0100
  [PATCH 3.2 42/60] ppp: fix pppoe_dev deletion condition in  pppoe_release() Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:30 +0100
  [PATCH 3.2 10/60] MIPS: dma-default: Fix 32-bit fall back to GFP_DMA Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:30 +0100
  [PATCH 3.2 50/60] sched: declare pid_alive as inline Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:30 +0100
  [PATCH 3.2 17/60] clocksource: Fix abs() usage w/ 64bit values Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:30 +0100
  [PATCH 3.2 36/60] crypto: api - Only abort operations on fatal signal Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:30 +0100
  [PATCH 3.2 16/60] md/raid0: apply base queue limits *before*  disk_stack_limits Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:30 +0100
  [PATCH 3.2 47/60] md/raid10: ensure device failure recorded  before write request returns. Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:30 +0100
  [PATCH 3.2 57/60] Failing to send a CLOSE if file is opened  WRONLY and server reboots on a 4.x mount Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:30 +0100
  [PATCH 3.2 14/60] [SMB3] Do not fall back to SMBWriteX in  set_file_size error cases Ben Hutchings <ben@decadent.org.uk> - 2015-11-15 03:30 +0100
  Re: [PATCH 3.2 00/60] 3.2.73-rc1 review Guenter Roeck <linux@roeck-us.net> - 2015-11-15 14:50 +0100
    Re: [PATCH 3.2 00/60] 3.2.73-rc1 review Ben Hutchings <ben@decadent.org.uk> - 2015-11-16 12:20 +0100

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