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Linux mainline fork with MSM8998 patches | https://mainline.space | Currently supported devices: OnePlus 5/5T, Xiaomi Mi 6, F(x)tec Pro¹ (2019 QX1000 model) & Sony Xperia XZ Premium (UNTESTED!)
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Paul Mackerras 8cfbdbdc24 KVM: PPC: Book3S: Fix guest DMA when guest partially backed by THP pages 
Commit 76fa4975f3 ("KVM: PPC: Check if IOMMU page is contained in
the pinned physical page", 2018-07-17) added some checks to ensure
that guest DMA mappings don't attempt to map more than the guest is
entitled to access. However, errors in the logic mean that legitimate
guest requests to map pages for DMA are being denied in some
situations. Specifically, if the first page of the range passed to
mm_iommu_get() is mapped with a normal page, and subsequent pages are
mapped with transparent huge pages, we end up with mem->pageshift ==
0. That means that the page size checks in mm_iommu_ua_to_hpa() and
mm_iommu_up_to_hpa_rm() will always fail for every page in that
region, and thus the guest can never map any memory in that region for
DMA, typically leading to a flood of error messages like this:

  qemu-system-ppc64: VFIO_MAP_DMA: -22
  qemu-system-ppc64: vfio_dma_map(0x10005f47780, 0x800000000000000, 0x10000, 0x7fff63ff0000) = -22 (Invalid argument)

The logic errors in mm_iommu_get() are:

  (a) use of 'ua' not 'ua + (i << PAGE_SHIFT)' in the find_linux_pte()
      call (meaning that find_linux_pte() returns the pte for the
      first address in the range, not the address we are currently up
      to);
  (b) use of 'pageshift' as the variable to receive the hugepage shift
      returned by find_linux_pte() - for a normal page this gets set
      to 0, leading to us setting mem->pageshift to 0 when we conclude
      that the pte returned by find_linux_pte() didn't match the page
      we were looking at;
  (c) comparing 'compshift', which is a page order, i.e. log base 2 of
      the number of pages, with 'pageshift', which is a log base 2 of
      the number of bytes.

To fix these problems, this patch introduces 'cur_ua' to hold the
current user address and uses that in the find_linux_pte() call;
introduces 'pteshift' to hold the hugepage shift found by
find_linux_pte(); and compares 'pteshift' with 'compshift +
PAGE_SHIFT' rather than 'compshift'.

The patch also moves the local_irq_restore to the point after the PTE
pointer returned by find_linux_pte() has been dereferenced because
otherwise the PTE could change underneath us, and adds a check to
avoid doing the find_linux_pte() call once mem->pageshift has been
reduced to PAGE_SHIFT, as an optimization.

Fixes: 76fa4975f3 ("KVM: PPC: Check if IOMMU page is contained in the pinned physical page")
Cc: stable@vger.kernel.org # v4.12+
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2018-08-23 23:40:10 +10:00
arch KVM: PPC: Book3S: Fix guest DMA when guest partially backed by THP pages 2018-08-23 23:40:10 +10:00
block for-linus-20180629 2018-06-30 10:47:46 -07:00
certs certs/blacklist: fix const confusion 2018-06-26 09:43:03 -07:00
crypto Revert changes to convert to ->poll_mask() and aio IOCB_CMD_POLL 2018-06-28 10:40:47 -07:00
Documentation Documentation: Update documentation on ppc-memtrace 2018-08-10 22:12:32 +10:00
drivers powerpc/powernv: provide a console flush operation for opal hvc driver 2018-08-20 20:19:54 +10:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs for-4.18-rc2-tag 2018-07-01 12:38:16 -07:00
include powerpc/64s: Fix page table fragment refcount race vs speculative references 2018-08-08 00:32:32 +10:00
init Kbuild fixes for v4.18 2018-06-30 13:05:30 -07:00
ipc ipc: use new return type vm_fault_t 2018-06-15 07:55:25 +09:00
kernel Add a missing export required by riscv and unicore 2018-07-01 10:45:13 -07:00
lib for-linus-20180629 2018-06-30 10:47:46 -07:00
LICENSES LICENSES: Add Linux-OpenIB license text 2018-04-27 16:41:53 -06:00
mm slub: fix failure when we delete and create a slab cache 2018-06-28 11:16:44 -07:00
net net: handle NULL ->poll gracefully 2018-06-29 06:51:51 -07:00
samples VFIO updates for v4.18 2018-06-12 13:11:26 -07:00
scripts scripts: Add ppc64le support for checkstack.pl 2018-07-02 23:54:28 +10:00
security selinux/stable-4.18 PR 20180629 2018-06-30 11:15:12 -07:00
sound powerpc/ps3: Set driver coherent_dma_mask 2018-07-20 12:50:37 +10:00
tools selftests/powerpc: Kill child processes on SIGINT 2018-08-08 18:52:24 +10:00
usr kbuild: rename built-in.o to built-in.a 2018-03-26 02:01:19 +09:00
virt KVM: arm64: Prevent KVM_COMPAT from being selected 2018-06-21 17:17:50 +01:00
.clang-format clang-format: add configuration file 2018-04-11 10:28:35 -07:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Kbuild updates for v4.17 (2nd) 2018-04-15 17:21:30 -07:00
.mailmap Merge branch 'asoc-4.17' into asoc-4.18 for compress dependencies 2018-04-26 12:24:28 +01:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS MAINTAINERS/CREDITS: Drop METAG ARCHITECTURE 2018-03-05 16:34:24 +00:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig kconfig: add basic helper macros to scripts/Kconfig.include 2018-05-29 03:31:19 +09:00
MAINTAINERS MAINTAINERS: Remove the entry for the orphaned ams driver 2018-07-19 21:58:10 +10:00
Makefile Linux 4.18-rc3 2018-07-01 16:04:53 -07:00
README Docs: Added a pointer to the formatted docs to README 2018-03-21 09:02:53 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.