linux.git/drivers/xen/privcmd.c, branch v6.4.1

mm: replace vma->vm_flags direct modifications with modifier calls

2023-02-10T00:51:39+00:00

Replace direct modifications to vma->vm_flags with calls to modifier
functions to be able to track flag changes and to keep vma locking
correctness.

[akpm@linux-foundation.org: fix drivers/misc/open-dice.c, per Hyeonggon Yoo]
Link: https://lkml.kernel.org/r/20230126193752.297968-5-surenb@google.com
Signed-off-by: Suren Baghdasaryan 
Acked-by: Michal Hocko 
Acked-by: Mel Gorman 
Acked-by: Mike Rapoport (IBM) 
Acked-by: Sebastian Reichel 
Reviewed-by: Liam R. Howlett 
Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: Andy Lutomirski 
Cc: Arjun Roy 
Cc: Axel Rasmussen 
Cc: David Hildenbrand 
Cc: David Howells 
Cc: Davidlohr Bueso 
Cc: David Rientjes 
Cc: Eric Dumazet 
Cc: Greg Thelen 
Cc: Hugh Dickins 
Cc: Ingo Molnar 
Cc: Jann Horn 
Cc: Joel Fernandes 
Cc: Johannes Weiner 
Cc: Kent Overstreet 
Cc: Laurent Dufour 
Cc: Lorenzo Stoakes 
Cc: Matthew Wilcox 
Cc: Minchan Kim 
Cc: Paul E. McKenney 
Cc: Peter Oskolkov 
Cc: Peter Xu 
Cc: Peter Zijlstra 
Cc: Punit Agrawal 
Cc: Sebastian Andrzej Siewior 
Cc: Shakeel Butt 
Cc: Soheil Hassas Yeganeh 
Cc: Song Liu 
Cc: Vlastimil Babka 
Cc: Will Deacon 
Signed-off-by: Andrew Morton

xen/privcmd: Fix a possible warning in privcmd_ioctl_mmap_resource()

2022-12-05T12:54:29+00:00

As 'kdata.num' is user-controlled data, if user tries to allocate
memory larger than(>=) MAX_ORDER, then kcalloc() will fail, it
creates a stack trace and messes up dmesg with a warning.

Call trace:
-> privcmd_ioctl
--> privcmd_ioctl_mmap_resource

Add __GFP_NOWARN in order to avoid too large allocation warning.
This is detected by static analysis using smatch.

Fixes: 3ad0876554ca ("xen/privcmd: add IOCTL_PRIVCMD_MMAP_RESOURCE")
Signed-off-by: Harshit Mogalapalli 
Reviewed-by: Juergen Gross 
Link: https://lore.kernel.org/r/20221126050745.778967-1-harshit.m.mogalapalli@oracle.com
Signed-off-by: Juergen Gross

xen: use vma_lookup() in privcmd_ioctl_mmap()

2022-09-27T02:46:16+00:00

vma_lookup() walks the VMA tree for a specific value, find_vma() will
search the tree after walking to a specific value.  It is more efficient
to only walk to the requested value since privcmd_ioctl_mmap() will exit
the loop if vm_start != msg->va.

Link: https://lkml.kernel.org/r/20220906194824.2110408-20-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett 
Acked-by: Vlastimil Babka 
Tested-by: Yu Zhao 
Cc: Catalin Marinas 
Cc: David Hildenbrand 
Cc: David Howells 
Cc: Davidlohr Bueso 
Cc: "Matthew Wilcox (Oracle)" 
Cc: SeongJae Park 
Cc: Sven Schnelle 
Cc: Will Deacon 
Signed-off-by: Andrew Morton

xen/privcmd: fix error exit of privcmd_ioctl_dm_op()

2022-08-25T14:40:28+00:00

The error exit of privcmd_ioctl_dm_op() is calling unlock_pages()
potentially with pages being NULL, leading to a NULL dereference.

Additionally lock_pages() doesn't check for pin_user_pages_fast()
having been completely successful, resulting in potentially not
locking all pages into memory. This could result in sporadic failures
when using the related memory in user mode.

Fix all of that by calling unlock_pages() always with the real number
of pinned pages, which will be zero in case pages being NULL, and by
checking the number of pages pinned by pin_user_pages_fast() matching
the expected number of pages.

Cc: 
Fixes: ab520be8cd5d ("xen/privcmd: Add IOCTL_PRIVCMD_DM_OP")
Reported-by: Rustam Subkhankulov 
Signed-off-by: Juergen Gross 
Reviewed-by: Jan Beulich 
Reviewed-by: Oleksandr Tyshchenko 
Link: https://lore.kernel.org/r/20220825141918.3581-1-jgross@suse.com
Signed-off-by: Juergen Gross

xen/privcmd: drop "pages" parameter from xen_remap_pfn()

2021-10-05T06:20:27+00:00

The function doesn't use it and all of its callers say in a comment that
their respective arguments are to be non-NULL only in auto-translated
mode. Since xen_remap_domain_mfn_array() isn't supposed to be used by
non-PV, drop the parameter there as well. It was bogusly passed as non-
NULL (PRIV_VMA_LOCKED) by its only caller anyway. For
xen_remap_domain_gfn_range(), otoh, it's not clear at all why this
wouldn't want / might not need to gain auto-translated support down the
road, so the parameter is retained there despite now remaining unused
(and the only caller passing NULL); correct a respective comment as
well.

Signed-off-by: Jan Beulich 
Reviewed-by: Boris Ostrovsky 

Link: https://lore.kernel.org/r/036ad8a2-46f9-ac3d-6219-bdc93ab9e10b@suse.com
Signed-off-by: Juergen Gross

xen/privcmd: fix error handling in mmap-resource processing

2021-10-05T06:20:22+00:00

xen_pfn_t is the same size as int only on 32-bit builds (and not even
on Arm32). Hence pfns[] can't be used directly to read individual error
values returned from xen_remap_domain_mfn_array(); every other error
indicator would be skipped/ignored on 64-bit.

Fixes: 3ad0876554ca ("xen/privcmd: add IOCTL_PRIVCMD_MMAP_RESOURCE")
Cc: stable@vger.kernel.org
Signed-off-by: Jan Beulich 
Reviewed-by: Boris Ostrovsky 

Link: https://lore.kernel.org/r/aa6d6a67-6889-338a-a910-51e889f792d5@suse.com
Signed-off-by: Juergen Gross

xen/privcmd: replace kcalloc() by kvcalloc() when allocating empty pages

2021-10-05T06:20:17+00:00

Osstest has been suffering test failures for a little while from order-4
allocation failures, resulting from alloc_empty_pages() calling
kcalloc(). As there's no need for physically contiguous space here,
switch to kvcalloc().

Signed-off-by: Jan Beulich 
Reviewed-by: Juergen Gross 
Link: https://lore.kernel.org/r/6d698901-98a4-05be-c421-bcd0713f5335@suse.com
Signed-off-by: Juergen Gross

xen/privcmd: allow fetching resource sizes

2021-01-13T11:31:17+00:00

Allow issuing an IOCTL_PRIVCMD_MMAP_RESOURCE ioctl with num = 0 and
addr = 0 in order to fetch the size of a specific resource.

Add a shortcut to the default map resource path, since fetching the
size requires no address to be passed in, and thus no VMA to setup.

This is missing from the initial implementation, and causes issues
when mapping resources that don't have fixed or known sizes.

Signed-off-by: Roger Pau Monné 
Reviewed-by: Juergen Gross 
Tested-by: Andrew Cooper 
Cc: stable@vger.kernel.org # >= 4.18
Link: https://lore.kernel.org/r/20210112115358.23346-1-roger.pau@citrix.com
Signed-off-by: Juergen Gross

Merge tag 'for-linus-5.9-rc4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip

2020-09-06T16:59:27+00:00

Pull xen updates from Juergen Gross:
 "A small series for fixing a problem with Xen PVH guests when running
  as backends (e.g. as dom0).

  Mapping other guests' memory is now working via ZONE_DEVICE, thus not
  requiring to abuse the memory hotplug functionality for that purpose"

* tag 'for-linus-5.9-rc4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  xen: add helpers to allocate unpopulated memory
  memremap: rename MEMORY_DEVICE_DEVDAX to MEMORY_DEVICE_GENERIC
  xen/balloon: add header guard

xen: add helpers to allocate unpopulated memory

2020-09-04T08:00:01+00:00

To be used in order to create foreign mappings. This is based on the
ZONE_DEVICE facility which is used by persistent memory devices in
order to create struct pages and kernel virtual mappings for the IOMEM
areas of such devices. Note that on kernels without support for
ZONE_DEVICE Xen will fallback to use ballooned pages in order to
create foreign mappings.

The newly added helpers use the same parameters as the existing
{alloc/free}_xenballooned_pages functions, which allows for in-place
replacement of the callers. Once a memory region has been added to be
used as scratch mapping space it will no longer be released, and pages
returned are kept in a linked list. This allows to have a buffer of
pages and prevents resorting to frequent additions and removals of
regions.

If enabled (because ZONE_DEVICE is supported) the usage of the new
functionality untangles Xen balloon and RAM hotplug from the usage of
unpopulated physical memory ranges to map foreign pages, which is the
correct thing to do in order to avoid mappings of foreign pages depend
on memory hotplug.

Note the driver is currently not enabled on Arm platforms because it
would interfere with the identity mapping required on some platforms.

Signed-off-by: Roger Pau Monné 
Reviewed-by: Juergen Gross 
Link: https://lore.kernel.org/r/20200901083326.21264-4-roger.pau@citrix.com
Signed-off-by: Juergen Gross