linux-stable.git/drivers/xen/gntdev.c, branch linux-4.1.y

xen/gntdev: Fix partial gntdev_mmap() cleanup

2018-03-21T03:49:46+00:00

[ Upstream commit cf2acf66ad43abb39735568f55e1f85f9844e990 ]

When cleaning up after a partially successful gntdev_mmap(), unmap the
successfully mapped grant pages otherwise Xen will kill the domain if
in debug mode (Attempt to implicitly unmap a granted PTE) or Linux will
kill the process and emit "BUG: Bad page map in process" if Xen is in
release mode.

This is only needed when use_ptemod is true because gntdev_put_map()
will unmap grant pages itself when use_ptemod is false.

Signed-off-by: Ross Lagerwall 
Reviewed-by: Boris Ostrovsky 
Signed-off-by: Boris Ostrovsky 
Signed-off-by: Sasha Levin

xen/gntdev: Fix off-by-one error when unmapping with holes

2018-03-21T03:49:46+00:00

[ Upstream commit 951a010233625b77cde3430b4b8785a9a22968d1 ]

If the requested range has a hole, the calculation of the number of
pages to unmap is off by one. Fix it.

Signed-off-by: Ross Lagerwall 
Reviewed-by: Boris Ostrovsky 
Signed-off-by: Boris Ostrovsky 
Signed-off-by: Sasha Levin

xen/gntdev: avoid out of bounds access in case of partial gntdev_mmap()

2017-11-06T04:54:37+00:00

[ Upstream commit 298d275d4d9bea3524ff4bc76678c140611d8a8d ]

In case gntdev_mmap() succeeds only partially in mapping grant pages
it will leave some vital information uninitialized needed later for
cleanup. This will lead to an out of bounds array access when unmapping
the already mapped pages.

So just initialize the data needed for unmapping the pages a little bit
earlier.

Cc: 
Reported-by: Arthur Borsboom 
Signed-off-by: Juergen Gross 
Reviewed-by: Boris Ostrovsky 
Signed-off-by: Boris Ostrovsky 
Signed-off-by: Sasha Levin

xen/gntdev: Use VM_MIXEDMAP instead of VM_IO to avoid NUMA balancing

2017-01-13T01:56:54+00:00

[ Upstream commit 30faaafdfa0c754c91bac60f216c9f34a2bfdf7e ]

Commit 9c17d96500f7 ("xen/gntdev: Grant maps should not be subject to
NUMA balancing") set VM_IO flag to prevent grant maps from being
subjected to NUMA balancing.

It was discovered recently that this flag causes get_user_pages() to
always fail with -EFAULT.

check_vma_flags
__get_user_pages
__get_user_pages_locked
__get_user_pages_unlocked
get_user_pages_fast
iov_iter_get_pages
dio_refill_pages
do_direct_IO
do_blockdev_direct_IO
do_blockdev_direct_IO
ext4_direct_IO_read
generic_file_read_iter
aio_run_iocb

(which can happen if guest's vdisk has direct-io-safe option).

To avoid this let's use VM_MIXEDMAP flag instead --- it prevents
NUMA balancing just as VM_IO does and has no effect on
check_vma_flags().

Cc: stable@vger.kernel.org

Reported-by: Olaf Hering 
Suggested-by: Hugh Dickins 
Signed-off-by: Boris Ostrovsky 
Acked-by: Hugh Dickins 
Tested-by: Olaf Hering 
Signed-off-by: Juergen Gross 
Signed-off-by: Sasha Levin

xen/gntdev: Grant maps should not be subject to NUMA balancing

2016-01-31T19:23:30+00:00

commit 9c17d96500f78d7ecdb71ca6942830158bc75a2b upstream.

Doing so will cause the grant to be unmapped and then, during
fault handling, the fault to be mistakenly treated as NUMA hint
fault.

In addition, even if those maps could partcipate in NUMA
balancing, it wouldn't provide any benefit since we are unable
to determine physical page's node (even if/when VNUMA is
implemented).

Marking grant maps' VMAs as VM_IO will exclude them from being
part of NUMA balancing.

Signed-off-by: Boris Ostrovsky 
Signed-off-by: David Vrabel 
Signed-off-by: Greg Kroah-Hartman

xen/gntdevt: Fix race condition in gntdev_release()

2015-08-17T03:52:19+00:00

commit 30b03d05e07467b8c6ec683ea96b5bffcbcd3931 upstream.

While gntdev_release() is called the MMU notifier is still registered
and can traverse priv->maps list even if no pages are mapped (which is
the case -- gntdev_release() is called after all). But
gntdev_release() will clear that list, so make sure that only one of
those things happens at the same time.

Signed-off-by: Marek Marczykowski-Górecki 
Signed-off-by: David Vrabel 
Signed-off-by: Greg Kroah-Hartman

xen/grant: introduce func gnttab_unmap_refs_sync()

2015-04-27T10:41:12+00:00

There are several place using gnttab async unmap and wait for
completion, so move the common code to a function
gnttab_unmap_refs_sync().

Signed-off-by: Bob Liu 
Acked-by: Roger Pau Monné 
Acked-by: Konrad Rzeszutek Wilk 
Signed-off-by: David Vrabel

xen/gntdev: provide find_special_page VMA operation

2015-01-28T14:04:58+00:00

For a PV guest, use the find_special_page op to find the right page.
To handle VMAs being split, remember the start of the original VMA so
the correct index in the pages array can be calculated.

Signed-off-by: David Vrabel 
Reviewed-by: Stefano Stabellini

xen/gntdev: mark userspace PTEs as special on x86 PV guests

2015-01-28T14:04:21+00:00

In an x86 PV guest, get_user_pages_fast() on a userspace address range
containing foreign mappings does not work correctly because the M2P
lookup of the MFN from a userspace PTE may return the wrong page.

Force get_user_pages_fast() to fail on such addresses by marking the PTEs
as special.

If Xen has XENFEAT_gnttab_map_avail_bits (available since at least
4.0), we can do so efficiently in the grant map hypercall.  Otherwise,
it needs to be done afterwards.  This is both inefficient and racy
(the mapping is visible to the task before we fixup the PTEs), but
will be fine for well-behaved applications that do not use the mapping
until after the mmap() system call returns.

Guests with XENFEAT_auto_translated_physmap (ARM and x86 HVM or PVH)
do not need this since get_user_pages() has always worked correctly
for them.

Signed-off-by: David Vrabel 
Reviewed-by: Stefano Stabellini

xen/gntdev: safely unmap grants in case they are still in use

2015-01-28T14:03:15+00:00

Use gnttab_unmap_refs_async() to wait until the mapped pages are no
longer in use before unmapping them.

This allows userspace programs to safely use Direct I/O and AIO to a
network filesystem which may retain refs to pages in queued skbs after
the filesystem I/O has completed.

Signed-off-by: Jennifer Herbert 
Reviewed-by: Stefano Stabellini 
Signed-off-by: David Vrabel