linux-stable.git/drivers/xen/gntdev.c, branch v4.2.4

xen/gntdevt: Fix race condition in gntdev_release()

2015-06-30T15:57:32+00:00

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 
Cc: 
Signed-off-by: David Vrabel

xen: Include xen/page.h rather than asm/xen/page.h

2015-06-17T15:14:18+00:00

Using xen/page.h will be necessary later for using common xen page
helpers.

As xen/page.h already include asm/xen/page.h, always use the later.

Signed-off-by: Julien Grall 
Reviewed-by: David Vrabel 
Cc: Stefano Stabellini 
Cc: Ian Campbell 
Cc: Wei Liu 
Cc: Konrad Rzeszutek Wilk 
Cc: Boris Ostrovsky 
Cc: netdev@vger.kernel.org
Signed-off-by: David Vrabel

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

xen/gntdev: convert priv->lock to a mutex

2015-01-28T14:03:14+00:00

Unmapping may require sleeping and we unmap while holding priv->lock, so
convert it to a mutex.

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

xen/grant-table: add helpers for allocating pages

2015-01-28T14:03:12+00:00

Add gnttab_alloc_pages() and gnttab_free_pages() to allocate/free pages
suitable to for granted maps.

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

xen/grant-table: pre-populate kernel unmap ops for xen_gnttab_unmap_refs()

2015-01-28T14:03:10+00:00

When unmapping grants, instead of converting the kernel map ops to
unmap ops on the fly, pre-populate the set of unmap ops.

This allows the grant unmap for the kernel mappings to be trivially
batched in the future.

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

Revert "xen/grant-table: Avoid m2p_override during mapping"

2014-02-03T11:44:49+00:00

This reverts commit 08ece5bb2312b4510b161a6ef6682f37f4eac8a1.

As it breaks ARM builds and needs more attention
on the ARM side.

Acked-by: David Vrabel 
Signed-off-by: Konrad Rzeszutek Wilk