linux-toradex.git/drivers/xen/grant-table.c, branch v4.9.14

xen: audit usages of module.h ; remove unnecessary instances

2016-03-21T15:13:32+00:00

Code that uses no modular facilities whatsoever should not be
sourcing module.h at all, since that header drags in a bunch
of other headers with it.

Similarly, code that is not explicitly using modular facilities
like module_init() but only is declaring module_param setup
variables should be using moduleparam.h and not the larger
module.h file for that.

In making this change, we also uncover an implicit use of BUG()
in inline fcns within arch/arm/include/asm/xen/hypercall.h so
we explicitly source  for that file now.

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

xen/grant-table: constify gnttab_ops structure

2015-12-21T14:41:01+00:00

The gnttab_ops structure is never modified, so declare it as const.

Done with the help of Coccinelle.

Signed-off-by: Julia Lawall 
Signed-off-by: David Vrabel

xen/grant-table: Add an helper to iterate over a specific number of grants

2015-10-23T13:20:46+00:00

With the 64KB page granularity support on ARM64, a Linux page may be
split accross multiple grant.

Currently we have the helper gnttab_foreach_grant_in_grant to break a
Linux page based on an offset and a len, but it doesn't fit when we only
have a number of grants in hand.

Introduce a new helper which take an array of Linux page and a number of
grant and will figure out the address of each grant.

Signed-off-by: Julien Grall 
Signed-off-by: David Vrabel

xen/grant-table: Make it running on 64KB granularity

2015-10-23T13:20:39+00:00

The Xen interface is using 4KB page granularity. This means that each
grant is 4KB.

The current implementation allocates a Linux page per grant. On Linux
using 64KB page granularity, only the first 4KB of the page will be
used.

We could decrease the memory wasted by sharing the page with multiple
grant. It will require some care with the {Set,Clear}ForeignPage macro.

Note that no changes has been made in the x86 code because both Linux
and Xen will only use 4KB page granularity.

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

xen/grant: Introduce helpers to split a page into grant

2015-10-23T13:20:33+00:00

Currently, a grant is always based on the Xen page granularity (i.e
4KB). When Linux is using a different page granularity, a single page
will be split between multiple grants.

The new helpers will be in charge of splitting the Linux page into grants
and call a function given by the caller on each grant.

Also provide an helper to count the number of grants within a given
contiguous region.

Note that the x86/include/asm/xen/page.h is now including
xen/interface/grant_table.h rather than xen/grant_table.h. It's
necessary because xen/grant_table.h depends on asm/xen/page.h and will
break the compilation. Furthermore, only definition in
interface/grant_table.h is required.

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

xen/balloon: make alloc_xenballoon_pages() always allocate low pages

2015-10-23T13:20:05+00:00

All users of alloc_xenballoon_pages() wanted low memory pages, so
remove the option for high memory.

Signed-off-by: David Vrabel 
Reviewed-by: Daniel Kiper

xen/grant-table: Remove unused macro SPP

2015-06-17T15:15:19+00:00

SPP was used by the grant table v2 code which has been removed in
commit 438b33c7145ca8a5131a30c36d8f59bce119a19a "xen/grant-table:
remove support for V2 tables".

Signed-off-by: Julien Grall 
Reviewed-by: David Vrabel 
Cc: Konrad Rzeszutek Wilk 
Cc: Boris Ostrovsky 
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/grant-table: add a mechanism to safely unmap pages that are in use

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

Introduce gnttab_unmap_refs_async() that can be used to safely unmap
pages that may be in use (ref count > 1).  If the pages are in use the
unmap is deferred and retried later.  This polling is not very clever
but it should be good enough if the cases where the delay is necessary
are rare.

The initial delay is 5 ms and is increased linearly on each subsequent
retry (to reduce load if the page is in use for a long time).

This is needed to allow block backends using grant mapping to safely
use network storage (block or filesystem based such as iSCSI or NFS).

The network storage driver may complete a block request whilst there
is a queued network packet retry (because the ack from the remote end
races with deciding to queue the retry).  The pages for the retried
packet would be grant unmapped and the network driver (or hardware)
would access the unmapped page.

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

xen: mark grant mapped pages as foreign

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

Use the "foreign" page flag to mark pages that have a grant map.  Use
page->private to store information of the grant (the granting domain
and the grant reference).

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