linux-toradex.git/drivers/xen/grant-table.c, branch v4.1.20

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

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

xen/grant-table: refactor error cleanup in grow_gnttab_list()

2014-09-23T13:36:18+00:00

The cleanup loop in grow_gnttab_list() is safe from the underflow of
the unsigned 'i' since nr_glist_frames is >= 1, but refactor it
anyway.

Signed-off-by: Chen Gang 
Signed-off-by: David Vrabel

xen/grant-table: remove support for V2 tables

2014-07-14T19:28:30+00:00

Since 11c7ff17c9b6dbf3a4e4f36be30ad531a6cf0ec9 (xen/grant-table: Force
to use v1 of grants.) the code for V2 grant tables is not used.

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

x86/xen: safely map and unmap grant frames when in atomic context

2014-07-14T19:28:02+00:00

arch_gnttab_map_frames() and arch_gnttab_unmap_frames() are called in
atomic context but were calling alloc_vm_area() which might sleep.

Also, if a driver attempts to allocate a grant ref from an interrupt
and the table needs expanding, then the CPU may already by in lazy MMU
mode and apply_to_page_range() will BUG when it tries to re-enable
lazy MMU mode.

These two functions are only used in PV guests.

Introduce arch_gnttab_init() to allocates the virtual address space in
advance.

Avoid the use of apply_to_page_range() by using saving and using the
array of PTE addresses from the alloc_vm_area() call.

N.B. 'alloc_vm_area' pre-allocates the pagetable so there is no need
to worry about having to do a PGD/PUD/PMD walk (like apply_to_page_range
does) and we can instead do set_pte.

Signed-off-by: David Vrabel 
Signed-off-by: Konrad Rzeszutek Wilk 
----
[v2: Add comment about alloc_vm_area]
[v3: Fix compile error found by 0-day bot]

xen/grant-table: fix suspend for non-PV guests

2014-06-18T09:58:01+00:00

Commit aa8532c32216ae07c3813b9aeb774517878a7573 (xen: refactor suspend
pre/post hooks) broke resuming PVHVM (auto-translated physmap) guests.

The gnttab_suspend() would clear the mapping for the grant table
frames, but the ->unmap_frames() call is only applicable to PV guests.

Signed-off-by: David Vrabel 
Reported-by: Konrad Rzeszutek Wilk 
Tested-by: Konrad Rzeszutek Wilk

xen/grant-table: Refactor gnttab_[un]map_refs to avoid m2p_override

2014-03-18T14:40:19+00:00

The grant mapping API does m2p_override unnecessarily: only gntdev needs it,
for blkback and future netback patches it just cause a lock contention, as
those pages never go to userspace. Therefore this series does the following:
- the bulk of the original function (everything after the mapping hypercall)
  is moved to arch-dependent set/clear_foreign_p2m_mapping
- the "if (xen_feature(XENFEAT_auto_translated_physmap))" branch goes to ARM
- therefore the ARM function could be much smaller, the m2p_override stubs
  could be also removed
- on x86 the set_phys_to_machine calls were moved up to this new funcion
  from m2p_override functions
- and m2p_override functions are only called when there is a kmap_ops param

It also removes a stray space from arch/x86/include/asm/xen/page.h.

Signed-off-by: Zoltan Kiss 
Suggested-by: Anthony Liguori 
Suggested-by: David Vrabel 
Suggested-by: Stefano Stabellini 
Signed-off-by: David Vrabel 
Signed-off-by: Stefano Stabellini