linux-stable.git/drivers/xen, branch v4.13.2

xen/gntdev: update to new mmu_notifier semantic

2017-08-31T23:13:00+00:00

Calls to mmu_notifier_invalidate_page() were replaced by calls to
mmu_notifier_invalidate_range() and are now bracketed by calls to
mmu_notifier_invalidate_range_start()/end()

Remove now useless invalidate_page callback.

Signed-off-by: Jérôme Glisse 
Reviewed-by: Boris Ostrovsky 
Cc: Konrad Rzeszutek Wilk 
Cc: Roger Pau Monné 
Cc: xen-devel@lists.xenproject.org (moderated for non-subscribers)
Cc: Kirill A. Shutemov 
Cc: Andrew Morton 
Cc: Andrea Arcangeli 
Signed-off-by: Linus Torvalds

Merge tag 'kbuild-fixes-v4.13' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild

2017-08-24T21:22:27+00:00

Pull Kbuild fixes from Masahiro Yamada:

 - fix linker script regression caused by dead code elimination support

 - fix typos and outdated comments

 - specify kselftest-clean as a PHONY target

 - fix "make dtbs_install" when $(srctree) includes shell special
   characters like '~'

 - Move -fshort-wchar to the global option list because defining it
   partially emits warnings

* tag 'kbuild-fixes-v4.13' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
  kbuild: update comments of Makefile.asm-generic
  kbuild: Do not use hyphen in exported variable name
  Makefile: add kselftest-clean to PHONY target list
  Kbuild: use -fshort-wchar globally
  fixdep: trivial: typo fix and correction
  kbuild: trivial cleanups on the comments
  kbuild: linker script do not match C names unless LD_DEAD_CODE_DATA_ELIMINATION is configured

Kbuild: use -fshort-wchar globally

2017-08-21T00:05:59+00:00

Commit 971a69db7dc0 ("Xen: don't warn about 2-byte wchar_t in efi")
added the --no-wchar-size-warning to the Makefile to avoid this
harmless warning:

arm-linux-gnueabi-ld: warning: drivers/xen/efi.o uses 2-byte wchar_t yet the output is to use 4-byte wchar_t; use of wchar_t values across objects may fail

Changing kbuild to use thin archives instead of recursive linking
unfortunately brings the same warning back during the final link.

The kernel does not use wchar_t string literals at this point, and
xen does not use wchar_t at all (only efi_char16_t), so the flag
has no effect, but as pointed out by Jan Beulich, adding a wchar_t
string literal would be bad here.

Since wchar_t is always defined as u16, independent of the toolchain
default, always passing -fshort-wchar is correct and lets us
remove the Xen specific hack along with fixing the warning.

Link: https://patchwork.kernel.org/patch/9275217/
Fixes: 971a69db7dc0 ("Xen: don't warn about 2-byte wchar_t in efi")
Signed-off-by: Arnd Bergmann 
Acked-by: David Vrabel 
Signed-off-by: Masahiro Yamada

Merge branch 'stable/for-jens-4.13' of git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen into for-linus

2017-08-16T15:56:34+00:00

Pull xen block changes from Konrad:

Two fixes, both of them spotted by Amazon:

 1) Fix in Xen-blkfront caused by the re-write in 4.8 time-frame.
 2) Fix in the xen_biovec_phys_mergeable which allowed guest
    requests when using NVMe - to slurp up more data than allowed
    leading to an XSA (which has been made public today).

xen: fix bio vec merging

2017-08-15T14:32:49+00:00

The current test for bio vec merging is not fully accurate and can be
tricked into merging bios when certain grant combinations are used.
The result of these malicious bio merges is a bio that extends past
the memory page used by any of the originating bios.

Take into account the following scenario, where a guest creates two
grant references that point to the same mfn, ie: grant 1 -> mfn A,
grant 2 -> mfn A.

These references are then used in a PV block request, and mapped by
the backend domain, thus obtaining two different pfns that point to
the same mfn, pfn B -> mfn A, pfn C -> mfn A.

If those grants happen to be used in two consecutive sectors of a disk
IO operation becoming two different bios in the backend domain, the
checks in xen_biovec_phys_mergeable will succeed, because bfn1 == bfn2
(they both point to the same mfn). However due to the bio merging,
the backend domain will end up with a bio that expands past mfn A into
mfn A + 1.

Fix this by making sure the check in xen_biovec_phys_mergeable takes
into account the offset and the length of the bio, this basically
replicates whats done in __BIOVEC_PHYS_MERGEABLE using mfns (bus
addresses). While there also remove the usage of
__BIOVEC_PHYS_MERGEABLE, since that's already checked by the callers
of xen_biovec_phys_mergeable.

CC: stable@vger.kernel.org
Reported-by: "Jan H. Schönherr" 
Signed-off-by: Roger Pau Monné 
Reviewed-by: Juergen Gross 
Signed-off-by: Konrad Rzeszutek Wilk

xen/events: Fix interrupt lost during irq_disable and irq_enable

2017-08-11T14:46:01+00:00

Here is a device has xen-pirq-MSI interrupt. Dom0 might lost interrupt
during driver irq_disable/irq_enable. Here is the scenario,
 1. irq_disable -> disable_dynirq -> mask_evtchn(irq channel)
 2. dev interrupt raised by HW and Xen mark its evtchn as pending
 3. irq_enable -> startup_pirq -> eoi_pirq ->
    clear_evtchn(channel of irq) -> clear pending status
 4. consume_one_event process the irq event without pending bit assert
    which result in interrupt lost once
 5. No HW interrupt raising anymore.

Now use enable_dynirq for enable_pirq of xen_pirq_chip to remove
eoi_pirq when irq_enable.

Signed-off-by: Liu Shuo 
Reviewed-by: Boris Ostrovsky 
Signed-off-by: Juergen Gross

xen: avoid deadlock in xenbus

2017-08-11T14:45:56+00:00

When starting the xenwatch thread a theoretical deadlock situation is
possible:

xs_init() contains:

    task = kthread_run(xenwatch_thread, NULL, "xenwatch");
    if (IS_ERR(task))
        return PTR_ERR(task);
    xenwatch_pid = task->pid;

And xenwatch_thread() does:

    mutex_lock(&xenwatch_mutex);
    ...
    event->handle->callback();
    ...
    mutex_unlock(&xenwatch_mutex);

The callback could call unregister_xenbus_watch() which does:

    ...
    if (current->pid != xenwatch_pid)
        mutex_lock(&xenwatch_mutex);
    ...

In case a watch is firing before xenwatch_pid could be set and the
callback of that watch unregisters a watch, then a self-deadlock would
occur.

Avoid this by setting xenwatch_pid in xenwatch_thread().

Signed-off-by: Juergen Gross 
Reviewed-by: Boris Ostrovsky 
Signed-off-by: Juergen Gross

xen: dont fiddle with event channel masking in suspend/resume

2017-07-27T17:55:46+00:00

Instead of fiddling with masking the event channels during suspend
and resume handling let do the irq subsystem do its job. It will do
the mask and unmask operations as needed.

Signed-off-by: Juergen Gross 
Acked-by: Thomas Gleixner 
Reviewed-by: Boris Ostrovsky 
Tested-by: Boris Ostrovsky 
Signed-off-by: Juergen Gross

xen: selfballoon: remove unnecessary static in frontswap_selfshrink()

2017-07-27T17:55:41+00:00

Remove unnecessary static on local variables last_frontswap_pages and
tgt_frontswap_pages. Such variables are initialized before being used,
on every execution path throughout the function. The statics have no
benefit and, removing them reduce the code size.

This issue was detected using Coccinelle and the following semantic patch:

@bad exists@
position p;
identifier x;
type T;
@@

static T x@p;
...
x = <+...x...+>

@@
identifier x;
expression e;
type T;
position p != bad.p;
@@

-static
 T x@p;
 ... when != x
     when strict
?x = e;

You can see a significant difference in the code size after executing
the size command, before and after the code change:

before:
   text	   data	    bss	    dec	    hex	filename
   5633	   3452	    384	   9469	   24fd	drivers/xen/xen-selfballoon.o

after:
   text	   data	    bss	    dec	    hex	filename
   5576	   3308	    256	   9140	   23b4	drivers/xen/xen-selfballoon.o

Signed-off-by: Gustavo A. R. Silva 
Reviewed-by: Juergen Gross 
Signed-off-by: Juergen Gross

xen: Drop un-informative message during boot

2017-07-27T17:55:34+00:00

On systems that are not booted as a Xen domain, the xenfs driver prints
the following message during boot.

[    3.460595] xenfs: not registering filesystem on non-xen platform

As the user chose not to boot a Xen domain, this message does not
provide useful information. Drop this message.

Signed-off-by: Punit Agrawal 
Cc: Boris Ostrovsky 
Cc: Juergen Gross 
Reviewed-by: Boris Ostrovsky 
Signed-off-by: Juergen Gross