KVM: PPC: Book3S HV: Fix physical address calculations

This fixes a bug in kvmppc_do_h_enter() where the physical address
for a page can be calculated incorrectly if transparent huge pages
(THP) are active.  Until THP came along, it was true that if we
encountered a large (16M) page in kvmppc_do_h_enter(), then the
associated memslot must be 16M aligned for both its guest physical
address and the userspace address, and the physical address
calculations in kvmppc_do_h_enter() assumed that.  With THP, that
is no longer true.

In the case where we are using MMU notifiers and the page size that
we get from the Linux page tables is larger than the page being mapped
by the guest, we need to fill in some low-order bits of the physical
address.  Without THP, these bits would be the same in the guest
physical address (gpa) and the host virtual address (hva).  With THP,
they can be different, and we need to use the bits from hva rather
than gpa.

In the case where we are not using MMU notifiers, the host physical
address we get from the memslot->arch.slot_phys[] array already
includes the low-order bits down to the PAGE_SIZE level, even if
we are using large pages.  Thus we can simplify the calculation in
this case to just add in the remaining bits in the case where
PAGE_SIZE is 64k and the guest is mapping a 4k page.

The same bug exists in kvmppc_book3s_hv_page_fault().  The basic fix
is to use psize (the page size from the HPTE) rather than pte_size
(the page size from the Linux PTE) when updating the HPTE low word
in r.  That means that pfn needs to be computed to PAGE_SIZE
granularity even if the Linux PTE is a huge page PTE.  That can be
arranged simply by doing the page_to_pfn() before setting page to
the head of the compound page.  If psize is less than PAGE_SIZE,
then we need to make sure we only update the bits from PAGE_SIZE
upwards, in order not to lose any sub-page offset bits in r.
On the other hand, if psize is greater than PAGE_SIZE, we need to
make sure we don't bring in non-zero low order bits in pfn, hence
we mask (pfn << PAGE_SHIFT) with ~(psize - 1).

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
KVM: PPC: Book3S HV: Refine barriers in guest entry/exit

Some users have reported instances of the host hanging with secondary
threads of a core waiting for the primary thread to exit the guest,
and the primary thread stuck in nap mode.  This prompted a review of
the memory barriers in the guest entry/exit code, and this is the
result.  Most of these changes are the suggestions of Dean Burdick
<deanburdick@us.ibm.com>.

The barriers between updating napping_threads and reading the
entry_exit_count on the one hand, and updating entry_exit_count and
reading napping_threads on the other, need to be isync not lwsync,
since we need to ensure that either the napping_threads update or the
entry_exit_count update get seen.  It is not sufficient to order the
load vs. lwarx, as lwsync does; we need to order the load vs. the
stwcx., so we need isync.

In addition, we need a full sync before sending IPIs to wake other
threads from nap, to ensure that the write to the entry_exit_count is
visible before the IPI occurs.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
KVM: PPC: Book3S HV: Make tbacct_lock irq-safe

Lockdep reported that there is a potential for deadlock because
vcpu->arch.tbacct_lock is not irq-safe, and is sometimes taken inside
the rq_lock (run-queue lock) in the scheduler, which is taken within
interrupts.  The lockdep splat looks like:

======================================================
[ INFO: HARDIRQ-safe -> HARDIRQ-unsafe lock order detected ]
3.12.0-rc5-kvm+ #8 Not tainted
------------------------------------------------------
qemu-system-ppc/4803 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire:
(&(&vcpu->arch.tbacct_lock)->rlock){+.+...}, at: [<c0000000000947ac>] .kvmppc_core_vcpu_put_hv+0x2c/0xa0

and this task is already holding:
(&rq->lock){-.-.-.}, at: [<c000000000ac16c0>] .__schedule+0x180/0xaa0
which would create a new lock dependency:
(&rq->lock){-.-.-.} -> (&(&vcpu->arch.tbacct_lock)->rlock){+.+...}

but this new dependency connects a HARDIRQ-irq-safe lock:
(&rq->lock){-.-.-.}
... which became HARDIRQ-irq-safe at:
 [<c00000000013797c>] .lock_acquire+0xbc/0x190
 [<c000000000ac3c74>] ._raw_spin_lock+0x34/0x60
 [<c0000000000f8564>] .scheduler_tick+0x54/0x180
 [<c0000000000c2610>] .update_process_times+0x70/0xa0
 [<c00000000012cdfc>] .tick_periodic+0x3c/0xe0
 [<c00000000012cec8>] .tick_handle_periodic+0x28/0xb0
 [<c00000000001ef40>] .timer_interrupt+0x120/0x2e0
 [<c000000000002868>] decrementer_common+0x168/0x180
 [<c0000000001c7ca4>] .get_page_from_freelist+0x924/0xc10
 [<c0000000001c8e00>] .__alloc_pages_nodemask+0x200/0xba0
 [<c0000000001c9eb8>] .alloc_pages_exact_nid+0x68/0x110
 [<c000000000f4c3ec>] .page_cgroup_init+0x1e0/0x270
 [<c000000000f24480>] .start_kernel+0x3e0/0x4e4
 [<c000000000009d30>] .start_here_common+0x20/0x70

to a HARDIRQ-irq-unsafe lock:
(&(&vcpu->arch.tbacct_lock)->rlock){+.+...}
... which became HARDIRQ-irq-unsafe at:
...  [<c00000000013797c>] .lock_acquire+0xbc/0x190
 [<c000000000ac3c74>] ._raw_spin_lock+0x34/0x60
 [<c0000000000946ac>] .kvmppc_core_vcpu_load_hv+0x2c/0x100
 [<c00000000008394c>] .kvmppc_core_vcpu_load+0x2c/0x40
 [<c000000000081000>] .kvm_arch_vcpu_load+0x10/0x30
 [<c00000000007afd4>] .vcpu_load+0x64/0xd0
 [<c00000000007b0f8>] .kvm_vcpu_ioctl+0x68/0x730
 [<c00000000025530c>] .do_vfs_ioctl+0x4dc/0x7a0
 [<c000000000255694>] .SyS_ioctl+0xc4/0xe0
 [<c000000000009ee4>] syscall_exit+0x0/0x98

Some users have reported this deadlock occurring in practice, though
the reports have been primarily on 3.10.x-based kernels.

This fixes the problem by making tbacct_lock be irq-safe.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
KVM: PPC: Book3S HV: Take SRCU read lock around kvm_read_guest() call

Running a kernel with CONFIG_PROVE_RCU=y yields the following diagnostic:

===============================
[ INFO: suspicious RCU usage. ]
3.12.0-rc5-kvm+ #9 Not tainted
-------------------------------

include/linux/kvm_host.h:473 suspicious rcu_dereference_check() usage!

other info that might help us debug this:

rcu_scheduler_active = 1, debug_locks = 0
1 lock held by qemu-system-ppc/4831:

stack backtrace:
CPU: 28 PID: 4831 Comm: qemu-system-ppc Not tainted 3.12.0-rc5-kvm+ #9
Call Trace:
[c000000be462b2a0] [c00000000001644c] .show_stack+0x7c/0x1f0 (unreliable)
[c000000be462b370] [c000000000ad57c0] .dump_stack+0x88/0xb4
[c000000be462b3f0] [c0000000001315e8] .lockdep_rcu_suspicious+0x138/0x180
[c000000be462b480] [c00000000007862c] .gfn_to_memslot+0x13c/0x170
[c000000be462b510] [c00000000007d384] .gfn_to_hva_prot+0x24/0x90
[c000000be462b5a0] [c00000000007d420] .kvm_read_guest_page+0x30/0xd0
[c000000be462b630] [c00000000007d528] .kvm_read_guest+0x68/0x110
[c000000be462b6e0] [c000000000084594] .kvmppc_rtas_hcall+0x34/0x180
[c000000be462b7d0] [c000000000097934] .kvmppc_pseries_do_hcall+0x74/0x830
[c000000be462b880] [c0000000000990e8] .kvmppc_vcpu_run_hv+0xff8/0x15a0
[c000000be462b9e0] [c0000000000839cc] .kvmppc_vcpu_run+0x2c/0x40
[c000000be462ba50] [c0000000000810b4] .kvm_arch_vcpu_ioctl_run+0x54/0x1b0
[c000000be462bae0] [c00000000007b508] .kvm_vcpu_ioctl+0x478/0x730
[c000000be462bca0] [c00000000025532c] .do_vfs_ioctl+0x4dc/0x7a0
[c000000be462bd80] [c0000000002556b4] .SyS_ioctl+0xc4/0xe0
[c000000be462be30] [c000000000009ee4] syscall_exit+0x0/0x98

To fix this, we take the SRCU read lock around the kvmppc_rtas_hcall()
call.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
powerpc: kvm: fix rare but potential deadlock scene

Since kvmppc_hv_find_lock_hpte() is called from both virtmode and
realmode, so it can trigger the deadlock.

Suppose the following scene:

Two physical cpuM, cpuN, two VM instances A, B, each VM has a group of
vcpus.

If on cpuM, vcpu_A_1 holds bitlock X (HPTE_V_HVLOCK), then is switched
out, and on cpuN, vcpu_A_2 try to lock X in realmode, then cpuN will be
caught in realmode for a long time.

What makes things even worse if the following happens,
  On cpuM, bitlockX is hold, on cpuN, Y is hold.
  vcpu_B_2 try to lock Y on cpuM in realmode
  vcpu_A_2 try to lock X on cpuN in realmode

Oops! deadlock happens

Signed-off-by: Liu Ping Fan <pingfank@linux.vnet.ibm.com>
Reviewed-by: Paul Mackerras <paulus@samba.org>
CC: stable@vger.kernel.org
Signed-off-by: Alexander Graf <agraf@suse.de>
ARM: shmobile: lager: phy fixup needs CONFIG_PHYLIB

Do not build the phy fixup unless CONFIG_PHYLIB is enabled.

Other than not being useful it is also not possible to link
the code under this condition as phy_register_fixup_for_id(),
mdiobus_read() and mdiobus_write() are absent.

arch/arm/mach-shmobile/built-in.o: In function `lager_ksz8041_fixup':
board-lager.c:(.text+0xb8): undefined reference to `mdiobus_read'
board-lager.c:(.text+0xd4): undefined reference to `mdiobus_write'
arch/arm/mach-shmobile/built-in.o: In function `lager_init':
board-lager.c:(.init.text+0xafc): undefined reference to `phy_register_fixup_for_id'

This problem was introduced by 48c8b96f21817aad
("ARM: shmobile: Lager: add Micrel KSZ8041 PHY fixup")

Cc: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
irqchip: renesas-intc-irqpin: Fix register bitfield shift calculation

The SENSE register bitfield position is incorrectly computed for SoCs
that use 2-bit IRQ sense fields. Fix it.

This has been tested on the Marzen (H1) and Bockw (M1) boards.

This bug has been present since the renesas-intc-irqpin driver was
introduced by 443580486e3b9657 ("irqchip: Renesas INTC External IRQ pin
driver") in v3.10-rc1.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Acked-by: Magnus Damm <damm@opensource.se>
Tested-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
ARM: shmobile: r8a7790: Fix GPIO resources in DTS

The r8a7790 GPIO resources are currently incorrect. Fix that
by making them match the English r8a7790 v0.6 data sheet.

Tested with GPIO LED using Lager DT reference.

This problem has been present since GPIOs were added to the r8a7790 SoC by
f98e10c88aa95bf7 ("ARM: shmobile: r8a7790: Add GPIO controller devices to
device tree") in v3.12-rc1.

Signed-off-by: Magnus Damm <damm@opensource.se>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
bcache: fix sparse non static symbol warning

Fixes the following sparse warning:

drivers/md/bcache/btree.c:2220:5: warning:
 symbol 'btree_insert_fn' was not declared. Should it be static?

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Kent Overstreet <kmo@daterainc.com>
libata: add ATA_HORKAGE_BROKEN_FPDMA_AA quirk for Seagate Momentus SpinPoint M8

We've received multiple reports in Fedora via (BZ 907193)
that the Seagate Momentus SpinPoint M8 errors out when enabling AA:
[    2.555905] ata2.00: failed to enable AA (error_mask=0x1)
[    2.568482] ata2.00: failed to enable AA (error_mask=0x1)

Add the ATA_HORKAGE_BROKEN_FPDMA_AA for this specific harddisk.

Reported-by: Nicholas <arealityfarbetween@googlemail.com>
Signed-off-by: Michele Baldessari <michele@acksyn.org>
Tested-by: Nicholas <arealityfarbetween@googlemail.com>
Acked-by: Alan Cox <gnomes@lxorguk.ukuu.org.uk>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: stable@vger.kernel.org
ext4: call ext4_error_inode() if jbd2_journal_dirty_metadata() fails

While it's true that errors can only happen if there is a bug in
jbd2_journal_dirty_metadata(), if a bug does happen, we need to halt
the kernel or remount the file system read-only in order to avoid
further data loss.  The ext4_journal_abort_handle() function doesn't
do any of this, and while it's likely that this call (since it doesn't
adjust refcounts) will likely result in the file system eventually
deadlocking since the current transaction will never be able to close,
it's much cleaner to call let ext4's error handling system deal with
this situation.

There's a separate bug here which is that if certain jbd2 errors
errors occur and file system is mounted errors=continue, the file
system will probably eventually end grind to a halt as described
above.  But things have been this way in a long time, and usually when
we have these sorts of errors it's pretty much a disaster --- and
that's why the jbd2 layer aggressively retries memory allocations,
which is the most likely cause of these jbd2 errors.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: stable@vger.kernel.org
ahci: imx: Explicitly clear IMX6Q_GPR13_SATA_MPLL_CLK_EN

We must clear this IMX6Q_GPR13_SATA_MPLL_CLK_EN bit on i.MX6Q, otherwise
Linux will fail to find the attached drive on some boards.

This entire fix was:
Reported-by: Eric Nelson <eric.nelson@boundarydevices.com>

Signed-off-by: Marek Vasut <marex@denx.de>
Reviewed-by: Shawn Guo <shawn.guo@linaro.org>
Cc: Richard Zhu <r65037@freescale.com>
Cc: Linux-IDE <linux-ide@vger.kernel.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: stable@vger.kernel.org
ext4: fix use-after-free in ext4_mb_new_blocks

ext4_mb_put_pa should hold pa->pa_lock before accessing pa->pa_count.
While ext4_mb_use_preallocated checks pa->pa_deleted first and then
increments pa->count later, ext4_mb_put_pa decrements pa->pa_count
before holding pa->pa_lock and then sets pa->pa_deleted.

* Free sequence
ext4_mb_put_pa (1):		atomic_dec_and_test pa->pa_count
ext4_mb_put_pa (2):		lock pa->pa_lock
ext4_mb_put_pa (3):			check pa->pa_deleted
ext4_mb_put_pa (4):			set pa->pa_deleted=1
ext4_mb_put_pa (5):		unlock pa->pa_lock
ext4_mb_put_pa (6):		remove pa from a list
ext4_mb_pa_callback:		free pa

* Use sequence
ext4_mb_use_preallocated (1):	iterate over preallocation
ext4_mb_use_preallocated (2):	lock pa->pa_lock
ext4_mb_use_preallocated (3):		check pa->pa_deleted
ext4_mb_use_preallocated (4):		increase pa->pa_count
ext4_mb_use_preallocated (5):	unlock pa->pa_lock
ext4_mb_release_context:	access pa

* Use-after-free sequence
[initial status]		<pa->pa_deleted = 0, pa_count = 1>
ext4_mb_use_preallocated (1):	iterate over preallocation
ext4_mb_use_preallocated (2):	lock pa->pa_lock
ext4_mb_use_preallocated (3):		check pa->pa_deleted
ext4_mb_put_pa (1):		atomic_dec_and_test pa->pa_count
[pa_count decremented]		<pa->pa_deleted = 0, pa_count = 0>
ext4_mb_use_preallocated (4):		increase pa->pa_count
[pa_count incremented]		<pa->pa_deleted = 0, pa_count = 1>
ext4_mb_use_preallocated (5):	unlock pa->pa_lock
ext4_mb_put_pa (2):		lock pa->pa_lock
ext4_mb_put_pa (3):			check pa->pa_deleted
ext4_mb_put_pa (4):			set pa->pa_deleted=1
[race condition!]		<pa->pa_deleted = 1, pa_count = 1>
ext4_mb_put_pa (5):		unlock pa->pa_lock
ext4_mb_put_pa (6):		remove pa from a list
ext4_mb_pa_callback:		free pa
ext4_mb_release_context:	access pa

AddressSanitizer has detected use-after-free in ext4_mb_new_blocks
Bug report: http://goo.gl/rG1On3

Signed-off-by: Junho Ryu <jayr@google.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@vger.kernel.org
ext4: check for overlapping extents in ext4_valid_extent_entries()

A corrupted ext4 may have out of order leaf extents, i.e.

extent: lblk 0--1023, len 1024, pblk 9217, flags: LEAF UNINIT
extent: lblk 1000--2047, len 1024, pblk 10241, flags: LEAF UNINIT
             ^^^^ overlap with previous extent

Reading such extent could hit BUG_ON() in ext4_es_cache_extent().

	BUG_ON(end < lblk);

The problem is that __read_extent_tree_block() tries to cache holes as
well but assumes 'lblk' is greater than 'prev' and passes underflowed
length to ext4_es_cache_extent(). Fix it by checking for overlapping
extents in ext4_valid_extent_entries().

I hit this when fuzz testing ext4, and am able to reproduce it by
modifying the on-disk extent by hand.

Also add the check for (ee_block + len - 1) in ext4_valid_extent() to
make sure the value is not overflow.

Ran xfstests on patched ext4 and no regression.

Cc: Lukáš Czerner <lczerner@redhat.com>
Signed-off-by: Eryu Guan <guaneryu@gmail.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Cc: stable@vger.kernel.org
ext2: Fix oops in ext2_get_block() called from ext2_quota_write()

ext2_quota_write() doesn't properly setup bh it passes to
ext2_get_block() and thus we hit assertion BUG_ON(maxblocks == 0) in
ext2_get_blocks() (or we could actually ask for mapping arbitrary number
of blocks depending on whatever value was on stack).

Fix ext2_quota_write() to properly fill in number of blocks to map.

CC: stable@vger.kernel.org # >= 2.6.12
Reviewed-by: "Theodore Ts'o" <tytso@mit.edu>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reported-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Jan Kara <jack@suse.cz>
XEN: Grant table address, xen_hvm_resume_frames, is a phys_addr not a pfn

From: Eric Trudeau <etrudeau@broadcom.com>

xen_hvm_resume_frames stores the physical address of the grant table.
englighten.c was incorrectly setting it as if it was a page frame number.
This caused the table to be mapped into the guest at an unexpected physical
address.

Additionally, a warning is improved to include the grant table address which
failed in xen_remap.

Signed-off-by: Eric Trudeau <etrudeau@broadcom.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
virtio_balloon: update_balloon_size(): update correct field

According to the virtio spec, the device configuration field
that should be updated after an inflation or deflation
operation is the 'actual' field, not the 'num_pages' one.

Commit 855e0c5288177bcb193f6f6316952d2490478e1c swapped them
in update_balloon_size(). Fix it.

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Fixes: 855e0c5288177bcb193f6f6316952d2490478e1c
percpu: fix spurious sparse warnings from DEFINE_PER_CPU()

When CONFIG_DEBUG_FORCE_WEAK_PER_CPU or CONFIG_ARCH_NEEDS_WEAK_PER_CPU
is set, DEFINE_PER_CPU() explodes into cryptic series of definitions
to still allow using "static" for percpu variables while keeping all
per-cpu symbols unique in the kernel image which is required for weak
symbols.  This ultimately converts the actual symbol to global whether
DEFINE_PER_CPU() is prefixed with static or not.

Unfortunately, the macro forgot to add explicit extern declartion of
the actual symbol ending up defining global symbol without preceding
declaration for static definitions which naturally don't have matching
DECLARE_PER_CPU().  The only ill effect is triggering of the following
warnings.

 fs/inode.c:74:8: warning: symbol 'nr_inodes' was not declared. Should it be static?
 fs/inode.c:75:8: warning: symbol 'nr_unused' was not declared. Should it be static?

Fix it by adding extern declaration in the DEFINE_PER_CPU() macro.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Wanlong Gao <gaowanlong@cn.fujitsu.com>
Tested-by: Wanlong Gao <gaowanlong@cn.fujitsu.com>
block: fix memory leaks on unplugging block device

All objects, which are allocated in blk_mq_register_disk, must be
released in blk_mq_unregister_disk.

I use a KVM virtual machine and virtio disk to reproduce this issue.

kmemleak: 18 new suspected memory leaks (see /sys/kernel/debug/kmemleak)
$ cat /sys/kernel/debug/kmemleak | head -n 30
unreferenced object 0xffff8800b6636150 (size 8):
  comm "kworker/0:2", pid 65, jiffies 4294809903 (age 86.358s)
  hex dump (first 8 bytes):
    76 69 72 74 69 6f 34 00                          virtio4.
  backtrace:
    [<ffffffff8165d41e>] kmemleak_alloc+0x4e/0xb0
    [<ffffffff8118cfc5>] __kmalloc_track_caller+0xf5/0x260
    [<ffffffff81155b11>] kstrdup+0x31/0x60
    [<ffffffff812242be>] sysfs_new_dirent+0x2e/0x140
    [<ffffffff81224678>] create_dir+0x38/0xe0
    [<ffffffff812249e3>] sysfs_create_dir_ns+0x73/0xc0
    [<ffffffff8130dfa9>] kobject_add_internal+0xc9/0x340
    [<ffffffff8130e535>] kobject_add+0x65/0xb0
    [<ffffffff813f34f8>] device_add+0x128/0x660
    [<ffffffff813f3a4a>] device_register+0x1a/0x20
    [<ffffffff813ae6f8>] register_virtio_device+0x98/0xe0
    [<ffffffff813b0cce>] virtio_pci_probe+0x12e/0x1c0
    [<ffffffff81340675>] local_pci_probe+0x45/0xa0
    [<ffffffff81341a51>] pci_device_probe+0x121/0x130
    [<ffffffff813f67f7>] driver_probe_device+0x87/0x390
    [<ffffffff813f6b3b>] __device_attach+0x3b/0x40
unreferenced object 0xffff8800b65aa1d8 (size 144):

Fixes: 320ae51feed5 (blk-mq: new multi-queue block IO queueing mechanism)
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
xen: privcmd: do not return pages which we have failed to unmap

This failure represents a hypervisor issue, but if it does occur then nothing
good can come of returning pages which still refer to a foreign owned page
into the general allocation pool.

Instead we are forced to leak them. Log that we have done so.

The potential for failure only exists for autotranslated guest (e.g. ARM and
x86 PVH).

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>