A new helper, defrag_one_range(), is introduced to defrag one range.

This function will mostly prepare the needed pages and extent status for
defrag_one_locked_target().

As we can only have a consistent view of extent map with page and extent
bits locked, we need to re-check the range passed in to get a real
target list for defrag_one_locked_target().

Since defrag_collect_targets() will call defrag_lookup_extent() and lock
extent range, we also need to teach those two functions to skip extent
lock.  Thus new parameter, @locked, is introduced to skip extent lock if
the caller has already locked the range.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

A new helper, defrag_one_locked_target(), introduced to do the real part
of defrag.

The caller needs to ensure both page and extents bits are locked, and no
ordered extent exists for the range, and all writeback is finished.

The core defrag part is pretty straight-forward:

- Reserve space
- Set extent bits to defrag
- Update involved pages to be dirty
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Introduce a helper, defrag_collect_targets(), to collect all possible
targets to be defragged.

This function will not consider things like max_sectors_to_defrag, thus
caller should be responsible to ensure we don't exceed the limit.

This function will be the first stage of later defrag rework.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

In cluster_pages_for_defrag(), we have complex code block inside one
for() loop.

The code block is to prepare one page for defrag, this will ensure:

- The page is locked and set up properly.
- No ordered extent exists in the page range.
- The page is uptodate.

This behavior is pretty common and will be reused by later defrag
rework.

So factor out the code into its own helper, defrag_prepare_one_page(),
for later usage, and cleanup the code by a little.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

When testing subpage defrag support, I always find some strange inode
nbytes error, after a lot of debugging, it turns out that
defrag_lookup_extent() is using PAGE_SIZE as size for
lookup_extent_mapping().

Since lookup_extent_mapping() is calling __lookup_extent_mapping() with
@strict == 1, this means any extent map smaller than one page will be
ignored, prevent subpage defrag to grab a correct extent map.

There are quite some PAGE_SIZE usage in ioctl.c, but most of them are
correct usages, and can be one of the following cases:

- ioctl structure size check
  We want ioctl structure to be contained inside one page.

- real page operations

The remaining cases in defrag_lookup_extent() and
check_defrag_in_cache() will be addressed in this patch.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

In function cluster_pages_for_defrag() we have a window where we unlock
page, either start the ordered range or read the content from disk.

When we re-lock the page, we need to make sure it still has the correct
page->private for subpage.

Thus add the extra PagePrivate check here to handle subpage cases
properly.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Currently btrfs_defrag_file() accepts both "struct inode" and "struct
file" as parameter.  We can easily grab "struct inode" from "struct
file" using file_inode() helper.

The reason why we need "struct file" is just to re-use its f_ra.

Change this to pass "struct file_ra_state" parameter, so that it's more
clear what we really want.  Since we're here, also add some comments on
the function btrfs_defrag_file().
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

btrfs_chunk_readonly() checks if the given chunk is writeable. It
returns 1 for readonly, and 0 for writeable. So the return argument type
bool shall suffice instead of the current type int.

Also, rename btrfs_chunk_readonly() to btrfs_chunk_writeable() as we
check if the bg is writeable, and helps to keep the logic at the parent
function simpler to understand.
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Fix a warning reported by smatch that ret could be returned without
initialized.  The dedupe operations are supposed to to return 0 for a 0
length range but the caller does not pass olen == 0. To keep this
behaviour and also fix the warning initialize ret to 0.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Sidong Yang <realwakka@gmail.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Currently we use u16 bitmap to make 4k sectorsize work for 64K page
size.

But this u16 bitmap is not large enough to contain larger page size like
128K, nor is space efficient for 16K page size.

To handle both cases, here we pack all subpage bitmaps into a larger
bitmap, now btrfs_subpage::bitmaps[] will be the ultimate bitmap for
subpage usage.

Each sub-bitmap will has its start bit number recorded in
btrfs_subpage_info::*_start, and its bitmap length will be recorded in
btrfs_subpage_info::bitmap_nr_bits.

All subpage bitmap operations will be converted from using direct u16
operations to bitmap operations, with above *_start calculated.

For 64K page size with 4K sectorsize, this should not cause much
difference.

While for 16K page size, we will only need 1 unsigned long (u32) to
store all the bitmaps, which saves quite some space.

Furthermore, this allows us to support larger page size like 128K and
258K.
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Currently we use fixed size u16 bitmap for subpage bitmap.  This is fine
for 4K sectorsize with 64K page size.

But for 4K sectorsize and larger page size, the bitmap is too small,
while for smaller page size like 16K, u16 bitmaps waste too much space.

Here we introduce a new helper structure, btrfs_subpage_bitmap_info, to
record the proper bitmap size, and where each bitmap should start at.

By this, we can later compact all subpage bitmaps into one u32 bitmap.
This patch is the first step.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

The existing calling convention of btrfs_alloc_subpage() is pretty
awful.  Change it to a more common pattern by returning struct
btrfs_subpage directly and let the caller to determine if the call
succeeded.
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

There are two call sites of btrfs_alloc_subpage():

- btrfs_attach_subpage()
  We have ensured sectorsize is smaller than PAGE_SIZE

- alloc_extent_buffer()
  We call btrfs_alloc_subpage() unconditionally.

The alloc_extent_buffer() forces us to check the sectorsize size against
page size inside btrfs_alloc_subpage().

Since the function name, btrfs_alloc_subpage(), already indicates it
should only get called for subpage cases, do the check in
alloc_extent_buffer() and add an ASSERT() in btrfs_alloc_subpage().
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Update it since commit 944d3f9f ("btrfs: switch seed device to
list api") did conversion from fs_devices::seed to fs_devices::seed_list.
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Su Yue <l@damenly.su>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

There is no need for the variable ret after d66105cfa873 ("btrfs:
allocate btrfs_ioctl_quota_rescan_args on stack"), remove it.
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

The out label is being overused, we can simply return if the condition
permits.

No functional changes.
Reviewed-by: Su Yue <l@damenly.su>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Marcos Paulo de Souza <mpdesouza@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

The user facing function used to allocate new chunks is
btrfs_chunk_alloc, unfortunately there is yet another similar sounding
function - btrfs_alloc_chunk. This creates confusion, especially since
the latter function can be considered "private" in the sense that it
implements the first stage of chunk creation and as such is called by
btrfs_chunk_alloc.

To avoid the awkwardness that comes with having similarly named but
distinctly different in their purpose function rename btrfs_alloc_chunk
to btrfs_create_chunk, given that the main purpose of this function is
to orchestrate the whole process of allocating a chunk - reserving space
into devices, deciding on characteristics of the stripe size and
creating the in-memory structures.
Reviewed-by: Filipe Manana <fdmanana@suse.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Nikolay Borisov <nborisov@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

Commit 11086054 ("mm/secretmem: use refcount_t instead of atomic_t")
attempted to fix the problem of secretmem_users wrapping to zero and
allowing suspend once again.

But it was reverted in commit 87066fdd ("Revert 'mm/secretmem: use
refcount_t instead of atomic_t'") because of the problems it caused - a
refcount_t was not semantically the right type to use.

Instead prevent secretmem_users from wrapping to zero by forbidding new
users if the number of users has wrapped from positive to negative.
This stops a long way short of reaching the necessary 4 billion users
where it wraps to zero again, so there's no need to be clever with
special anti-wrap types or checking the return value from atomic_inc().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Jordy Zomer <jordy@pwning.systems>
Cc: Kees Cook <keescook@chromium.org>,
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Commit efafec27 ("spi: Fix tegra20 build with CONFIG_PM=n") already
fixed the build without PM support once.  There was an alternative fix
by Guenter in commit 2bab9409 ("spi: tegra20-slink: Declare runtime
suspend and resume functions conditionally"), and Mark then merged the
two correctly in ffb1e76f ("Merge tag 'v5.15-rc2' into spi-5.15").

But for some inexplicable reason, Mark then merged things _again_ in
commit 59c4e190 ("Merge tag 'v5.15-rc3' into spi-5.15"), and screwed
things up at that point, and the __maybe_unused attribute on
tegra_slink_runtime_resume() went missing.

Reinstate it, so that alpha (and other architectures without PM support)
builds cleanly again.

Btw, this is another prime example of how random back-merges are not
good.  Just don't do them.  Subsystem developers should not merge my
tree in any normal circumstances.  Both of those merge commits pointed
to above are bad: even the one that got the merge result right doesn't
even mention _why_ it was done, and the one that got it wrong is
obviously broken.
Reported-by: Guenter Roeck <linux@roeck-us.net>
Cc: Mark Brown <broonie@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull ARM fixes from Russell King:

 - Fix clang-related relocation warning in futex code

 - Fix incorrect use of get_kernel_nofault()

 - Fix bad code generation in __get_user_check() when kasan is enabled

 - Ensure TLB function table is correctly aligned

 - Remove duplicated string function definitions in decompressor

 - Fix link-time orphan section warnings

 - Fix old-style function prototype for arch_init_kprobes()

 - Only warn about XIP address when not compile testing

 - Handle BE32 big endian for keystone2 remapping

* tag 'for-linus' of git://git.armlinux.org.uk/~rmk/linux-arm:
  ARM: 9148/1: handle CONFIG_CPU_ENDIAN_BE32 in arch/arm/kernel/head.S
  ARM: 9141/1: only warn about XIP address when not compile testing
  ARM: 9139/1: kprobes: fix arch_init_kprobes() prototype
  ARM: 9138/1: fix link warning with XIP + frame-pointer
  ARM: 9134/1: remove duplicate memcpy() definition
  ARM: 9133/1: mm: proc-macros: ensure *_tlb_fns are 4B aligned
  ARM: 9132/1: Fix __get_user_check failure with ARM KASAN images
  ARM: 9125/1: fix incorrect use of get_kernel_nofault()
  ARM: 9122/1: select HAVE_FUTEX_CMPXCHG

Pull libata fix from Damien Le Moal:
 "A single fix in this pull request addressing an invalid error code
  return in the sata_mv driver (from Zheyu)"

* tag 'libata-5.15-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/dlemoal/libata:
  ata: sata_mv: Fix the error handling of mv_chip_id()

Pull pin control fixes from Linus Walleij:
 "Some late pin control fixes, the most generally annoying will probably
  be the AMD IRQ storm fix affecting the Microsoft surface.

  Summary:

   - Three fixes pertaining to Broadcom DT bindings. Some stuff didn't
     work out as inteded, we need to back out

   - A resume bug fix in the STM32 driver

   - Disable and mask the interrupts on probe in the AMD pinctrl driver,
     affecting Microsoft surface"

* tag 'pinctrl-v5.15-3' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl:
  pinctrl: amd: disable and mask interrupts on probe
  pinctrl: stm32: use valid pin identifier in stm32_pinctrl_resume()
  Revert "pinctrl: bcm: ns: support updated DT binding as syscon subnode"
  dt-bindings: pinctrl: brcm,ns-pinmux: drop unneeded CRU from example
  Revert "dt-bindings: pinctrl: bcm4708-pinmux: rework binding to use syscon"

My intel-ixp42x-welltech-epbx100 no longer boot since 4.14.
This is due to commit 463dbba4 ("ARM: 9104/2: Fix Keystone 2 kernel
mapping regression")
which forgot to handle CONFIG_CPU_ENDIAN_BE32 as possible BE config.
Suggested-by: Krzysztof Hałasa <khalasa@piap.pl>
Fixes: 463dbba4 ("ARM: 9104/2: Fix Keystone 2 kernel mapping regression")
Signed-off-by: Corentin Labbe <clabbe.montjoie@gmail.com>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>

mv_init_host() propagates the value returned by mv_chip_id() which in turn
gets propagated by mv_pci_init_one() and hits local_pci_probe().

During the process of driver probing, the probe function should return < 0
for failure, otherwise, the kernel will treat value > 0 as success.

Since this is a bug rather than a recoverable runtime error we should
use dev_alert() instead of dev_err().
Signed-off-by: Zheyu Ma <zheyuma97@gmail.com>
Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>

This reverts commit 11086054.

Converting the "secretmem_users" counter to a refcount is incorrect,
because a refcount is special in zero and can't just be incremented (but
a count of users is not, and "no users" is actually perfectly valid and
not a sign of a free'd resource).

Reported-by: syzbot+75639e6a0331cd61d3e2@syzkaller.appspotmail.com
Cc: Jordy Zomer <jordy@pwning.systems>
Cc: Kees Cook <keescook@chromium.org>,
Cc: Jordy Zomer <jordy@jordyzomer.github.io>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Pull autofs fix from Al Viro:
 "Fix for a braino of mine (in getting rid of open-coded
  dentry_path_raw() in autofs a couple of cycles ago).

  Mea culpa...  Obvious -stable fodder"

* 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  autofs: fix wait name hash calculation in autofs_wait()

Pull scheduler fix from Borislav Petkov:
 "Reset clang's Shadow Call Stack on hotplug to prevent it from
  overflowing"

* tag 'sched_urgent_for_v5.15_rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/scs: Reset the shadow stack when idle_task_exit

Pull x86 fix from Borislav Petkov:
 "A single change adding Dave Hansen to our maintainers team"

* tag 'x86_urgent_for_v5.15_rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  MAINTAINERS: Add Dave Hansen to the x86 maintainer team

Pull ksmbd fixes from Steve French:
 "Ten fixes for the ksmbd kernel server, for improved security and
  additional buffer overflow checks:

   - a security improvement to session establishment to reduce the
     possibility of dictionary attacks

   - fix to ensure that maximum i/o size negotiated in the protocol is
     not less than 64K and not more than 8MB to better match expected
     behavior

   - fix for crediting (flow control) important to properly verify that
     sufficient credits are available for the requested operation

   - seven additional buffer overflow, buffer validation checks"

* tag '5.15-rc6-ksmbd-fixes' of git://git.samba.org/ksmbd:
  ksmbd: add buffer validation in session setup
  ksmbd: throttle session setup failures to avoid dictionary attacks
  ksmbd: validate OutputBufferLength of QUERY_DIR, QUERY_INFO, IOCTL requests
  ksmbd: validate credit charge after validating SMB2 PDU body size
  ksmbd: add buffer validation for smb direct
  ksmbd: limit read/write/trans buffer size not to exceed 8MB
  ksmbd: validate compound response buffer
  ksmbd: fix potencial 32bit overflow from data area check in smb2_write
  ksmbd: improve credits management
  ksmbd: add validation in smb2_ioctl

Pull SCSI fixes from James Bottomley:
 "Ten fixes, seven of which are in drivers.

  The core fixes are one to fix a potential crash on resume, one to sort
  out our reference count releases to avoid releasing in-use modules and
  one to adjust the cmd per lun calculation to avoid an overflow in
  hyper-v"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: ufs: ufs-pci: Force a full restore after suspend-to-disk
  scsi: qla2xxx: Fix unmap of already freed sgl
  scsi: qla2xxx: Fix a memory leak in an error path of qla2x00_process_els()
  scsi: qla2xxx: Return -ENOMEM if kzalloc() fails
  scsi: sd: Fix crashes in sd_resume_runtime()
  scsi: mpi3mr: Fix duplicate device entries when scanning through sysfs
  scsi: core: Put LLD module refcnt after SCSI device is released
  scsi: storvsc: Fix validation for unsolicited incoming packets
  scsi: iscsi: Fix set_param() handling
  scsi: core: Fix shost->cmd_per_lun calculation in scsi_add_host_with_dma()

Pull block fixes from Jens Axboe:
 "Fix for the cgroup code not ussing irq safe stats updates, and one fix
  for an error handling condition in add_partition()"

* tag 'block-5.15-2021-10-22' of git://git.kernel.dk/linux-block:
  block: fix incorrect references to disk objects
  blk-cgroup: blk_cgroup_bio_start() should use irq-safe operations on blkg->iostat_cpu

Pull io_uring fixes from Jens Axboe:
 "Two fixes for the max workers limit API that was introduced this
  series: one fix for an issue with that code, and one fixing a linked
  timeout regression in this series"

* tag 'io_uring-5.15-2021-10-22' of git://git.kernel.dk/linux-block:
  io_uring: apply worker limits to previous users
  io_uring: fix ltimeout unprep
  io_uring: apply max_workers limit to all future users
  io-wq: max_worker fixes

Pull fuse fixes from Miklos Szeredi:
 "Syzbot discovered a race in case of reusing the fuse sb (introduced in
  this cycle).

  Fix it by doing the s_fs_info initialization at the proper place"

* tag 'fuse-fixes-5.15-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse:
  fuse: clean up error exits in fuse_fill_super()
  fuse: always initialize sb->s_fs_info
  fuse: clean up fuse_mount destruction
  fuse: get rid of fuse_put_super()
  fuse: check s_root when destroying sb

Merge tag 'hyperv-fixes-signed-20211022' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux

Pull hyper-v fix from Wei Liu:

 - Fix vmbus ARM64 build (Arnd Bergmann)

* tag 'hyperv-fixes-signed-20211022' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux:
  hyperv/vmbus: include linux/bitops.h

On arm64 randconfig builds, hyperv sometimes fails with this
error:

In file included from drivers/hv/hv_trace.c:3:
In file included from drivers/hv/hyperv_vmbus.h:16:
In file included from arch/arm64/include/asm/sync_bitops.h:5:
arch/arm64/include/asm/bitops.h:11:2: error: only <linux/bitops.h> can be included directly
In file included from include/asm-generic/bitops/hweight.h:5:
include/asm-generic/bitops/arch_hweight.h:9:9: error: implicit declaration of function '__sw_hweight32' [-Werror,-Wimplicit-function-declaration]
include/asm-generic/bitops/atomic.h:17:7: error: implicit declaration of function 'BIT_WORD' [-Werror,-Wimplicit-function-declaration]

Include the correct header first.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20211018131929.2260087-1-arnd@kernel.orgSigned-off-by: Wei Liu <wei.liu@kernel.org>

Pull ACPI fixes from Rafael Wysocki:
 "These fix two regressions, one related to ACPI power resources
  management and one that broke ACPI tools compilation.

  Specifics:

   - Stop turning off unused ACPI power resources in an unknown state to
     address a regression introduced during the 5.14 cycle (Rafael
     Wysocki).

   - Fix an ACPI tools build issue introduced recently when the minimal
     stdarg.h was added (Miguel Bernal Marin)"

* tag 'acpi-5.15-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  ACPI: PM: Do not turn off power resources in unknown state
  ACPI: tools: fix compilation error

Pull more x86 kvm fixes from Paolo Bonzini:

 - Cache coherency fix for SEV live migration

 - Fix for instruction emulation with PKU

 - fixes for rare delaying of interrupt delivery

 - fix for SEV-ES buffer overflow

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: SEV-ES: go over the sev_pio_data buffer in multiple passes if needed
  KVM: SEV-ES: keep INS functions together
  KVM: x86: remove unnecessary arguments from complete_emulator_pio_in
  KVM: x86: split the two parts of emulator_pio_in
  KVM: SEV-ES: clean up kvm_sev_es_ins/outs
  KVM: x86: leave vcpu->arch.pio.count alone in emulator_pio_in_out
  KVM: SEV-ES: rename guest_ins_data to sev_pio_data
  KVM: SEV: Flush cache on non-coherent systems before RECEIVE_UPDATE_DATA
  KVM: MMU: Reset mmu->pkru_mask to avoid stale data
  KVM: nVMX: promptly process interrupts delivered while in guest mode
  KVM: x86: check for interrupts before deciding whether to exit the fast path

Merge a fix for a recent ACPI tools bild regresson.

* acpi-tools:
  ACPI: tools: fix compilation error

The PIO scratch buffer is larger than a single page, and therefore
it is not possible to copy it in a single step to vcpu->arch/pio_data.
Bound each call to emulator_pio_in/out to a single page; keep
track of how many I/O operations are left in vcpu->arch.sev_pio_count,
so that the operation can be restarted in the complete_userspace_io
callback.

For OUT, this means that the previous kvm_sev_es_outs implementation
becomes an iterator of the loop, and we can consume the sev_pio_data
buffer before leaving to userspace.

For IN, instead, consuming the buffer and decreasing sev_pio_count
is always done in the complete_userspace_io callback, because that
is when the memcpy is done into sev_pio_data.

Cc: stable@vger.kernel.org
Fixes: 7ed9abfe ("KVM: SVM: Support string IO operations for an SEV-ES guest")
Reported-by: Felix Wilhelm <fwilhelm@google.com>
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>