So far, at mount time, gfs2 would take the freeze glock in shared mode
and then immediately drop it again, turning it into a cached glock that
can be reclaimed at any time.  To freeze the filesystem cluster-wide,
the node initiating the freeze would take the freeze glock in exclusive
mode, which would cause the freeze glock's freeze_go_sync() callback to
run on each node.  There, gfs2 would freeze the filesystem and schedule
gfs2_freeze_func() to run.  gfs2_freeze_func() would re-acquire the
freeze glock in shared mode, thaw the filesystem, and drop the freeze
glock again.  The initiating node would keep the freeze glock held in
exclusive mode.  To thaw the filesystem, the initiating node would drop
the freeze glock again, which would allow gfs2_freeze_func() to resume
on all nodes, leaving the filesystem in the thawed state.

It turns out that in freeze_go_sync(), we cannot reliably and safely
freeze the filesystem.  This is primarily because the final unmount of a
filesystem takes a write lock on the s_umount rw semaphore before
calling into gfs2_put_super(), and freeze_go_sync() needs to call
freeze_super() which also takes a write lock on the same semaphore,
causing a deadlock.  We could work around this by trying to take an
active reference on the super block first, which would prevent unmount
from running at the same time.  But that can fail, and freeze_go_sync()
isn't actually allowed to fail.

To get around this, this patch changes the freeze glock locking scheme
as follows:

At mount time, each node takes the freeze glock in shared mode.  To
freeze a filesystem, the initiating node first freezes the filesystem
locally and then drops and re-acquires the freeze glock in exclusive
mode.  All other nodes notice that there is contention on the freeze
glock in their go_callback callbacks, and they schedule
gfs2_freeze_func() to run.  There, they freeze the filesystem locally
and drop and re-acquire the freeze glock before re-thawing the
filesystem.  This is happening outside of the glock state engine, so
there, we are allowed to fail.

From a cluster point of view, taking and immediately dropping a glock is
indistinguishable from taking the glock and only dropping it upon
contention, so this new scheme is compatible with the old one.

Thanks to Li Dong <lidong@vivo.com> for reporting a locking bug in
gfs2_freeze_func() in a previous version of this commit.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Rename the SDF_FS_FROZEN flag to SDF_FREEZE_INITIATOR to indicate more
clearly that the node that has this flag set is the initiator of the
freeze.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com

Reconfiguring a frozen filesystem is already rejected in
reconfigure_super(), so there is no need to check for that condition
again at the filesystem level.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Rename gfs2_freeze_lock to gfs2_freeze_lock_shared to make it a bit more
obvious that this function establishes the "thawed" state of the freeze
glock.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Rename gfs2_freeze to gfs2_freeze_super and gfs2_unfreeze to
gfs2_thaw_super to match the names of the corresponding super
operations.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

The transaction glock was repurposed to serve as the new freeze glock
years ago.  Don't refer to it as the transaction glock anymore.

Also, to be more precise, call it the "freeze glock" instead of the
"freeze lock".  Ditto for the journal glock.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

The iomap-based read operations done by gfs2 for its system files, such
as rindex, may sometimes be interrupted and return -EINTR.   This
confuses some users of gfs2_internal_read().  Fix that by retrying
interrupted reads.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Some fields such as gt_logd_secs of the struct gfs2_tune are accessed
without holding the lock gt_spin in gfs2_show_options():

  val = sdp->sd_tune.gt_logd_secs;
  if (val != 30)
    seq_printf(s, ",commit=%d", val);

And thus can cause data races when gfs2_show_options() and other functions
such as gfs2_reconfigure() are concurrently executed:

  spin_lock(&gt->gt_spin);
  gt->gt_logd_secs = newargs->ar_commit;

To fix these possible data races, the lock sdp->sd_tune.gt_spin is
acquired before accessing the fields of gfs2_tune and released after these
accesses.

Further changes by Andreas:

- Don't hold the spin lock over the seq_printf operations.
Reported-by: BassCheck <bass@buaa.edu.cn>
Signed-off-by: Tuo Li <islituo@gmail.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

In gfs2_file_buffered_write(), we currently jump from the second call of
function should_fault_in_pages() to above the first call, so
should_fault_in_pages() is getting called twice in a row, causing it to
accidentally fall back to single-page writes rather than trying the more
efficient multi-page writes first.

Fix that by moving the retry label to the correct place, behind the
first call to should_fault_in_pages().

Fixes: e1fa9ea8 ("gfs2: Stop using glock holder auto-demotion for now")
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Since commit a2ad63da ("VFS: add FMODE_CAN_ODIRECT file flag"), file
systems can just set the FMODE_CAN_ODIRECT flag at open time instead of
wiring up a dummy direct_IO method to indicate support for direct I/O.

Remove .direct_IO from gfs2_aops and set FMODE_CAN_ODIRECT in
gfs2_open_common for regular files that do not use data journalling.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

This patch changes function evict_unlinked_inode so it does not call
gfs2_inode_remember_delete until it gets a good return code from
gfs2_dinode_dealloc.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Function gfs2_free_di was changing the rgrp lvb count of unlinked
dinodes after the lock was released. This patch moves it inside the
lock.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

This patch fixes a case in which function gfs2_quota_hold encounters an
assert error and exits. The lack of gfs2_qa_put causes further problems
when the inode is evicted and the get/put count is non-zero.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Before this patch, function gfs2_dinode_dealloc would abort if it got a
bad return code from gfs2_rindex_update(). The problem is that it left the
dinode in the unlinked (not free) state, which meant subsequent fsck
would clean it up and flag an error. That meant some of our QE tests
would fail.

The sole purpose of gfs2_rindex_update(), in this code path, is to read in
any newer rgrps added by gfs2_grow. But since this is a delete operation
it won't actually use any of those new rgrps. It can really only twiddle
the bits from "Unlinked" to "Free" in an existing rgrp. Therefore the
error should not prevent the transition from unlinked to free.

This patch makes gfs2_dinode_dealloc ignore the bad return code and
proceed with freeing the dinode so the QE tests will not be tripped up.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

This patch introduces a new out_free label and consolidates the three
places function gdlm_put_lock freed the glock.  No change in
functionality.
Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>

Pull gfs2 fix from Andreas Gruenbacher:

 - Don't get stuck writing page onto itself under direct I/O

* tag 'gfs2-v6.4-rc4-fix' of git://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2:
  gfs2: Don't get stuck writing page onto itself under direct I/O

Merge tag 'platform-drivers-x86-v6.4-4' of git://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86

Pull x86 platform driver fixes from Hans de Goede:

 - various Microsoft Surface support fixes

 - one fix for the INT3472 driver

* tag 'platform-drivers-x86-v6.4-4' of git://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86:
  platform/x86: int3472: Avoid crash in unregistering regulator gpio
  platform/surface: aggregator_tabletsw: Add support for book mode in POS subsystem
  platform/surface: aggregator_tabletsw: Add support for book mode in KIP subsystem
  platform/surface: aggregator: Allow completion work-items to be executed in parallel
  platform/surface: aggregator: Make to_ssam_device_driver() respect constness

Pull HID fix from Jiri Kosina:

 - Final, confirmed fix for regression causing some devices connected
   via Logitech HID++ Unifying receiver take too long to initialize
   (Benjamin Tissoires)

* tag 'for-linus-2023060501' of git://git.kernel.org/pub/scm/linux/kernel/git/hid/hid:
  HID: hidpp: terminate retry loop on success

It seems we forgot the normal case to terminate the retry loop,
making us asking 3 times each command, which is probably a little bit
too much.

And remove the ugly "goto exit" that can be replaced by a simpler "break"

Fixes: 586e8fed ("HID: logitech-hidpp: Retry commands when device is busy")
Suggested-by: Mark Lord <mlord@pobox.com>
Tested-by: Mark Lord <mlord@pobox.com>
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

Pull asymmetric keys fix from Roberto Sassu:
 "Here is a small fix to make an unconditional copy of the buffer passed
  to crypto operations, to take into account the case of the stack not
  in the linear mapping area.

  It has been tested and verified to fix the bug"
Acked-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: David Howells <dhowells@redhat.com>

* tag 'asym-keys-fix-for-linus-v6.4-rc5' of https://github.com/robertosassu/linux:
  KEYS: asymmetric: Copy sig and digest in public_key_verify_signature()

Pull irq fix from Borislav Petkov:

 - Fix open firmware quirks validation so that they don't get applied
   wrongly

* tag 'irq_urgent_for_v6.4_rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  irqchip/gic: Correctly validate OF quirk descriptors

Pull media fixes from Mauro Carvalho Chehab:
 "Some driver fixes:
   - a regression fix for the verisilicon driver
   - uvcvideo: don't expose unsupported video formats to userspace
   - camss-video: don't zero subdev format after init
   - mediatek: some fixes for 4K decoder formats
   - fix a Sphinx build warning (missing doc for client_caps)
   - some fixes for imx and atomisp staging drivers

  And two CEC core fixes:
   - don't set last_initiator if TX in progress
   - disable adapter in cec_devnode_unregister"

* tag 'media/v6.4-4' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media:
  media: uvcvideo: Don't expose unsupported formats to userspace
  media: v4l2-subdev: Fix missing kerneldoc for client_caps
  media: staging: media: imx: initialize hs_settle to avoid warning
  media: v4l2-mc: Drop subdev check in v4l2_create_fwnode_links_to_pad()
  media: staging: media: atomisp: init high & low vars
  media: cec: core: don't set last_initiator if tx in progress
  media: cec: core: disable adapter in cec_devnode_unregister
  media: mediatek: vcodec: Only apply 4K frame sizes on decoder formats
  media: camss: camss-video: Don't zero subdev format again after initialization
  media: verisilicon: Additional fix for the crash when opening the driver

Pull char/misc driver fixes from Greg KH:
 "Here are a bunch of tiny char/misc/other driver fixes for 6.4-rc5 that
  resolve a number of reported issues. Included in here are:

   - iio driver fixes

   - fpga driver fixes

   - test_firmware bugfixes

   - fastrpc driver tiny bugfixes

   - MAINTAINERS file updates for some subsystems

  All of these have been in linux-next this past week with no reported
  issues"

* tag 'char-misc-6.4-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (34 commits)
  test_firmware: fix the memory leak of the allocated firmware buffer
  test_firmware: fix a memory leak with reqs buffer
  test_firmware: prevent race conditions by a correct implementation of locking
  firmware_loader: Fix a NULL vs IS_ERR() check
  MAINTAINERS: Vaibhav Gupta is the new ipack maintainer
  dt-bindings: fpga: replace Ivan Bornyakov maintainership
  MAINTAINERS: update Microchip MPF FPGA reviewers
  misc: fastrpc: reject new invocations during device removal
  misc: fastrpc: return -EPIPE to invocations on device removal
  misc: fastrpc: Reassign memory ownership only for remote heap
  misc: fastrpc: Pass proper scm arguments for secure map request
  iio: imu: inv_icm42600: fix timestamp reset
  iio: adc: ad_sigma_delta: Fix IRQ issue by setting IRQ_DISABLE_UNLAZY flag
  dt-bindings: iio: adc: renesas,rcar-gyroadc: Fix adi,ad7476 compatible value
  iio: dac: mcp4725: Fix i2c_master_send() return value handling
  iio: accel: kx022a fix irq getting
  iio: bu27034: Ensure reset is written
  iio: dac: build ad5758 driver when AD5758 is selected
  iio: addac: ad74413: fix resistance input processing
  iio: light: vcnl4035: fixed chip ID check
  ...

Pull driver core fixes from Greg KH:
 "Here are two small driver core cacheinfo fixes for 6.4-rc5 that
  resolve a number of reported issues with that file. These changes have
  been in linux-next this past week with no reported problems"

* tag 'driver-core-6.4-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core:
  drivers: base: cacheinfo: Update cpu_map_populated during CPU Hotplug
  drivers: base: cacheinfo: Fix shared_cpu_map changes in event of CPU hotplug

Pull tty/serial driver fixes from Greg KH:
 "Here are some small tty/serial driver fixes for 6.4-rc5 that have all
  been in linux-next this past week with no reported problems. Included
  in here are:

   - 8250_tegra driver bugfix

   - fsl uart driver bugfixes

   - Kconfig fix for dependancy issue

   - dt-bindings fix for the 8250_omap driver"

* tag 'tty-6.4-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
  dt-bindings: serial: 8250_omap: add rs485-rts-active-high
  serial: cpm_uart: Fix a COMPILE_TEST dependency
  soc: fsl: cpm1: Fix TSA and QMC dependencies in case of COMPILE_TEST
  tty: serial: fsl_lpuart: use UARTCTRL_TXINV to send break instead of UARTCTRL_SBK
  serial: 8250_tegra: Fix an error handling path in tegra_uart_probe()

Pull USB fixes from Greg KH:
 "Here are some USB driver and core fixes for 6.4-rc5. Most of these are
  tiny driver fixes, including:

   - udc driver bugfix

   - f_fs gadget driver bugfix

   - cdns3 driver bugfix

   - typec bugfixes

  But the "big" thing in here is a fix yet-again for how the USB buffers
  are handled from userspace when dealing with DMA issues. The changes
  were discussed a lot, and tested a lot, on the list, and acked by the
  relevant mm maintainers and have been in linux-next all this past week
  with no reported problems"

* tag 'usb-6.4-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb:
  usb: typec: tps6598x: Fix broken polling mode after system suspend/resume
  mm: page_table_check: Ensure user pages are not slab pages
  mm: page_table_check: Make it dependent on EXCLUSIVE_SYSTEM_RAM
  usb: usbfs: Use consistent mmap functions
  usb: usbfs: Enforce page requirements for mmap
  dt-bindings: usb: snps,dwc3: Fix "snps,hsphy_interface" type
  usb: gadget: udc: fix NULL dereference in remove()
  usb: gadget: f_fs: Add unbind event before functionfs_unbind
  usb: cdns3: fix NCM gadget RX speed 20x slow than expection at iMX8QM

Pull kvm fixes from Paolo Bonzini:
 "ARM:

   - Address some fallout of the locking rework, this time affecting the
     way the vgic is configured

   - Fix an issue where the page table walker frees a subtree and then
     proceeds with walking what it has just freed...

   - Check that a given PA donated to the guest is actually memory (only
     affecting pKVM)

   - Correctly handle MTE CMOs by Set/Way

   - Fix the reported address of a watchpoint forwarded to userspace

   - Fix the freeing of the root of stage-2 page tables

   - Stop creating spurious PMU events to perform detection of the
     default PMU and use the existing PMU list instead

  x86:

   - Fix a memslot lookup bug in the NX recovery thread that could
     theoretically let userspace bypass the NX hugepage mitigation

   - Fix a s/BLOCKING/PENDING bug in SVM's vNMI support

   - Account exit stats for fastpath VM-Exits that never leave the super
     tight run-loop

   - Fix an out-of-bounds bug in the optimized APIC map code, and add a
     regression test for the race"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: selftests: Add test for race in kvm_recalculate_apic_map()
  KVM: x86: Bail from kvm_recalculate_phys_map() if x2APIC ID is out-of-bounds
  KVM: x86: Account fastpath-only VM-Exits in vCPU stats
  KVM: SVM: vNMI pending bit is V_NMI_PENDING_MASK not V_NMI_BLOCKING_MASK
  KVM: x86/mmu: Grab memslot for correct address space in NX recovery worker
  KVM: arm64: Document default vPMU behavior on heterogeneous systems
  KVM: arm64: Iterate arm_pmus list to probe for default PMU
  KVM: arm64: Drop last page ref in kvm_pgtable_stage2_free_removed()
  KVM: arm64: Populate fault info for watchpoint
  KVM: arm64: Reload PTE after invoking walker callback on preorder traversal
  KVM: arm64: Handle trap of tagged Set/Way CMOs
  arm64: Add missing Set/Way CMO encodings
  KVM: arm64: Prevent unconditional donation of unmapped regions from the host
  KVM: arm64: vgic: Fix a comment
  KVM: arm64: vgic: Fix locking comment
  KVM: arm64: vgic: Wrap vgic_its_create() with config_lock
  KVM: arm64: vgic: Fix a circular locking issue

Pull powerpc fixes from Michael Ellerman:

 - Fix link errors in new aes-gcm-p10 code when built-in with other
   drivers

 - Limit number of TCEs passed to H_STUFF_TCE hcall as per spec

 - Use KSYM_NAME_LEN in xmon array size to avoid possible OOB write

Thanks to Gaurav Batra and Maninder Singh Vishal Chourasia.

* tag 'powerpc-6.4-4' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/xmon: Use KSYM_NAME_LEN in array size
  powerpc/iommu: Limit number of TCEs to 512 for H_STUFF_TCE hcall
  powerpc/crypto: Fix aes-gcm-p10 link errors

KVM x86 fixes for 6.4

 - Fix a memslot lookup bug in the NX recovery thread that could
   theoretically let userspace bypass the NX hugepage mitigation

 - Fix a s/BLOCKING/PENDING bug in SVM's vNMI support

 - Account exit stats for fastpath VM-Exits that never leave the super
   tight run-loop

 - Fix an out-of-bounds bug in the optimized APIC map code, and add a
   regression test for the race.

Merge tag 'kvmarm-fixes-6.4-3' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD

KVM/arm64 fixes for 6.4, take #3

- Fix the reported address of a watchpoint forwarded to userspace

- Fix the freeing of the root of stage-2 page tables

- Stop creating spurious PMU events to perform detection of the
  default PMU and use the existing PMU list instead.

Merge tag 'kvmarm-fixes-6.4-2' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD

KVM/arm64 fixes for 6.4, take #2

- Address some fallout of the locking rework, this time affecting
  the way the vgic is configured

- Fix an issue where the page table walker frees a subtree and
  then proceeds with walking what it has just freed...

- Check that a given PA donated to the gues is actually memory
  (only affecting pKVM)

- Correctly handle MTE CMOs by Set/Way

Pull SCSI fixes from James Bottomley:
 "Five fixes, all in drivers.

  The most extensive is the target change to fix the hang in the login
  code, which involves changing timers from per login to per connection"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: stex: Fix gcc 13 warnings
  scsi: qla2xxx: Fix NULL pointer dereference in target mode
  scsi: target: iscsi: Prevent login threads from racing between each other
  scsi: target: iscsi: Remove unused transport_timer
  scsi: target: iscsi: Fix hang in the iSCSI login code

Pull LED fix from Johan Hovold:
 "Here's a fix for a regression in 6.4-rc1 which broke the backlight on
  machines such as the Lenovo ThinkPad X13s"
Acked-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/lkml/20230602091928.GR449117@google.com/

* tag 'leds-6.4-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/johan/linux:
  leds: qcom-lpg: Fix PWM period limits

The introduction of high resolution PWM support changed the order of the
operations in the calculation of min and max period. The result in both
divisions is in most cases a truncation to 0, which limits the period to
the range of [0, 0].

Both numerators (and denominators) are within 64 bits, so the whole
expression can be put directly into the div64_u64, instead of doing it
partially.

Fixes: b00d2ed3 ("leds: rgb: leds-qcom-lpg: Add support for high resolution PWM")
Reviewed-by: Caleb Connolly <caleb.connolly@linaro.org>
Tested-by: Steev Klimaszewski <steev@kali.org>
Signed-off-by: Bjorn Andersson <quic_bjorande@quicinc.com>
Acked-by: Lee Jones <lee@kernel.org>
Tested-by: Johan Hovold <johan+linaro@kernel.org>
Tested-by: Neil Armstrong <neil.armstrong@linaro.org> # on SM8550-QRD
Link: https://lore.kernel.org/r/20230515162604.649203-1-quic_bjorande@quicinc.comSigned-off-by: Johan Hovold <johan@kernel.org>

Pull probes fixes from Masami Hiramatsu:

 - Return NULL if the trace_probe list on trace_probe_event is empty

 - selftests/ftrace: Choose testing symbol name for filtering feature
   from sample data instead of fixed symbol

* tag 'probes-fixes-6.4-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  selftests/ftrace: Choose target function for filter test from samples
  tracing/probe: trace_probe_primary_from_call(): checked list_first_entry

Since the event-filter-function.tc expects the 'exit_mmap()' directly
calls 'kmem_cache_free()', this is vulnerable to code modifications.

Choose the target function for the filter test from the sample
event data so that it can keep test running correctly even if the caller
function name will be changed.

Link: https://lore.kernel.org/linux-trace-kernel/167919441260.1922645.18355804179347364057.stgit@mhiramat.roam.corp.google.com/

Link: https://lore.kernel.org/all/CA+G9fYtF-XEKi9YNGgR=Kf==7iRb2FrmEC7qtwAeQbfyah-UhA@mail.gmail.com/Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
Fixes: 7f09d639 ("tracing/selftests: Add test for event filtering on function name")
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Keep switching between LAPIC_MODE_X2APIC and LAPIC_MODE_DISABLED during
APIC map construction to hunt for TOCTOU bugs in KVM.  KVM's optimized map
recalc makes multiple passes over the list of vCPUs, and the calculations
ignore vCPU's whose APIC is hardware-disabled, i.e. there's a window where
toggling LAPIC_MODE_DISABLED is quite interesting.
Signed-off-by: Michal Luczaj <mhal@rbox.co>
Co-developed-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20230602233250.1014316-4-seanjc@google.comSigned-off-by: Sean Christopherson <seanjc@google.com>

Bail from kvm_recalculate_phys_map() and disable the optimized map if the
target vCPU's x2APIC ID is out-of-bounds, i.e. if the vCPU was added
and/or enabled its local APIC after the map was allocated.  This fixes an
out-of-bounds access bug in the !x2apic_format path where KVM would write
beyond the end of phys_map.

Check the x2APIC ID regardless of whether or not x2APIC is enabled,
as KVM's hardcodes x2APIC ID to be the vCPU ID, i.e. it can't change, and
the map allocation in kvm_recalculate_apic_map() doesn't check for x2APIC
being enabled, i.e. the check won't get false postivies.

Note, this also affects the x2apic_format path, which previously just
ignored the "x2apic_id > new->max_apic_id" case.  That too is arguably a
bug fix, as ignoring the vCPU meant that KVM would not send interrupts to
the vCPU until the next map recalculation.  In practice, that "bug" is
likely benign as a newly present vCPU/APIC would immediately trigger a
recalc.  But, there's no functional downside to disabling the map, and
a future patch will gracefully handle the -E2BIG case by retrying instead
of simply disabling the optimized map.

Opportunistically add a sanity check on the xAPIC ID size, along with a
comment explaining why the xAPIC ID is guaranteed to be "good".
Reported-by: Michal Luczaj <mhal@rbox.co>
Fixes: 5b84b029 ("KVM: x86: Honor architectural behavior for aliased 8-bit APIC IDs")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20230602233250.1014316-2-seanjc@google.comSigned-off-by: Sean Christopherson <seanjc@google.com>