Currently, aio_poll_wake() will always remove the poll request from the
waitqueue.  Then, if aio_poll_complete_work() sees that none of the
polled events are ready and the request isn't cancelled, it re-adds the
request to the waitqueue.  (This can easily happen when polling a file
that doesn't pass an event mask when waking up its waitqueue.)

This is fundamentally broken for two reasons:

  1. If a wakeup occurs between vfs_poll() and the request being
     re-added to the waitqueue, it will be missed because the request
     wasn't on the waitqueue at the time.  Therefore, IOCB_CMD_POLL
     might never complete even if the polled file is ready.

  2. When the request isn't on the waitqueue, there is no way to be
     notified that the waitqueue is being freed (which happens when its
     lifetime is shorter than the struct file's).  This is supposed to
     happen via the waitqueue entries being woken up with POLLFREE.

Therefore, leave the requests on the waitqueue until they are actually
completed (or cancelled).  To keep track of when aio_poll_complete_work
needs to be scheduled, use new fields in struct poll_iocb.  Remove the
'done' field which is now redundant.

Note that this is consistent with how sys_poll() and eventpoll work;
their wakeup functions do *not* remove the waitqueue entries.

Fixes: 2c14fa83 ("aio: implement IOCB_CMD_POLL")
Cc: <stable@vger.kernel.org> # v4.18+
Link: https://lore.kernel.org/r/20211209010455.42744-5-ebiggers@kernel.orgSigned-off-by: Eric Biggers <ebiggers@google.com>

wake_up_poll() uses nr_exclusive=1, so it's not guaranteed to wake up
all exclusive waiters.  Yet, POLLFREE *must* wake up all waiters.  epoll
and aio poll are fortunately not affected by this, but it's very
fragile.  Thus, the new function wake_up_pollfree() has been introduced.

Convert signalfd to use wake_up_pollfree().
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Fixes: d80e731e ("epoll: introduce POLLFREE to flush ->signalfd_wqh before kfree()")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20211209010455.42744-4-ebiggers@kernel.orgSigned-off-by: Eric Biggers <ebiggers@google.com>

wake_up_poll() uses nr_exclusive=1, so it's not guaranteed to wake up
all exclusive waiters.  Yet, POLLFREE *must* wake up all waiters.  epoll
and aio poll are fortunately not affected by this, but it's very
fragile.  Thus, the new function wake_up_pollfree() has been introduced.

Convert binder to use wake_up_pollfree().
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Fixes: f5cb779b ("ANDROID: binder: remove waitqueue when thread exits.")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20211209010455.42744-3-ebiggers@kernel.orgSigned-off-by: Eric Biggers <ebiggers@google.com>

Several ->poll() implementations are special in that they use a
waitqueue whose lifetime is the current task, rather than the struct
file as is normally the case.  This is okay for blocking polls, since a
blocking poll occurs within one task; however, non-blocking polls
require another solution.  This solution is for the queue to be cleared
before it is freed, using 'wake_up_poll(wq, EPOLLHUP | POLLFREE);'.

However, that has a bug: wake_up_poll() calls __wake_up() with
nr_exclusive=1.  Therefore, if there are multiple "exclusive" waiters,
and the wakeup function for the first one returns a positive value, only
that one will be called.  That's *not* what's needed for POLLFREE;
POLLFREE is special in that it really needs to wake up everyone.

Considering the three non-blocking poll systems:

- io_uring poll doesn't handle POLLFREE at all, so it is broken anyway.

- aio poll is unaffected, since it doesn't support exclusive waits.
  However, that's fragile, as someone could add this feature later.

- epoll doesn't appear to be broken by this, since its wakeup function
  returns 0 when it sees POLLFREE.  But this is fragile.

Although there is a workaround (see epoll), it's better to define a
function which always sends POLLFREE to all waiters.  Add such a
function.  Also make it verify that the queue really becomes empty after
all waiters have been woken up.
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20211209010455.42744-2-ebiggers@kernel.orgSigned-off-by: Eric Biggers <ebiggers@google.com>

Pull parisc fixes from Helge Deller:
 "Some bug and warning fixes:

   - Fix "make install" to use debians "installkernel" script which is
     now in /usr/sbin

   - Fix the bindeb-pkg make target by giving the correct KBUILD_IMAGE
     file name

   - Fix compiler warnings by annotating parisc agp init functions with
     __init

   - Fix timekeeping on SMP machines with dual-core CPUs

   - Enable some more config options in the 64-bit defconfig"

* tag 'for-5.16/parisc-6' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux:
  parisc: Mark cr16 CPU clocksource unstable on all SMP machines
  parisc: Fix "make install" on newer debian releases
  parisc/agp: Annotate parisc agp init functions with __init
  parisc: Enable sata sil, audit and usb support on 64-bit defconfig
  parisc: Fix KBUILD_IMAGE for self-extracting kernel

Pull USB fixes from Greg KH:
 "Here are some small USB fixes for a few reported issues. Included in
  here are:

   - xhci fix for a _much_ reported regression. I don't think there's a
     community distro that has not reported this problem yet :(

   - new USB quirk addition

   - cdns3 minor fixes

   - typec regression fix.

  All of these have been in linux-next with no reported problems, and
  the xhci fix has been reported by many to resolve their reported
  problem"

* tag 'usb-5.16-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb:
  usb: cdnsp: Fix a NULL pointer dereference in cdnsp_endpoint_init()
  usb: cdns3: gadget: fix new urb never complete if ep cancel previous requests
  usb: typec: tcpm: Wait in SNK_DEBOUNCED until disconnect
  USB: NO_LPM quirk Lenovo Powered USB-C Travel Hub
  xhci: Fix commad ring abort, write all 64 bits to CRCR register.

Pull tty/serial fixes from Greg KH:
 "Here are some small TTY and Serial driver fixes for 5.16-rc4 to
  resolve a number of reported problems.

  They include:

   - liteuart serial driver fixes

   - 8250_pci serial driver fixes for pericom devices

   - 8250 RTS line control fix while in RS-485 mode

   - tegra serial driver fix

   - msm_serial driver fix

   - pl011 serial driver new id

   - fsl_lpuart revert of broken change

   - 8250_bcm7271 serial driver fix

   - MAINTAINERS file update for rpmsg tty driver that came in 5.16-rc1

   - vgacon fix for reported problem

  All of these, except for the 8250_bcm7271 fix have been in linux-next
  with no reported problem. The 8250_bcm7271 fix was added to the tree
  on Friday so no chance to be linux-next yet. But it should be fine as
  the affected developers submitted it"

* tag 'tty-5.16-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
  serial: 8250_bcm7271: UART errors after resuming from S2
  serial: 8250_pci: rewrite pericom_do_set_divisor()
  serial: 8250_pci: Fix ACCES entries in pci_serial_quirks array
  serial: 8250: Fix RTS modem control while in rs485 mode
  Revert "tty: serial: fsl_lpuart: drop earlycon entry for i.MX8QXP"
  serial: tegra: Change lower tolerance baud rate limit for tegra20 and tegra30
  serial: liteuart: relax compile-test dependencies
  serial: liteuart: fix minor-number leak on probe errors
  serial: liteuart: fix use-after-free and memleak on unbind
  serial: liteuart: Fix NULL pointer dereference in ->remove()
  vgacon: Propagate console boot parameters before calling `vc_resize'
  tty: serial: msm_serial: Deactivate RX DMA for polling support
  serial: pl011: Add ACPI SBSA UART match id
  serial: core: fix transmit-buffer reset and memleak
  MAINTAINERS: Add rpmsg tty driver maintainer

Pull timer fix from Borislav Petkov:

 - Prevent a tick storm when a dedicated timekeeper CPU in nohz_full
   mode runs for prolonged periods with interrupts disabled and ends up
   programming the next tick in the past, leading to that storm

* tag 'timers_urgent_for_v5.16_rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  timers/nohz: Last resort update jiffies on nohz_full IRQ entry

Pull scheduler fixes from Borislav Petkov:

 - Properly init uclamp_flags of a runqueue, on first enqueuing

 - Fix preempt= callback return values

 - Correct utime/stime resource usage reporting on nohz_full to return
   the proper times instead of shorter ones

* tag 'sched_urgent_for_v5.16_rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/uclamp: Fix rq->uclamp_max not set on first enqueue
  preempt/dynamic: Fix setup_preempt_mode() return value
  sched/cputime: Fix getrusage(RUSAGE_THREAD) with nohz_full

Pull x86 fixes from Borislav Petkov:

 - Fix a couple of SWAPGS fencing issues in the x86 entry code

 - Use the proper operand types in __{get,put}_user() to prevent
   truncation in SEV-ES string io

 - Make sure the kernel mappings are present in trampoline_pgd in order
   to prevent any potential accesses to unmapped memory after switching
   to it

 - Fix a trivial list corruption in objtool's pv_ops validation

 - Disable the clocksource watchdog for TSC on platforms which claim
   that the TSC is constant, doesn't stop in sleep states, CPU has TSC
   adjust and the number of sockets of the platform are max 2, to
   prevent erroneous markings of the TSC as unstable.

 - Make sure TSC adjust is always checked not only when going idle

 - Prevent a stack leak by initializing struct _fpx_sw_bytes properly in
   the FPU code

 - Fix INTEL_FAM6_RAPTORLAKE define naming to adhere to the convention

* tag 'x86_urgent_for_v5.16_rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/xen: Add xenpv_restore_regs_and_return_to_usermode()
  x86/entry: Use the correct fence macro after swapgs in kernel CR3
  x86/entry: Add a fence for kernel entry SWAPGS in paranoid_entry()
  x86/sev: Fix SEV-ES INS/OUTS instructions for word, dword, and qword
  x86/64/mm: Map all kernel memory into trampoline_pgd
  objtool: Fix pv_ops noinstr validation
  x86/tsc: Disable clocksource watchdog for TSC on qualified platorms
  x86/tsc: Add a timer to make sure TSC_adjust is always checked
  x86/fpu/signal: Initialize sw_bytes in save_xstate_epilog()
  x86/cpu: Drop spurious underscore from RAPTOR_LAKE #define

Pull more kvm fixes from Paolo Bonzini:

 - Static analysis fix

 - New SEV-ES protocol for communicating invalid VMGEXIT requests

 - Ensure APICv is considered inactive if there is no APIC

 - Fix reserved bits for AMD PerfEvtSeln register

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: SVM: Do not terminate SEV-ES guests on GHCB validation failure
  KVM: SEV: Fall back to vmalloc for SEV-ES scratch area if necessary
  KVM: SEV: Return appropriate error codes if SEV-ES scratch setup fails
  KVM: x86/mmu: Retry page fault if root is invalidated by memslot update
  KVM: VMX: Set failure code in prepare_vmcs02()
  KVM: ensure APICv is considered inactive if there is no APIC
  KVM: x86/pmu: Fix reserved bits for AMD PerfEvtSeln register

Currently, an SEV-ES guest is terminated if the validation of the VMGEXIT
exit code or exit parameters fails.

The VMGEXIT instruction can be issued from userspace, even though
userspace (likely) can't update the GHCB. To prevent userspace from being
able to kill the guest, return an error through the GHCB when validation
fails rather than terminating the guest. For cases where the GHCB can't be
updated (e.g. the GHCB can't be mapped, etc.), just return back to the
guest.

The new error codes are documented in the lasest update to the GHCB
specification.

Fixes: 291bd20d ("KVM: SVM: Add initial support for a VMGEXIT VMEXIT")
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Message-Id: <b57280b5562893e2616257ac9c2d4525a9aeeb42.1638471124.git.thomas.lendacky@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Use kvzalloc() to allocate KVM's buffer for SEV-ES's GHCB scratch area so
that KVM falls back to __vmalloc() if physically contiguous memory isn't
available.  The buffer is purely a KVM software construct, i.e. there's
no need for it to be physically contiguous.

Cc: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211109222350.2266045-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Return appropriate error codes if setting up the GHCB scratch area for an
SEV-ES guest fails.  In particular, returning -EINVAL instead of -ENOMEM
when allocating the kernel buffer could be confusing as userspace would
likely suspect a guest issue.

Fixes: 8f423a80 ("KVM: SVM: Support MMIO for an SEV-ES guest")
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20211109222350.2266045-2-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Pull xfs fix from Darrick Wong:
 "Remove an unnecessary (and backwards) rename flags check that
  duplicates a VFS level check"

* tag 'xfs-5.16-fixes-2' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
  xfs: remove incorrect ASSERT in xfs_rename

Pull cifs fixes from Steve French:
 "Three SMB3 multichannel/fscache fixes and a DFS fix.

  In testing multichannel reconnect scenarios recently various problems
  with the cifs.ko implementation of fscache were found (e.g. incorrect
  initialization of fscache cookies in some cases)"

* tag '5.16-rc3-smb3-fixes' of git://git.samba.org/sfrench/cifs-2.6:
  cifs: avoid use of dstaddr as key for fscache client cookie
  cifs: add server conn_id to fscache client cookie
  cifs: wait for tcon resource_id before getting fscache super
  cifs: fix missed refcounting of ipc tcon

In commit c8c37359 ("parisc: Enhance detection of synchronous cr16
clocksources") I assumed that CPUs on the same physical core are syncronous.
While booting up the kernel on two different C8000 machines, one with a
dual-core PA8800 and one with a dual-core PA8900 CPU, this turned out to be
wrong. The symptom was that I saw a jump in the internal clocks printed to the
syslog and strange overall behaviour.  On machines which have 4 cores (2
dual-cores) the problem isn't visible, because the current logic already marked
the cr16 clocksource unstable in this case.

This patch now marks the cr16 interval timers unstable if we have more than one
CPU in the system, and it fixes this issue.

Fixes: c8c37359 ("parisc: Enhance detection of synchronous cr16 clocksources")
Signed-off-by: Helge Deller <deller@gmx.de>
Cc: <stable@vger.kernel.org> # v5.15+

On newer debian releases the debian-provided "installkernel" script is
installed in /usr/sbin. Fix the kernel install.sh script to look for the
script in this directory as well.
Signed-off-by: Helge Deller <deller@gmx.de>
Cc: <stable@vger.kernel.org> # v3.13+

Pull block fix from Jens Axboe:
 "A single fix for repeated printk spam from loop"

* tag 'block-5.16-2021-12-03' of git://git.kernel.dk/linux-block:
  loop: Use pr_warn_once() for loop_control_remove() warning

Pull io_uring fix from Jens Axboe:
 "Just a single fix preventing repeated retries of task_work based io-wq
  thread creation, fixing a regression from when io-wq was made more (a
  bit too much) resilient against signals"

* tag 'io_uring-5.16-2021-12-03' of git://git.kernel.dk/linux-block:
  io-wq: don't retry task_work creation failure on fatal conditions

Pull SCSI fixes from James Bottomley:
 "Two patches, both in drivers.

  One is a fix to FC recovery (lpfc) and the other is an enhancement to
  support the Intel Alder Motherboard with the UFS driver which comes
  under the -rc exception process for hardware enabling"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: ufs: ufs-pci: Add support for Intel ADL
  scsi: lpfc: Fix non-recovery of remote ports following an unsolicited LOGO

Pull gfs2 fixes from Andreas Gruenbacher:

 - Since commit 486408d6 ("gfs2: Cancel remote delete work
   asynchronously"), inode create and lookup-by-number can overlap more
   easily and we can end up with temporary duplicate inodes. Fix the
   code to prevent that.

 - Fix a BUG demoting weak glock holders from a remote node.

* tag 'gfs2-v5.16-rc4-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2:
  gfs2: gfs2_create_inode rework
  gfs2: gfs2_inode_lookup rework
  gfs2: gfs2_inode_lookup cleanup
  gfs2: Fix remote demote of weak glock holders

Commit d81ae8aa ("sched/uclamp: Fix initialization of struct
uclamp_rq") introduced a bug where uclamp_max of the rq is not reset to
match the woken up task's uclamp_max when the rq is idle.

The code was relying on rq->uclamp_max initialized to zero, so on first
enqueue

	static inline void uclamp_rq_inc_id(struct rq *rq, struct task_struct *p,
					    enum uclamp_id clamp_id)
	{
		...

		if (uc_se->value > READ_ONCE(uc_rq->value))
			WRITE_ONCE(uc_rq->value, uc_se->value);
	}

was actually resetting it. But since commit d81ae8aa changed the
default to 1024, this no longer works. And since rq->uclamp_flags is
also initialized to 0, neither above code path nor uclamp_idle_reset()
update the rq->uclamp_max on first wake up from idle.

This is only visible from first wake up(s) until the first dequeue to
idle after enabling the static key. And it only matters if the
uclamp_max of this task is < 1024 since only then its uclamp_max will be
effectively ignored.

Fix it by properly initializing rq->uclamp_flags = UCLAMP_FLAG_IDLE to
ensure uclamp_idle_reset() is called which then will update the rq
uclamp_max value as expected.

Fixes: d81ae8aa ("sched/uclamp: Fix initialization of struct uclamp_rq")
Signed-off-by: Qais Yousef <qais.yousef@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <Valentin.Schneider@arm.com>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://lkml.kernel.org/r/20211202112033.1705279-1-qais.yousef@arm.com

__setup() callbacks expect 1 for success and 0 for failure. Correct the
usage here to reflect that.

Fixes: 826bfeb3 ("preempt/dynamic: Support dynamic preempt with preempt= boot option")
Reported-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Andrew Halaney <ahalaney@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20211203233203.133581-1-ahalaney@redhat.com

Pull VFIO fixes from Alex Williamson:

 - Fix OpRegion pointer arithmetic (Zhenyu Wang)

 - Fix comment format triggering kernel-doc warnings (Randy Dunlap)

* tag 'vfio-v5.16-rc4' of git://github.com/awilliam/linux-vfio:
  vfio/pci: Fix OpRegion read
  vfio: remove all kernel-doc notation

Pull power management fixes from Rafael Wysocki:
 "These fix a CPU hot-add issue in the cpufreq core, fix a comment in
  the cpufreq core code and update its documentation, and disable the
  DTPM (Dynamic Thermal Power Management) code for the time being to
  prevent it from causing issues to appear.

  Specifics:

   - Disable DTPM for this cycle to prevent it from causing issues to
     appear on otherwise functional systems (Daniel Lezcano)

   - Fix cpufreq sysfs interface failure related to physical CPU hot-add
     (Xiongfeng Wang)

   - Fix comment in cpufreq core and update its documentation (Tang
     Yizhou)"

* tag 'pm-5.16-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  powercap: DTPM: Drop unused local variable from init_dtpm()
  cpufreq: docs: Update core.rst
  cpufreq: Fix a comment in cpufreq_policy_free
  powercap/drivers/dtpm: Disable DTPM at boot time
  cpufreq: Fix get_cpu_device() failure in add_cpu_dev_symlink()

Pull s390 fixes from Heiko Carstens:

 - Fix potential overlap of pseudo-MMIO addresses with MIO addresses

 - Fix stack unwinder test case inline assembly compile error that
   happens with LLVM's integrated assembler

 - Update defconfigs

* tag 's390-5.16-4' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
  s390: update defconfigs
  s390/pci: move pseudo-MMIO to prevent MIO overlap
  s390/test_unwind: use raw opcode instead of invalid instruction

Pull arm64 fixes from Will Deacon:
 "Three arm64 fixes for -rc4.

  One of them is just a trivial documentation fix, whereas the other two
  address a warning in the kexec code and a crash in ftrace on systems
  implementing BTI.

  The latter patch has a couple of ugly ifdefs which Mark plans to clean
  up separately, but as-is the patch is straightforward for backporting
  to stable kernels.

  Summary:

   - Add missing BTI landing instructions to the ftrace*_caller
     trampolines

   - Fix kexec() WARN when DEBUG_VIRTUAL is enabled

   - Fix PAC documentation by removing stale references to compiler
     flags"

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64: ftrace: add missing BTIs
  arm64: kexec: use __pa_symbol(empty_zero_page)
  arm64: update PAC description for kernel

Pull i2c fixes from Wolfram Sang:
 "I2C has another set of driver bugfixes, mostly for the stm32f7 driver"

* 'i2c/for-current' of git://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux:
  i2c: rk3x: Handle a spurious start completion interrupt flag
  i2c: stm32f7: use proper DMAENGINE API for termination
  i2c: stm32f7: stop dma transfer in case of NACK
  i2c: stm32f7: recover the bus on access timeout
  i2c: stm32f7: flush TX FIFO upon transfer errors
  i2c: cbus-gpio: set atomic transfer callback

Pull libata fixes from Damien Le Moal:
 "Two sparse warning fixes and a couple of patches to fix an issue with
  sata_fsl driver module removal:

   - A couple of patches to avoid sparse warnings in libata-sata and in
     the pata_falcon driver (from Yang and Finn).

   - A couple of sata_fsl driver patches fixing IRQ free and proc
     unregister on module removal (from Baokun)"

* tag 'libata-5.16-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/dlemoal/libata:
  ata: replace snprintf in show functions with sysfs_emit
  sata_fsl: fix warning in remove_proc_entry when rmmod sata_fsl
  sata_fsl: fix UAF in sata_fsl_port_stop when rmmod sata_fsl
  pata_falcon: Avoid type warnings from sparse

server->dstaddr can change when the DNS mapping for the
server hostname changes. But conn_id is a u64 counter
that is incremented each time a new TCP connection
is setup. So use only that as a key.
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: Steve French <stfrench@microsoft.com>

The fscache client cookie uses the server address
(and port) as the cookie key. This is a problem when
nosharesock is used. Two different connections will
use duplicate cookies. Avoid this by adding
server->conn_id to the key, so that it's guaranteed
that cookie will not be duplicated.

Also, for secondary channels of a session, copy the
fscache pointer from the primary channel. The primary
channel is guaranteed not to go away as long as secondary
channels are in use.  Also addresses minor problem found
by kernel test robot.
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: Steve French <stfrench@microsoft.com>

The logic for initializing tcon->resource_id is done inside
cifs_root_iget. fscache super cookie relies on this for aux
data. So we need to push the fscache initialization to this
later point during mount.
Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: Steve French <stfrench@microsoft.com>

Fix missed refcounting of IPC tcon used for getting domain-based DFS
root referrals.  We want to keep it alive as long as mount is active
and can be refreshed.  For standalone DFS root referrals it wouldn't
be a problem as the client ends up having an IPC tcon for both mount
and cache.

Fixes: c88f7dcd ("cifs: support nested dfs links over reconnect")
Signed-off-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Reviewed-by: Enzo Matsumiya <ematsumiya@suse.de>
Signed-off-by: Steve French <stfrench@microsoft.com>

In the native case, PER_CPU_VAR(cpu_tss_rw + TSS_sp0) is the
trampoline stack. But XEN pv doesn't use trampoline stack, so
PER_CPU_VAR(cpu_tss_rw + TSS_sp0) is also the kernel stack.

In that case, source and destination stacks are identical, which means
that reusing swapgs_restore_regs_and_return_to_usermode() in XEN pv
would cause %rsp to move up to the top of the kernel stack and leave the
IRET frame below %rsp.

This is dangerous as it can be corrupted if #NMI / #MC hit as either of
these events occurring in the middle of the stack pushing would clobber
data on the (original) stack.

And, with  XEN pv, swapgs_restore_regs_and_return_to_usermode() pushing
the IRET frame on to the original address is useless and error-prone
when there is any future attempt to modify the code.

 [ bp: Massage commit message. ]

Fixes: 7f2590a1 ("x86/entry/64: Use a per-CPU trampoline stack for IDT entries")
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Link: https://lkml.kernel.org/r/20211126101209.8613-4-jiangshanlai@gmail.com

The commit

  c7589070 ("x86/entry/64: Remove unneeded kernel CR3 switching")

removed a CR3 write in the faulting path of load_gs_index().

But the path's FENCE_SWAPGS_USER_ENTRY has no fence operation if PTI is
enabled, see spectre_v1_select_mitigation().

Rather, it depended on the serializing CR3 write of SWITCH_TO_KERNEL_CR3
and since it got removed, add a FENCE_SWAPGS_KERNEL_ENTRY call to make
sure speculation is blocked.

 [ bp: Massage commit message and comment. ]

Fixes: c7589070 ("x86/entry/64: Remove unneeded kernel CR3 switching")
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20211126101209.8613-3-jiangshanlai@gmail.com

Jann Horn points out that there is another possible race wrt Unix domain
socket garbage collection, somewhat reminiscent of the one fixed in
commit cbcf0112 ("af_unix: fix garbage collect vs MSG_PEEK").

See the extended comment about the garbage collection requirements added
to unix_peek_fds() by that commit for details.

The race comes from how we can locklessly look up a file descriptor just
as it is in the process of being closed, and with the right artificial
timing (Jann added a few strategic 'mdelay(500)' calls to do that), the
Unix domain socket garbage collector could see the reference count
decrement of the close() happen before fget() took its reference to the
file and the file was attached onto a new file descriptor.

This is all (intentionally) correct on the 'struct file *' side, with
RCU lookups and lockless reference counting very much part of the
design.  Getting that reference count out of order isn't a problem per
se.

But the garbage collector can get confused by seeing this situation of
having seen a file not having any remaining external references and then
seeing it being attached to an fd.

In commit cbcf0112 ("af_unix: fix garbage collect vs MSG_PEEK") the
fix was to serialize the file descriptor install with the garbage
collector by taking and releasing the unix_gc_lock.

That's not really an option here, but since this all happens when we are
in the process of looking up a file descriptor, we can instead simply
just re-check that the file hasn't been closed in the meantime, and just
re-do the lookup if we raced with a concurrent close() of the same file
descriptor.
Reported-and-tested-by: Jann Horn <jannh@google.com>
Acked-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Commit

  18ec54fd ("x86/speculation: Prepare entry code for Spectre v1 swapgs mitigations")

added FENCE_SWAPGS_{KERNEL|USER}_ENTRY for conditional SWAPGS. In
paranoid_entry(), it uses only FENCE_SWAPGS_KERNEL_ENTRY for both
branches. This is because the fence is required for both cases since the
CR3 write is conditional even when PTI is enabled.

But

  96b23714 ("x86/entry/64: Switch CR3 before SWAPGS in paranoid entry")

changed the order of SWAPGS and the CR3 write. And it missed the needed
FENCE_SWAPGS_KERNEL_ENTRY for the user gsbase case.

Add it back by changing the branches so that FENCE_SWAPGS_KERNEL_ENTRY
can cover both branches.

  [ bp: Massage, fix typos, remove obsolete comment while at it. ]

Fixes: 96b23714 ("x86/entry/64: Switch CR3 before SWAPGS in paranoid entry")
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20211126101209.8613-2-jiangshanlai@gmail.com

Merge DTPM fixes for 5.16-rc4.

* powercap:
  powercap: DTPM: Drop unused local variable from init_dtpm()
  powercap/drivers/dtpm: Disable DTPM at boot time