The kill() syscall operates on process identifiers (pid). After a process
has exited its pid can be reused by another process. If a caller sends a
signal to a reused pid it will end up signaling the wrong process. This
issue has often surfaced and there has been a push to address this problem [1].

This patch uses file descriptors (fd) from proc/<pid> as stable handles on
struct pid. Even if a pid is recycled the handle will not change. The fd
can be used to send signals to the process it refers to.
Thus, the new syscall pidfd_send_signal() is introduced to solve this
problem. Instead of pids it operates on process fds (pidfd).

/* prototype and argument /*
long pidfd_send_signal(int pidfd, int sig, siginfo_t *info, unsigned int flags);

/* syscall number 424 */
The syscall number was chosen to be 424 to align with Arnd's rework in his
y2038 to minimize merge conflicts (cf. [25]).

In addition to the pidfd and signal argument it takes an additional
siginfo_t and flags argument. If the siginfo_t argument is NULL then
pidfd_send_signal() is equivalent to kill(<positive-pid>, <signal>). If it
is not NULL pidfd_send_signal() is equivalent to rt_sigqueueinfo().
The flags argument is added to allow for future extensions of this syscall.
It currently needs to be passed as 0. Failing to do so will cause EINVAL.

/* pidfd_send_signal() replaces multiple pid-based syscalls */
The pidfd_send_signal() syscall currently takes on the job of
rt_sigqueueinfo(2) and parts of the functionality of kill(2), Namely, when a
positive pid is passed to kill(2). It will however be possible to also
replace tgkill(2) and rt_tgsigqueueinfo(2) if this syscall is extended.

/* sending signals to threads (tid) and process groups (pgid) */
Specifically, the pidfd_send_signal() syscall does currently not operate on
process groups or threads. This is left for future extensions.
In order to extend the syscall to allow sending signal to threads and
process groups appropriately named flags (e.g. PIDFD_TYPE_PGID, and
PIDFD_TYPE_TID) should be added. This implies that the flags argument will
determine what is signaled and not the file descriptor itself. Put in other
words, grouping in this api is a property of the flags argument not a
property of the file descriptor (cf. [13]). Clarification for this has been
requested by Eric (cf. [19]).
When appropriate extensions through the flags argument are added then
pidfd_send_signal() can additionally replace the part of kill(2) which
operates on process groups as well as the tgkill(2) and
rt_tgsigqueueinfo(2) syscalls.
How such an extension could be implemented has been very roughly sketched
in [14], [15], and [16]. However, this should not be taken as a commitment
to a particular implementation. There might be better ways to do it.
Right now this is intentionally left out to keep this patchset as simple as
possible (cf. [4]).

/* naming */
The syscall had various names throughout iterations of this patchset:
- procfd_signal()
- procfd_send_signal()
- taskfd_send_signal()
In the last round of reviews it was pointed out that given that if the
flags argument decides the scope of the signal instead of different types
of fds it might make sense to either settle for "procfd_" or "pidfd_" as
prefix. The community was willing to accept either (cf. [17] and [18]).
Given that one developer expressed strong preference for the "pidfd_"
prefix (cf. [13]) and with other developers less opinionated about the name
we should settle for "pidfd_" to avoid further bikeshedding.

The  "_send_signal" suffix was chosen to reflect the fact that the syscall
takes on the job of multiple syscalls. It is therefore intentional that the
name is not reminiscent of neither kill(2) nor rt_sigqueueinfo(2). Not the
fomer because it might imply that pidfd_send_signal() is a replacement for
kill(2), and not the latter because it is a hassle to remember the correct
spelling - especially for non-native speakers - and because it is not
descriptive enough of what the syscall actually does. The name
"pidfd_send_signal" makes it very clear that its job is to send signals.

/* zombies */
Zombies can be signaled just as any other process. No special error will be
reported since a zombie state is an unreliable state (cf. [3]). However,
this can be added as an extension through the @flags argument if the need
ever arises.

/* cross-namespace signals */
The patch currently enforces that the signaler and signalee either are in
the same pid namespace or that the signaler's pid namespace is an ancestor
of the signalee's pid namespace. This is done for the sake of simplicity
and because it is unclear to what values certain members of struct
siginfo_t would need to be set to (cf. [5], [6]).

/* compat syscalls */
It became clear that we would like to avoid adding compat syscalls
(cf. [7]).  The compat syscall handling is now done in kernel/signal.c
itself by adding __copy_siginfo_from_user_generic() which lets us avoid
compat syscalls (cf. [8]). It should be noted that the addition of
__copy_siginfo_from_user_any() is caused by a bug in the original
implementation of rt_sigqueueinfo(2) (cf. 12).
With upcoming rework for syscall handling things might improve
significantly (cf. [11]) and __copy_siginfo_from_user_any() will not gain
any additional callers.

/* testing */
This patch was tested on x64 and x86.

/* userspace usage */
An asciinema recording for the basic functionality can be found under [9].
With this patch a process can be killed via:

 #define _GNU_SOURCE
 #include <errno.h>
 #include <fcntl.h>
 #include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/stat.h>
 #include <sys/syscall.h>
 #include <sys/types.h>
 #include <unistd.h>

 static inline int do_pidfd_send_signal(int pidfd, int sig, siginfo_t *info,
                                         unsigned int flags)
 {
 #ifdef __NR_pidfd_send_signal
         return syscall(__NR_pidfd_send_signal, pidfd, sig, info, flags);
 #else
         return -ENOSYS;
 #endif
 }

 int main(int argc, char *argv[])
 {
         int fd, ret, saved_errno, sig;

         if (argc < 3)
                 exit(EXIT_FAILURE);

         fd = open(argv[1], O_DIRECTORY | O_CLOEXEC);
         if (fd < 0) {
                 printf("%s - Failed to open \"%s\"\n", strerror(errno), argv[1]);
                 exit(EXIT_FAILURE);
         }

         sig = atoi(argv[2]);

         printf("Sending signal %d to process %s\n", sig, argv[1]);
         ret = do_pidfd_send_signal(fd, sig, NULL, 0);

         saved_errno = errno;
         close(fd);
         errno = saved_errno;

         if (ret < 0) {
                 printf("%s - Failed to send signal %d to process %s\n",
                        strerror(errno), sig, argv[1]);
                 exit(EXIT_FAILURE);
         }

         exit(EXIT_SUCCESS);
 }

/* Q&A
 * Given that it seems the same questions get asked again by people who are
 * late to the party it makes sense to add a Q&A section to the commit
 * message so it's hopefully easier to avoid duplicate threads.
 *
 * For the sake of progress please consider these arguments settled unless
 * there is a new point that desperately needs to be addressed. Please make
 * sure to check the links to the threads in this commit message whether
 * this has not already been covered.
 */
Q-01: (Florian Weimer [20], Andrew Morton [21])
      What happens when the target process has exited?
A-01: Sending the signal will fail with ESRCH (cf. [22]).

Q-02:  (Andrew Morton [21])
       Is the task_struct pinned by the fd?
A-02:  No. A reference to struct pid is kept. struct pid - as far as I
       understand - was created exactly for the reason to not require to
       pin struct task_struct (cf. [22]).

Q-03: (Andrew Morton [21])
      Does the entire procfs directory remain visible? Just one entry
      within it?
A-03: The same thing that happens right now when you hold a file descriptor
      to /proc/<pid> open (cf. [22]).

Q-04: (Andrew Morton [21])
      Does the pid remain reserved?
A-04: No. This patchset guarantees a stable handle not that pids are not
      recycled (cf. [22]).

Q-05: (Andrew Morton [21])
      Do attempts to signal that fd return errors?
A-05: See {Q,A}-01.

Q-06: (Andrew Morton [22])
      Is there a cleaner way of obtaining the fd? Another syscall perhaps.
A-06: Userspace can already trivially retrieve file descriptors from procfs
      so this is something that we will need to support anyway. Hence,
      there's no immediate need to add another syscalls just to make
      pidfd_send_signal() not dependent on the presence of procfs. However,
      adding a syscalls to get such file descriptors is planned for a
      future patchset (cf. [22]).

Q-07: (Andrew Morton [21] and others)
      This fd-for-a-process sounds like a handy thing and people may well
      think up other uses for it in the future, probably unrelated to
      signals. Are the code and the interface designed to permit such
      future applications?
A-07: Yes (cf. [22]).

Q-08: (Andrew Morton [21] and others)
      Now I think about it, why a new syscall? This thing is looking
      rather like an ioctl?
A-08: This has been extensively discussed. It was agreed that a syscall is
      preferred for a variety or reasons. Here are just a few taken from
      prior threads. Syscalls are safer than ioctl()s especially when
      signaling to fds. Processes are a core kernel concept so a syscall
      seems more appropriate. The layout of the syscall with its four
      arguments would require the addition of a custom struct for the
      ioctl() thereby causing at least the same amount or even more
      complexity for userspace than a simple syscall. The new syscall will
      replace multiple other pid-based syscalls (see description above).
      The file-descriptors-for-processes concept introduced with this
      syscall will be extended with other syscalls in the future. See also
      [22], [23] and various other threads already linked in here.

Q-09: (Florian Weimer [24])
      What happens if you use the new interface with an O_PATH descriptor?
A-09:
      pidfds opened as O_PATH fds cannot be used to send signals to a
      process (cf. [2]). Signaling processes through pidfds is the
      equivalent of writing to a file. Thus, this is not an operation that
      operates "purely at the file descriptor level" as required by the
      open(2) manpage. See also [4].

/* References */
[1]:  https://lore.kernel.org/lkml/20181029221037.87724-1-dancol@google.com/
[2]:  https://lore.kernel.org/lkml/874lbtjvtd.fsf@oldenburg2.str.redhat.com/
[3]:  https://lore.kernel.org/lkml/20181204132604.aspfupwjgjx6fhva@brauner.io/
[4]:  https://lore.kernel.org/lkml/20181203180224.fkvw4kajtbvru2ku@brauner.io/
[5]:  https://lore.kernel.org/lkml/20181121213946.GA10795@mail.hallyn.com/
[6]:  https://lore.kernel.org/lkml/20181120103111.etlqp7zop34v6nv4@brauner.io/
[7]:  https://lore.kernel.org/lkml/36323361-90BD-41AF-AB5B-EE0D7BA02C21@amacapital.net/
[8]:  https://lore.kernel.org/lkml/87tvjxp8pc.fsf@xmission.com/
[9]:  https://asciinema.org/a/IQjuCHew6bnq1cr78yuMv16cy
[11]: https://lore.kernel.org/lkml/F53D6D38-3521-4C20-9034-5AF447DF62FF@amacapital.net/
[12]: https://lore.kernel.org/lkml/87zhtjn8ck.fsf@xmission.com/
[13]: https://lore.kernel.org/lkml/871s6u9z6u.fsf@xmission.com/
[14]: https://lore.kernel.org/lkml/20181206231742.xxi4ghn24z4h2qki@brauner.io/
[15]: https://lore.kernel.org/lkml/20181207003124.GA11160@mail.hallyn.com/
[16]: https://lore.kernel.org/lkml/20181207015423.4miorx43l3qhppfz@brauner.io/
[17]: https://lore.kernel.org/lkml/CAGXu5jL8PciZAXvOvCeCU3wKUEB_dU-O3q0tDw4uB_ojMvDEew@mail.gmail.com/
[18]: https://lore.kernel.org/lkml/20181206222746.GB9224@mail.hallyn.com/
[19]: https://lore.kernel.org/lkml/20181208054059.19813-1-christian@brauner.io/
[20]: https://lore.kernel.org/lkml/8736rebl9s.fsf@oldenburg.str.redhat.com/
[21]: https://lore.kernel.org/lkml/20181228152012.dbf0508c2508138efc5f2bbe@linux-foundation.org/
[22]: https://lore.kernel.org/lkml/20181228233725.722tdfgijxcssg76@brauner.io/
[23]: https://lwn.net/Articles/773459/
[24]: https://lore.kernel.org/lkml/8736rebl9s.fsf@oldenburg.str.redhat.com/
[25]: https://lore.kernel.org/lkml/CAK8P3a0ej9NcJM8wXNPbcGUyOUZYX+VLoDFdbenW3s3114oQZw@mail.gmail.com/

Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Jann Horn <jannh@google.com>
Cc: Andy Lutomirsky <luto@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Florian Weimer <fweimer@redhat.com>
Signed-off-by: Christian Brauner <christian@brauner.io>
Reviewed-by: Tycho Andersen <tycho@tycho.ws>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Serge Hallyn <serge@hallyn.com>
Acked-by: Aleksa Sarai <cyphar@cyphar.com>

Pull x86 fixes from Thomas Gleixner:
 "A set of fixes for x86:

   - Fix the swapped outb() parameters in the KASLR code

   - Fix the PKEY handling at fork which missed to preserve the pkey
     state for the child. Comes with a test case to validate that.

   - Fix the entry stack handling for XEN PV to respect that XEN PV
     systems enter the function already on the current thread stack and
     not on the trampoline.

   - Fix kexec load failure caused by using a stale value when the
     kexec_buf structure is reused for subsequent allocations.

   - Fix a bogus sizeof() in the memory encryption code

   - Enforce PCI dependency for the Intel Low Power Subsystem

   - Enforce PCI_LOCKLESS_CONFIG when PCI is enabled"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/Kconfig: Select PCI_LOCKLESS_CONFIG if PCI is enabled
  x86/entry/64/compat: Fix stack switching for XEN PV
  x86/kexec: Fix a kexec_file_load() failure
  x86/mm/mem_encrypt: Fix erroneous sizeof()
  x86/selftests/pkeys: Fork() to check for state being preserved
  x86/pkeys: Properly copy pkey state at fork()
  x86/kaslr: Fix incorrect i8254 outb() parameters
  x86/intel/lpss: Make PCI dependency explicit

Pull x86 timer fixes from Thomas Gleixner:
 "Two commits which were missed to be sent during the merge window.

   - The TSC calibration fix turns out to be more urgent as recent
     Skylake-X systems seem to have massive trouble with calibration
     disturbance. This should go back into stable for that reason and it
     the risk of breakage is rather low.

   - Drop an unused define"

* 'x86-timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/hpet: Remove unused FSEC_PER_NSEC define
  x86/tsc: Make calibration refinement more robust

Pull timer fix from Thomas Glexiner:
 "A single regression fix to address the unintended breakage of posix
  cpu timers.

  This is caused by a new sanity check in the common code, which fails
  for posix cpu timers under certain conditions because the posix cpu
  timer code never updates the variable which is checked"

* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  posix-cpu-timers: Unbreak timer rearming

Pull locking fixes from Thomas Gleixner:
 "A small series of fixes which all address possible missed wakeups:

   - Document and fix the wakeup ordering of wake_q

   - Add the missing barrier in rcuwait_wake_up(), which was documented
     in the comment but missing in the code

   - Fix the possible missed wakeups in the rwsem and futex code"

* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  locking/rwsem: Fix (possible) missed wakeup
  futex: Fix (possible) missed wakeup
  sched/wake_q: Fix wakeup ordering for wake_q
  sched/wake_q: Document wake_q_add()
  sched/wait: Fix rcuwait_wake_up() ordering

Pull irq fixes from Thomas Gleixner:
 "A small set of fixes for the interrupt subsystem:

   - Fix a double increment in the irq descriptor allocator which
     resulted in a sanity check only being done for every second
     affinity mask

   - Add a missing device tree translation in the stm32-exti driver.
     Without that the interrupt association is completely wrong.

   - Initialize the mutex in the GIC-V3 MBI driver

   - Fix the alignment for aliasing devices in the GIC-V3-ITS driver so
     multi MSI allocations work correctly

   - Ensure that the initial affinity of a interrupt is not empty at
     startup time.

   - Drop bogus include in the madera irq chip driver

   - Fix KernelDoc regression"

* 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  irqchip/gic-v3-its: Align PCI Multi-MSI allocation on their size
  genirq/irqdesc: Fix double increment in alloc_descs()
  genirq: Fix the kerneldoc comment for struct irq_affinity_desc
  irqchip/madera: Drop GPIO includes
  irqchip/gic-v3-mbi: Fix uninitialized mbi_lock
  irqchip/stm32-exti: Add domain translate function
  genirq: Make sure the initial affinity is not empty

Pull EDAC fix from Borislav Petkov:
 "Fix persistent register offsets of altera_edac, from Thor Thayer"

* tag 'edac_fix_for_5.0' of git://git.kernel.org/pub/scm/linux/kernel/git/bp/bp:
  EDAC, altera: Fix S10 persistent register offset

Pull block revert from Jens Axboe:
 "Silly error snuck into a patch from the last series, let's do a revert
  to avoid a potential use-after-free"

* tag 'for-linus-20190127' of git://git.kernel.dk/linux-block:
  Revert "block: cover another queue enter recursion via BIO_QUEUE_ENTERED"

Pull KVM fixes from Paolo Bonzini:
 "Quite a few fixes for x86: nested virtualization save/restore, AMD
  nested virtualization and virtual APIC, 32-bit fixes, an important fix
  to restore operation on older processors, and a bunch of hyper-v
  bugfixes. Several are marked stable.

  There are also fixes for GCC warnings and for a GCC/objtool interaction"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: x86: Mark expected switch fall-throughs
  KVM: x86: fix TRACE_INCLUDE_PATH and remove -I. header search paths
  KVM: selftests: check returned evmcs version range
  x86/kvm/hyper-v: nested_enable_evmcs() sets vmcs_version incorrectly
  KVM: VMX: Move vmx_vcpu_run()'s VM-Enter asm blob to a helper function
  kvm: selftests: Fix region overlap check in kvm_util
  kvm: vmx: fix some -Wmissing-prototypes warnings
  KVM: nSVM: clear events pending from svm_complete_interrupts() when exiting to L1
  svm: Fix AVIC incomplete IPI emulation
  svm: Add warning message for AVIC IPI invalid target
  KVM: x86: WARN_ONCE if sending a PV IPI returns a fatal error
  KVM: x86: Fix PV IPIs for 32-bit KVM host
  x86/kvm/hyper-v: recommend using eVMCS only when it is enabled
  x86/kvm/hyper-v: don't recommend doing reset via synthetic MSR
  kvm: x86/vmx: Use kzalloc for cached_vmcs12
  KVM: VMX: Use the correct field var when clearing VM_ENTRY_LOAD_IA32_PERF_GLOBAL_CTRL
  KVM: x86: Fix single-step debugging
  x86/kvm/hyper-v: don't announce GUEST IDLE MSR support

Pull dma-mapping fix from Christoph Hellwig:
 "Fix a xen-swiotlb regression on arm64"

* tag 'dma-mapping-5.0-2' of git://git.infradead.org/users/hch/dma-mapping:
  arm64/xen: fix xen-swiotlb cache flushing

Pull libnvdimm fixes from Dan Williams:
 "A fix for namespace label support for non-Intel NVDIMMs that implement
  the ACPI standard label method.

  This has apparently never worked and could wait for v5.1. However it
  has enough visibility with hardware vendors [1] and distro bug
  trackers [2], and low enough risk that I decided it should go in for
  -rc4. The other fixups target the new, for v5.0, nvdimm security
  functionality. The larger init path fixup closes a memory leak and a
  potential userspace lockup due to missed notifications.

    [1] https://github.com/pmem/ndctl/issues/78
    [2] https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1811785

  These have all soaked in -next for a week with no reported issues.

  Summary:

   - Fix support for NVDIMMs that implement the ACPI standard label
     methods.

   - Fix error handling for security overwrite (memory leak / userspace
     hang condition), and another one-line security cleanup"

* tag 'libnvdimm-fixes-5.0-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm:
  acpi/nfit: Fix command-supported detection
  acpi/nfit: Block function zero DSMs
  libnvdimm/security: Require nvdimm_security_setup_events() to succeed
  nfit_test: fix security state pull for nvdimm security nfit_test

Pull input fixes from Dmitry Torokhov:
 "A fixup for the input_event fix for y2038 Sparc64, and couple other
  minor fixes"

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input:
  Input: input_event - fix the CONFIG_SPARC64 mixup
  Input: olpc_apsp - assign priv->dev earlier
  Input: uinput - fix undefined behavior in uinput_validate_absinfo()
  Input: raspberrypi-ts - fix link error
  Input: xpad - add support for SteelSeries Stratus Duo
  Input: input_event - provide override for sparc64

Pull networking fixes from David Miller:

 1) Count ttl-dropped frames properly in mac80211, from Bob Copeland.

 2) Integer overflow in ktime handling of bcm can code, from Oliver
    Hartkopp.

 3) Fix RX desc handling wrt. hw checksumming in ravb, from Simon
    Horman.

 4) Various hash key fixes in hv_netvsc, from Haiyang Zhang.

 5) Use after free in ax25, from Eric Dumazet.

 6) Several fixes to the SSN support in SCTP, from Xin Long.

 7) Do not process frames after a NAPI reschedule in ibmveth, from
    Thomas Falcon.

 8) Fix NLA_POLICY_NESTED arguments, from Johannes Berg.

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (42 commits)
  qed: Revert error handling changes.
  cfg80211: extend range deviation for DMG
  cfg80211: reg: remove warn_on for a normal case
  mac80211: Add attribute aligned(2) to struct 'action'
  mac80211: don't initiate TDLS connection if station is not associated to AP
  nl80211: fix NLA_POLICY_NESTED() arguments
  ibmveth: Do not process frames after calling napi_reschedule
  net: dev_is_mac_header_xmit() true for ARPHRD_RAWIP
  net: usb: asix: ax88772_bind return error when hw_reset fail
  MAINTAINERS: Update cavium networking drivers
  net/mlx4_core: Fix error handling when initializing CQ bufs in the driver
  net/mlx4_core: Add masking for a few queries on HCA caps
  sctp: set flow sport from saddr only when it's 0
  sctp: set chunk transport correctly when it's a new asoc
  sctp: improve the events for sctp stream adding
  sctp: improve the events for sctp stream reset
  ip_tunnel: Make none-tunnel-dst tunnel port work with lwtunnel
  ax25: fix possible use-after-free
  sfc: suppress duplicate nvmem partition types in efx_ef10_mtd_probe
  hv_netvsc: fix typos in code comments
  ...

We can't touch a bio after ->make_request_fn(), for all we know it could
already have been completed by the time this function returns.

This reverts commit 698cef17.

Reported-by: syzbot+4df6ca820108fd248943@syzkaller.appspotmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Pull smb3 fixes from Steve French:
 "A set of small smb3 fixes, some fixing various crediting issues
  discovered during xfstest runs, five for stable"

* tag '5.0-rc3-smb3-fixes' of git://git.samba.org/sfrench/cifs-2.6:
  cifs: print CIFSMaxBufSize as part of /proc/fs/cifs/DebugData
  smb3: add credits we receive from oplock/break PDUs
  CIFS: Fix mounts if the client is low on credits
  CIFS: Do not assume one credit for async responses
  CIFS: Fix credit calculations in compound mid callback
  CIFS: Fix credit calculation for encrypted reads with errors
  CIFS: Fix credits calculations for reads with errors
  CIFS: Do not reconnect TCP session in add_credits()
  smb3: Cleanup license mess
  CIFS: Fix possible hang during async MTU reads and writes
  cifs: fix memory leak of an allocated cifs_ntsd structure

Pull VFIO fixes from Alex Williamson:

 - cleanup licenses in new files (Thomas Gleixner)

 - cleanup new compiler warnings (Alexey Kardashevskiy)

* tag 'vfio-v5.0-rc4' of git://github.com/awilliam/linux-vfio:
  vfio-pci/nvlink2: Fix ancient gcc warnings
  vfio/pci: Cleanup license mess

Pull SCSI fixes from James Bottomley:
 "Six fixes, all of which appear to have user visible consequences.

  The DMA one is a regression fix from the merge window and of the
  others, four are driver specific and one specific to the target code"

* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
  scsi: ufs: Use explicit access size in ufshcd_dump_regs
  scsi: tcmu: fix use after free
  scsi: csiostor: fix NULL pointer dereference in csio_vport_set_state()
  scsi: lpfc: nvmet: avoid hang / use-after-free when destroying targetport
  scsi: lpfc: nvme: avoid hang / use-after-free when destroying localport
  scsi: communicate max segment size to the DMA mapping code

Pull block fixes from Jens Axboe:
 "A collection of fixes for this release. This contains:

   - Silence sparse rightfully complaining about non-static wbt
     functions (Bart)

   - Fixes for the zoned comments/ioctl documentation (Damien)

   - direct-io fix that's been lingering for a while (Ernesto)

   - cgroup writeback fix (Tejun)

   - Set of NVMe patches for nvme-rdma/tcp (Sagi, Hannes, Raju)

   - Block recursion tracking fix (Ming)

   - Fix debugfs command flag naming for a few flags (Jianchao)"

* tag 'for-linus-20190125' of git://git.kernel.dk/linux-block:
  block: Fix comment typo
  uapi: fix ioctl documentation
  blk-wbt: Declare local functions static
  blk-mq: fix the cmd_flag_name array
  nvme-multipath: drop optimization for static ANA group IDs
  nvmet-rdma: fix null dereference under heavy load
  nvme-rdma: rework queue maps handling
  nvme-tcp: fix timeout handler
  nvme-rdma: fix timeout handler
  writeback: synchronize sync(2) against cgroup writeback membership switches
  block: cover another queue enter recursion via BIO_QUEUE_ENTERED
  direct-io: allow direct writes to empty inodes

This is new code and not bug fixes.

This reverts all changes added by merge commit
8fb18be9Signed-off-by: David S. Miller <davem@davemloft.net>

Pull MMC fixes from Ulf Hansson:

 - sdhci-acpi: Fixup build dependency for PCI

 - sdhci-omap: Resolve Kconfig warnings on keystone

 - sdhci-iproc: Propagate errors from DT parsing

 - meson-gx: Fixup IRQ handling in release callback

 - meson-gx: Use signal re-sampling to fixup tuning

 - dw_mmc-bluefield: Fix the license information

* tag 'mmc-v5.0-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/ulfh/mmc:
  mmc: dw_mmc-bluefield: : Fix the license information
  mmc: meson-gx: enable signal re-sampling together with tuning
  mmc: sdhci-iproc: handle mmc_of_parse() errors during probe
  mmc: meson-gx: Free irq in release() callback
  mmc: host: Fix Kconfig warnings on keystone_defconfig
  mmc: sdhci-acpi: Make PCI dependency explicit

Pull char/misc driver fixes from Greg KH:
 "Here are some small char and misc driver fixes to resolve some
  reported issues, as well as a number of binderfs fixups that were
  found after auditing the filesystem code by Al Viro. As binderfs
  hasn't been in a previous release yet, it's good to get these in now
  before the first users show up.

  All of these have been in linux-next for a bit with no reported
  issues"

* tag 'char-misc-5.0-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (26 commits)
  i3c: master: Fix an error checking typo in 'cdns_i3c_master_probe()'
  binderfs: switch from d_add() to d_instantiate()
  binderfs: drop lock in binderfs_binder_ctl_create
  binderfs: kill_litter_super() before cleanup
  binderfs: rework binderfs_binder_device_create()
  binderfs: rework binderfs_fill_super()
  binderfs: prevent renaming the control dentry
  binderfs: remove outdated comment
  binderfs: use __u32 for device numbers
  binderfs: use correct include guards in header
  misc: pvpanic: fix warning implicit declaration
  char/mwave: fix potential Spectre v1 vulnerability
  misc: ibmvsm: Fix potential NULL pointer dereference
  binderfs: fix error return code in binderfs_fill_super()
  mei: me: add denverton innovation engine device IDs
  mei: me: mark LBG devices as having dma support
  mei: dma: silent the reject message
  binderfs: handle !CONFIG_IPC_NS builds
  binderfs: reserve devices for initial mount
  binderfs: rename header to binderfs.h
  ...

Pull staging driver fixes from Greg KH:
 "Here are some small staging driver fixes for 5.0-rc4.

  They resolve some reported bugs and add a new device id for one
  driver. Nothing major at all, but all good to have.

  All of these have been in linux-next for a while with no reported
  issues"

* tag 'staging-5.0-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging:
  staging: android: ion: Support cpu access during dma_buf_detach
  staging: rtl8723bs: Fix build error with Clang when inlining is disabled
  staging: rtl8188eu: Add device code for D-Link DWA-121 rev B1
  staging: vchiq: Fix local event signalling
  Staging: wilc1000: unlock on error in init_chip()
  staging: wilc1000: fix memory leak in wilc_add_rx_gtk
  staging: wilc1000: fix registration frame size

Pull tty/serial driver fixes from Greg KH:
 "Here are a number of small tty core and serial driver fixes for
  5.0-rc4 to resolve some reported issues.

  Nothing major, the small serial driver fixes, a tty core fixup for a
  crash that was reported, and some good vt fixes from Nicolas Pitre as
  he seems to be auditing that chunk of code a lot lately.

  All of these have been in linux-next for a while with no reported
  issues"

* tag 'tty-5.0-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty:
  serial: fsl_lpuart: fix maximum acceptable baud rate with over-sampling
  tty: serial: qcom_geni_serial: Allow mctrl when flow control is disabled
  tty: Handle problem if line discipline does not have receive_buf
  vgacon: unconfuse vc_origin when using soft scrollback
  vt: invoke notifier on screen size change
  vt: always call notifier with the console lock held
  vt: make vt_console_print() compatible with the unicode screen buffer
  tty/n_hdlc: fix __might_sleep warning
  serial: 8250: Fix serial8250 initialization crash
  uart: Fix crash in uart_write and uart_put_char

Pull USB/PHY fixes from Greg KH:
 "Here are a number of small USB and PHY driver fixes for 5.0-rc4.

  Nothing major at all, just the usual selection of USB gadget bugfixes,
  some new USB serial driver ids, some SPDX fixes, and some PHY driver
  fixes for reported issues.

  All of these have been in linux-next for a while with no reported
  issues"

* tag 'usb-5.0-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb:
  USB: serial: keyspan_usa: add proper SPDX lines for .h files
  USB: EHCI: ehci-mv: add MODULE_DEVICE_TABLE
  USB: leds: fix regression in usbport led trigger
  usb: chipidea: fix static checker warning for NULL pointer
  MAINTAINERS: email address update in MAINTAINERS entries
  USB: usbip: delete README file
  USB: serial: pl2303: add new PID to support PL2303TB
  usb: dwc2: gadget: Fix Remote Wakeup interrupt bit clearing
  phy: ath79-usb: Fix the main reset name to match the DT binding
  phy: ath79-usb: Fix the power on error path
  phy: fix build breakage: add PHY_MODE_SATA
  phy: ti: ensure priv is not null before dereferencing it
  USB: serial: ftdi_sio: fix GPIO not working in autosuspend
  usb: gadget: Potential NULL dereference on allocation error
  usb: dwc3: gadget: Fix the uninitialized link_state when udc starts
  usb: dwc3: gadget: Clear req->needs_extra_trb flag on cleanup
  usb: dwc3: gadget: synchronize_irq dwc irq in suspend
  USB: serial: simple: add Motorola Tetra TPG2200 device id

Merge tag 'mac80211-for-davem-2019-01-25' of git://git.kernel.org/pub/scm/linux/kernel/git/jberg/mac80211

Johannes Berg says:

====================
Just a few small fixes:
 * avoid trying to operate TDLS when not connection,
   this is not valid and led to issues
 * count TTL-dropped frames in mesh better
 * deal with new WiGig channels in regulatory code
 * remove a WARN_ON() that can trigger due to benign
   races during device/driver registration
 * fix nested netlink policy maxattrs (syzkaller)
 * fix hwsim n_limits (syzkaller)
 * propagate __aligned(2) to a surrounding struct
 * return proper error in virt_wifi error path
====================
Signed-off-by: David S. Miller <davem@davemloft.net>

In preparation to enabling -Wimplicit-fallthrough, mark switch
cases where we are expecting to fall through.

This patch fixes the following warnings:

arch/x86/kvm/lapic.c:1037:27: warning: this statement may fall through [-Wimplicit-fallthrough=]
arch/x86/kvm/lapic.c:1876:3: warning: this statement may fall through [-Wimplicit-fallthrough=]
arch/x86/kvm/hyperv.c:1637:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
arch/x86/kvm/svm.c:4396:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
arch/x86/kvm/mmu.c:4372:36: warning: this statement may fall through [-Wimplicit-fallthrough=]
arch/x86/kvm/x86.c:3835:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
arch/x86/kvm/x86.c:7938:23: warning: this statement may fall through [-Wimplicit-fallthrough=]
arch/x86/kvm/vmx/vmx.c:2015:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
arch/x86/kvm/vmx/vmx.c:1773:6: warning: this statement may fall through [-Wimplicit-fallthrough=]

Warning level 3 was used: -Wimplicit-fallthrough=3

This patch is part of the ongoing efforts to enabling -Wimplicit-fallthrough.
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

The header search path -I. in kernel Makefiles is very suspicious;
it allows the compiler to search for headers in the top of $(srctree),
where obviously no header file exists.

The reason of having -I. here is to make the incorrectly set
TRACE_INCLUDE_PATH working.

As the comment block in include/trace/define_trace.h says,
TRACE_INCLUDE_PATH should be a relative path to the define_trace.h

Fix the TRACE_INCLUDE_PATH, and remove the iffy include paths.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Check that KVM_CAP_HYPERV_ENLIGHTENED_VMCS returns correct version range.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Commit e2e871ab ("x86/kvm/hyper-v: Introduce nested_get_evmcs_version()
helper") broke EVMCS enablement: to set vmcs_version we now call
nested_get_evmcs_version() but this function checks
enlightened_vmcs_enabled flag which is not yet set so we end up returning
zero.

Fix the issue by re-arranging things in nested_enable_evmcs().

Fixes: e2e871ab ("x86/kvm/hyper-v: Introduce nested_get_evmcs_version() helper")
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

...along with the function's STACK_FRAME_NON_STANDARD tag.  Moving the
asm blob results in a significantly smaller amount of code that is
marked with STACK_FRAME_NON_STANDARD, which makes it far less likely
that gcc will split the function and trigger a spurious objtool warning.
As a bonus, removing STACK_FRAME_NON_STANDARD from vmx_vcpu_run() allows
the bulk of code to be properly checked by objtool.

Because %rbp is not loaded via VMCS fields, vmx_vcpu_run() must manually
save/restore the host's RBP and load the guest's RBP prior to calling
vmx_vmenter().  Modifying %rbp triggers objtool's stack validation code,
and so vmx_vcpu_run() is tagged with STACK_FRAME_NON_STANDARD since it's
impossible to avoid modifying %rbp.

Unfortunately, vmx_vcpu_run() is also a gigantic function that gcc will
split into separate functions, e.g. so that pieces of the function can
be inlined.  Splitting the function means that the compiled Elf file
will contain one or more vmx_vcpu_run.part.* functions in addition to
a vmx_vcpu_run function.  Depending on where the function is split,
objtool may warn about a "call without frame pointer save/setup" in
vmx_vcpu_run.part.* since objtool's stack validation looks for exact
names when whitelisting functions tagged with STACK_FRAME_NON_STANDARD.

Up until recently, the undesirable function splitting was effectively
blocked because vmx_vcpu_run() was tagged with __noclone.  At the time,
__noclone had an unintended side effect that put vmx_vcpu_run() into a
separate optimization unit, which in turn prevented gcc from inlining
the function (or any of its own function calls) and thus eliminated gcc's
motivation to split the function.  Removing the __noclone attribute
allowed gcc to optimize vmx_vcpu_run(), exposing the objtool warning.

Kudos to Qian Cai for root causing that the fnsplit optimization is what
caused objtool to complain.

Fixes: 453eafbe ("KVM: VMX: Move VM-Enter + VM-Exit handling to non-inline sub-routines")
Tested-by: Qian Cai <cai@lca.pw>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Fix a call to userspace_mem_region_find to conform to its spec of
taking an inclusive, inclusive range. It was previously being called
with an inclusive, exclusive range. Also remove a redundant region bounds
check in vm_userspace_mem_region_add. Region overlap checking is already
performed by the call to userspace_mem_region_find.

Tested: Compiled tools/testing/selftests/kvm with -static
	Ran all resulting test binaries on an Intel Haswell test machine
	All tests passed
Signed-off-by: Ben Gardon <bgardon@google.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

We get some warnings when building kernel with W=1:
arch/x86/kvm/vmx/vmx.c:426:5: warning: no previous prototype for ‘kvm_fill_hv_flush_list_func’ [-Wmissing-prototypes]
arch/x86/kvm/vmx/nested.c:58:6: warning: no previous prototype for ‘init_vmcs_shadow_fields’ [-Wmissing-prototypes]

Make them static to fix this.
Signed-off-by: Yi Wang <wang.yi59@zte.com.cn>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

kvm-unit-tests' eventinj "NMI failing on IDT" test results in NMI being
delivered to the host (L1) when it's running nested. The problem seems to
be: svm_complete_interrupts() raises 'nmi_injected' flag but later we
decide to reflect EXIT_NPF to L1. The flag remains pending and we do NMI
injection upon entry so it got delivered to L1 instead of L2.

It seems that VMX code solves the same issue in prepare_vmcs12(), this was
introduced with code refactoring in commit 5f3d5799 ("KVM: nVMX: Rework
event injection and recovery").
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

In case of incomplete IPI with invalid interrupt type, the current
SVM driver does not properly emulate the IPI, and fails to boot
FreeBSD guests with multiple vcpus when enabling AVIC.

Fix this by update APIC ICR high/low registers, which also
emulate sending the IPI.
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Print warning message when IPI target ID is invalid due to one of
the following reasons:
  * In logical mode: cluster > max_cluster (64)
  * In physical mode: target > max_physical (512)
  * Address is not present in the physical or logical ID tables
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

KVM hypercalls return a negative value error code in case of a fatal
error, e.g. when the hypercall isn't supported or was made with invalid
parameters.  WARN_ONCE on fatal errors when sending PV IPIs as any such
error all but guarantees an SMP system will hang due to a missing IPI.

Fixes: aaffcfd1 ("KVM: X86: Implement PV IPIs in linux guest")
Cc: stable@vger.kernel.org
Cc: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

The recognition of the KVM_HC_SEND_IPI hypercall was unintentionally
wrapped in "#ifdef CONFIG_X86_64", causing 32-bit KVM hosts to reject
any and all PV IPI requests despite advertising the feature.  This
results in all KVM paravirtualized guests hanging during SMP boot due
to IPIs never being delivered.

Fixes: 4180bf1b ("KVM: X86: Implement "send IPI" hypercall")
Cc: stable@vger.kernel.org
Cc: Wanpeng Li <wanpengli@tencent.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

We shouldn't probably be suggesting using Enlightened VMCS when it's not
enabled (not supported from guest's point of view). Hyper-V on KVM seems
to be fine either way but let's be consistent.

Fixes: 2bc39970 ("x86/kvm/hyper-v: Introduce KVM_GET_SUPPORTED_HV_CPUID")
Reviewed-by: Liran Alon <liran.alon@oracle.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

System reset through synthetic MSR is not recommended neither by genuine
Hyper-V nor my QEMU.

Fixes: 2bc39970 ("x86/kvm/hyper-v: Introduce KVM_GET_SUPPORTED_HV_CPUID")
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Liran Alon <liran.alon@oracle.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>