Check if port-helper exists and is executable. If not, write an error
message to the kernel log with information to help the user diagnose the
issue and exit with an error. If UML_PORT_HELPER was not set, write a
message suggesting that the user set it. This makes it easier to understand
why telneting to the UML instance is failing and what can be done to fix it.

Signed-off-by: Glenn Washburn <development@efficientek.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

This is useful when the uml-utilities user-space package has not been
installed by the administrator and an unprivileged user wants to be able to
telnet into a UML instance. The user can install the port-helper binary to
a writable path and set UML_PORT_HELPER. Fallback to using hardcoded path to
port-helper if environment variable is not set.

Signed-off-by: Glenn Washburn <development@efficientek.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

This allows in.telnetd to be run from non-standard installation locations
and is especially useful when running a UML instance as an unprivileged user
on a system where the administrator has not installed the in.telnetd binary.

Signed-off-by: Glenn Washburn <development@efficientek.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

Moving to an EPOLL based IRQ controller broke uml_mconsole stop/go
commands. This fixes it and restores stop/go functionality.

Fixes: ff6a17989c08 ("Epoll based IRQ controller")
Signed-off-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

Since the constification of MAC addresses, the argument
to uml_vector_default_bpf() must be const.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Acked-By: anton ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

Call to fallocate with FALLOC_FL_PUNCH_HOLE on a device backed by a sparse
file can end up by missing data, zeroes data range, if the underlying file
is used with a tool like bmaptool which will referenced only used spaces.

Signed-off-by: Frédéric Danis <frederic.danis@collabora.com>
Acked-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

Migrate UML vector drivers from a bespoke scheduling mechanism
to NAPI.

Signed-off-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

Pull virtio updates from Michael Tsirkin:
 "virtio,vdpa,qemu_fw_cfg: features, cleanups, and fixes.

   - partial support for < MAX_ORDER - 1 granularity for virtio-mem

   - driver_override for vdpa

   - sysfs ABI documentation for vdpa

   - multiqueue config support for mlx5 vdpa

   - and misc fixes, cleanups"

* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost: (42 commits)
  vdpa/mlx5: Fix tracking of current number of VQs
  vdpa/mlx5: Fix is_index_valid() to refer to features
  vdpa: Protect vdpa reset with cf_mutex
  vdpa: Avoid taking cf_mutex lock on get status
  vdpa/vdpa_sim_net: Report max device capabilities
  vdpa: Use BIT_ULL for bit operations
  vdpa/vdpa_sim: Configure max supported virtqueues
  vdpa/mlx5: Report max device capabilities
  vdpa: Support reporting max device capabilities
  vdpa/mlx5: Restore cur_num_vqs in case of failure in change_num_qps()
  vdpa: Add support for returning device configuration information
  vdpa/mlx5: Support configuring max data virtqueue
  vdpa/mlx5: Fix config_attr_mask assignment
  vdpa: Allow to configure max data virtqueues
  vdpa: Read device configuration only if FEATURES_OK
  vdpa: Sync calls set/get config/status with cf_mutex
  vdpa/mlx5: Distribute RX virtqueues in RQT object
  vdpa: Provide interface to read driver features
  vdpa: clean up get_config_size ret value handling
  virtio_ring: mark ring unused on error
  ...

This will enable cleanups down the road.
The idea is to disable cbs, then add "flush_queued_cbs" callback
as a parameter, this way drivers can flush any work
queued after callbacks have been disabled.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Link: https://lore.kernel.org/r/20211013105226.20225-1-mst@redhat.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

Pull UML updates from Richard Weinberger:

 - set_fs removal

 - Devicetree support

 - Many cleanups from Al

 - Various virtio and build related fixes

* tag 'for-linus-5.17-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml: (31 commits)
  um: virtio_uml: Allow probing from devicetree
  um: Add devicetree support
  um: Extract load file helper from initrd.c
  um: remove set_fs
  hostfs: Fix writeback of dirty pages
  um: Use swap() to make code cleaner
  um: header debriding - sigio.h
  um: header debriding - os.h
  um: header debriding - net_*.h
  um: header debriding - mem_user.h
  um: header debriding - activate_ipi()
  um: common-offsets.h debriding...
  um, x86: bury crypto_tfm_ctx_offset
  um: unexport handle_page_fault()
  um: remove a dangling extern of syscall_trace()
  um: kill unused cpu()
  uml/i386: missing include in barrier.h
  um: stop polluting the namespace with registers.h contents
  logic_io instance of iounmap() needs volatile on argument
  um: move amd64 variant of mmap(2) to arch/x86/um/syscalls_64.c
  ...