Merge remote-tracking branch 'remotes/stefanha-gitlab/tags/block-pull-request' into staging

Pull request

v4:
 * Add PCI_EXPRESS Kconfig dependency to fix s390x in "multi-process: setup PCI
   host bridge for remote device" [Philippe and Thomas]

# gpg: Signature made Wed 10 Feb 2021 09:26:14 GMT
# gpg:                using RSA key 8695A8BFD3F97CDAAC35775A9CA4ABB381AB73C8
# gpg: Good signature from "Stefan Hajnoczi <stefanha@redhat.com>" [full]
# gpg:                 aka "Stefan Hajnoczi <stefanha@gmail.com>" [full]
# Primary key fingerprint: 8695 A8BF D3F9 7CDA AC35  775A 9CA4 ABB3 81AB 73C8

* remotes/stefanha-gitlab/tags/block-pull-request: (27 commits)
  docs: fix Parallels Image "dirty bitmap" section
  multi-process: perform device reset in the remote process
  multi-process: Retrieve PCI info from remote process
  multi-process: create IOHUB object to handle irq
  multi-process: Synchronize remote memory
  multi-process: PCI BAR read/write handling for proxy & remote endpoints
  multi-process: Forward PCI config space acceses to the remote process
  multi-process: add proxy communication functions
  multi-process: introduce proxy object
  multi-process: setup memory manager for remote device
  multi-process: Associate fd of a PCIDevice with its object
  multi-process: Initialize message handler in remote device
  multi-process: define MPQemuMsg format and transmission functions
  io: add qio_channel_readv_full_all_eof & qio_channel_readv_full_all helpers
  io: add qio_channel_writev_full_all helper
  multi-process: setup a machine object for remote device process
  multi-process: setup PCI host bridge for remote device
  multi-process: Add config option for multi-process QEMU
  memory: alloc RAM from file at offset
  multi-process: add configure and usage information
  ...

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>