hostmem-memfd: add checks before adding hostmem-memfd & properties

Run some memfd-related checks before registering hostmem-memfd &
various properties. This will help libvirt to figure out what the

hostmem-memfd: add checks before adding hostmem-memfd & properties

Run some memfd-related checks before registering hostmem-memfd &
various properties. This will help libvirt to figure out what the host
is supposed to be capable of.

qemu_memfd_check() is changed to a less optimized version, since it is
used with various flags, it no longer caches the result.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20180906161415.8543-1-marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

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Merge remote-tracking branch 'remotes/bonzini/tags/for-upstream' into staging

* socket option parsing fix (Daniel)
* SCSI fixes (Fam)
* Readline double-free fix (Greg)
* More HVF attribution fixes (

Merge remote-tracking branch 'remotes/bonzini/tags/for-upstream' into staging

* socket option parsing fix (Daniel)
* SCSI fixes (Fam)
* Readline double-free fix (Greg)
* More HVF attribution fixes (Izik)
* WHPX (Windows Hypervisor Platform Extensions) support (Justin)
* POLLHUP handler (Klim)
* ivshmem fixes (Ladi)
* memfd memory backend (Marc-André)
* improved error message (Marcelo)
* Memory fixes (Peter Xu, Zhecheng)
* Remove obsolete code and comments (Peter M.)
* qdev API improvements (Philippe)
* Add CONFIG_I2C switch (Thomas)

# gpg: Signature made Wed 07 Feb 2018 15:24:08 GMT
# gpg: using RSA key BFFBD25F78C7AE83
# gpg: Good signature from "Paolo Bonzini <bonzini@gnu.org>"
# gpg: aka "Paolo Bonzini <pbonzini@redhat.com>"
# Primary key fingerprint: 46F5 9FBD 57D6 12E7 BFD4 E2F7 7E15 100C CD36 69B1
# Subkey fingerprint: F133 3857 4B66 2389 866C 7682 BFFB D25F 78C7 AE83

* remotes/bonzini/tags/for-upstream: (47 commits)
Add the WHPX acceleration enlightenments
Introduce the WHPX impl
Add the WHPX vcpu API
Add the Windows Hypervisor Platform accelerator.
tests/test-filter-redirector: move close()
tests: use memfd in vhost-user-test
vhost-user-test: make read-guest-mem setup its own qemu
tests: keep compiling failing vhost-user tests
Add memfd based hostmem
memfd: add hugetlbsize argument
memfd: add hugetlb support
memfd: add error argument, instead of perror()
cpus: join thread when removing a vCPU
cpus: hvf: unregister thread with RCU
cpus: tcg: unregister thread with RCU, fix exiting of loop on unplug
cpus: dummy: unregister thread with RCU, exit loop on unplug
cpus: kvm: unregister thread with RCU
cpus: hax: register/unregister thread with RCU, exit loop on unplug
ivshmem: Disable irqfd on device reset
ivshmem: Improve MSI irqfd error handling
...

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

# Conflicts:
# cpus.c

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Add memfd based hostmem

Add a new memory backend, similar to hostmem-file, except that it
doesn't need to create files. It also enforces memory sealing.

This backend is mainly useful for sharing th

Add memfd based hostmem

Add a new memory backend, similar to hostmem-file, except that it
doesn't need to create files. It also enforces memory sealing.

This backend is mainly useful for sharing the memory with other
processes.

Note that Linux supports transparent huge-pages of shmem/memfd memory
since 4.8. It is relatively easier to set up THP than a dedicate
hugepage mount point by using "madvise" in
/sys/kernel/mm/transparent_hugepage/shmem_enabled.

Since 4.14, memfd allows to set hugetlb requirement explicitly.

Pending for merge in 4.16 is memfd sealing support for hugetlb backed
memory.

Usage:
-object memory-backend-memfd,id=mem1,size=1G

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20180201132757.23063-5-marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

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