Merge remote-tracking branch 'remotes/ehabkost/tags/x86-next-pull-request' into staging

Merge remote-tracking branch 'remotes/ehabkost/tags/x86-next-pull-request' into staging

x86 queue for -rc1

A few fixes that missed -rc0:
* CPU model documentation updates (Daniel P. Berrangé)
* Fix bogus OSPKE warnings (Eduardo Habkost)
* Work around KVM bugs when handing arch_capabilities
  (Eduardo Habkost)

# gpg: Signature made Thu 21 Mar 2019 19:32:02 GMT
# gpg:                using RSA key 2807936F984DC5A6
# gpg: Good signature from "Eduardo Habkost <[email protected]>" [full]
# Primary key fingerprint: 5A32 2FD5 ABC4 D3DB ACCF  D1AA 2807 936F 984D C5A6

* remotes/ehabkost/tags/x86-next-pull-request:
  docs: add note about stibp CPU feature for spectre v2
  docs: clarify that spec-ctrl is only needed for Spectre v2
  i386: Disable OSPKE on CPU model definitions
  i386: Make arch_capabilities migratable
  i386: kvm: Disable arch_capabilities if MSR can't be set

Signed-off-by: Peter Maydell <[email protected]>