Merge remote-tracking branch 'remotes/sstabellini/tags/xen-15-06-02-tag' into staging

XSA 128 129 130 131

# gpg: Signature made Tue Jun  2 16:46:38 2015 BST using RSA key ID 70E1AE90
# gpg: Good signature from "Stefano Stabellini <stefano.stabellini@eu.citrix.com>"

* remotes/sstabellini/tags/xen-15-06-02-tag:
  xen/pt: unknown PCI config space fields should be read-only
  xen/pt: add a few PCI config space field descriptions
  xen/pt: mark reserved bits in PCI config space fields
  xen/pt: mark all PCIe capability bits read-only
  xen/pt: split out calculation of throughable mask in PCI config space handling
  xen/pt: correctly handle PM status bit
  xen/pt: consolidate PM capability emu_mask
  xen/MSI: don't open-code pass-through of enable bit modifications
  xen/MSI-X: limit error messages
  xen: don't allow guest to control MSI mask register
  xen: properly gate host writes of modified PCI CFG contents

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