Pull xen updates from Juergen Gross:

 - some small cleanups

 - a fix for a bug when running as Xen PV guest which could result in
   not all memory being transferred in case of a migration of the guest

 - a small series for getting rid of code for supporting very old Xen
   hypervisor versions nobody should be using since many years now

 - a series for hardening the Xen block frontend driver

 - a fix for Xen PV boot code issuing warning messages due to a stray
   preempt_disable() on the non-boot processors

* tag 'for-linus-5.15-rc1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  xen: remove stray preempt_disable() from PV AP startup code
  xen/pcifront: Removed unnecessary __ref annotation
  x86: xen: platform-pci-unplug: use pr_err() and pr_warn() instead of raw printk()
  drivers/xen/xenbus/xenbus_client.c: fix bugon.cocci warnings
  xen/blkfront: don't trust the backend response data blindly
  xen/blkfront: don't take local copy of a request from the ring page
  xen/blkfront: read response from backend only once
  xen: assume XENFEAT_gnttab_map_avail_bits being set for pv guests
  xen: assume XENFEAT_mmu_pt_update_preserve_ad being set for pv guests
  xen: check required Xen features
  xen: fix setting of max_pfn in shared_info