xen: simplify xen_enabled

No need for preprocessor conditionals in xen_enabled: xen_allowed is
always defined.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
CC: qemu-stable@nongnu.org
main_loop: do not set nonblocking if xen_enabled()

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
CC: qemu-stable@nongnu.org
xen_machine_pv: do not create a dummy CPU in machine->init

This fixes a regression introduced by:

commit 62fc403f11523169eb4264de31279745f48e3ecc
Author: Igor Mammedov <imammedo@redhat.com>
Date:   Mon Apr 29 18:54:13 2013 +0200

    target-i386: Attach ICC bus to CPU on its creation

    X86CPU should have parent bus so it could provide bus for child APIC.

The commit makes it mandatory to pass a valid ICC bus to cpu_x86_create,
but cpu_x86_init just passes NULL to it.
xen_machine_pv uses cpu_x86_init, therefore it has been broken.

This patch fixes the problem by removing the dummy CPU creation
altogether from xen_init_pv, relying on the fact that QEMU can now cope
with a machine without an emulated CPU.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: Andreas Färber <afaerber@suse.de>
CC: imammedo@redhat.com
CC: qemu-stable@nongnu.org
xen: start PCI hole at 0xe0000000 (same as pc_init1 and qemu-xen-traditional)

We are currently setting the PCI hole to start at HVM_BELOW_4G_RAM_END,
that is 0xf0000000.
Start the PCI hole at 0xe0000000 instead, that is the same value used by
pc_init1 and qemu-xen-traditional.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
CC: qemu-stable@nongnu.org
xen: remove xen_vcpu_init

No need for xen_vcpu_init anymore:

- the RTC emulator doesn't have any periodic timers continuously running
even in absence of guest interactions anymore;

- qemu_dummy_start_vcpu takes care of disabling TCG for us, so we don't
need to do it manually here.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: Andreas Färber <afaerber@suse.de>
xen: use pc_init_pci instead of pc_init_pci_no_kvmclock

Call kvmclock_create only if kvmclock_enabled.
Use pc_init_pci on Xen rather than pc_init_pci_no_kvmclock.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Merge remote-tracking branch 'sstabellini/xen_fixes_20130603' into staging

* sstabellini/xen_fixes_20130603:
  xen: use pc_init_pci instead of pc_init_pci_no_kvmclock
  xen: remove xen_vcpu_init
  xen: start PCI hole at 0xe0000000 (same as pc_init1 and qemu-xen-traditional)
  xen_machine_pv: do not create a dummy CPU in machine->init
  main_loop: do not set nonblocking if xen_enabled()
  xen: simplify xen_enabled

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>