xen: SMP guest support

This is a fairly straightforward Xen implementation of smp_ops.

Xen has its own IPI mechanisms, and has no dependency on any
APIC-based IPI.  The smp_ops hooks and the flush_tlb_others pv_op
allow a Xen guest to avoid all APIC code in arch/i386 (the only apic
operation is a single apic_read for the apic version number).

One subtle point which needs to be addressed is unpinning pagetables
when another cpu may have a lazy tlb reference to the pagetable. Xen
will not allow an in-use pagetable to be unpinned, so we must find any
other cpus with a reference to the pagetable and get them to shoot
down their references.

Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Andi Kleen <ak@suse.de>

1 files changed, 2 insertions, 0 deletions

diff --git a/arch/i386/xen/Makefile b/arch/i386/xen/Makefile
index bf51cabed0d2..fd05f243a3f8 100644
--- a/arch/i386/xen/Makefile
+++ b/arch/i386/xen/Makefile
@@ -1,2 +1,4 @@
 obj-y           := enlighten.o setup.o features.o multicalls.o mmu.o \
                         events.o time.o
+
+obj-$(CONFIG_SMP)       += smp.o