KVM: PPC: e500mc: Add doorbell emulation support

When one vcpu wants to kick another, it can issue a special IPI instruction
called msgsnd. This patch emulates this instruction, its clearing counterpart
and the infrastructure required to actually trigger that interrupt inside
a guest vcpu.

With this patch, SMP guests on e500mc work.

Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>

diff --git a/arch/powerpc/include/asm/dbell.h b/arch/powerpc/include/asm/dbell.h
index d7365b0..154c067 100644
--- a/arch/powerpc/include/asm/dbell.h
+++ b/arch/powerpc/include/asm/dbell.h
@@ -19,7 +19,9 @@
 
 #define PPC_DBELL_MSG_BRDCAST	(0x04000000)
 #define PPC_DBELL_TYPE(x)	(((x) & 0xf) << (63-36))
+#define PPC_DBELL_TYPE_MASK	PPC_DBELL_TYPE(0xf)
 #define PPC_DBELL_LPID(x)	((x) << (63 - 49))
+#define PPC_DBELL_PIR_MASK	0x3fff
 enum ppc_dbell {
 	PPC_DBELL = 0,		/* doorbell */
 	PPC_DBELL_CRIT = 1,	/* critical doorbell */