KVM: PPC: Paravirtualize SPRG4-7, ESR, PIR, MASn

This allows additional registers to be accessed by the guest
in PR-mode KVM without trapping.

SPRG4-7 are readable from userspace.  On booke, KVM will sync
these registers when it enters the guest, so that accesses from
guest userspace will work.  The guest kernel, OTOH, must consistently
use either the real registers or the shared area between exits.  This
also applies to the already-paravirted SPRG3.

On non-booke, it's not clear to what extent SPRG4-7 are supported
(they're not architected for book3s, but exist on at least some classic
chips).  They are copied in the get/set regs ioctls, but I do not see any
non-booke emulation.  I also do not see any syncing with real registers
(in PR-mode) including the user-readable SPRG3.  This patch should not
make that situation any worse.

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

diff --git a/arch/powerpc/kvm/booke_emulate.c b/arch/powerpc/kvm/booke_emulate.c
index 1260f5f..bae9288 100644
--- a/arch/powerpc/kvm/booke_emulate.c
+++ b/arch/powerpc/kvm/booke_emulate.c
@@ -107,7 +107,7 @@
 	case SPRN_DEAR:
 		vcpu->arch.shared->dar = spr_val; break;
 	case SPRN_ESR:
-		vcpu->arch.esr = spr_val; break;
+		vcpu->arch.shared->esr = spr_val; break;
 	case SPRN_DBCR0:
 		vcpu->arch.dbcr0 = spr_val; break;
 	case SPRN_DBCR1:
@@ -125,13 +125,13 @@
 	 * loaded into the real SPRGs when resuming the
 	 * guest. */
 	case SPRN_SPRG4:
-		vcpu->arch.sprg4 = spr_val; break;
+		vcpu->arch.shared->sprg4 = spr_val; break;
 	case SPRN_SPRG5:
-		vcpu->arch.sprg5 = spr_val; break;
+		vcpu->arch.shared->sprg5 = spr_val; break;
 	case SPRN_SPRG6:
-		vcpu->arch.sprg6 = spr_val; break;
+		vcpu->arch.shared->sprg6 = spr_val; break;
 	case SPRN_SPRG7:
-		vcpu->arch.sprg7 = spr_val; break;
+		vcpu->arch.shared->sprg7 = spr_val; break;
 
 	case SPRN_IVPR:
 		vcpu->arch.ivpr = spr_val;
@@ -202,7 +202,7 @@
 	case SPRN_DEAR:
 		kvmppc_set_gpr(vcpu, rt, vcpu->arch.shared->dar); break;
 	case SPRN_ESR:
-		kvmppc_set_gpr(vcpu, rt, vcpu->arch.esr); break;
+		kvmppc_set_gpr(vcpu, rt, vcpu->arch.shared->esr); break;
 	case SPRN_DBCR0:
 		kvmppc_set_gpr(vcpu, rt, vcpu->arch.dbcr0); break;
 	case SPRN_DBCR1: