kvm/ppc/booke: Hold srcu lock when calling gfn functions

KVM core expects arch code to acquire the srcu lock when calling
gfn_to_memslot and similar functions.

Signed-off-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
diff --git a/arch/powerpc/kvm/44x_tlb.c b/arch/powerpc/kvm/44x_tlb.c
index 5dd3ab4..ed03854 100644
--- a/arch/powerpc/kvm/44x_tlb.c
+++ b/arch/powerpc/kvm/44x_tlb.c
@@ -441,6 +441,7 @@
 	struct kvmppc_vcpu_44x *vcpu_44x = to_44x(vcpu);
 	struct kvmppc_44x_tlbe *tlbe;
 	unsigned int gtlb_index;
+	int idx;
 
 	gtlb_index = kvmppc_get_gpr(vcpu, ra);
 	if (gtlb_index >= KVM44x_GUEST_TLB_SIZE) {
@@ -473,6 +474,8 @@
 		return EMULATE_FAIL;
 	}
 
+	idx = srcu_read_lock(&vcpu->kvm->srcu);
+
 	if (tlbe_is_host_safe(vcpu, tlbe)) {
 		gva_t eaddr;
 		gpa_t gpaddr;
@@ -489,6 +492,8 @@
 		kvmppc_mmu_map(vcpu, eaddr, gpaddr, gtlb_index);
 	}
 
+	srcu_read_unlock(&vcpu->kvm->srcu, idx);
+
 	trace_kvm_gtlb_write(gtlb_index, tlbe->tid, tlbe->word0, tlbe->word1,
 			     tlbe->word2);