KVM: arm/arm64: VGIC/ITS save/restore: protect kvm_read_guest() calls

kvm_read_guest() will eventually look up in kvm_memslots(), which requires
either to hold the kvm->slots_lock or to be inside a kvm->srcu critical
section.
In contrast to x86 and s390 we don't take the SRCU lock on every guest
exit, so we have to do it individually for each kvm_read_guest() call.
Use the newly introduced wrapper for that.

Cc: Stable <stable@vger.kernel.org> # 4.12+
Reported-by: Jan Glauber <jan.glauber@caviumnetworks.com>
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Acked-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/virt/kvm/arm/vgic/vgic-v3.c b/virt/kvm/arm/vgic/vgic-v3.c
index c7423f3..bdcf8e7 100644
--- a/virt/kvm/arm/vgic/vgic-v3.c
+++ b/virt/kvm/arm/vgic/vgic-v3.c
@@ -344,7 +344,7 @@ int vgic_v3_lpi_sync_pending_status(struct kvm *kvm, struct vgic_irq *irq)
 	bit_nr = irq->intid % BITS_PER_BYTE;
 	ptr = pendbase + byte_offset;
 
-	ret = kvm_read_guest(kvm, ptr, &val, 1);
+	ret = kvm_read_guest_lock(kvm, ptr, &val, 1);
 	if (ret)
 		return ret;
 
@@ -397,7 +397,7 @@ int vgic_v3_save_pending_tables(struct kvm *kvm)
 		ptr = pendbase + byte_offset;
 
 		if (byte_offset != last_byte_offset) {
-			ret = kvm_read_guest(kvm, ptr, &val, 1);
+			ret = kvm_read_guest_lock(kvm, ptr, &val, 1);
 			if (ret)
 				return ret;
 			last_byte_offset = byte_offset;