diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 359c79cdf0cc82..1182cfd7985715 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -485,7 +485,13 @@ static unsigned long do_h_register_vpa(struct kvm_vcpu *vcpu,
 
 	switch (subfunc) {
 	case H_VPA_REG_VPA:		/* register VPA */
-		if (len < sizeof(struct lppaca))
+		/*
+		 * The size of our lppaca is 1kB because of the way we align
+		 * it for the guest to avoid crossing a 4kB boundary. We only
+		 * use 640 bytes of the structure though, so we should accept
+		 * clients that set a size of 640.
+		 */
+		if (len < 640)
 			break;
 		vpap = &tvcpu->arch.vpa;
 		err = 0;