virtio: use KVM_S390_VIRTIO_RING_ALIGN instead of relying on pagesize

This doesn't really matter, since s390 pagesize is 4k anyway.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>

2 files changed, 10 insertions, 3 deletions

diff --git a/arch/s390/include/asm/kvm_virtio.h b/arch/s390/include/asm/kvm_virtio.h
index c13568b9351c..0503936f101f 100644
--- a/arch/s390/include/asm/kvm_virtio.h
+++ b/arch/s390/include/asm/kvm_virtio.h
@@ -50,6 +50,10 @@ struct kvm_vqconfig {
 #define KVM_S390_VIRTIO_RESET           1
 #define KVM_S390_VIRTIO_SET_STATUS      2
 
+/* The alignment to use between consumer and producer parts of vring.
+ * This is pagesize for historical reasons. */
+#define KVM_S390_VIRTIO_RING_ALIGN      4096
+
 #ifdef __KERNEL__
 /* early virtio console setup */
 #ifdef CONFIG_S390_GUEST
diff --git a/drivers/s390/kvm/kvm_virtio.c b/drivers/s390/kvm/kvm_virtio.c
index 3d442444c618..f5a2dbe75575 100644
--- a/drivers/s390/kvm/kvm_virtio.c
+++ b/drivers/s390/kvm/kvm_virtio.c
@@ -188,7 +188,8 @@ static struct virtqueue *kvm_find_vq(struct virtio_device *vdev,
         config = kvm_vq_config(kdev->desc)+index;
 
         err = vmem_add_mapping(config->address,
-                               vring_size(config->num, PAGE_SIZE));
+                               vring_size(config->num,
+                                          KVM_S390_VIRTIO_RING_ALIGN));
         if (err)
                 goto out;
 
@@ -209,7 +210,8 @@ static struct virtqueue *kvm_find_vq(struct virtio_device *vdev,
         return vq;
 unmap:
         vmem_remove_mapping(config->address,
-                            vring_size(config->num, PAGE_SIZE));
+                            vring_size(config->num,
+                                       KVM_S390_VIRTIO_RING_ALIGN));
 out:
         return ERR_PTR(err);
 }
@@ -220,7 +222,8 @@ static void kvm_del_vq(struct virtqueue *vq)
 
         vring_del_virtqueue(vq);
         vmem_remove_mapping(config->address,
-                            vring_size(config->num, PAGE_SIZE));
+                            vring_size(config->num,
+                                       KVM_S390_VIRTIO_RING_ALIGN));
 }
 
 /*