Specify the length of the mapping requested from 'paddr_guest2host()'.

This seems prudent to do in its own right but it also opens up the possibility
of not having to mmap the entire guest address space in the 'bhyve' process
context.

Discussed with:	grehan
Obtained from:	NetApp

1 files changed, 15 insertions, 0 deletions

diff --git a/usr.sbin/bhyve/virtio.h b/usr.sbin/bhyve/virtio.h
index 04ef586..fe6fb1a 100644
--- a/usr.sbin/bhyve/virtio.h
+++ b/usr.sbin/bhyve/virtio.h
@@ -85,4 +85,19 @@ struct virtio_used {
 #define VTCFG_R_CFG1		24	/* With MSI-X */
 #define VTCFG_R_MSIX		20
 
+/* From section 2.3, "Virtqueue Configuration", of the virtio specification */
+static inline u_int
+vring_size(u_int qsz)
+{
+	u_int size;
+
+	size = sizeof(struct virtio_desc) * qsz + sizeof(uint16_t) * (3 + qsz);
+	size = roundup2(size, VRING_ALIGN);
+
+	size += sizeof(uint16_t) * 3 + sizeof(struct virtio_used) * qsz;
+	size = roundup2(size, VRING_ALIGN);
+
+	return (size);
+}
+
 #endif	/* _VIRTIO_H_ */