[dpdk-dev] [RFC 16/19] vhost-user: translate ring addresses when IOMMU enabled

[Maxime Coquelin <maxime.coquelin@redhat.com>]

When IOMMU is enabled, the ring addresses set by the
VHOST_USER_SET_VRING_ADDR requests are guest's IO virtual addresses,
whereas Qemu virtual addresses when IOMMU is disabled.

When enabled and the required translation is not in the IOTLB cache,
an IOTLB miss request is sent, but being called by the vhost-user
socket handling thread, the function does not wait for the requested
IOTLB update.

The function will be called again on the next IOTLB update message
reception if matching the vring addresses.

Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
---
 lib/librte_vhost/vhost_user.c | 43 +++++++++++++++++++++++++++++++++----------
 1 file changed, 33 insertions(+), 10 deletions(-)

diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
index d9712e9..8230578 100644
--- a/lib/librte_vhost/vhost_user.c
+++ b/lib/librte_vhost/vhost_user.c
@@ -290,10 +290,7 @@ numa_realloc(struct virtio_net *dev, int index __rte_unused)
 }
 #endif
 
-/*
- * Converts QEMU virtual address to Vhost virtual address. This function is
- * used to convert the ring addresses to our address space.
- */
+/* Converts QEMU virtual address to Vhost virtual address. */
 static uint64_t
 qva_to_vva(struct virtio_net *dev, uint64_t qva)
 {
@@ -314,6 +311,29 @@ qva_to_vva(struct virtio_net *dev, uint64_t qva)
 	return 0;
 }
 
+
+/*
+ * Converts ring address to Vhost virtual address.
+ * If IOMMU is enabled, the ring address is a guest IO virtual address,
+ * else it is a QEMU virtual address.
+ */
+static uint64_t
+ring_addr_to_vva(struct virtio_net *dev, struct vhost_virtqueue *vq,
+		uint64_t ra, uint64_t size)
+{
+	if (dev->features & (1ULL << VIRTIO_F_IOMMU_PLATFORM)) {
+		uint64_t vva;
+
+		vva = vhost_user_iotlb_find(vq, ra, &size, VHOST_ACCESS_RW);
+		if (!vva)
+			vhost_user_iotlb_miss(dev, ra, VHOST_ACCESS_RW);
+
+		return vva;
+	}
+
+	return qva_to_vva(dev, ra);
+}
+
 /*
  * The virtio device sends us the desc, used and avail ring addresses.
  * This function then converts these to our address space.
@@ -346,8 +366,11 @@ static struct virtio_net *translate_ring_addresses(struct virtio_net *dev,
 	struct vhost_vring_addr *addr = &vq->ring_addrs;
 
 	/* The addresses are converted from QEMU virtual to Vhost virtual. */
-	vq->desc = (struct vring_desc *)(uintptr_t)qva_to_vva(dev,
-			addr->desc_user_addr);
+	if (vq->desc && vq->avail && vq->used)
+		return dev;
+
+	vq->desc = (struct vring_desc *)(uintptr_t)ring_addr_to_vva(dev,
+			vq, addr->desc_user_addr, sizeof(struct vring_desc));
 	if (vq->desc == 0) {
 		RTE_LOG(ERR, VHOST_CONFIG,
 			"(%d) failed to find desc ring address.\n",
@@ -358,8 +381,8 @@ static struct virtio_net *translate_ring_addresses(struct virtio_net *dev,
 	dev = numa_realloc(dev, vq_index);
 	vq = dev->virtqueue[vq_index];
 
-	vq->avail = (struct vring_avail *)(uintptr_t)qva_to_vva(dev,
-			addr->avail_user_addr);
+	vq->avail = (struct vring_avail *)(uintptr_t)ring_addr_to_vva(dev,
+			vq, addr->avail_user_addr, sizeof(struct vring_avail));
 	if (vq->avail == 0) {
 		RTE_LOG(ERR, VHOST_CONFIG,
 			"(%d) failed to find avail ring address.\n",
@@ -367,8 +390,8 @@ static struct virtio_net *translate_ring_addresses(struct virtio_net *dev,
 		return NULL;
 	}
 
-	vq->used = (struct vring_used *)(uintptr_t)qva_to_vva(dev,
-			addr->used_user_addr);
+	vq->used = (struct vring_used *)(uintptr_t)ring_addr_to_vva(dev,
+			vq, addr->used_user_addr, sizeof(struct vring_used));
 	if (vq->used == 0) {
 		RTE_LOG(ERR, VHOST_CONFIG,
 			"(%d) failed to find used ring address.\n",
-- 
2.9.4