vdpasim: control virtqueue support

This patch introduces the control virtqueue support for vDPA
simulator. This is a requirement for supporting advanced features like
multiqueue.

A requirement for control virtqueue is to isolate its memory access
from the rx/tx virtqueues. This is because when using vDPA device
for VM, the control virqueue is not directly assigned to VM. Userspace
(Qemu) will present a shadow control virtqueue to control for
recording the device states.

The isolation is done via the virtqueue groups and ASID support in
vDPA through vhost-vdpa. The simulator is extended to have:

1) three virtqueues: RXVQ, TXVQ and CVQ (control virtqueue)
2) two virtqueue groups: group 0 contains RXVQ and TXVQ; group 1
   contains CVQ
3) two address spaces and the simulator simply implements the address
   spaces by mapping it 1:1 to IOTLB.

For the VM use cases, userspace(Qemu) may set AS 0 to group 0 and AS 1
to group 1. So we have:

1) The IOTLB for virtqueue group 0 contains the mappings of guest, so
   RX and TX can be assigned to guest directly.
2) The IOTLB for virtqueue group 1 contains the mappings of CVQ which
   is the buffers that allocated and managed by VMM only. So CVQ of
   vhost-vdpa is visible to VMM only. And Guest can not access the CVQ
   of vhost-vdpa.

For the other use cases, since AS 0 is associated to all virtqueue
groups by default. All virtqueues share the same mapping by default.

To demonstrate the function, VIRITO_NET_F_CTRL_MACADDR is
implemented in the simulator for the driver to set mac address.
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Gautam Dawar <gdawar@xilinx.com>
Message-Id: <20220330180436.24644-20-gdawar@xilinx.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

drivers/vdpa/vdpa_sim/vdpa_sim.c

@@ -96,11 +96,17 @@ static void vdpasim_do_reset(struct vdpasim *vdpasim)
 {
 	int i;
 
-	for (i = 0; i < vdpasim->dev_attr.nvqs; i++)
+	spin_lock(&vdpasim->iommu_lock);
+
+	for (i = 0; i < vdpasim->dev_attr.nvqs; i++) {
 		vdpasim_vq_reset(vdpasim, &vdpasim->vqs[i]);
+		vringh_set_iotlb(&vdpasim->vqs[i].vring, &vdpasim->iommu[0],
+				 &vdpasim->iommu_lock);
+	}
+
+	for (i = 0; i < vdpasim->dev_attr.nas; i++)
+		vhost_iotlb_reset(&vdpasim->iommu[i]);
 
-	spin_lock(&vdpasim->iommu_lock);
-	vhost_iotlb_reset(vdpasim->iommu);
 	spin_unlock(&vdpasim->iommu_lock);
 
 	vdpasim->features = 0;
@@ -145,7 +151,7 @@ static dma_addr_t vdpasim_map_range(struct vdpasim *vdpasim, phys_addr_t paddr,
 	dma_addr = iova_dma_addr(&vdpasim->iova, iova);
 
 	spin_lock(&vdpasim->iommu_lock);
-	ret = vhost_iotlb_add_range(vdpasim->iommu, (u64)dma_addr,
+	ret = vhost_iotlb_add_range(&vdpasim->iommu[0], (u64)dma_addr,
 				    (u64)dma_addr + size - 1, (u64)paddr, perm);
 	spin_unlock(&vdpasim->iommu_lock);
 
@@ -161,7 +167,7 @@ static void vdpasim_unmap_range(struct vdpasim *vdpasim, dma_addr_t dma_addr,
 				size_t size)
 {
 	spin_lock(&vdpasim->iommu_lock);
-	vhost_iotlb_del_range(vdpasim->iommu, (u64)dma_addr,
+	vhost_iotlb_del_range(&vdpasim->iommu[0], (u64)dma_addr,
 			      (u64)dma_addr + size - 1);
 	spin_unlock(&vdpasim->iommu_lock);
 
@@ -250,8 +256,9 @@ struct vdpasim *vdpasim_create(struct vdpasim_dev_attr *dev_attr)
 	else
 		ops = &vdpasim_config_ops;
 
-	vdpasim = vdpa_alloc_device(struct vdpasim, vdpa, NULL, ops, 1,
-				    1, dev_attr->name, false);
+	vdpasim = vdpa_alloc_device(struct vdpasim, vdpa, NULL, ops,
+				    dev_attr->ngroups, dev_attr->nas,
+				    dev_attr->name, false);
 	if (IS_ERR(vdpasim)) {
 		ret = PTR_ERR(vdpasim);
 		goto err_alloc;
@@ -278,16 +285,20 @@ struct vdpasim *vdpasim_create(struct vdpasim_dev_attr *dev_attr)
 	if (!vdpasim->vqs)
 		goto err_iommu;
 
-	vdpasim->iommu = vhost_iotlb_alloc(max_iotlb_entries, 0);
+	vdpasim->iommu = kmalloc_array(vdpasim->dev_attr.nas,
+				       sizeof(*vdpasim->iommu), GFP_KERNEL);
 	if (!vdpasim->iommu)
 		goto err_iommu;
 
+	for (i = 0; i < vdpasim->dev_attr.nas; i++)
+		vhost_iotlb_init(&vdpasim->iommu[i], 0, 0);
+
 	vdpasim->buffer = kvmalloc(dev_attr->buffer_size, GFP_KERNEL);
 	if (!vdpasim->buffer)
 		goto err_iommu;
 
 	for (i = 0; i < dev_attr->nvqs; i++)
-		vringh_set_iotlb(&vdpasim->vqs[i].vring, vdpasim->iommu,
+		vringh_set_iotlb(&vdpasim->vqs[i].vring, &vdpasim->iommu[0],
 				 &vdpasim->iommu_lock);
 
 	ret = iova_cache_get();
@@ -401,6 +412,10 @@ static u32 vdpasim_get_vq_align(struct vdpa_device *vdpa)
 
 static u32 vdpasim_get_vq_group(struct vdpa_device *vdpa, u16 idx)
 {
+	/* RX and TX belongs to group 0, CVQ belongs to group 1 */
+	if (idx == 2)
+		return 1;
+	else
 		return 0;
 }
 
@@ -539,20 +554,53 @@ static struct vdpa_iova_range vdpasim_get_iova_range(struct vdpa_device *vdpa)
 	return range;
 }
 
+static int vdpasim_set_group_asid(struct vdpa_device *vdpa, unsigned int group,
+				  unsigned int asid)
+{
+	struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
+	struct vhost_iotlb *iommu;
+	int i;
+
+	if (group > vdpasim->dev_attr.ngroups)
+		return -EINVAL;
+
+	if (asid > vdpasim->dev_attr.nas)
+		return -EINVAL;
+
+	iommu = &vdpasim->iommu[asid];
+
+	spin_lock(&vdpasim->lock);
+
+	for (i = 0; i < vdpasim->dev_attr.nvqs; i++)
+		if (vdpasim_get_vq_group(vdpa, i) == group)
+			vringh_set_iotlb(&vdpasim->vqs[i].vring, iommu,
+					 &vdpasim->iommu_lock);
+
+	spin_unlock(&vdpasim->lock);
+
+	return 0;
+}
+
 static int vdpasim_set_map(struct vdpa_device *vdpa, unsigned int asid,
 			   struct vhost_iotlb *iotlb)
 {
 	struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
 	struct vhost_iotlb_map *map;
+	struct vhost_iotlb *iommu;
 	u64 start = 0ULL, last = 0ULL - 1;
 	int ret;
 
+	if (asid >= vdpasim->dev_attr.nas)
+		return -EINVAL;
+
 	spin_lock(&vdpasim->iommu_lock);
-	vhost_iotlb_reset(vdpasim->iommu);
+
+	iommu = &vdpasim->iommu[asid];
+	vhost_iotlb_reset(iommu);
 
 	for (map = vhost_iotlb_itree_first(iotlb, start, last); map;
 	     map = vhost_iotlb_itree_next(map, start, last)) {
-		ret = vhost_iotlb_add_range(vdpasim->iommu, map->start,
+		ret = vhost_iotlb_add_range(iommu, map->start,
 					    map->last, map->addr, map->perm);
 		if (ret)
 			goto err;
@@ -561,7 +609,7 @@ static int vdpasim_set_map(struct vdpa_device *vdpa, unsigned int asid,
 	return 0;
 
 err:
-	vhost_iotlb_reset(vdpasim->iommu);
+	vhost_iotlb_reset(iommu);
 	spin_unlock(&vdpasim->iommu_lock);
 	return ret;
 }
@@ -573,9 +621,12 @@ static int vdpasim_dma_map(struct vdpa_device *vdpa, unsigned int asid,
 	struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
 	int ret;
 
+	if (asid >= vdpasim->dev_attr.nas)
+		return -EINVAL;
+
 	spin_lock(&vdpasim->iommu_lock);
-	ret = vhost_iotlb_add_range_ctx(vdpasim->iommu, iova, iova + size - 1,
-					pa, perm, opaque);
+	ret = vhost_iotlb_add_range_ctx(&vdpasim->iommu[asid], iova,
+					iova + size - 1, pa, perm, opaque);
 	spin_unlock(&vdpasim->iommu_lock);
 
 	return ret;
@@ -586,8 +637,11 @@ static int vdpasim_dma_unmap(struct vdpa_device *vdpa, unsigned int asid,
 {
 	struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
 
+	if (asid >= vdpasim->dev_attr.nas)
+		return -EINVAL;
+
 	spin_lock(&vdpasim->iommu_lock);
-	vhost_iotlb_del_range(vdpasim->iommu, iova, iova + size - 1);
+	vhost_iotlb_del_range(&vdpasim->iommu[asid], iova, iova + size - 1);
 	spin_unlock(&vdpasim->iommu_lock);
 
 	return 0;
@@ -611,7 +665,6 @@ static void vdpasim_free(struct vdpa_device *vdpa)
 	}
 
 	kvfree(vdpasim->buffer);
-	if (vdpasim->iommu)
 	vhost_iotlb_free(vdpasim->iommu);
 	kfree(vdpasim->vqs);
 	kfree(vdpasim->config);
@@ -643,6 +696,7 @@ static const struct vdpa_config_ops vdpasim_config_ops = {
 	.set_config             = vdpasim_set_config,
 	.get_generation         = vdpasim_get_generation,
 	.get_iova_range         = vdpasim_get_iova_range,
+	.set_group_asid         = vdpasim_set_group_asid,
 	.dma_map                = vdpasim_dma_map,
 	.dma_unmap              = vdpasim_dma_unmap,
 	.free                   = vdpasim_free,
@@ -674,6 +728,7 @@ static const struct vdpa_config_ops vdpasim_batch_config_ops = {
 	.set_config             = vdpasim_set_config,
 	.get_generation         = vdpasim_get_generation,
 	.get_iova_range         = vdpasim_get_iova_range,
+	.set_group_asid         = vdpasim_set_group_asid,
 	.set_map                = vdpasim_set_map,
 	.free                   = vdpasim_free,
 };

drivers/vdpa/vdpa_sim/vdpa_sim.h

@@ -41,6 +41,8 @@ struct vdpasim_dev_attr {
 	size_t buffer_size;
 	int nvqs;
 	u32 id;
+	u32 ngroups;
+	u32 nas;
 
 	work_func_t work_fn;
 	void (*get_config)(struct vdpasim *vdpasim, void *config);

drivers/vdpa/vdpa_sim/vdpa_sim_net.c

@@ -27,9 +27,14 @@
 
 #define VDPASIM_NET_FEATURES	(VDPASIM_FEATURES | \
 				 (1ULL << VIRTIO_NET_F_MAC) | \
-				 (1ULL << VIRTIO_NET_F_MTU))
+				 (1ULL << VIRTIO_NET_F_MTU) | \
+				 (1ULL << VIRTIO_NET_F_CTRL_VQ) | \
+				 (1ULL << VIRTIO_NET_F_CTRL_MAC_ADDR))
 
-#define VDPASIM_NET_VQ_NUM	2
+/* 3 virtqueues, 2 address spaces, 2 virtqueue groups */
+#define VDPASIM_NET_VQ_NUM	3
+#define VDPASIM_NET_AS_NUM	2
+#define VDPASIM_NET_GROUP_NUM	2
 
 static void vdpasim_net_complete(struct vdpasim_virtqueue *vq, size_t len)
 {
@@ -63,6 +68,81 @@ static bool receive_filter(struct vdpasim *vdpasim, size_t len)
 	return false;
 }
 
+static virtio_net_ctrl_ack vdpasim_handle_ctrl_mac(struct vdpasim *vdpasim,
+						   u8 cmd)
+{
+	struct virtio_net_config *vio_config = vdpasim->config;
+	struct vdpasim_virtqueue *cvq = &vdpasim->vqs[2];
+	virtio_net_ctrl_ack status = VIRTIO_NET_ERR;
+	size_t read;
+
+	switch (cmd) {
+	case VIRTIO_NET_CTRL_MAC_ADDR_SET:
+		read = vringh_iov_pull_iotlb(&cvq->vring, &cvq->in_iov,
+					     vio_config->mac, ETH_ALEN);
+		if (read == ETH_ALEN)
+			status = VIRTIO_NET_OK;
+		break;
+	default:
+		break;
+	}
+
+	return status;
+}
+
+static void vdpasim_handle_cvq(struct vdpasim *vdpasim)
+{
+	struct vdpasim_virtqueue *cvq = &vdpasim->vqs[2];
+	virtio_net_ctrl_ack status = VIRTIO_NET_ERR;
+	struct virtio_net_ctrl_hdr ctrl;
+	size_t read, write;
+	int err;
+
+	if (!(vdpasim->features & (1ULL << VIRTIO_NET_F_CTRL_VQ)))
+		return;
+
+	if (!cvq->ready)
+		return;
+
+	while (true) {
+		err = vringh_getdesc_iotlb(&cvq->vring, &cvq->in_iov,
+					   &cvq->out_iov,
+					   &cvq->head, GFP_ATOMIC);
+		if (err <= 0)
+			break;
+
+		read = vringh_iov_pull_iotlb(&cvq->vring, &cvq->in_iov, &ctrl,
+					     sizeof(ctrl));
+		if (read != sizeof(ctrl))
+			break;
+
+		switch (ctrl.class) {
+		case VIRTIO_NET_CTRL_MAC:
+			status = vdpasim_handle_ctrl_mac(vdpasim, ctrl.cmd);
+			break;
+		default:
+			break;
+		}
+
+		/* Make sure data is wrote before advancing index */
+		smp_wmb();
+
+		write = vringh_iov_push_iotlb(&cvq->vring, &cvq->out_iov,
+					      &status, sizeof(status));
+		vringh_complete_iotlb(&cvq->vring, cvq->head, write);
+		vringh_kiov_cleanup(&cvq->in_iov);
+		vringh_kiov_cleanup(&cvq->out_iov);
+
+		/* Make sure used is visible before rasing the interrupt. */
+		smp_wmb();
+
+		local_bh_disable();
+		if (cvq->cb)
+			cvq->cb(cvq->private);
+		local_bh_enable();
+	}
+}
+
 static void vdpasim_net_work(struct work_struct *work)
 {
 	struct vdpasim *vdpasim = container_of(work, struct vdpasim, work);
@@ -77,6 +157,8 @@ static void vdpasim_net_work(struct work_struct *work)
 	if (!(vdpasim->status & VIRTIO_CONFIG_S_DRIVER_OK))
 		goto out;
 
+	vdpasim_handle_cvq(vdpasim);
+
 	if (!txq->ready || !rxq->ready)
 		goto out;
 
@@ -162,6 +244,8 @@ static int vdpasim_net_dev_add(struct vdpa_mgmt_dev *mdev, const char *name,
 	dev_attr.id = VIRTIO_ID_NET;
 	dev_attr.supported_features = VDPASIM_NET_FEATURES;
 	dev_attr.nvqs = VDPASIM_NET_VQ_NUM;
+	dev_attr.ngroups = VDPASIM_NET_GROUP_NUM;
+	dev_attr.nas = VDPASIM_NET_AS_NUM;
 	dev_attr.config_size = sizeof(struct virtio_net_config);
 	dev_attr.get_config = vdpasim_net_get_config;
 	dev_attr.work_fn = vdpasim_net_work;