[PATCH 21/21] vdpasim: control virtqueue support

[Jason Wang <jasowang@redhat.com>]

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>
---
 drivers/vdpa/vdpa_sim/vdpa_sim.c | 189 +++++++++++++++++++++++++++----
 1 file changed, 166 insertions(+), 23 deletions(-)

diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.c b/drivers/vdpa/vdpa_sim/vdpa_sim.c
index fe90a783bde4..0fd06ac491cd 100644
--- a/drivers/vdpa/vdpa_sim/vdpa_sim.c
+++ b/drivers/vdpa/vdpa_sim/vdpa_sim.c
@@ -60,14 +60,18 @@ struct vdpasim_virtqueue {
 #define VDPASIM_QUEUE_MAX 256
 #define VDPASIM_DEVICE_ID 0x1
 #define VDPASIM_VENDOR_ID 0
-#define VDPASIM_VQ_NUM 0x2
+#define VDPASIM_VQ_NUM 0x3
+#define VDPASIM_AS_NUM 0x2
+#define VDPASIM_GROUP_NUM 0x2
 #define VDPASIM_NAME "vdpasim-netdev"
 
 static u64 vdpasim_features = (1ULL << VIRTIO_F_ANY_LAYOUT) |
 			      (1ULL << VIRTIO_F_VERSION_1)  |
 			      (1ULL << VIRTIO_F_ACCESS_PLATFORM) |
+			      (1ULL << VIRTIO_NET_F_MTU) |
 			      (1ULL << VIRTIO_NET_F_MAC) |
-			      (1ULL << VIRTIO_NET_F_MTU);
+			      (1ULL << VIRTIO_NET_F_CTRL_VQ) |
+			      (1ULL << VIRTIO_NET_F_CTRL_MAC_ADDR);
 
 /* State of each vdpasim device */
 struct vdpasim {
@@ -147,11 +151,17 @@ static void vdpasim_reset(struct vdpasim *vdpasim)
 {
 	int i;
 
-	for (i = 0; i < VDPASIM_VQ_NUM; i++)
+	spin_lock(&vdpasim->iommu_lock);
+
+	for (i = 0; i < VDPASIM_VQ_NUM; i++) {
 		vdpasim_vq_reset(&vdpasim->vqs[i]);
+		vringh_set_iotlb(&vdpasim->vqs[i].vring,
+				 &vdpasim->iommu[0]);
+	}
 
-	spin_lock(&vdpasim->iommu_lock);
-	vhost_iotlb_reset(vdpasim->iommu);
+	for (i = 0; i < VDPASIM_AS_NUM; i++) {
+		vhost_iotlb_reset(&vdpasim->iommu[i]);
+	}
 	spin_unlock(&vdpasim->iommu_lock);
 
 	vdpasim->features = 0;
@@ -191,6 +201,81 @@ static bool receive_filter(struct vdpasim *vdpasim, size_t len)
 	return false;
 }
 
+virtio_net_ctrl_ack vdpasim_handle_ctrl_mac(struct vdpasim *vdpasim,
+					    u8 cmd)
+{
+	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,
+					     (void *)vdpasim->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_work(struct work_struct *work)
 {
 	struct vdpasim *vdpasim = container_of(work, struct
@@ -276,7 +361,7 @@ static dma_addr_t vdpasim_map_page(struct device *dev, struct page *page,
 				   unsigned long attrs)
 {
 	struct vdpasim *vdpasim = dev_to_sim(dev);
-	struct vhost_iotlb *iommu = vdpasim->iommu;
+	struct vhost_iotlb *iommu = &vdpasim->iommu[0];
 	u64 pa = (page_to_pfn(page) << PAGE_SHIFT) + offset;
 	int ret, perm = dir_to_perm(dir);
 
@@ -301,7 +386,7 @@ static void vdpasim_unmap_page(struct device *dev, dma_addr_t dma_addr,
 			       unsigned long attrs)
 {
 	struct vdpasim *vdpasim = dev_to_sim(dev);
-	struct vhost_iotlb *iommu = vdpasim->iommu;
+	struct vhost_iotlb *iommu = &vdpasim->iommu[0];
 
 	spin_lock(&vdpasim->iommu_lock);
 	vhost_iotlb_del_range(iommu, (u64)dma_addr,
@@ -314,7 +399,7 @@ static void *vdpasim_alloc_coherent(struct device *dev, size_t size,
 				    unsigned long attrs)
 {
 	struct vdpasim *vdpasim = dev_to_sim(dev);
-	struct vhost_iotlb *iommu = vdpasim->iommu;
+	struct vhost_iotlb *iommu = &vdpasim->iommu[0];
 	void *addr = kmalloc(size, flag);
 	int ret;
 
@@ -344,7 +429,7 @@ static void vdpasim_free_coherent(struct device *dev, size_t size,
 				  unsigned long attrs)
 {
 	struct vdpasim *vdpasim = dev_to_sim(dev);
-	struct vhost_iotlb *iommu = vdpasim->iommu;
+	struct vhost_iotlb *iommu = &vdpasim->iommu[0];
 
 	spin_lock(&vdpasim->iommu_lock);
 	vhost_iotlb_del_range(iommu, (u64)dma_addr,
@@ -370,14 +455,17 @@ static struct vdpasim *vdpasim_create(void)
 	struct vdpasim *vdpasim;
 	struct device *dev;
 	int ret = -ENOMEM;
+	int i;
 
 	if (batch_mapping)
 		ops = &vdpasim_net_batch_config_ops;
 	else
 		ops = &vdpasim_net_config_ops;
 
+	/* 3 virtqueues, 2 address spaces, 2 virtqueue groups */
 	vdpasim = vdpa_alloc_device(struct vdpasim, vdpa, NULL, ops,
-				    VDPASIM_VQ_NUM, 1, 1);
+				    VDPASIM_VQ_NUM, VDPASIM_AS_NUM,
+				    VDPASIM_GROUP_NUM);
 	if (!vdpasim)
 		goto err_alloc;
 
@@ -391,10 +479,14 @@ static struct vdpasim *vdpasim_create(void)
 		goto err_iommu;
 	set_dma_ops(dev, &vdpasim_dma_ops);
 
-	vdpasim->iommu = vhost_iotlb_alloc(2048, 0);
+	vdpasim->iommu = kmalloc_array(VDPASIM_AS_NUM,
+				       sizeof(*vdpasim->iommu), GFP_KERNEL);
 	if (!vdpasim->iommu)
 		goto err_iommu;
 
+	for (i = 0; i < VDPASIM_AS_NUM; i++)
+		vhost_iotlb_init(&vdpasim->iommu[i], 0, 0);
+
 	vdpasim->buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
 	if (!vdpasim->buffer)
 		goto err_iommu;
@@ -409,8 +501,9 @@ static struct vdpasim *vdpasim_create(void)
 		eth_random_addr(vdpasim->config.mac);
 	}
 
-	vringh_set_iotlb(&vdpasim->vqs[0].vring, vdpasim->iommu);
-	vringh_set_iotlb(&vdpasim->vqs[1].vring, vdpasim->iommu);
+	/* Make sure that default ASID is zero */
+	for (i = 0; i < VDPASIM_VQ_NUM; i++)
+		vringh_set_iotlb(&vdpasim->vqs[i].vring, &vdpasim->iommu[0]);
 
 	vdpasim->vdpa.dma_dev = dev;
 	ret = vdpa_register_device(&vdpasim->vdpa);
@@ -452,7 +545,14 @@ static void vdpasim_kick_vq(struct vdpa_device *vdpa, u16 idx)
 	struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
 	struct vdpasim_virtqueue *vq = &vdpasim->vqs[idx];
 
-	if (vq->ready)
+	if (idx == 2) {
+		/* Kernel virtio driver will do busy waiting for the
+		 * result, so we can't handle cvq in the workqueue.
+		 */
+		spin_lock(&vdpasim->lock);
+		vdpasim_handle_cvq(vdpasim);
+		spin_unlock(&vdpasim->lock);
+	} else if (vq->ready)
 		schedule_work(&vdpasim->work);
 }
 
@@ -518,7 +618,11 @@ static u32 vdpasim_get_vq_align(struct vdpa_device *vdpa)
 
 static u32 vdpasim_get_vq_group(struct vdpa_device *vdpa, u16 idx)
 {
-	return 0;
+	/* RX and TX belongs to group 0, CVQ belongs to group 1 */
+	if (idx == 2)
+		return 1;
+	else
+		return 0;
 }
 
 static u64 vdpasim_get_features(struct vdpa_device *vdpa)
@@ -624,20 +728,52 @@ static struct vdpa_iova_range vdpasim_get_iova_range(struct vdpa_device *vdpa)
 	return range;
 }
 
+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_GROUP_NUM)
+		return -EINVAL;
+
+	if (asid > VDPASIM_AS_NUM)
+		return -EINVAL;
+
+	iommu = &vdpasim->iommu[asid];
+
+	spin_lock(&vdpasim->lock);
+
+	for (i = 0; i < VDPASIM_VQ_NUM; i++)
+		if (vdpasim_get_vq_group(vdpa, i) == group)
+			vringh_set_iotlb(&vdpasim->vqs[i].vring, iommu);
+
+	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_AS_NUM)
+		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;
@@ -646,7 +782,7 @@ 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;
 }
@@ -658,9 +794,12 @@ static int vdpasim_dma_map(struct vdpa_device *vdpa, unsigned int asid,
 	struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
 	int ret;
 
+	if (asid >= VDPASIM_AS_NUM)
+		return -EINVAL;
+
 	spin_lock(&vdpasim->iommu_lock);
-	ret = vhost_iotlb_add_range(vdpasim->iommu, iova, iova + size - 1, pa,
-				    perm);
+	ret = vhost_iotlb_add_range(&vdpasim->iommu[asid], iova,
+				    iova + size - 1, pa, perm);
 	spin_unlock(&vdpasim->iommu_lock);
 
 	return ret;
@@ -671,8 +810,11 @@ static int vdpasim_dma_unmap(struct vdpa_device *vdpa, unsigned int asid,
 {
 	struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
 
+	if (asid >= VDPASIM_AS_NUM)
+		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;
@@ -684,8 +826,7 @@ static void vdpasim_free(struct vdpa_device *vdpa)
 
 	cancel_work_sync(&vdpasim->work);
 	kfree(vdpasim->buffer);
-	if (vdpasim->iommu)
-		vhost_iotlb_free(vdpasim->iommu);
+	vhost_iotlb_free(vdpasim->iommu);
 }
 
 static const struct vdpa_config_ops vdpasim_net_config_ops = {
@@ -711,6 +852,7 @@ static const struct vdpa_config_ops vdpasim_net_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,
@@ -739,6 +881,7 @@ static const struct vdpa_config_ops vdpasim_net_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,
 };
-- 
2.25.1