Re: [dpdk-dev] [PATCH 10/15] net/virtio: add vDPA op to configure and start the device

[Tiwei Bie <tiwei.bie@intel.com>]

On Tue, Sep 03, 2019 at 09:40:25AM +0200, Maxime Coquelin wrote:
> On 9/3/19 7:30 AM, Tiwei Bie wrote:
> > On Thu, Aug 29, 2019 at 09:59:55AM +0200, Maxime Coquelin wrote:
> >> In order to support multi-queue, we need to implement the control
> >> path. The problem is that both the Vhost-user master and slave use
> >> VAs in their processes address spaces as IOVAs, which creates
> >> collusions between the data rings IOVAs managed the master, and
> >> the Control ring IOVAs. The trick here is to remmap the Control
> >> ring memory to another range, after the slave is aware of master's
> >> ranges.
> >>
> >> Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
> >> ---
> >>  drivers/net/virtio/virtio_vdpa.c | 255 +++++++++++++++++++++++++++++++
> >>  1 file changed, 255 insertions(+)
> >>
> >> diff --git a/drivers/net/virtio/virtio_vdpa.c b/drivers/net/virtio/virtio_vdpa.c
> >> index fc52a8e92..13b4dd07d 100644
> >> --- a/drivers/net/virtio/virtio_vdpa.c
> >> +++ b/drivers/net/virtio/virtio_vdpa.c
> >> @@ -106,6 +106,127 @@ find_internal_resource_by_dev(struct rte_pci_device *pdev)
> >>  	return list;
> >>  }
> >>  
> >> +static int
> >> +virtio_vdpa_dma_map_ctrl_queue(struct virtio_vdpa_device *dev, int do_map,
> >> +		uint64_t iova)
> >> +{
> >> +	const struct rte_memzone *mz;
> >> +	int ret;
> >> +
> >> +	/*
> >> +	 * IOVAs are processes VAs. We cannot use them as the Data and Control
> >> +	 * paths are run in different processes, which may (does) lead to
> >> +	 * collusions. The trick here is to fixup Ctrl path IOVAs so that they
> >> +	 * start after the Data path ranges.
> >> +	 */
> >> +	if (do_map) {
> >> +		mz = dev->cvq->cq.mz;
> >> +		ret = rte_vfio_container_dma_map(dev->vfio_container_fd,
> >> +				(uint64_t)(uintptr_t)mz->addr,
> >> +				iova, mz->len);
> >> +		if (ret < 0) {
> >> +			DRV_LOG(ERR, "Failed to map ctrl ring (%d)", ret);
> >> +			return ret;
> >> +		}
> >> +
> >> +		dev->cvq->vq_ring_mem = iova;
> >> +		iova += mz->len;
> >> +
> >> +		mz = dev->cvq->cq.virtio_net_hdr_mz;
> >> +		ret = rte_vfio_container_dma_map(dev->vfio_container_fd,
> >> +				(uint64_t)(uintptr_t)mz->addr,
> >> +				iova, mz->len);
> >> +		if (ret < 0) {
> >> +			DRV_LOG(ERR, "Failed to map ctrl headers (%d)", ret);
> >> +			return ret;
> >> +		}
> > 
> > This will allow guest to access the cq.mz and cq.virtio_net_hdr_mz
> > via the device which may have potential risks.
> 
> I get what you mean, but I'm not sure to see how we could avoid that.
> AFAIU, we need to map the control queue in the device IOMMU, otherwise
> how could the host (in case of virtual device) or the NIC (in case of
> Virtio offload), could access the ring?
> Any thoughts?

I also don't see a way to avoid that. That's why I said in below
thread that I think the control queue based interface seems not a
quite good interface for a backend device:

https://lkml.org/lkml/2019/9/2/934

In IFCVF NIC, we added a MMIO based interface to replace control
queue for the multiqueue setup in vDPA mode.

Jason is proposing some changes to make virtio device suitable
for backend device. I'm not sure whether it's possible to cover
this case as well..

Regards,
Tiwei

> 
> Thanks,
> Maxime
> > Regards,
> > Tiwei
> > 
> >> +
> >> +		dev->cvq->cq.virtio_net_hdr_mem = iova;
> >> +	} else {
> >> +		mz = dev->cvq->cq.mz;
> >> +		ret = rte_vfio_container_dma_unmap(dev->vfio_container_fd,
> >> +				(uint64_t)(uintptr_t)mz->addr,
> >> +				iova, mz->len);
> >> +		if (ret < 0) {
> >> +			DRV_LOG(ERR, "Failed to unmap ctrl ring (%d)", ret);
> >> +			return ret;
> >> +		}
> >> +
> >> +		dev->cvq->vq_ring_mem = 0;
> >> +		iova += mz->len;
> >> +
> >> +		mz = dev->cvq->cq.virtio_net_hdr_mz;
> >> +		ret = rte_vfio_container_dma_unmap(dev->vfio_container_fd,
> >> +				(uint64_t)(uintptr_t)mz->addr,
> >> +				iova, mz->len);
> >> +		if (ret < 0) {
> >> +			DRV_LOG(ERR, "Failed to unmap ctrl headers (%d)", ret);
> >> +			return ret;
> >> +		}
> >> +
> >> +		dev->cvq->cq.virtio_net_hdr_mem = 0;
> >> +	}
> >> +
> >> +	return 0;
> >> +}
> >> +
> >> +static int
> >> +virtio_vdpa_dma_map(struct virtio_vdpa_device *dev, int do_map)
> >> +{
> >> +	uint32_t i;
> >> +	int ret;
> >> +	struct rte_vhost_memory *mem = NULL;
> >> +	int vfio_container_fd;
> >> +	uint64_t avail_iova = 0;
> >> +
> >> +	ret = rte_vhost_get_mem_table(dev->vid, &mem);
> >> +	if (ret < 0 || !mem) {
> >> +		DRV_LOG(ERR, "failed to get VM memory layout.");
> >> +		return ret;
> >> +	}
> >> +
> >> +	vfio_container_fd = dev->vfio_container_fd;
> >> +
> >> +	for (i = 0; i < mem->nregions; i++) {
> >> +		struct rte_vhost_mem_region *reg;
> >> +
> >> +		reg = &mem->regions[i];
> >> +		DRV_LOG(INFO, "%s, region %u: HVA 0x%" PRIx64 ", "
> >> +			"GPA 0x%" PRIx64 ", size 0x%" PRIx64 ".",
> >> +			do_map ? "DMA map" : "DMA unmap", i,
> >> +			reg->host_user_addr, reg->guest_phys_addr, reg->size);
> >> +
> >> +		if (reg->guest_phys_addr + reg->size > avail_iova)
> >> +			avail_iova = reg->guest_phys_addr + reg->size;
> >> +
> >> +		if (do_map) {
> >> +			ret = rte_vfio_container_dma_map(vfio_container_fd,
> >> +				reg->host_user_addr, reg->guest_phys_addr,
> >> +				reg->size);
> >> +			if (ret < 0) {
> >> +				DRV_LOG(ERR, "DMA map failed.");
> >> +				goto exit;
> >> +			}
> >> +		} else {
> >> +			ret = rte_vfio_container_dma_unmap(vfio_container_fd,
> >> +				reg->host_user_addr, reg->guest_phys_addr,
> >> +				reg->size);
> >> +			if (ret < 0) {
> >> +				DRV_LOG(ERR, "DMA unmap failed.");
> >> +				goto exit;
> >> +			}
> >> +		}
> >> +	}
> >> +
> >> +	if (dev->cvq)
> >> +		ret = virtio_vdpa_dma_map_ctrl_queue(dev, do_map, avail_iova);
> >> +
> >> +exit:
> >> +	free(mem);
> >> +
> >> +	return ret;
> >> +}
> >> +
> >>  static int
> >>  virtio_vdpa_vfio_setup(struct virtio_vdpa_device *dev)
> >>  {
> >> @@ -216,10 +337,144 @@ virtio_vdpa_get_protocol_features(int did __rte_unused, uint64_t *features)
> >>  	return 0;
> >>  }
> >>  
> >> +static uint64_t
> >> +hva_to_gpa(int vid, uint64_t hva)
> >> +{
> >> +	struct rte_vhost_memory *mem = NULL;
> >> +	struct rte_vhost_mem_region *reg;
> >> +	uint32_t i;
> >> +	uint64_t gpa = 0;
> >> +
> >> +	if (rte_vhost_get_mem_table(vid, &mem) < 0)
> >> +		goto exit;
> >> +
> >> +	for (i = 0; i < mem->nregions; i++) {
> >> +		reg = &mem->regions[i];
> >> +
> >> +		if (hva >= reg->host_user_addr &&
> >> +				hva < reg->host_user_addr + reg->size) {
> >> +			gpa = hva - reg->host_user_addr + reg->guest_phys_addr;
> >> +			break;
> >> +		}
> >> +	}
> >> +
> >> +exit:
> >> +	if (mem)
> >> +		free(mem);
> >> +	return gpa;
> >> +}
> >> +
> >> +static int
> >> +virtio_vdpa_start(struct virtio_vdpa_device *dev)
> >> +{
> >> +	struct virtio_hw *hw = &dev->hw;
> >> +	int i, vid, nr_vring, ret;
> >> +	struct rte_vhost_vring vr;
> >> +	struct virtio_pmd_ctrl ctrl;
> >> +	int dlen[1];
> >> +
> >> +	vid = dev->vid;
> >> +	nr_vring = rte_vhost_get_vring_num(vid);
> >> +
> >> +	if (dev->vqs)
> >> +		rte_free(dev->vqs);
> >> +
> >> +	dev->vqs = rte_zmalloc("virtio_vdpa", sizeof(*dev->vqs) * nr_vring, 0);
> >> +
> >> +	for (i = 0; i < nr_vring; i++) {
> >> +		struct virtqueue *vq = &dev->vqs[i];
> >> +
> >> +		rte_vhost_get_vhost_vring(vid, i, &vr);
> >> +
> >> +		vq->vq_queue_index = i;
> >> +		vq->vq_nentries = vr.size;
> >> +		vq->vq_ring_mem = hva_to_gpa(vid, (uint64_t)(uintptr_t)vr.desc);
> >> +		if (vq->vq_ring_mem  == 0) {
> >> +			DRV_LOG(ERR, "Fail to get GPA for descriptor ring.");
> >> +			ret = -1;
> >> +			goto out_free_vqs;
> >> +		}
> >> +
> >> +		ret = VTPCI_OPS(hw)->setup_queue(hw, vq);
> >> +		if (ret) {
> >> +			DRV_LOG(ERR, "Fail to setup queue.");
> >> +			goto out_free_vqs;
> >> +		}
> >> +	}
> >> +
> >> +	if (dev->cvq) {
> >> +		ret = VTPCI_OPS(hw)->setup_queue(hw, dev->cvq);
> >> +		if (ret) {
> >> +			DRV_LOG(ERR, "Fail to setup ctrl queue.");
> >> +			goto out_free_vqs;
> >> +		}
> >> +	}
> >> +
> >> +	vtpci_set_status(hw, VIRTIO_CONFIG_STATUS_DRIVER_OK);
> >> +
> >> +	if (!dev->cvq)
> >> +		return 0;
> >> +
> >> +	ctrl.hdr.class = VIRTIO_NET_CTRL_MQ;
> >> +	ctrl.hdr.cmd = VIRTIO_NET_CTRL_MQ_VQ_PAIRS_SET;
> >> +	memcpy(ctrl.data, &dev->max_queue_pairs, sizeof(uint16_t));
> >> +
> >> +	dlen[0] = sizeof(uint16_t);
> >> +
> >> +	ret = virtio_send_command(hw->cvq, &ctrl, dlen, 1);
> >> +	if (ret) {
> >> +		DRV_LOG(ERR, "Multiqueue configured but send command "
> >> +			  "failed, this is too late now...");
> >> +		ret = -EINVAL;
> >> +		goto out_free_vqs;
> >> +	}
> >> +
> >> +	return 0;
> >> +out_free_vqs:
> >> +	rte_free(dev->vqs);
> >> +
> >> +	return ret;
> >> +}
> >> +
> >> +static int
> >> +virtio_vdpa_dev_config(int vid)
> >> +{
> >> +	int did, ret;
> >> +	struct internal_list *list;
> >> +	struct virtio_vdpa_device *dev;
> >> +
> >> +	did = rte_vhost_get_vdpa_device_id(vid);
> >> +	list = find_internal_resource_by_did(did);
> >> +	if (list == NULL) {
> >> +		DRV_LOG(ERR, "Invalid device id: %d", did);
> >> +		return -1;
> >> +	}
> >> +
> >> +	dev = list->dev;
> >> +	dev->vid = vid;
> >> +
> >> +	rte_spinlock_lock(&dev->lock);
> >> +
> >> +	ret = virtio_vdpa_dma_map(dev, 1);
> >> +	if (ret)
> >> +		goto out_unlock;
> >> +
> >> +	ret = virtio_vdpa_start(dev);
> >> +
> >> +	if (rte_vhost_host_notifier_ctrl(vid, true) != 0)
> >> +		DRV_LOG(NOTICE, "vDPA (%d): software relay is used.", did);
> >> +
> >> +out_unlock:
> >> +	rte_spinlock_unlock(&dev->lock);
> >> +
> >> +	return ret;
> >> +}
> >> +
> >>  static struct rte_vdpa_dev_ops virtio_vdpa_ops = {
> >>  	.get_queue_num = virtio_vdpa_get_queue_num,
> >>  	.get_features = virtio_vdpa_get_features,
> >>  	.get_protocol_features = virtio_vdpa_get_protocol_features,
> >> +	.dev_conf = virtio_vdpa_dev_config,
> >>  };
> >>  
> >>  static inline int
> >> -- 
> >> 2.21.0
> >>