在 2021/6/1 上午11:27, Zhu, Lingshan 写道:

On 5/31/2021 3:56 PM, Jason Wang wrote:

quoted

在 2021/5/31 下午3:33, Zhu Lingshan 写道:

quoted

This commit implements doorbell mapping feature for ifcvf.
This feature maps the notify page to userspace, to eliminate
vmexit when kick a vq.

Signed-off-by: Zhu Lingshan <redacted>
---
  drivers/vdpa/ifcvf/ifcvf_main.c | 17 +++++++++++++++++
  1 file changed, 17 insertions(+)

diff --git a/drivers/vdpa/ifcvf/ifcvf_main.c 

b/drivers/vdpa/ifcvf/ifcvf_main.c
index ab0ab5cf0f6e..effb0e549135 100644

--- a/drivers/vdpa/ifcvf/ifcvf_main.c
+++ b/drivers/vdpa/ifcvf/ifcvf_main.c

@@ -413,6 +413,22 @@ static int ifcvf_vdpa_get_vq_irq(struct 

vdpa_device *vdpa_dev,
      return vf->vring[qid].irq;
  }
  +static struct vdpa_notification_area 
ifcvf_get_vq_notification(struct vdpa_device *vdpa_dev,
+                                   u16 idx)
+{
+    struct ifcvf_adapter *adapter = vdpa_to_adapter(vdpa_dev);
+    struct ifcvf_hw *vf = vdpa_to_vf(vdpa_dev);
+    struct pci_dev *pdev = adapter->pdev;
+    struct vdpa_notification_area area;
+
+    area.addr = vf->vring[idx].notify_pa;
+    area.size = PAGE_SIZE;
+    if (area.addr % PAGE_SIZE)
+        IFCVF_DBG(pdev, "vq %u doorbell address is not PAGE_SIZE 
aligned\n", idx);

Let's leave the decision to upper layer by: (see 
vp_vdpa_get_vq_notification)

area.addr = notify_pa;
area.size = notify_offset_multiplier;

Thanks

Hi Jason,

notify_offset_multiplier can be zero, means vqs share the same 
doorbell address, distinguished by qid.
and in vdpa.c:

        if (vma->vm_end - vma->vm_start != notify.size)
                return -ENOTSUPP;

so a zero size would cause this feature failure.
mmap should work on at least a page, so if we really want "area.size = 
notify_offset_multiplier;"
I think we should add some code in vdpa.c, like:

if(!notify.size)
    notify.size = PAGE_SIZE;

sounds good?

It's the responsibility of the driver to report a correct one. So I 
think it's better to tweak it as:

area.size = notify_offset_multiplier ?: PAGE_SIZE;

Thanks

Thanks
Zhu Lingshan

quoted

quoted

+
+    return area;
+}
+
  /*
   * IFCVF currently does't have on-chip IOMMU, so not
   * implemented set_map()/dma_map()/dma_unmap()

@@ -440,6 +456,7 @@ static const struct vdpa_config_ops ifc_vdpa_ops 

= {
      .get_config    = ifcvf_vdpa_get_config,
      .set_config    = ifcvf_vdpa_set_config,
      .set_config_cb  = ifcvf_vdpa_set_config_cb,
+    .get_vq_notification = ifcvf_get_vq_notification,
  };
    static int ifcvf_probe(struct pci_dev *pdev, const struct 
pci_device_id *id)

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