Re: [PATCH V3 6/6] vDPA/ifcvf: verify mandatory feature bits for vDPA

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On 2021/3/11 12:16 下午, Zhu Lingshan wrote:


On 3/11/2021 11:20 AM, Jason Wang wrote:

On 2021/3/10 5:00 下午, Zhu Lingshan wrote:
vDPA requres VIRTIO_F_ACCESS_PLATFORM as a must, this commit
examines this when set features.

Signed-off-by: Zhu Lingshan <lingshan.zhu@xxxxxxxxx>
---
  drivers/vdpa/ifcvf/ifcvf_base.c | 8 ++++++++
  drivers/vdpa/ifcvf/ifcvf_base.h | 1 +
  drivers/vdpa/ifcvf/ifcvf_main.c | 5 +++++
  3 files changed, 14 insertions(+)

diff --git a/drivers/vdpa/ifcvf/ifcvf_base.c b/drivers/vdpa/ifcvf/ifcvf_base.c
index ea6a78791c9b..58f47fdce385 100644
--- a/drivers/vdpa/ifcvf/ifcvf_base.c
+++ b/drivers/vdpa/ifcvf/ifcvf_base.c
@@ -224,6 +224,14 @@ u64 ifcvf_get_features(struct ifcvf_hw *hw)
      return hw->hw_features;
  }
  +int ifcvf_verify_min_features(struct ifcvf_hw *hw)
+{
+    if (!(hw->hw_features & BIT_ULL(VIRTIO_F_ACCESS_PLATFORM)))
+        return -EINVAL;
+
+    return 0;
+}
+
  void ifcvf_read_net_config(struct ifcvf_hw *hw, u64 offset,
                 void *dst, int length)
  {
diff --git a/drivers/vdpa/ifcvf/ifcvf_base.h b/drivers/vdpa/ifcvf/ifcvf_base.h
index dbb8c10aa3b1..91c5735d4dc9 100644
--- a/drivers/vdpa/ifcvf/ifcvf_base.h
+++ b/drivers/vdpa/ifcvf/ifcvf_base.h
@@ -123,6 +123,7 @@ void io_write64_twopart(u64 val, u32 *lo, u32 *hi);
  void ifcvf_reset(struct ifcvf_hw *hw);
  u64 ifcvf_get_features(struct ifcvf_hw *hw);
  u64 ifcvf_get_hw_features(struct ifcvf_hw *hw);
+int ifcvf_verify_min_features(struct ifcvf_hw *hw);
  u16 ifcvf_get_vq_state(struct ifcvf_hw *hw, u16 qid);
  int ifcvf_set_vq_state(struct ifcvf_hw *hw, u16 qid, u16 num);
  struct ifcvf_adapter *vf_to_adapter(struct ifcvf_hw *hw);
diff --git a/drivers/vdpa/ifcvf/ifcvf_main.c b/drivers/vdpa/ifcvf/ifcvf_main.c
index 25fb9dfe23f0..f624f202447d 100644
--- a/drivers/vdpa/ifcvf/ifcvf_main.c
+++ b/drivers/vdpa/ifcvf/ifcvf_main.c
@@ -179,6 +179,11 @@ static u64 ifcvf_vdpa_get_features(struct vdpa_device *vdpa_dev)   static int ifcvf_vdpa_set_features(struct vdpa_device *vdpa_dev, u64 features)
  {
      struct ifcvf_hw *vf = vdpa_to_vf(vdpa_dev);
+    int ret;
+
+    ret = ifcvf_verify_min_features(vf);


So this validate device features instead of driver which is the one we really want to check?

Thanks

Hi Jason,

Here we check device feature bits to make sure the device support ACCESS_PLATFORM.


If you want to check device features, you need to do that during probe() and fail the probing if without the feature. But I think you won't ship cards without ACCESS_PLATFORM.


In get_features(),
it will return a intersection of device features bit and driver supported features bits(which includes ACCESS_PLATFORM). Other components like QEMU should not set features bits more than this intersection of bits. so we can make sure if this ifcvf_verify_min_features() passed, both device and driver support ACCESS_PLATFORM.

Are you suggesting check driver feature bits in ifcvf_verify_min_features() in the meantime as well?


So it really depends on your hardware. If you hardware can always offer ACCESS_PLATFORM, you just need to check driver features. This is how vdpa_sim and mlx5_vdpa work.

Thanks



Thanks!


+    if (ret)
+        return ret;
        vf->req_features = features;

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