On 7/13/2022 1:31 PM, Michael S. Tsirkin wrote:

On Fri, Jul 01, 2022 at 09:28:21PM +0800, Zhu Lingshan wrote:

quoted

ifcvf_get_config_size() should return a virtio device type specific value,
however the ret_value should not be greater than the onboard size of
the device implementation. E.g., for virtio_net, config_size should be
the minimum value of sizeof(struct virtio_net_config) and the onboard
cap size.

Signed-off-by: Zhu Lingshan <redacted>
---
  drivers/vdpa/ifcvf/ifcvf_base.c | 13 +++++++++++--
  drivers/vdpa/ifcvf/ifcvf_base.h |  2 ++
  2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/vdpa/ifcvf/ifcvf_base.c b/drivers/vdpa/ifcvf/ifcvf_base.c
index 48c4dadb0c7c..fb957b57941e 100644
--- a/drivers/vdpa/ifcvf/ifcvf_base.c
+++ b/drivers/vdpa/ifcvf/ifcvf_base.c

@@ -128,6 +128,7 @@ int ifcvf_init_hw(struct ifcvf_hw *hw, struct pci_dev *pdev)
  			break;
  		case VIRTIO_PCI_CAP_DEVICE_CFG:
  			hw->dev_cfg = get_cap_addr(hw, &cap);
+			hw->cap_dev_config_size = le32_to_cpu(cap.length);
  			IFCVF_DBG(pdev, "hw->dev_cfg = %p\n", hw->dev_cfg);
  			break;
  		}

@@ -233,15 +234,23 @@ int ifcvf_verify_min_features(struct ifcvf_hw *hw, u64 features)
  u32 ifcvf_get_config_size(struct ifcvf_hw *hw)
  {
  	struct ifcvf_adapter *adapter;
+	u32 net_config_size = sizeof(struct virtio_net_config);
+	u32 blk_config_size = sizeof(struct virtio_blk_config);
+	u32 cap_size = hw->cap_dev_config_size;
  	u32 config_size;
  
  	adapter = vf_to_adapter(hw);
+	/* If the onboard device config space size is greater than
+	 * the size of struct virtio_net/blk_config, only the spec
+	 * implementing contents size is returned, this is very
+	 * unlikely, defensive programming.
+	 */
  	switch (hw->dev_type) {
  	case VIRTIO_ID_NET:
-		config_size = sizeof(struct virtio_net_config);
+		config_size = cap_size >= net_config_size ? net_config_size : cap_size;
  		break;
  	case VIRTIO_ID_BLOCK:
-		config_size = sizeof(struct virtio_blk_config);
+		config_size = cap_size >= blk_config_size ? blk_config_size : cap_size;
  		break;
  	default:
  		config_size = 0;

There's a min macro for this.

yes, a min macro is better.

Thanks,
Zhu Lingshan

quoted

diff --git a/drivers/vdpa/ifcvf/ifcvf_base.h b/drivers/vdpa/ifcvf/ifcvf_base.h
index 115b61f4924b..f5563f665cc6 100644
--- a/drivers/vdpa/ifcvf/ifcvf_base.h
+++ b/drivers/vdpa/ifcvf/ifcvf_base.h

@@ -87,6 +87,8 @@ struct ifcvf_hw {
  	int config_irq;
  	int vqs_reused_irq;
  	u16 nr_vring;
+	/* VIRTIO_PCI_CAP_DEVICE_CFG size */
+	u32 cap_dev_config_size;
  };
  
  struct ifcvf_adapter {

-- 
2.31.1