Re: [RFC v3 03/11] vdpa: Remove the restriction that only supports virtio-net devices

On 2021/1/27 下午4:57, Stefano Garzarella wrote:

On Wed, Jan 27, 2021 at 11:33:03AM +0800, Jason Wang wrote:

quoted

On 2021/1/20 下午7:08, Stefano Garzarella wrote:

quoted

On Wed, Jan 20, 2021 at 11:46:38AM +0800, Jason Wang wrote:

quoted

On 2021/1/19 下午12:59, Xie Yongji wrote:

quoted

With VDUSE, we should be able to support all kinds of virtio devices.

Signed-off-by: Xie Yongji <redacted>
---
 drivers/vhost/vdpa.c | 29 +++--------------------------
 1 file changed, 3 insertions(+), 26 deletions(-)

diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
index 29ed4173f04e..448be7875b6d 100644
--- a/drivers/vhost/vdpa.c
+++ b/drivers/vhost/vdpa.c

@@ -22,6 +22,7 @@

 #include <linux/nospec.h>
 #include <linux/vhost.h>
 #include <linux/virtio_net.h>
+#include <linux/virtio_blk.h>
 #include "vhost.h"

@@ -185,26 +186,6 @@ static long vhost_vdpa_set_status(struct 

vhost_vdpa *v, u8 __user *statusp)
     return 0;
 }
-static int vhost_vdpa_config_validate(struct vhost_vdpa *v,
-                      struct vhost_vdpa_config *c)
-{
-    long size = 0;
-
-    switch (v->virtio_id) {
-    case VIRTIO_ID_NET:
-        size = sizeof(struct virtio_net_config);
-        break;
-    }
-
-    if (c->len == 0)
-        return -EINVAL;
-
-    if (c->len > size - c->off)
-        return -E2BIG;
-
-    return 0;
-}

I think we should use a separate patch for this.

For the vdpa-blk simulator I had the same issues and I'm adding a 
.get_config_size() callback to vdpa devices.

Do you think make sense or is better to remove this check in 
vhost/vdpa, delegating the boundaries checks to 
get_config/set_config callbacks.

A question here. How much value could we gain from get_config_size() 
consider we can let vDPA parent to validate the length in its 
get_config().

I agree, most of the implementations already validate the length, the 
only gain is an error returned since get_config() is void, but 
eventually we can add a return value to it.

Right, one problem here is that. For the virito path, its get_config() 
returns void. So we can not propagate error to virtio drivers. But it 
might not be a big issue since we trust kernel virtio driver.

So I think it makes sense to change the return value in the vdpa config ops.

Thanks

Thanks,
Stefano