Linux Virtualization - Jan 2021 - [RFC v3 03/11] vdpa: Remove the restriction that only supports virtio-net devices

On 2021/1/20 ??7:08, Stefano Garzarella wrote:
> On Wed, Jan 20, 2021 at 11:46:38AM +0800, Jason Wang wrote:
>>
>> On 2021/1/19 ??12:59, Xie Yongji wrote:
>>> With VDUSE, we should be able to support all kinds of virtio
devices.
>>>
>>> Signed-off-by: Xie Yongji <xieyongji at bytedance.com>
>>> ---
>>> ?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().

Thanks

>
> Thanks,
> Stefano
>

On Wed, Jan 27, 2021 at 11:33:03AM +0800, Jason Wang
wrote:
>
>On 2021/1/20 ??7:08, Stefano Garzarella wrote:
>>On Wed, Jan 20, 2021 at 11:46:38AM +0800, Jason Wang wrote:
>>>
>>>On 2021/1/19 ??12:59, Xie Yongji wrote:
>>>>With VDUSE, we should be able to support all kinds of virtio
devices.
>>>>
>>>>Signed-off-by: Xie Yongji <xieyongji at bytedance.com>
>>>>---
>>>>?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.

Thanks,
Stefano