? 2021/4/22 ??4:07, Eli Cohen ??:> On Thu, Apr 22, 2021 at 09:03:58AM +0300, Eli Cohen wrote:
>> On Thu, Apr 22, 2021 at 10:37:38AM +0800, Jason Wang wrote:
>>> ? 2021/4/21 ??6:41, Eli Cohen ??:
>>>> Implement mlx5_get_vq_notification() to return the doorbell
address.
>>>> Size is set to one system page as required.
>>>>
>>>> Signed-off-by: Eli Cohen <elic at nvidia.com>
>>>> ---
>>>> drivers/vdpa/mlx5/core/mlx5_vdpa.h | 1 +
>>>> drivers/vdpa/mlx5/core/resources.c | 1 +
>>>> drivers/vdpa/mlx5/net/mlx5_vnet.c | 6 ++++++
>>>> 3 files changed, 8 insertions(+)
>>>>
>>>> diff --git a/drivers/vdpa/mlx5/core/mlx5_vdpa.h
b/drivers/vdpa/mlx5/core/mlx5_vdpa.h
>>>> index b6cc53ba980c..49de62cda598 100644
>>>> --- a/drivers/vdpa/mlx5/core/mlx5_vdpa.h
>>>> +++ b/drivers/vdpa/mlx5/core/mlx5_vdpa.h
>>>> @@ -41,6 +41,7 @@ struct mlx5_vdpa_resources {
>>>> u32 pdn;
>>>> struct mlx5_uars_page *uar;
>>>> void __iomem *kick_addr;
>>>> + u64 phys_kick_addr;
>>>> u16 uid;
>>>> u32 null_mkey;
>>>> bool valid;
>>>> diff --git a/drivers/vdpa/mlx5/core/resources.c
b/drivers/vdpa/mlx5/core/resources.c
>>>> index 6521cbd0f5c2..665f8fc1710f 100644
>>>> --- a/drivers/vdpa/mlx5/core/resources.c
>>>> +++ b/drivers/vdpa/mlx5/core/resources.c
>>>> @@ -247,6 +247,7 @@ int mlx5_vdpa_alloc_resources(struct
mlx5_vdpa_dev *mvdev)
>>>> goto err_key;
>>>> kick_addr = mdev->bar_addr + offset;
>>>> + res->phys_kick_addr = kick_addr;
>>>> res->kick_addr = ioremap(kick_addr, PAGE_SIZE);
>>>> if (!res->kick_addr) {
>>>> diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c
b/drivers/vdpa/mlx5/net/mlx5_vnet.c
>>>> index 10c5fef3c020..680751074d2a 100644
>>>> --- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
>>>> +++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
>>>> @@ -1865,8 +1865,14 @@ static void mlx5_vdpa_free(struct
vdpa_device *vdev)
>>>> static struct vdpa_notification_area
mlx5_get_vq_notification(struct vdpa_device *vdev, u16 idx)
>>>> {
>>>> + struct mlx5_vdpa_dev *mvdev = to_mvdev(vdev);
>>>> struct vdpa_notification_area ret = {};
>>>> + struct mlx5_vdpa_net *ndev;
>>>> +
>>>> + ndev = to_mlx5_vdpa_ndev(mvdev);
>>>> + ret.addr = (phys_addr_t)ndev->mvdev.res.phys_kick_addr;
>>>> + ret.size = PAGE_SIZE;
>>>
>>> Note that the page will be mapped in to guest, so it's only
safe if the
>>> doorbeel exclusively own the page. This means if there're other
registers in
>>> the page, we can not let the doorbell bypass to work.
>>>
>>> So this is suspicious at least in the case of subfunction where we
calculate
>>> the bar length in mlx5_sf_dev_table_create() as:
>>>
>>> table->sf_bar_length = 1 << (MLX5_CAP_GEN(dev,
log_min_sf_size) + 12);
>>>
>>> It looks to me this can only work for the arch with PAGE_SIZE =
4096,
>>> otherwise we can map more into the userspace(guest).
>>>
>> Correct, so I guess I should return here 4096.
I'm not quite sure but since the calculation of the sf_bar_length is
doen via a shift of 12, it might be correct.
And please double check if the doorbell own the page exclusively.
>>
>> I also think that the check in vhost_vdpa_mmap() should verify that the
>> returned size is not smaller than PAGE_SIZE because the returned
address
> Actually I think it's ok since you verify the size equals
vma->vm_end -
> vma->vm_start which must be at least PAGE_SIZE.
Yes.
Thanks
>
>> might just be aligned to PAGE_SIZE. I think this should be enoght but
>> maybe also use the same logic in vhost_vdpa_fault().