From: Jason Wang <jasowang@redhat.com>
To: "Zhu, Lingshan" <lingshan.zhu@intel.com>, mst@redhat.com
Cc: virtualization@lists.linux-foundation.org,
netdev@vger.kernel.org, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] vDPA/ifcvf: implement doorbell mapping for ifcvf
Date: Wed, 28 Apr 2021 17:21:48 +0800 [thread overview]
Message-ID: <1984491f-cd5e-d4bc-b328-41e2f2e935fd@redhat.com> (raw)
In-Reply-To: <5052fced-cd9a-e453-5cb2-39cdde60a208@intel.com>
在 2021/4/28 下午4:59, Zhu, Lingshan 写道:
>
>
> On 4/28/2021 4:42 PM, Jason Wang wrote:
>>
>> 在 2021/4/28 下午4:21, Zhu Lingshan 写道:
>>> This commit implements doorbell mapping feature for ifcvf.
>>> This feature maps the notify page to userspace, to eliminate
>>> vmexit when kick a vq.
>>>
>>> Signed-off-by: Zhu Lingshan <lingshan.zhu@intel.com>
>>> ---
>>> drivers/vdpa/ifcvf/ifcvf_main.c | 18 ++++++++++++++++++
>>> 1 file changed, 18 insertions(+)
>>>
>>> diff --git a/drivers/vdpa/ifcvf/ifcvf_main.c
>>> b/drivers/vdpa/ifcvf/ifcvf_main.c
>>> index e48e6b74fe2e..afcb71bc0f51 100644
>>> --- a/drivers/vdpa/ifcvf/ifcvf_main.c
>>> +++ b/drivers/vdpa/ifcvf/ifcvf_main.c
>>> @@ -413,6 +413,23 @@ static int ifcvf_vdpa_get_vq_irq(struct
>>> vdpa_device *vdpa_dev,
>>> return vf->vring[qid].irq;
>>> }
>>> +static struct vdpa_notification_area
>>> ifcvf_get_vq_notification(struct vdpa_device *vdpa_dev,
>>> + u16 idx)
>>> +{
>>> + struct ifcvf_hw *vf = vdpa_to_vf(vdpa_dev);
>>> + struct vdpa_notification_area area;
>>> +
>>> + if (vf->notify_pa % PAGE_SIZE) {
>>> + area.addr = 0;
>>> + area.size = 0;
>>
>>
>> We don't need this since:
>>
>> 1) there's a check in the vhost vDPA
> I think you mean this code block in vdpa.c
> notify = ops->get_vq_notification(vdpa, index);
> if (notify.addr & (PAGE_SIZE - 1))
> return -EINVAL;
>
> This should work, however, I think the parent driver should ensure it
> passes a PAGE_SIZE aligned address to userspace, to be robust, to be
> reliable.
The point is parent is unaware of whether or not there's a userspace.
>> 2) device is unaware of the bound driver, non page aligned doorbell
>> doesn't necessarily meant it can be used
> Yes, non page aligned doorbell can not be used, so there is a check.
Typo, what I meant is "it can't be used". That is to say, we should let
the vDPA bus driver to decide whether or not it can be used.
Thanks
>
> Thanks
> Zhu Lingshan
>>
>> Let's leave those polices to the driver.
>>
>> Thanks
>>
>>
>>> + } else {
>>> + area.addr = vf->notify_pa;
>>> + area.size = PAGE_SIZE;
>>> + }
>>> +
>>> + return area;
>>> +}
>>> +
>>> /*
>>> * IFCVF currently does't have on-chip IOMMU, so not
>>> * implemented set_map()/dma_map()/dma_unmap()
>>> @@ -440,6 +457,7 @@ static const struct vdpa_config_ops ifc_vdpa_ops ={
>>> .get_config = ifcvf_vdpa_get_config,
>>> .set_config = ifcvf_vdpa_set_config,
>>> .set_config_cb = ifcvf_vdpa_set_config_cb,
>>> + .get_vq_notification = ifcvf_get_vq_notification,
>>> };
>>> static int ifcvf_probe(struct pci_dev *pdev, const struct
>>> pci_device_id *id)
>>
>
next prev parent reply other threads:[~2021-04-28 9:22 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-28 8:21 [PATCH 0/2] vDPA/ifcvf: implement doorbell mapping feature Zhu Lingshan
2021-04-28 8:21 ` [PATCH 1/2] vDPA/ifcvf: record virtio notify base Zhu Lingshan
2021-04-28 8:39 ` Jason Wang
2021-04-28 10:00 ` Zhu, Lingshan
2021-04-28 10:09 ` Jason Wang
2021-04-28 10:18 ` Zhu, Lingshan
2021-04-28 11:48 ` kernel test robot
2021-04-28 8:21 ` [PATCH 2/2] vDPA/ifcvf: implement doorbell mapping for ifcvf Zhu Lingshan
2021-04-28 8:42 ` Jason Wang
2021-04-28 8:59 ` Zhu, Lingshan
2021-04-28 9:21 ` Jason Wang [this message]
2021-04-28 9:56 ` Zhu, Lingshan
2021-04-28 10:03 ` Jason Wang
2021-04-28 10:20 ` Zhu, Lingshan
2021-04-28 13:08 ` Jason Wang
2021-04-29 11:26 ` Zhu, Lingshan
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