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Message-ID: <47713210-e9d9-d185-6e2e-433e2c436de9@redhat.com>
Date: Tue, 12 May 2020 13:51:25 +0800
From: Jason Wang <jasowang@...hat.com>
To: "Zhu, Lingshan" <lingshan.zhu@...el.com>, mst@...hat.com,
kvm@...r.kernel.org, virtualization@...ts.linux-foundation.org,
linux-kernel@...r.kernel.org, netdev@...r.kernel.org
Cc: lulu@...hat.com, dan.daly@...el.com, cunming.liang@...el.com
Subject: Re: [PATCH] ifcvf: move IRQ request/free to status change handlers
On 2020/5/12 上午11:38, Jason Wang wrote:
>>>>
>>>> static int ifcvf_start_datapath(void *private)
>>>> {
>>>> struct ifcvf_hw *vf = ifcvf_private_to_vf(private);
>>>> @@ -118,9 +172,12 @@ static void ifcvf_vdpa_set_status(struct
>>>> vdpa_device *vdpa_dev, u8 status)
>>>> {
>>>> struct ifcvf_adapter *adapter;
>>>> struct ifcvf_hw *vf;
>>>> + u8 status_old;
>>>> + int ret;
>>>> vf = vdpa_to_vf(vdpa_dev);
>>>> adapter = dev_get_drvdata(vdpa_dev->dev.parent);
>>>> + status_old = ifcvf_get_status(vf);
>>>> if (status == 0) {
>>>> ifcvf_stop_datapath(adapter);
>>>> @@ -128,7 +185,22 @@ static void ifcvf_vdpa_set_status(struct
>>>> vdpa_device *vdpa_dev, u8 status)
>>>> return;
>>>> }
>>>> - if (status & VIRTIO_CONFIG_S_DRIVER_OK) {
>>>> + if ((status_old & VIRTIO_CONFIG_S_DRIVER_OK) &&
>>>> + !(status & VIRTIO_CONFIG_S_DRIVER_OK)) {
>>>> + ifcvf_stop_datapath(adapter);
>>>> + ifcvf_free_irq(adapter, IFCVF_MAX_QUEUE_PAIRS * 2);
>>>> + }
>>>> +
>>>> + if ((status & VIRTIO_CONFIG_S_DRIVER_OK) &&
>>>> + !(status_old & VIRTIO_CONFIG_S_DRIVER_OK)) {
>>>> + ret = ifcvf_request_irq(adapter);
>>>> + if (ret) {
>>>> + status = ifcvf_get_status(vf);
>>>> + status |= VIRTIO_CONFIG_S_FAILED;
>>>> + ifcvf_set_status(vf, status);
>>>> + return;
>>>> + }
>>>> +
>>>
>>>
>>> Have a hard though on the logic here.
>>>
>>> This depends on the status setting from guest or userspace. Which
>>> means it can not deal with e.g when qemu or userspace is crashed? Do
>>> we need to care this or it's a over engineering?
>>>
>>> Thanks
>> If qemu crash, I guess users may re-run qmeu / re-initialize the
>> device, according to the spec, there should be a reset routine.
>> This code piece handles status change on DRIVER_OK flipping. I am not
>> sure I get your point, mind to give more hints?
>
>
> The problem is if we don't launch new qemu instance, the interrupt
> will be still there?
Ok, we reset on vhost_vdpa_release() so the following is suspicious:
With the patch, we do:
static void ifcvf_vdpa_set_status(struct vdpa_device *vdpa_dev, u8 status)
{
struct ifcvf_adapter *adapter;
struct ifcvf_hw *vf;
u8 status_old;
int ret;
vf = vdpa_to_vf(vdpa_dev);
adapter = dev_get_drvdata(vdpa_dev->dev.parent);
status_old = ifcvf_get_status(vf);
if (status == 0) {
ifcvf_stop_datapath(adapter);
ifcvf_reset_vring(adapter);
return;
}
if ((status_old & VIRTIO_CONFIG_S_DRIVER_OK) &&
!(status & VIRTIO_CONFIG_S_DRIVER_OK)) {
ifcvf_stop_datapath(adapter);
ifcvf_free_irq(adapter, IFCVF_MAX_QUEUE_PAIRS * 2);
}
...
So the handling of status == 0 looks wrong.
The OK -> !OK check should already cover the datapath stopping and irq
stuffs.
We only need to deal with vring reset and only need to do it after we
stop the datapath/irq stuffs.
Thanks
>
> Thanks
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