From: "Chen, Jiqian" <Jiqian.Chen@amd.com>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>,
"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
"Huang, Ray" <Ray.Huang@amd.com>,
"Chen, Jiqian" <Jiqian.Chen@amd.com>
Subject: Re: [RFC QEMU PATCH v8 2/2] virtio-pci: implement No_Soft_Reset bit
Date: Tue, 2 Apr 2024 03:03:23 +0000 [thread overview]
Message-ID: <BL1PR12MB5849AA89DC28465714590B56E73E2@BL1PR12MB5849.namprd12.prod.outlook.com> (raw)
In-Reply-To: <20240329064431-mutt-send-email-mst@kernel.org>
On 2024/3/29 18:44, Michael S. Tsirkin wrote:
> On Fri, Mar 29, 2024 at 03:20:59PM +0800, Jason Wang wrote:
>> On Fri, Mar 29, 2024 at 3:07 PM Chen, Jiqian <Jiqian.Chen@amd.com> wrote:
>>>
>>> On 2024/3/28 20:36, Michael S. Tsirkin wrote:
>>>>>>> +}
>>>>>>> +
>>>>>>> static void virtio_pci_bus_reset_hold(Object *obj)
>>>>>>> {
>>>>>>> PCIDevice *dev = PCI_DEVICE(obj);
>>>>>>> DeviceState *qdev = DEVICE(obj);
>>>>>>>
>>>>>>> + if (virtio_pci_no_soft_reset(dev)) {
>>>>>>> + return;
>>>>>>> + }
>>>>>>> +
>>>>>>> virtio_pci_reset(qdev);
>>>>>>>
>>>>>>> if (pci_is_express(dev)) {
>>>>>>> @@ -2484,6 +2511,8 @@ static Property virtio_pci_properties[] = {
>>>>>>> VIRTIO_PCI_FLAG_INIT_LNKCTL_BIT, true),
>>>>>>> DEFINE_PROP_BIT("x-pcie-pm-init", VirtIOPCIProxy, flags,
>>>>>>> VIRTIO_PCI_FLAG_INIT_PM_BIT, true),
>>>>>>> + DEFINE_PROP_BIT("x-pcie-pm-no-soft-reset", VirtIOPCIProxy, flags,
>>>>>>> + VIRTIO_PCI_FLAG_PM_NO_SOFT_RESET_BIT, false),
>>
>> Why does it come with an x prefix?
>>
>>>>>>> DEFINE_PROP_BIT("x-pcie-flr-init", VirtIOPCIProxy, flags,
>>>>>>> VIRTIO_PCI_FLAG_INIT_FLR_BIT, true),
>>>>>>> DEFINE_PROP_BIT("aer", VirtIOPCIProxy, flags,
>>>>>>
>>>>>> I am a bit confused about this part.
>>>>>> Do you want to make this software controllable?
>>>>> Yes, because even the real hardware, this bit is not always set.
>>
>> We are talking about emulated devices here.
>>
>>>>
>>>> So which virtio devices should and which should not set this bit?
>>> This depends on the scenario the virtio-device is used, if we want to trigger an internal soft reset for the virtio-device during S3, this bit shouldn't be set.
>>
>> If the device doesn't need reset, why bother the driver for this?
>>
>> Btw, no_soft_reset is insufficient for some cases, there's a proposal
>> for the virtio-spec. I think we need to wait until it is done.
>
> That seems orthogonal or did I miss something?
Yes, I looked the detail of the proposal, I also think they are unrelated.
I will set the default value of No_Soft_Reset bit to true in next version according to your opinion.
About the compatibility of old machine types, which types should I consider? Does the same as x-pcie-pm-init(hw_compat_2_8)?
Forgive me for not knowing much about compatibility.
>
>>> In my use case on my environment, I don't want to reset virtio-gpu during S3,
>>> because once the display resources are destroyed, there are not enough information to re-create them, so this bit should be set.
>>> Making this bit software controllable is convenient for users to take their own choices.
>>
>> Thanks
>>
>>>
>>>>
>>>>>> Or should this be set to true by default and then
>>>>>> changed to false for old machine types?
>>>>> How can I do so?
>>>>> Do you mean set this to true by default, and if old machine types don't need this bit, they can pass false config to qemu when running qemu?
>>>>
>>>> No, you would use compat machinery. See how is x-pcie-flr-init handled.
>>>>
>>>>
>>>
>>> --
>>> Best regards,
>>> Jiqian Chen.
>
--
Best regards,
Jiqian Chen.
next prev parent reply other threads:[~2024-04-02 3:03 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-28 10:39 [RFC QEMU PATCH v8 0/1] S3 support Jiqian Chen
2024-03-28 10:39 ` [RFC QEMU PATCH v8 1/2] virtio-pci: only reset pm state during resetting Jiqian Chen
2024-03-28 10:39 ` [RFC QEMU PATCH v8 2/2] virtio-pci: implement No_Soft_Reset bit Jiqian Chen
2024-03-28 10:57 ` Michael S. Tsirkin
2024-03-28 11:08 ` Chen, Jiqian
2024-03-28 12:36 ` Michael S. Tsirkin
2024-03-29 7:00 ` Chen, Jiqian
2024-03-29 7:20 ` Jason Wang
2024-03-29 8:00 ` Chen, Jiqian
2024-03-29 10:38 ` Jason Wang
2024-04-02 2:56 ` Chen, Jiqian
2024-03-29 10:44 ` Michael S. Tsirkin
2024-04-02 3:03 ` Chen, Jiqian [this message]
2024-04-07 3:20 ` Jason Wang
2024-04-07 11:49 ` Michael S. Tsirkin
2024-04-08 4:56 ` Jason Wang
2024-04-12 6:10 ` Chen, Jiqian
2024-04-12 6:04 ` Chen, Jiqian
2024-04-12 6:41 ` Jason Wang
2024-04-12 6:49 ` Chen, Jiqian
2024-04-12 5:59 ` Chen, Jiqian
2024-04-12 6:42 ` Jason Wang
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