From: "Chen, Jiqian" <Jiqian.Chen@amd.com>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: "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: Fri, 29 Mar 2024 07:00:02 +0000 [thread overview]
Message-ID: <BL1PR12MB5849C37A0B0E1AF02644C203E73A2@BL1PR12MB5849.namprd12.prod.outlook.com> (raw)
In-Reply-To: <20240328083503-mutt-send-email-mst@kernel.org>
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),
>>>> 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.
>
> 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.
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.
>
>>> 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.
next prev parent reply other threads:[~2024-03-29 7:05 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 [this message]
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
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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