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Re: [PATCH] pci: Refuse to hotplug PCI Devices when the Guest OS is not
From: |
David Gibson |
Subject: |
Re: [PATCH] pci: Refuse to hotplug PCI Devices when the Guest OS is not ready |
Date: |
Wed, 28 Oct 2020 14:34:34 +1100 |
On Tue, 27 Oct 2020 09:02:06 -0400
"Michael S. Tsirkin" <mst@redhat.com> wrote:
> On Tue, Oct 27, 2020 at 01:54:26PM +0100, Igor Mammedov wrote:
> [...]
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> > I have more questions wrt the suggestion/workflow:
> > * at what place would you suggest buffering it?
>
> PCIESlot maybe?
>
> > * what would be the request in this case, i.e. create PCI device anyways
> > and try to signal hotplug event later?
>
>
> that was my idea, yes.
Actually, I don't think that will quite work. A whole chunk of the
problem here is that because the device is realized, the guest sees it
as part of its general scan *before* the hotplug event (ABP and PDC
interrupts) appears. That makes the guest misinterpret the ABP as an
*unplug* request.
So delaying the interrupt without delaying the realize (or at least
filtering config space access to it based on.. something) will just
trigger the same problem AFAICT.
> > * what would baremethal do in such case?
>
> exactly the same, human would wait until blinking stops.
>
> > * what to do in case guest is never ready, what user should do in such
> > case?
>
> As in guest is stuck? Do we care? It can't use the device.
>
> > * can be such device be removed?
>
> why not? device_del could complete immediately ...
>
> [...]
>
> I'd say let's get expected behaviour for existing commands first.
> We can add events and stuff on top.
>
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>
--
David Gibson <dgibson@redhat.com>
Principal Software Engineer, Virtualization, Red Hat
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- Re: [PATCH] pci: Refuse to hotplug PCI Devices when the Guest OS is not ready, (continued)
- Re: [PATCH] pci: Refuse to hotplug PCI Devices when the Guest OS is not ready, David Gibson, 2020/10/26
- Re: [PATCH] pci: Refuse to hotplug PCI Devices when the Guest OS is not ready, Marcel Apfelbaum, 2020/10/23
- Re: [PATCH] pci: Refuse to hotplug PCI Devices when the Guest OS is not ready, David Gibson, 2020/10/26
- Re: [PATCH] pci: Refuse to hotplug PCI Devices when the Guest OS is not ready, Michael S. Tsirkin, 2020/10/27
- Re: [PATCH] pci: Refuse to hotplug PCI Devices when the Guest OS is not ready, Igor Mammedov, 2020/10/27
- Re: [PATCH] pci: Refuse to hotplug PCI Devices when the Guest OS is not ready, Michael S. Tsirkin, 2020/10/27
- Re: [PATCH] pci: Refuse to hotplug PCI Devices when the Guest OS is not ready,
David Gibson <=
- Re: [PATCH] pci: Refuse to hotplug PCI Devices when the Guest OS is not ready, David Gibson, 2020/10/27
- Re: [PATCH] pci: Refuse to hotplug PCI Devices when the Guest OS is not ready, Igor Mammedov, 2020/10/28
- Re: [PATCH] pci: Refuse to hotplug PCI Devices when the Guest OS is not ready, Michael S. Tsirkin, 2020/10/28
- Re: [PATCH] pci: Refuse to hotplug PCI Devices when the Guest OS is not ready, Michael S. Tsirkin, 2020/10/27
- Re: [PATCH] pci: Refuse to hotplug PCI Devices when the Guest OS is not ready, David Gibson, 2020/10/22