RE: [PATCH v2 00/12] New paravirtual PCI front-end for Hyper-V VMs

From: Jake Oshins
Date: Tue Sep 15 2015 - 19:33:01 EST


> -----Original Message-----
> From: Marc Zyngier [mailto:marc.zyngier@xxxxxxx]
> Sent: Tuesday, September 15, 2015 2:57 AM
> To: Jake Oshins <jakeo@xxxxxxxxxxxxx>; gregkh@xxxxxxxxxxxxxxxxxxx; KY
> Srinivasan <kys@xxxxxxxxxxxxx>; linux-kernel@xxxxxxxxxxxxxxx;
> devel@xxxxxxxxxxxxxxxxxxxxxx; olaf@xxxxxxxxx; apw@xxxxxxxxxxxxx;
> vkuznets@xxxxxxxxxx; linux-pci@xxxxxxxxxxxxxxx; bhelgaas@xxxxxxxxxx;
> tglx@xxxxxxxxxxxxx; Jiang Liu <jiang.liu@xxxxxxxxxxxxxxx>
> Subject: Re: [PATCH v2 00/12] New paravirtual PCI front-end for Hyper-V
> VMs
>


> >
> > Is there a way to do that with the infrastructure that you're
> > introducing?
>
> The ACPI/GSI stuff is a red herring, and is completely unrelated to the
> problem you're trying to solve. What I think is of interest to you is
> contained in the first three patches.
>
> In your 4th patch, you have the following code:
>
> + pci_domain = pci_domain_nr(bus);
> + d = irq_find_matching_host(NULL, DOMAIN_BUS_PCI_MSI,
> &pci_domain);
>
> which really feels like you're trying to create a namespace that is
> parallel to the one defined by the device_node parameter. What I'm
> trying to do is to be able to replace the device_node by something more
> generic (at the moment, you can either pass a device_node or some token
> that the irqdomain subsystem generates for you - see patch #7 for an
> example).
>
> You could pass this token to pci_msi_create_irq_domain (which obviously
> needs some repainting not to take a device_node), store it in your bus
> structure, and perform the lookup based on this value. Or store the
> actual domain there, whatever.
>
> What I want to do is really to make this device_node pointer for systems
> that do not have a DT node to pass there, which is exactly your case (by
> the look of it, the bus number is your identifier of choice, but I
> suspect a pointer to an internal structure would be better suited).
>
> M.
> --

Got it. I'll rebase on your changes and send this series again, using the strategy that you outline here. I may wait a little while until your patches make it into linux-next.

Thanks again,
Jake Oshins

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