Re: [Xen-devel] [PATCH for-4.6 0/5] xen: arm: Parse PCI DT nodes' ranges and interrupt-map

[Julien Grall <julien.grall@xxxxxxxxxx>]

Hi Suravee,

On 18/02/2015 05:28, Suravee Suthikulanit wrote:
> Actually, that seems to be more related to the PCI pass-through devices.
> Isn't the Cavium guys already done that work to support their PCI device
> pass-through?
They were working on it, but so far there is no patch series on the ML. 
It would be nice to come with a common solution (i.e between GICv2m and 
GICv3 ITS) for MSI.
> Anyways, at this point, I am able to generated Dom0 device tree with
> correct v2m node, and I can see Dom0 gicv2m driver probing and
> initializing correctly as it would on bare-metal.
>
> # Snippet from /sys/firmware/fdt showing dom0 GIC node
>      interrupt-controller {
>          compatible = "arm,gic-400", "arm,cortex-a15-gic";
>          #interrupt-cells = <0x3>;
>          interrupt-controller;
>          reg = <0x0 0xe1110000 0x0 0x1000 0x0 0xe112f000 0x0 0x2000>;
>          phandle = <0x1>;
>          #address-cells = <0x2>;
>          #size-cells = <0x2>;
>          ranges = <0x0 0x0 0x0 0xe1100000 0x0 0x100000>;
>
>          v2m {
>              compatible = "arm,gic-v2m-frame";
>              msi-controller;
>              arm,msi-base-spi = <0x40>;
>              arm,msi-num-spis = <0x100>;
>              phandle = <0x5>;
>              reg = <0x0 0x80000 0x0 0x1000>;
>          };
>      };
>
> linux:~ # dmesg | grep v2m
> [    0.000000] GICv2m: Overriding V2M MSI_TYPER (base:64, num:256)
> [    0.000000] GICv2m: Node v2m: range[0xe1180000:0xe1180fff], SPI[64:320]
>
> So, during setting up v2m in hypervisor, I also call
> route_irq_to_guest() for the all SPIs used for MSI (i.e. 64-320 on
> Seattle), which will force the MSIs to Dom0. However, we would need to
> figure out how to detach and re-route certain interrupts to a specific
> DomU in case of passing through PCI devices in the future.
Who decide to assign the MSI n to the SPI x? DOM0 or Xen?

Wouldn't it be possible to route the SPI dynamically when the domain 
decide to use the MSI n? We would need to implement PHYSDEVOP_map_pirq 
for MSI.
[..]

> And there you have it.... GICv2m MSI(-X) supports in Dom 0 for Seattle
> ;)  Thanks to Ian's PCI patch, which makes porting much simpler.
>
> Next, I'll clean up the code and send out Xen patch for review. I'll
> also push Linux changes (for adding ARM64 PCI Generic host controller
> supports and MSI IRQ domain from Marc) into my Linux tree on Github.
> Then you could give it a try on your Seattle box.
Congrats!

--
Julien Grall

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