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Re: [Xen-devel] ARM64: PCIe in DOM0


On 05/10/2018 12:06, Bharat Bhushan wrote:
Further update:
If I change Kconfig to enable this default

CONFIG_HAS_ITS is in tech preview. For having access to it, you need to pass XEN_CONFIG_EXPERT on *all* the make command line.

Then DOM0 Linux Boots but MSIs are not still working,

Getting below error:
   - pci 0001:00:00.0: Failed to add - passthrough or MSI/MSI-X might fail!

This is a red-herring. This lines happen because PHYSDEVOP_pci_device_add is not implemented on Xen Arm.

Any help is very useful,!!

Can you please provide the full log?

-----Original Message-----
From: Bharat Bhushan
Sent: Friday, October 5, 2018 2:09 PM
To: Xen-devel@xxxxxxxxxxxxxxxxxxxx
Subject: ARM64: PCIe in DOM0

Hi All,

I am booting XEN for the first time on my platform and observing that
PCIe are not working.

Here are my observations on this.

1) "git-its" node (below) from device tree is not available in DOM0
device tree.

                 its: gic-its@6020000 {
                         compatible = "arm,gic-v3-its";
                         reg = <0x0 0x6020000 0 0x20000>;

   We have "msi-parent" property in PCIe controller node which provides
phandle of above mentioned node.
   Linux (DOM0) error out if it does find a valid msi-parent.

First question I have is, What is the reason for removing gic-its node?

If CONFIG_HAS_ITS is disabled, then the virtual ITS is not built. Therefore the node is removed to prevent Dom0 using ITS.

2) Use Legacy interrupts rather than MSI

   Used "pci=nomsi" in DOM0 bootargs to move away from MSIs,

  Legacy interrupts are also not received and see netdev-watchdog.

Did you check whether legacy interrupts are routed to Dom0?


Julien Grall

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