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

[Julien Grall <julien.grall@xxxxxxx>]

On 09/10/2018 12:25, Bharat Bhushan wrote:
> Hi,
Hi Bharat,

> > -----Original Message-----
> > From: Julien Grall <julien.grall@xxxxxxx>
> > Sent: Friday, October 5, 2018 6:51 PM
> > To: Bharat Bhushan <bharat.bhushan@xxxxxxx>; Xen-
> > devel@xxxxxxxxxxxxxxxxxxxx
> > Subject: Re: [Xen-devel] ARM64: PCIe in DOM0
> >
> > Hi,
> >
> > 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.
> I tried with this and I can see "its" node in Dom0 device-tree
> My compilation steps are:
> I am cross-compiling, so set toolchain path.
>
> make dist-xen XEN_TARGET_ARCH=arm64 XEN_CONFIG_EXPERT=y 
> CONFIG_EARLY_PRINTK=8250,0x21c0600,0
> mkimage -A arm64 -T kernel -a 0x80000000 -e 0x80000000 -C none -d ./xen/xen 
> xen4.11-uImage
>
> > > 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.
> I assume PCI device will still be working on ARM64 based platforms
That's correct.

> > > Any help is very useful,!!
> > Can you please provide the full log?
> Please find attached logs.
> I have one UART of a DUART working, So at a time I am not able to provide same 
> to XEN or DOM0.
> So for you will see two set of log, one when console provided to XEN and 
> another same console provided to DOM0 while used for early-prints of XEN.
Xen provides para-virtualized console through hypercall for Dom0. 
Assuming you have the driver enabled (CONFIG_HVC_XEN), you could add on 
your Dom0 command line "console=hvc0". This will give you a full console 
access to Dom0 while still allow Xen to print message.
To narrow down the cause, I would disable the IOMMU. Looking at the 
logs, I noticed you have some specific ITS driver (fsl-mc) for your 
board. Xen does not have any knowledge for it. Could it have an impact 
on the interrupts if not configured correctly?
At the moment, Xen implements a generic ITS and GICv3. Should we expect 
some specific additions for your platform to use interrupts?
On your previous e-mail you mention you tried to pass "pci=nomsi". Does 
this setup works without Xen (e.g booting a bare linux)? If so, I would 
start by exploring whether interrupt are effectively unmask by Xen on 
guest request.
You could add some print in the GICv3 emulation (arch/arm/vgic-v3.c) and 
ITS (arch/arm/vgic-v3-its.c).
> I am new to XEN so might be doing something wrong.
My knowledge on the board you are using is limited. I have CCed Peng Fan 
who is also working at NXP and have Xen knowledge.
Cheers,

--
Julien Grall

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