Re: [Xen-devel] Problems building and running Xen on Hikey960

[Julien Grall <julien.grall@xxxxxxx>]

Hi Omkar,

Please configure your e-mail client to quote properly and remove the disclaimer 
below.
On 09/11/2018 16:55, Omkar Bolla wrote:
> On Fri, Nov 9, 2018 at 4:52 PM Julien Grall <julien.grall@xxxxxxx 
> <mailto:julien.grall@xxxxxxx>> wrote:
>
>
>     On 08/11/2018 07:07, Matthew Daley wrote:
>      > Hi all,
>
>     Hi Matthew,
>
>      >
>      > I'm trying to build and run Linux (Debian) on top of Xen on a Hikey960
>      > ARM board but am having trouble.
>      >
>      > I've been following Konrad's guide on the Wiki (at
>      > https://wiki.xenproject.org/wiki/HiKey960), namely:
>      > * I have upgraded the board's base firmware to support UEFI
>      > * I am building the hikey960-upstream-rebase branch of
>      > https://github.com/96boards-hikey/linux.git (with a patch from Linus's
>      > tree to fix a Hynix UFS bug)
>      > * I am building the master branch of Xen unstable
>      > * I am building the master branch of GRUB (with a patch to fix a DTB
>      > padding bug)
>      >
>      > However, I see two problems when booting.
>      >
>      > Firstly, Xen fails to bring up any other CPUs but the one it is booting 
> on:
>      >
>      > (XEN) Bringing up CPU1
>      > (XEN) Failed to bring up CPU1
>      > (XEN) Failed to bring up CPU 1 (error -9)
>      > (XEN) Bringing up CPU2
>      > (XEN) Failed to bring up CPU2
>      > (XEN) Failed to bring up CPU 2 (error -9)
>      > (XEN) Bringing up CPU3
>      > (XEN) Failed to bring up CPU3
>      > (XEN) Failed to bring up CPU 3 (error -9)
>      > (XEN) Bringing up CPU4
>      > (XEN) Failed to bring up CPU4
>      > (XEN) Failed to bring up CPU 4 (error -9)
>      > (XEN) Bringing up CPU5
>      > (XEN) Failed to bring up CPU5
>      > (XEN) Failed to bring up CPU 5 (error -9)
>      > (XEN) Bringing up CPU6
>      > (XEN) Failed to bring up CPU6
>      > (XEN) Failed to bring up CPU 6 (error -9)
>      > (XEN) Bringing up CPU7
>      > (XEN) Failed to bring up CPU7
>      > (XEN) Failed to bring up CPU 7 (error -9)
>      > (XEN) Brought up 1 CPUs
>      >
>      > I have traced this error code -9 being returned by call_psci_cpu_on.
>
>     A similar error was reported a couple of months on the mailing list. From 
> the
>     report, a regression was introduced between Xen 4.8 and unstable.
>
>     Unfortunately, I don't have an hikey board to bisect it. May I ask if you 
> can
>     bisect it? If you can point the offending commit, I should be able to 
> provide
>     ideas why it breaks.
>
> As Julien said,
> For your CPUs problem in Hikey960, use 4.8 of xen source, Then all CPUs will be 
> enabled and worked properly.
I would strongly discourage anyone to use Xen 4.8 for the Hikey 960. Firstly 
because this release is out of support. Secondly because it does not contain any 
fixes for Spectre on Arm.
The Hikey 960 has cores vulnerable to some variants of Spectre & Meltdown. So an 
upgrade to the latest Xen is highly recommended to benefits of the latest 
security fixes.
For the benefit of everyone it would be nice if someone actually spend a couple 
of hours bisecting Xen on Hikey to find the offending commit. I can provide 
support for that.
Cheers,

[1] 
https://developer.arm.com/support/arm-security-updates/speculative-processor-vulnerability
--
Julien Grall

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