Re: [FSL P50x0] KVM HV doesn't work anymore

On 17. May 2021, at 11:43, Christian Zigotzky [off-list ref] wrote:

On 17 May 2021 at 09:42am, Nicholas Piggin wrote:

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Excerpts from Christian Zigotzky's message of May 15, 2021 11:46 pm:

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On 15 May 2021 at 12:08pm Christophe Leroy wrote:

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Le 15/05/2021 à 11:48, Christian Zigotzky a écrit :

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Hi All,

I bisected today [1] and the bisecting itself was OK but the
reverting of the bad commit doesn't solve the issue. Do you have an
idea which commit could be resposible for this issue? Maybe the
bisecting wasn't successful. I will look in the kernel git log. Maybe
there is a commit that affected KVM HV on FSL P50x0 machines.

If the uImage doesn't load, it may be because of the size of uImage.

See https://github.com/linuxppc/issues/issues/208

Is there a significant size difference with and without KVM HV ?

Maybe you can try to remove another option to reduce the size of the
uImage.

I tried it but it doesn't solve the issue. The uImage works without KVM
HV in a virtual e5500 QEMU machine.

Any more progress with this? I would say that bisect might have just
been a bit unstable and maybe by chance some things did not crash so
it's pointing to the wrong patch.

Upstream merge of powerpc-5.13-1 was good and powerpc-5.13-2 was bad?

Between that looks like some KVM MMU rework. You could try the patch
before this one b1c5356e873c ("KVM: PPC: Convert to the gfn-based MMU
notifier callbacks"). That won't revert cleanly so just try run the
tree at that point. If it works, test the patch and see if it fails.

Thanks,
Nick

Hi Nick,

Thanks a lot for your answer. Yes, there is a little bit of progress. The RC2 of kernel 5.13 successfully boots with -smp 3 in a virtual e5500 QEMU machine.
-smp 4 doesn't work anymore since the PowerPC updates 5.13-2. I used -smp 4 before 5.13 because my FSL P5040 machine has 4 cores.

Could you please post a patch for reverting the commit before b1c5356e873c ("KVM: PPC: Convert to the gfn-based MMU notifier callbacks")?

Thanks in advance,

Christian

For me it is ok to work with -smp 1, 2, and 3 but I am curious why -smp 4 doesn’t work.

-Christian