linux-kernel - Re: [PATCH] KVM: arm64: nv: Set ISTATUS for emulated timers, If timer expired

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Message-ID: <864j2zrhdi.wl-maz@kernel.org>
Date: Thu, 19 Dec 2024 12:23:37 +0000
From: Marc Zyngier <maz@...nel.org>
To: Ganapatrao Kulkarni <gankulkarni@...amperecomputing.com>
Cc: Eric Auger <eauger@...hat.com>,
	kvmarm <kvmarm@...ts.linux.dev>,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	oliver.upton@...ux.dev,
	christoffer.dall@....com,
	suzuki.poulose@....com,
	will@...nel.org,
	catalin.marinas@....com,
	coltonlewis@...gle.com,
	joey.gouly@....com,
	yuzenghui@...wei.com,
	darren@...amperecomputing.com,
	vishnu@...amperecomputing.com
Subject: Re: [PATCH] KVM: arm64: nv: Set ISTATUS for emulated timers, If timer expired

On Thu, 19 Dec 2024 09:30:11 +0000,
Ganapatrao Kulkarni <gankulkarni@...amperecomputing.com> wrote:
> 
> 
> 
> On 09-12-2024 11:04 pm, Eric Auger wrote:
> > Hi Marc,
> > 
> > On 12/9/24 18:30, Marc Zyngier wrote:
> >> On Mon, 09 Dec 2024 16:46:30 +0000,
> >> Eric Auger <eauger@...hat.com> wrote:
> >>> 
> >>> Hi,
> >>> 
> >>> On 12/9/24 16:39, Ganapatrao Kulkarni wrote:
> >>>> 
> >>>> 
> >>>> On 09-12-2024 06:50 pm, Marc Zyngier wrote:
> >>>>> On Mon, 09 Dec 2024 12:25:34 +0000,
> >>>>> Ganapatrao Kulkarni <gankulkarni@...amperecomputing.com> wrote:
> >>>>>>>> 
> >>>>>>>> During automated testing of Nested Virtualization using avocado-vt,
> >>>>>>> 
> >>>>>>> Which is not merged upstream. So what branch are you using? Based on
> >>>>>>> what kernel version? On what HW? With which virtualisation features?
> >>>>>>> 
> >>>>>> 
> >>>>>> Testing is done on Ampere's AmpereOne platform using 6.10 based kernel
> >>>>>> with NV patches from your repo.
> >>>>> 
> >>>>> Grmbl... *Which* patches? At least give me the SHA1 of the branch,
> >>>>> because I have no idea what you are running. And 6.10 is definitely
> >>>>> not something I care about. If you're using the NV patches, the
> >>>>> *minimum* you should run is 6.13-rc1, because that's what the current
> >>>>> code is based on.
> >>>>> 
> >>>> 
> >>>> I tried 6.13-rc1 based nv-next branch today, which failed to boot
> >>>> UEFI as L1. Yet to debug this.
> >>> 
> >>> I confirm am stuck with the same issue with nv-next on AmpereOne.
> >> 
> >> All I can say is that it Works For Me (TM) on M2 and Snapdragon, using
> >> kvmtool, a fresh EDK2 built by Ard, and with the guest running purely
> >> VHE (FEAT_E2H0 not implemented).
> >> 
> >> I haven't tried QEMU, I don't have an AmpereOne. I have also spent way
> >> too much time on this recently. So I'm afraid people interested in
> >> making this particular combination work will have to debug it.
> > 
> > yes I do agree. I am currently setting up kvmtool to double check and I
> > will debug the qemu issue.
> 
> I could boot Guest-hypervisor using QEMU with -bios and nv-next as L0
> with edk2 (QEMU_EFI.fd) built from upstream tree and fedora-41 as
> Guest-Hypervisor.

Cool. This shows that Ard's hard work on EDK2 is paying off.

> 
> The issue was disappeared when upgraded from fc39 to fc41. Same was
> experienced with the kvmtool boot as well(KVMTOOL_EFI.fd).

I guess the fc39 kernel is too old to understand the VHE-only ID
registers, which was introduced in 6.9.

Once you teach QEMU how to disable VHE, you should be able to boot
older kernels that predate this change.

	M.

-- 
Without deviation from the norm, progress is not possible.