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

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Message-ID: <86y0zavcos.wl-maz@kernel.org>
Date: Thu, 16 Jan 2025 18:25:07 +0000
From: Marc Zyngier <maz@...nel.org>
To: Eric Auger <eauger@...hat.com>
Cc: Ganapatrao Kulkarni <gankulkarni@...amperecomputing.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

Hi Eric,

On Thu, 16 Jan 2025 17:52:10 +0000,
Eric Auger <eauger@...hat.com> wrote:
> 
> >>>> I tested on AmpereOne and Grace-Hopper systems
> >>>
> >>> Thanks for the confirmation. I haven't had a chance to try QEMU yet,
> >>> but I expect that save/restore will not work. Something to look into,
> >> I have not tested this yet.I will give it a try.
> > 
> > Thanks, that'd be super helpful.
> 
> I confirm the migration fails when putting some registers on the dest
> side. I will further investigate.

Thanks for confirming.

I suspect that the kernel visibility bits are not exactly correct (or
depend on some odd ordering). If you can point me to a register that
fails to restore correctly, that'd be useful. Hopefully, most
EL2-specific registers suffer from the same defect.

Cheers,

	M.

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