linux-kernel - Re: [PATCH 0/7] arm64/boot: Enable EL2 requirements for FEAT

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Message-ID: <Z4kmlhnlpKjS_MII@arm.com>
Date: Thu, 16 Jan 2025 15:32:38 +0000
From: Catalin Marinas <catalin.marinas@....com>
To: Rob Herring <robh@...nel.org>
Cc: Marc Zyngier <maz@...nel.org>,
	Anshuman Khandual <anshuman.khandual@....com>,
	linux-arm-kernel@...ts.infradead.org, Will Deacon <will@...nel.org>,
	Ryan Roberts <ryan.roberts@....com>,
	Mark Rutland <mark.rutland@....com>,
	Oliver Upton <oliver.upton@...ux.dev>,
	Jonathan Corbet <corbet@....net>,
	Eric Auger <eric.auger@...hat.com>, kvmarm@...ts.linux.dev,
	linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/7] arm64/boot: Enable EL2 requirements for FEAT_PMUv3p9

On Wed, Jan 08, 2025 at 07:47:16AM -0600, Rob Herring wrote:
> On Wed, Jan 8, 2025 at 5:15 AM Marc Zyngier <maz@...nel.org> wrote:
> > On Tue, 07 Jan 2025 22:13:47 +0000,
> > Rob Herring <robh@...nel.org> wrote:
> > > On Tue, Jan 7, 2025 at 6:13 AM Catalin Marinas <catalin.marinas@....com> wrote:
> > > > But does KVM actually expose the feature to EL1 in ID_AA64DFR1_EL1 and
> > > > than traps it at EL2?
> > >
> > > As Marc pointed out KVM only advertises PMUv3.8. Regardless, guest
> > > accesses to these registers are trapped with or without this series.
> >
> > And most probably generates a nice splat in the kernel log, as nobody
> > updated KVM to handle *correctly* PMICNTR_EL0 traps, let alone deal
> > with the FGT2 registers.
> 
> Isn't that this series[1]? Should that have come first, I guess I know
> that *now*.
[...]
> [1] https://lore.kernel.org/all/20241210055311.780688-1-anshuman.khandual@arm.com/

It's not any clearer to me. Does this series depend on the 46-patch one?
Or, if we had the other, is this no longer needed? Or none of these,
they are independent.

-- 
Catalin