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Message-ID: <6a2107864d45bd6ac403c218d68bf97025eca971.camel@infradead.org>
Subject: Re: [RFC PATCH v2 2/4] KVM: arm64: Add PSCI SYSTEM_OFF2 function
 for hibernation
From: David Woodhouse <dwmw2@infradead.org>
To: Marc Zyngier <maz@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org, Paolo Bonzini
 <pbonzini@redhat.com>, Jonathan Corbet <corbet@lwn.net>, Oliver Upton
 <oliver.upton@linux.dev>, James Morse <james.morse@arm.com>, Suzuki K
 Poulose <suzuki.poulose@arm.com>, Zenghui Yu <yuzenghui@huawei.com>,
 Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>,
 Mark Rutland <mark.rutland@arm.com>, Lorenzo Pieralisi
 <lpieralisi@kernel.org>, "Rafael J. Wysocki" <rafael@kernel.org>, Len Brown
 <len.brown@intel.com>, Pavel Machek <pavel@ucw.cz>, Mostafa Saleh
 <smostafa@google.com>, Jean-Philippe Brucker <jean-philippe@linaro.org>, 
 linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
 kvmarm@lists.linux.dev,  linux-pm@vger.kernel.org
Date: Mon, 18 Mar 2024 17:54:06 +0000
In-Reply-To: <86v85jzbw8.wl-maz@kernel.org>
References: <20240318164646.1010092-1-dwmw2@infradead.org>
	 <20240318164646.1010092-3-dwmw2@infradead.org>
	 <86v85jzbw8.wl-maz@kernel.org>
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On Mon, 2024-03-18 at 17:29 +0000, Marc Zyngier wrote:
>=20
> Again, I really oppose this way of doing things. We already have an
> infrastructure for selecting PSCI levels. You may not like it, but it
> exists, and I'm not going entertain supporting yet another bike-shed
> model. Adding an orthogonal cap for a feature that is specific to a
> new PSCI version is just awful.

Huh? This isn't a "new bike-shed model". This is a straight copy of
what we *already* have for SYSTEM_RESET2.

If I were bike-shedding, I wouldn't do separate caps for them; I'd have
done it as a *bitmask* of the optional PSCI calls that should be
enabled.

The *mandatory* ones should obviously come from the PSCI version alone,
but I can't see how that makes sense for the optional ones...

> Please make PSCI 1.3 the only version of PSCI supporting suspend in a
> non-optional way, and be done with it.

SYSTEM_OFF2 is an *optional* feature in PSCI v1.3. As are
CLEAR_INV_MEMREGION and CLEAR_INV_MEMREGION_ATTRIBUTES.

Are you suggesting that enabling v1.3 should automatically enable *all*
of the optional features that were defined in that version (and
previous versions) of the spec?


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