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From: Marc Zyngier <maz@kernel.org>
To: David Woodhouse <dwmw2@infradead.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>,
	David Woodhouse <dwmw@amazon.co.uk>,
	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
Subject: Re: [RFC PATCH 0/2] Add PSCI v1.3 SYSTEM_OFF2 support for hibernation
Date: Tue, 12 Mar 2024 15:24:23 +0000	[thread overview]
Message-ID: <87wmq7pj6g.wl-maz@kernel.org> (raw)
In-Reply-To: <20240312135958.727765-1-dwmw2@infradead.org>

On Tue, 12 Mar 2024 13:51:27 +0000,
David Woodhouse <dwmw2@infradead.org> wrote:
> 
> The upcoming PSCI v1.3 specification adds support for a SYSTEM_OFF2

Pointer to the spec? Crucially, this is in the Alpha state, meaning
that it is still subject to change [1].

> function which is analogous to ACPI S4 state. This will allow hosting 
> environments to determine that a guest is hibernated rather than just 
> powered off, and ensure that they preserve the virtual environment 
> appropriately to allow the guest to resume safely (or bump the 
> hardware_signature in the FACS to trigger a clean reboot instead).
> 
> This adds support for it to KVM, and to the guest hibernate code.
> 
> Strictly, we should perhaps also allow the guest to detect PSCI v1.3, 
> but when v1.1 was added in commit 512865d83fd9 it was done 
> unconditionally, which seems wrong. Shouldn't we have a way for 
> userspace to control what gets exposed, rather than silently changing 
> the guest behaviour with newer host kernels? Should I add a 
> KVM_CAP_ARM_PSCI_VERSION?

Do you mean something like 85bd0ba1ff98?

	M.

[1] https://documentation-service.arm.com/static/65e59325837c4d065f6556a6

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

WARNING: multiple messages have this Message-ID (diff)
From: Marc Zyngier <maz@kernel.org>
To: David Woodhouse <dwmw2@infradead.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>,
	David Woodhouse <dwmw@amazon.co.uk>,
	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
Subject: Re: [RFC PATCH 0/2] Add PSCI v1.3 SYSTEM_OFF2 support for hibernation
Date: Tue, 12 Mar 2024 15:24:23 +0000	[thread overview]
Message-ID: <87wmq7pj6g.wl-maz@kernel.org> (raw)
In-Reply-To: <20240312135958.727765-1-dwmw2@infradead.org>

On Tue, 12 Mar 2024 13:51:27 +0000,
David Woodhouse <dwmw2@infradead.org> wrote:
> 
> The upcoming PSCI v1.3 specification adds support for a SYSTEM_OFF2

Pointer to the spec? Crucially, this is in the Alpha state, meaning
that it is still subject to change [1].

> function which is analogous to ACPI S4 state. This will allow hosting 
> environments to determine that a guest is hibernated rather than just 
> powered off, and ensure that they preserve the virtual environment 
> appropriately to allow the guest to resume safely (or bump the 
> hardware_signature in the FACS to trigger a clean reboot instead).
> 
> This adds support for it to KVM, and to the guest hibernate code.
> 
> Strictly, we should perhaps also allow the guest to detect PSCI v1.3, 
> but when v1.1 was added in commit 512865d83fd9 it was done 
> unconditionally, which seems wrong. Shouldn't we have a way for 
> userspace to control what gets exposed, rather than silently changing 
> the guest behaviour with newer host kernels? Should I add a 
> KVM_CAP_ARM_PSCI_VERSION?

Do you mean something like 85bd0ba1ff98?

	M.

[1] https://documentation-service.arm.com/static/65e59325837c4d065f6556a6

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

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  parent reply	other threads:[~2024-03-12 15:24 UTC|newest]

Thread overview: 32+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-03-12 13:51 [RFC PATCH 0/2] Add PSCI v1.3 SYSTEM_OFF2 support for hibernation David Woodhouse
2024-03-12 13:51 ` David Woodhouse
2024-03-12 13:51 ` [RFC PATCH 1/2] KVM: arm64: Add PSCI SYSTEM_OFF2 function " David Woodhouse
2024-03-12 13:51   ` David Woodhouse
2024-03-12 15:36   ` Marc Zyngier
2024-03-12 15:36     ` Marc Zyngier
2024-03-12 17:06     ` David Woodhouse
2024-03-12 17:06       ` David Woodhouse
2024-03-12 15:47   ` Oliver Upton
2024-03-12 15:47     ` Oliver Upton
2024-03-13 12:53     ` David Woodhouse
2024-03-13 12:53       ` David Woodhouse
2024-03-13 19:42       ` Oliver Upton
2024-03-13 19:42         ` Oliver Upton
2024-03-13 23:01         ` David Woodhouse
2024-03-13 23:01           ` David Woodhouse
2024-03-12 13:51 ` [RFC PATCH 2/2] arm64: Use SYSTEM_OFF2 PSCI call to power off for hibernate David Woodhouse
2024-03-12 13:51   ` David Woodhouse
2024-03-12 15:57   ` Sudeep Holla
2024-03-12 15:57     ` Sudeep Holla
2024-03-12 16:36     ` David Woodhouse
2024-03-12 16:36       ` David Woodhouse
2024-03-13 15:34       ` Sudeep Holla
2024-03-13 15:34         ` Sudeep Holla
2024-03-14 11:09         ` Sudeep Holla
2024-03-14 11:09           ` Sudeep Holla
2024-03-14 11:27           ` David Woodhouse
2024-03-14 11:27             ` David Woodhouse
2024-03-12 15:24 ` Marc Zyngier [this message]
2024-03-12 15:24   ` [RFC PATCH 0/2] Add PSCI v1.3 SYSTEM_OFF2 support for hibernation Marc Zyngier
2024-03-12 17:01   ` David Woodhouse
2024-03-12 17:01     ` David Woodhouse

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