From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EA5AE7BB08; Tue, 12 Mar 2024 15:24:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710257074; cv=none; b=WRd6g+LBLqQlOm9MuJkzfbA08WsfSEkAlEPHMKT1dXgOlcLpsQ440fMRvlwfIoHvTYy00QnSSp89NfIV9bfcg1baMxr7qDyLsZ73ozWtssGfO+2RlCXGzhC3X3h4W1lO/LFCUZlPz+qpKvq264FH0UXFjFs4Q2ngb6YY0ZakK+c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710257074; c=relaxed/simple; bh=nqKmQTSmr2KuGua3AdiEOFKyMoOcoM2xLn6yrACNOR4=; h=Date:Message-ID:From:To:Cc:Subject:In-Reply-To:References: MIME-Version:Content-Type; b=UPQTdGFALdpOtiIJ94XA9/oTbs5N0UDIbyvYX/Fy9Jm1FsTQg+ArZO2VTX8Lf1BakDyCD1+1u5YWGUrbw1MA8Qcv7yrQv+lop7LqR4l5zJVFtNz2VamlbLoOkL0OsIS4pn/x8wuW3aGSQDkzXcdti8sDn1dXYVOcS4X2vLnWWFg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=sxa/mtLK; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="sxa/mtLK" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 67C3BC433F1; Tue, 12 Mar 2024 15:24:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1710257073; bh=nqKmQTSmr2KuGua3AdiEOFKyMoOcoM2xLn6yrACNOR4=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=sxa/mtLKCqHRQ47Z3IGh8g9wEghLqDd4mEdsnmIZ8+rKVeNnIOe7nLGAm8nDyfpfj 9KxyWcia6zoGbsG0CtfaZAKs7CFMwLVbGzY4t9ApEYLyUI08BKL131Efsf5saBdez6 rHerJrF3Zq92BkXrsRTgoXJH099pAxBbqeRbXZRXepBR0iRLuBYDuXi57aDpIDf5Nk LfxsBtnoRnotjh3fEOqOxOuK2VwGVlBhw7FExY/kO9fzAbb0z0JF+68a0SzxECKKkL LkwIwhgvT/op/wvS116Vy2CGPWSBUv7lp5r9crmuinVWb4keHgw0k87cRWbQlixRKK EISGo5xgHdODA== Received: from [209.214.232.173] (helo=wait-a-minute.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1rk3zS-00Blz8-6P; Tue, 12 Mar 2024 15:24:30 +0000 Date: Tue, 12 Mar 2024 15:24:23 +0000 Message-ID: <87wmq7pj6g.wl-maz@kernel.org> From: Marc Zyngier To: David Woodhouse Cc: linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org, Paolo Bonzini , Jonathan Corbet , Oliver Upton , James Morse , Suzuki K Poulose , Zenghui Yu , Catalin Marinas , Will Deacon , Mark Rutland , Lorenzo Pieralisi , "Rafael J. Wysocki" , Len Brown , Pavel Machek , David Woodhouse , Mostafa Saleh , Jean-Philippe Brucker , 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 In-Reply-To: <20240312135958.727765-1-dwmw2@infradead.org> References: <20240312135958.727765-1-dwmw2@infradead.org> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/28.2 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO) Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 209.214.232.173 X-SA-Exim-Rcpt-To: dwmw2@infradead.org, linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org, pbonzini@redhat.com, corbet@lwn.net, oliver.upton@linux.dev, james.morse@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, catalin.marinas@arm.com, will@kernel.org, mark.rutland@arm.com, lpieralisi@kernel.org, rafael@kernel.org, len.brown@intel.com, pavel@ucw.cz, dwmw@amazon.co.uk, smostafa@google.com, jean-philippe@linaro.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, kvmarm@lists.linux.dev, linux-pm@vger.kernel.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false On Tue, 12 Mar 2024 13:51:27 +0000, David Woodhouse 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.