From patchwork Mon Mar 18 16:14:22 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Woodhouse X-Patchwork-Id: 781007 Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (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 82DBF2C6B7; Mon, 18 Mar 2024 16:47:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.92.199 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710780432; cv=none; b=LR/FPDQouCwEJTjACCSoDgQAMgasn4ha2bFSAGAthKsHIjpXMqPzhdH8aOlUaPYcuKyCj28XS6VUUh3dIwfpuNTUlXmV5fFE7AbLRWfb6Ql2Px9XHPsKdCOBZk3Pcz9FMwrnIbMke39yOyZeLWcQXDaH03O5zT4tOGp85qXv8c8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1710780432; c=relaxed/simple; bh=b0h1VbEHFh9qD1o7D7bZULRZA5Hxn9NGATbuk1naP50=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=B/rM5H822taZQ/ZirrPD44VYfrG2alnxjQ82ySQlEcmxmTe97o7GGTA/+cb39wO+P/GlTqNwXTLEwHzDKUP2e6tn7Nj3yTrj5b/Sq1/sfBOM2K7imXv1Ao+VHrJ8ANbVSEhDIE/e4nATiBDD3I4Clbk92Fk3sOchYLf84ivfJeM= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=desiato.srs.infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=eLDnx06l; arc=none smtp.client-ip=90.155.92.199 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=desiato.srs.infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="eLDnx06l" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=Sender:Content-Transfer-Encoding: MIME-Version:Message-ID:Date:Subject:Cc:To:From:Reply-To:Content-Type: Content-ID:Content-Description:In-Reply-To:References; bh=PepfWuDb0qWcSY62ic0M/q/leQ8EAPZZpQYANiCR9/0=; b=eLDnx06lB1n0d9bn85UZrkkWTI hE3cwCH64vBWVmVAyRNCovdc7I04JyPFUnR+MMxag37V6dpdmF02pjb1JzAulwnek4W1vfUQnJVZU lq6arc45Z3h/rVIxLnfp7GwgAHE73Uzc7YScPvMI9hTiQh/nSoQsjFn0cyKV86XzlRgO6i2d750VN S6znG4zO08OV+32EV1CNXFl16h/mn/Ttz2/2pVrRNUVThXNlcJ14AtSvKyzRnmJKkHlz454dfswdB EBiCgdPegSNpUlq2u/fYp3TK2zVpc4zFB1+8UJzBsUBXUli6ab8pWKsabG40DS7M0SQczFoy4D3xW Axl4yGkQ==; Received: from [2001:8b0:10b:1::ebe] (helo=i7.infradead.org) by desiato.infradead.org with esmtpsa (Exim 4.97.1 #2 (Red Hat Linux)) id 1rmG8Z-0000000CjyA-1kHI; Mon, 18 Mar 2024 16:46:59 +0000 Received: from dwoodhou by i7.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1rmG8W-00000004F1A-0SES; Mon, 18 Mar 2024 16:46:56 +0000 From: David Woodhouse To: linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org Cc: Paolo Bonzini , Jonathan Corbet , Marc Zyngier , 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: [RFC PATCH v2 0/4] arm64: Add PSCI v1.3 SYSTEM_OFF2 support for hibernation Date: Mon, 18 Mar 2024 16:14:22 +0000 Message-ID: <20240318164646.1010092-1-dwmw2@infradead.org> X-Mailer: git-send-email 2.44.0 Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Sender: David Woodhouse X-SRS-Rewrite: SMTP reverse-path rewritten from by desiato.infradead.org. See http://www.infradead.org/rpr.html The PSCI v1.3 spec (https://developer.arm.com/documentation/den0022, currently in Alpha state, hence 'RFC') adds support for a SYSTEM_OFF2 function enabling a HIBERNATE_OFF state which is analogous to ACPI S4. 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, exactly the same way as the existing support for SYSTEM_RESET2 as added in commits d43583b890e7 ("KVM: arm64: Expose PSCI SYSTEM_RESET2 call to the guest") and 34739fd95fab ("KVM: arm64: Indicate SYSTEM_RESET2 in kvm_run::system_event flags field"). Back then, KVM was unconditionally bumped to expose PSCI v1.1. This means that a kernel upgrade causes guest visible behaviour changes without any explicit opt-in from the VMM, which is... unconventional. In some cases, a PSCI update isn't just about new optional calls; PSCI v1.2 for example adds a new permitted error return from the existing CPU_ON function. There *is* a way for a VMM to opt *out* of newer PSCI versions... by setting a per-vCPU "special" register that actually ends up setting the PSCI version KVM-wide. Quite why this isn't just a simple KVM_CAP, I have no idea. There *is* a KVM_CAP_ARM_PSCI_0_2 but that's just for 0.1 vs. 0.2+, not the specific v0.2+ version that's exposed. Since the SYSTEM_OFF2 call is optional and discoverable through the PSCI_FEATURES call, I'm electing not to touch the PSCI versioning awfulness at all. Like the existing SYSTEM_RESET2, there's a KVM_CAP to enable it explicitly (as it's an optional call even in v1.3), and like the existing SYSTEM_RESET2 it doesn't depend on the advertised PSCI version. For the guest side, add a new SYS_OFF_MODE_POWER_OFF handler with higher priority than the EFI one, but which *only* triggers when there's a hibernation in progress. There are other ways to do this (see the commit message for more details) but this seemed like the simplest. Version 2 of the patch series splits out the psci.h definitions into a separate commit (a dependency for both the guest and KVM side), and adds definitions for the other new functions added in v1.3. It also moves the pKVM psci-relay support to a separate commit; although in arch/arm64/kvm that's actually about the *guest* side of SYSTEM_OFF2 (i.e. using it from the host kernel, relayed through nVHE). David Woodhouse (4): firmware/psci: Add definitions for PSCI v1.3 specification (ALPHA) KVM: arm64: Add PSCI SYSTEM_OFF2 function for hibernation KVM: arm64: nvhe: Pass through PSCI v1.3 SYSTEM_OFF2 call arm64: Use SYSTEM_OFF2 PSCI call to power off for hibernate Documentation/virt/kvm/api.rst | 11 +++++++++++ arch/arm64/include/asm/kvm_host.h | 2 ++ arch/arm64/include/uapi/asm/kvm.h | 6 ++++++ arch/arm64/kvm/arm.c | 5 +++++ arch/arm64/kvm/hyp/nvhe/psci-relay.c | 2 ++ arch/arm64/kvm/psci.c | 37 ++++++++++++++++++++++++++++++++++++ drivers/firmware/psci/psci.c | 35 ++++++++++++++++++++++++++++++++++ include/uapi/linux/kvm.h | 1 + include/uapi/linux/psci.h | 20 +++++++++++++++++++ kernel/power/hibernate.c | 5 ++++- 10 files changed, 123 insertions(+), 1 deletion(-)