From nobody Mon Feb 9 07:22:05 2026 Received: from smtp-fw-80008.amazon.com (smtp-fw-80008.amazon.com [99.78.197.219]) (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 D41C4155391; Tue, 9 Apr 2024 17:02:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=99.78.197.219 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712682141; cv=none; b=KBoQt1gEpr6l2+mJfO/kDHQDZyyfjsxElG8E4t0bZqFrbp2amRaN185+w8/u2tMVN6wwNleftqoNnYKFOuRJDuA/oHbdiwDRD1ZlxqThc7wTsKDlDbAKSU3TulU54OZLNSmtStyANNBPVlDTscLcp/Q8VZWd+aEQtBK6DyBvO3c= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712682141; c=relaxed/simple; bh=dn+lAleatEKuaifZlrvPWySPzKxUqpTQLCOmlh50Oqs=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=jMuQq0gfMj6XL1QNTyyqVPM0SWEEfg8lCeH71N5uyFZrL2Mdb/Ee1kmQZg2M2m0TEwnWjfbfdlxuZnkGUP4KgN18igx6WdXc8qA+3PlPDyjCemYktRUgDT4oYPFEsUTn/x1pp9ZX7LtrBAFynV7h+9Vzkrmpa+KV3NGvHfgUKvA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amazon.com; spf=pass smtp.mailfrom=amazon.co.uk; dkim=pass (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b=nl3uHo+7; arc=none smtp.client-ip=99.78.197.219 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=amazon.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=amazon.co.uk Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b="nl3uHo+7" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1712682139; x=1744218139; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=lgg88BB+Hs9vOysnsDN018CMkG589f+hMJJXDN4bMMc=; b=nl3uHo+70CEivZfCEpue9rHMRVPcKF7MEWAFRJ+TxbxCpkWFY8y45Zoi ghOzuFrHDK9E54DK/5aqdMTx8i/zt7EAgctT1pJLGW7pO4l6MdIp1JgOT k43WID82RCVcvNBLkxHbRCzuIbHuUDcHYSZsTYV1+EXbRGKwHbD2eOxRf k=; X-IronPort-AV: E=Sophos;i="6.07,190,1708387200"; d="scan'208";a="79859137" Received: from pdx4-co-svc-p1-lb2-vlan3.amazon.com (HELO smtpout.prod.us-east-1.prod.farcaster.email.amazon.dev) ([10.25.36.214]) by smtp-border-fw-80008.pdx80.corp.amazon.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 09 Apr 2024 17:02:17 +0000 Received: from EX19MTAEUB001.ant.amazon.com [10.0.10.100:33596] by smtpin.naws.eu-west-1.prod.farcaster.email.amazon.dev [10.0.4.194:2525] with esmtp (Farcaster) id c734f48e-9821-4d47-8048-be66beb41896; Tue, 9 Apr 2024 17:02:16 +0000 (UTC) X-Farcaster-Flow-ID: c734f48e-9821-4d47-8048-be66beb41896 Received: from EX19D036EUC002.ant.amazon.com (10.252.61.191) by EX19MTAEUB001.ant.amazon.com (10.252.51.26) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1258.28; Tue, 9 Apr 2024 17:02:15 +0000 Received: from bcd074994f7f.amazon.com (10.95.97.144) by EX19D036EUC002.ant.amazon.com (10.252.61.191) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1258.28; Tue, 9 Apr 2024 17:02:11 +0000 From: Sudan Landge To: , , , , , , , , , , CC: , , , Subject: [PATCH v4 4/5] dt-bindings: rng: Add vmgenid support Date: Tue, 9 Apr 2024 18:01:36 +0100 Message-ID: <20240409170137.79197-5-sudanl@amazon.com> X-Mailer: git-send-email 2.39.3 (Apple Git-146) In-Reply-To: <20240409170137.79197-1-sudanl@amazon.com> References: <20240409170137.79197-1-sudanl@amazon.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ClientProxiedBy: EX19D044UWA001.ant.amazon.com (10.13.139.100) To EX19D036EUC002.ant.amazon.com (10.252.61.191) Content-Type: text/plain; charset="utf-8" Virtual Machine Generation ID driver was introduced in commit af6b54e2b5ba ("virt: vmgenid: notify RNG of VM fork and supply generation ID"), as an ACPI only device. VMGenID specification http://go.microsoft.com/fwlink/?LinkId=3D260709 defin= es a mechanism for the BIOS/hypervisors to communicate to the virtual machine that it is executed with a different configuration (e.g. snapshot execution or creation from a template). The guest operating system can use the notification for various purposes such as re-initializing its random number generator etc. As per the specs, hypervisor should provide a globally unique identified, or GUID via ACPI. This patch tries to mimic the mechanism to provide the same functionality which is for a hypervisor/BIOS to notify the virtual machine when it is executed with a different configuration. As part of this support the devicetree bindings requires the hypervisors or BIOS to provide a memory address which holds the GUID and an IRQ which is used to notify when there is a change in the GUID. The memory exposed in the DT should follow the rules defined in the vmgenid spec mentioned above. *Reason for this change*: Chosing ACPI or devicetree is an intrinsic part of an hypervisor design. Without going into details of why a hypervisor would choose DT over ACPI, we would like to highlight that the hypervisors that have chose devicetree and now want to make use of the vmgenid functionality cannot do so today because vmgenid is an ACPI only device. This forces these hypervisors to change their design which could have undesirable impacts on their use-cases, test-scenarios etc. vmgenid exposes to the guest a 16-byte cryptographically random number, the value of which changes every time it starts executing from a new configuration (snapshot, backup, etc.). During initialization, the device exposes to the guest the address of the generation ID and an interrupt number, which the device will use to notify the guest when the generation ID changes. These attributes can be trivially communicated via device tree bindings. We believe that adding a devicetree binding for vmgenid is a simpler alternative way to expose the device to the guest than forcing the hypervisors to implement ACPI. More references to vmgenid specs: - https://www.qemu.org/docs/master/specs/vmgenid.html - https://learn.microsoft.com/en-us/windows/win32/hyperv_v2/virtual- machine-generation-identifier Signed-off-by: Sudan Landge --- .../bindings/rng/microsoft,vmgenid.yaml | 49 +++++++++++++++++++ MAINTAINERS | 1 + 2 files changed, 50 insertions(+) create mode 100644 Documentation/devicetree/bindings/rng/microsoft,vmgenid= .yaml diff --git a/Documentation/devicetree/bindings/rng/microsoft,vmgenid.yaml b= /Documentation/devicetree/bindings/rng/microsoft,vmgenid.yaml new file mode 100644 index 000000000000..8f20dee93e7e --- /dev/null +++ b/Documentation/devicetree/bindings/rng/microsoft,vmgenid.yaml @@ -0,0 +1,49 @@ +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/rng/microsoft,vmgenid.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml# + +title: Virtual Machine Generation ID + +maintainers: + - Jason A. Donenfeld + +description: + Firmwares or hypervisors can use this devicetree to describe an + interrupt and a shared resource to inject a Virtual Machine Generation I= D. + Virtual Machine Generation ID is a globally unique identifier (GUID) and + the devicetree binding follows VMGenID specification defined in + http://go.microsoft.com/fwlink/?LinkId=3D260709. + +properties: + compatible: + const: microsoft,vmgenid + + reg: + description: + Specifies a 16-byte VMGenID in endianness-agnostic hexadecimal forma= t. + maxItems: 1 + + interrupts: + description: + Interrupt used to notify that a new VMGenID is available. + maxItems: 1 + +required: + - compatible + - reg + - interrupts + +additionalProperties: false + +examples: + - | + #include + rng@80000000 { + compatible =3D "microsoft,vmgenid"; + reg =3D <0x80000000 0x1000>; + interrupts =3D ; + }; + +... diff --git a/MAINTAINERS b/MAINTAINERS index aea47e04c3a5..243607744b7e 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -18476,6 +18476,7 @@ M: "Theodore Ts'o" M: Jason A. Donenfeld S: Maintained T: git https://git.kernel.org/pub/scm/linux/kernel/git/crng/random.git +F: Documentation/devicetree/bindings/rng/microsoft,vmgenid.yaml F: drivers/char/random.c F: drivers/virt/vmgenid.c =20 --=20 2.34.1