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Thu, 11 Aug 2022 21:41:56 GMT Received: from hu-eberman-lv.qualcomm.com (10.49.16.6) by nasanex01b.na.qualcomm.com (10.46.141.250) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.986.22; Thu, 11 Aug 2022 14:41:55 -0700 From: Elliot Berman To: Bjorn Andersson , , Jonathan Corbet CC: Elliot Berman , Murali Nalajala , Trilok Soni , "Srivatsa Vaddagiri" , Carl van Schaik , Andy Gross , Dmitry Baryshkov , , "Mark Rutland" , Lorenzo Pieralisi , Sudeep Holla , "Marc Zyngier" , Rob Herring , "Krzysztof Kozlowski" , Will Deacon , Catalin Marinas , , Subject: [PATCH v3 02/12] docs: gunyah: Introduce Gunyah Hypervisor Date: Thu, 11 Aug 2022 14:40:57 -0700 Message-ID: <20220811214107.1074343-3-quic_eberman@quicinc.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220811214107.1074343-1-quic_eberman@quicinc.com> References: <20220811214107.1074343-1-quic_eberman@quicinc.com> MIME-Version: 1.0 X-Originating-IP: [10.49.16.6] X-ClientProxiedBy: nalasex01b.na.qualcomm.com (10.47.209.197) To nasanex01b.na.qualcomm.com (10.46.141.250) X-QCInternal: smtphost X-Proofpoint-Virus-Version: vendor=nai engine=6200 definitions=5800 signatures=585085 X-Proofpoint-ORIG-GUID: kr5S5-CNIo-5dY5orITU_TAtRWkWfWfn X-Proofpoint-GUID: kr5S5-CNIo-5dY5orITU_TAtRWkWfWfn X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.883,Hydra:6.0.517,FMLib:17.11.122.1 definitions=2022-08-11_13,2022-08-11_01,2022-06-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 clxscore=1015 phishscore=0 priorityscore=1501 mlxscore=0 spamscore=0 mlxlogscore=999 malwarescore=0 adultscore=0 impostorscore=0 suspectscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2207270000 definitions=main-2208110065 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220811_144704_743755_0DA7EB7E X-CRM114-Status: GOOD ( 33.66 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Gunyah is an open-source Type-1 hypervisor developed by Qualcomm. It does not depend on any lower-privileged OS/kernel code for its core functionality. This increases its security and can support a smaller trusted computing based when compared to Type-2 hypervisors. Add documentation describing the Gunyah hypervisor and the main components of the Gunyah hypervisor which are of interest to Linux virtualization development. Signed-off-by: Elliot Berman --- Documentation/virt/gunyah/index.rst | 102 ++++++++++++++++++++ Documentation/virt/gunyah/message-queue.rst | 52 ++++++++++ Documentation/virt/index.rst | 1 + MAINTAINERS | 7 ++ 4 files changed, 162 insertions(+) create mode 100644 Documentation/virt/gunyah/index.rst create mode 100644 Documentation/virt/gunyah/message-queue.rst diff --git a/Documentation/virt/gunyah/index.rst b/Documentation/virt/gunyah/index.rst new file mode 100644 index 000000000000..780ff958a83b --- /dev/null +++ b/Documentation/virt/gunyah/index.rst @@ -0,0 +1,102 @@ +.. SPDX-License-Identifier: GPL-2.0 + +================= +Gunyah Hypervisor +================= + +.. toctree:: + :maxdepth: 1 + + message-queue + +Gunyah is a Type-1 hypervisor which is independent of any OS kernel, and runs in +a higher CPU privilege level. It does not depend on any lower-privileged operating system +for its core functionality. This increases its security and can support a much smaller +trusted computing base than a Type-2 hypervisor. + +Gunyah is an open source hypervisor. The source repo is available at +https://github.com/quic/gunyah-hypervisor. + +Gunyah provides these following features. + +- Scheduling: + A scheduler for virtual CPUs (vCPUs) on physical CPUs and enables time-sharing + of the CPUs. Gunyah supports two models of scheduling: + 1. "Behind the back" scheduling in which Gunyah hypervisor schedules vCPUS on its own + 2. "Proxy" scheduling in which a delegated VM can donate part of one of its vCPU slice + to another VM's vCPU via a hypercall. +- Memory Management: + APIs handling memory, abstracted as objects, limiting direct use of physical + addresses. Memory ownership and usage tracking of all memory under its control. + Memory partitioning between VMs is a fundamental security feature. +- Interrupt Virtualization: + Uses CPU hardware interrupt virtualization capabilities. Interrupts are handled + in the hypervisor and routed to the assigned VM. +- Inter-VM Communication: + There are several different mechanisms provided for communicating between VMs. +- Virtual platform: + Architectural devices such as interrupt controllers and CPU timers are directly provided + by the hypervisor as well as core virtual platform devices and system APIs such as ARM PSCI. +- Device Virtualization: + Para-virtualization of devices is supported using inter-VM communication. + +Architectures supported +======================= +AArch64 with a GIC + +Resources and Capabilities +========================== + +Some services or resources provided by the Gunyah hypervisor are described to a virtual machine by +capability IDs. For instance, inter-VM communication is performed with doorbells and message queues. +Gunyah allows access to manipulate that doorbell via the capability ID. These devices are described +in Linux as a struct gunyah_device. + +High level management of these resources is performed by the resource manager VM. RM informs a +guest VM about resources it can access through either the device tree or via guest-initiated RPC. + +For each virtual machine, Gunyah maintains a table of resources which can be accessed by that VM. +An entry in this table is called a "capability" and VMs can only access resources via this +capability table. Hence, virtual Gunyah devices are referenced by a "capability IDs" and not a +"resource IDs". A VM can have multiple capability IDs mapping to the same resource. If 2 VMs have +access to the same resource, they may not be using the same capability ID to access that resource +since the tables are independent per VM. + +Resource Manager +================ + +The resource manager (RM) is a privileged application VM supporting the Gunyah Hypervisor. +It provides policy enforcement aspects of the virtualization system. The resource manager can +be treated as an extension of the Hypervisor but is separated to its own partition to ensure +that the hypervisor layer itself remains small and secure and to maintain a separation of policy +and mechanism in the platform. On arm64, RM runs at NS-EL1 similar to other virtual machines. + +Communication with the resource manager from each guest VM happens with message-queue.rst. Details +about the specific messages can be found in drivers/virt/gunyah/rsc_mgr.c + +:: + + +-------+ +--------+ +--------+ + | RM | | VM_A | | VM_B | + +-.-.-.-+ +---.----+ +---.----+ + | | | | + +-.-.-----------.------------.----+ + | | \==========/ | | + | \========================/ | + | Gunyah | + +---------------------------------+ + +The source for the resource manager is available at https://github.com/quic/gunyah-resource-manager. + +The resource manager provides the following features: + +- VM lifecycle management: allocating a VM, starting VMs, destruction of VMs +- VM access control policy, including memory sharing and lending +- Interrupt routing configuration +- Forwarding of system-level events (e.g. VM shutdown) to owner VM + +When booting a virtual machine which uses a devicetree, resource manager overlays a +/hypervisor node. This node can let Linux know it is running as a Gunyah guest VM, +how to communicate with resource manager, and basic description and capabilities of +this VM. See Documentation/devicetree/bindings/firmware/gunyah-hypervisor.yaml for a description +of this node. diff --git a/Documentation/virt/gunyah/message-queue.rst b/Documentation/virt/gunyah/message-queue.rst new file mode 100644 index 000000000000..e130f124ed52 --- /dev/null +++ b/Documentation/virt/gunyah/message-queue.rst @@ -0,0 +1,52 @@ +.. SPDX-License-Identifier: GPL-2.0 + +Message Queues +============== +Message queue is a simple low-capacity IPC channel between two VMs. It is +intended for sending small control and configuration messages. Each message +queue object is unidirectional, so a full-duplex IPC channel requires a pair of +objects. + +Messages can be up to 1024 bytes in length. Longer messages require a further +protocol on top of the message queue messages themselves. For instance, communication +with the resource manager adds a header field for sending longer messages via multiple +message fragments. + +The diagram below shows how message queue works. A typical configuration involves +2 message queues. Message queue 1 allows VM_A to send messages to VM_B. Message +queue 2 allows VM_B to send messages to VM_A. + +1. VM_A sends a message of up to 1024 bytes in length. It raises a hypercall + with the message to inform the hypervisor to add the message to + message queue 1's queue. +2. Gunyah raises the corresponding interrupt for VM_B when any of these happens: + a. gh_msgq_send has PUSH flag. Queue is immediately flushed. This is the typical case. + b. Explicility with gh_msgq_push command from VM_A. + c. Message queue has reached a threshold depth. +3. VM_B calls gh_msgq_recv and Gunyah copies message to requested buffer. + +For VM_B to send a message to VM_A, the process is identical, except that hypercalls +reference message queue 2's capability ID. + +:: + + +---------------+ +-----------------+ +---------------+ + | VM_A | |Gunyah hypervisor| | VM_B | + | | | | | | + | | | | | | + | | Tx | | | | + | |-------->| | Rx vIRQ | | + |gh_msgq_send() | Tx vIRQ |Message queue 1 |-------->|gh_msgq_recv() | + | |<------- | | | | + | | | | | | + | Message Queue | | | | Message Queue | + | driver | | | | driver | + | | | | | | + | | | | | | + | | | | Tx | | + | | Rx vIRQ | |<--------| | + |gh_msgq_recv() |<--------|Message queue 2 | Tx vIRQ |gh_msgq_send() | + | | | |-------->| | + | | | | | | + | | | | | | + +---------------+ +-----------------+ +---------------+ diff --git a/Documentation/virt/index.rst b/Documentation/virt/index.rst index 492f0920b988..dd4e8ef284eb 100644 --- a/Documentation/virt/index.rst +++ b/Documentation/virt/index.rst @@ -14,6 +14,7 @@ Linux Virtualization Support ne_overview acrn/index coco/sev-guest + gunyah/index .. only:: html and subproject diff --git a/MAINTAINERS b/MAINTAINERS index 64379c699903..24d1660bbafa 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -8734,6 +8734,13 @@ L: linux-efi@vger.kernel.org S: Maintained F: block/partitions/efi.* +GUNYAH HYPERVISOR DRIVER +M: Elliot Berman +M: Murali Nalajala +L: linux-arm-msm@vger.kernel.org +S: Supported +F: Documentation/virt/gunyah/ + HABANALABS PCI DRIVER M: Oded Gabbay S: Supported