On Wed, Sep 28, 2022 at 12:56:20PM -0700, Elliot Berman wrote: > diff --git a/Documentation/virt/gunyah/index.rst b/Documentation/virt/gunyah/index.rst > new file mode 100644 > index 000000000000..959f451caccd > --- /dev/null > +++ b/Documentation/virt/gunyah/index.rst > @@ -0,0 +1,114 @@ > +.. 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_resource. > + > +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. The documentation LGTM. > 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 > <snipped>... > +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. > + The nested list above should be separated with blank lines to be rendered properly: ---- >8 ---- diff --git a/Documentation/virt/gunyah/message-queue.rst b/Documentation/virt/gunyah/message-queue.rst index e130f124ed525a..afaad99db215e6 100644 --- a/Documentation/virt/gunyah/message-queue.rst +++ b/Documentation/virt/gunyah/message-queue.rst @@ -20,9 +20,11 @@ queue 2 allows VM_B to send messages to VM_A. 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 Thanks. -- An old man doll... just what I always wanted! - Clara
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