Re: [PATCH v6 21/21] docs: gunyah: Document Gunyah VM Manager
From: Bagas Sanjaya <hidden>
Date: 2022-11-02 13:05:18
Also in:
linux-arm-msm, linux-devicetree, linux-doc, lkml
Subsystem:
documentation, the rest · Maintainers:
Jonathan Corbet, Linus Torvalds
On Wed, Oct 26, 2022 at 11:58:46AM -0700, Elliot Berman wrote:
quoted hunk ↗ jump to hunk
diff --git a/Documentation/virt/gunyah/vm-manager.rst b/Documentation/virt/gunyah/vm-manager.rst new file mode 100644 index 000000000000..c232ba05de7e --- /dev/null +++ b/Documentation/virt/gunyah/vm-manager.rst@@ -0,0 +1,94 @@ +.. SPDX-License-Identifier: GPL-2.0 + +======================= +Virtual Machine Manager +======================= + +The Gunyah Virtual Machine Manager is a Linux driver to support launching virtual machines. + +Summary +======= + +Gunyah VMM presently supports launching non-proxy scheduled Linux-like virtual machines. + +Sample Userspace VMM +==================== + +A sample userspace VMM is included in samples/gunyah/ along with a sample minimal devicetree +that can be used to launch a Linux-like virtual machine under Gunyah. To build this sample, enable +CONFIG_SAMPLE_GUNYAH. + +IOCTLs and userspace VMM flows +============================== + +The kernel exposes a char device interface at /dev/gunyah. + +To create a VM, use the GH_CREATE_VM ioctl. A successful call will return a "Gunyah VM" file descriptor. + +/dev/gunyah API Descriptions +---------------------------- + +GH_CREATE_VM +~~~~~~~~~~~~ + +Creates a Gunyah VM. The argument is reserved for future use and must be 0. + +Gunyah VM API Descriptions +-------------------------- + +GH_VM_SET_USER_MEM_REGION +~~~~~~~~~~~~~~~~~~~~~~~~~ + +:: + + struct gh_userspace_memory_region { + __u32 label; + __u32 flags; + __u64 guest_phys_addr; + __u64 memory_size; + __u64 userspace_addr; + }; + +This ioctl allows the user to create or delete a memory parcel for a guest +virtual machine. Each memory region is uniquely identified by a label; +attempting to create two memory regions with the same label is not allowed. + +While VMM is guest-agnostic and allows runtime addition of memory regions, +Linux guest virtual machines do not support accepting memory regions at runtime. +Thus, memory regions should be provided before starting the VM and the VM +configured to accept those memory regions at boot-up. + +The guest physical address is used by Linux to check the requested user regions +do not overlap and to help find a corresponding memory region for calls like +GH_VM_SET_DTB_CONFIG. + +To delete a memory region, call GH_VM_SET_USER_MEM_REGION with label set to the +memory region of interest and memory_size set to 0. + +The flags field of gh_userspace_memory_region can set the following bits. All +other bits must be 0 and are reserved for future use. The ioctl will return +-EINVAL if an unsupported bit is detected. + + - GH_MEM_ALLOW_READ/GH_MEM_ALLOW_WRITE/GH_MEM_ALLOW_EXEC sets read/write/exec permissions + for the guest, respectively. + + - GH_MEM_LENT means that the memory will be unmapped from the host and be unaccessible by + the host while the guest has the region. + +GH_VM_SET_DTB_CONFIG +~~~~~~~~~~~~~~~~~~~~ + +:: + + struct gh_vm_dtb_config { + __u64 gpa; + __u64 size; + }; + +This ioctl sets the location of the VM's devicetree blob and is used by Gunyah +Resource Manager to allocate resources. + +GH_VM_START +~~~~~~~~~~~ + +This ioctl starts the virtual machine.
I think the wording can be better: ---- >8 ----
diff --git a/Documentation/virt/gunyah/vm-manager.rst b/Documentation/virt/gunyah/vm-manager.rst
index c232ba05de7e96..772fd970b91d7e 100644
--- a/Documentation/virt/gunyah/vm-manager.rst
+++ b/Documentation/virt/gunyah/vm-manager.rst@@ -4,18 +4,15 @@ Virtual Machine Manager ======================= -The Gunyah Virtual Machine Manager is a Linux driver to support launching virtual machines. - -Summary -======= - -Gunyah VMM presently supports launching non-proxy scheduled Linux-like virtual machines. +The Gunyah Virtual Machine Manager is a Linux driver for launching virtual +machines using Gunyah. It presently supports launching non-proxy scheduled +Linux-like virtual machines. Sample Userspace VMM ==================== -A sample userspace VMM is included in samples/gunyah/ along with a sample minimal devicetree -that can be used to launch a Linux-like virtual machine under Gunyah. To build this sample, enable +A sample userspace VMM is included in samples/gunyah/ along with a minimal +devicetree that can be used to launch a VM. To build this sample, enable CONFIG_SAMPLE_GUNYAH. IOCTLs and userspace VMM flows
@@ -23,7 +20,8 @@ IOCTLs and userspace VMM flows The kernel exposes a char device interface at /dev/gunyah. -To create a VM, use the GH_CREATE_VM ioctl. A successful call will return a "Gunyah VM" file descriptor. +To create a VM, use the GH_CREATE_VM ioctl. A successful call will return a +"Gunyah VM" file descriptor. /dev/gunyah API Descriptions ----------------------------
@@ -51,29 +49,28 @@ GH_VM_SET_USER_MEM_REGION This ioctl allows the user to create or delete a memory parcel for a guest virtual machine. Each memory region is uniquely identified by a label; -attempting to create two memory regions with the same label is not allowed. +attempting to create two regions with the same label is not allowed. While VMM is guest-agnostic and allows runtime addition of memory regions, Linux guest virtual machines do not support accepting memory regions at runtime. -Thus, memory regions should be provided before starting the VM and the VM -configured to accept those memory regions at boot-up. +Thus, memory regions should be provided before starting the VM and the VM must +be configured to accept these at boot-up. -The guest physical address is used by Linux to check the requested user regions -do not overlap and to help find a corresponding memory region for calls like -GH_VM_SET_DTB_CONFIG. +The guest physical address is used by Linux kernel to check that the requested +user regions do not overlap and to help find the corresponding memory region +for calls like GH_VM_SET_DTB_CONFIG. To delete a memory region, call GH_VM_SET_USER_MEM_REGION with label set to the -memory region of interest and memory_size set to 0. +desired region and memory_size set to 0. -The flags field of gh_userspace_memory_region can set the following bits. All +The flags field of gh_userspace_memory_region accepts the following bits. All other bits must be 0 and are reserved for future use. The ioctl will return -EINVAL if an unsupported bit is detected. - - GH_MEM_ALLOW_READ/GH_MEM_ALLOW_WRITE/GH_MEM_ALLOW_EXEC sets read/write/exec permissions - for the guest, respectively. - - - GH_MEM_LENT means that the memory will be unmapped from the host and be unaccessible by - the host while the guest has the region. + - GH_MEM_ALLOW_READ/GH_MEM_ALLOW_WRITE/GH_MEM_ALLOW_EXEC sets read/write/exec + permissions for the guest, respectively. + - GH_MEM_LENT means that the memory will be unmapped from the host and be + unaccessible by the host while the guest has the region. GH_VM_SET_DTB_CONFIG ~~~~~~~~~~~~~~~~~~~~
@@ -91,4 +88,4 @@ Resource Manager to allocate resources. GH_VM_START ~~~~~~~~~~~ -This ioctl starts the virtual machine. +This ioctl starts the VM.
Thanks. -- An old man doll... just what I always wanted! - Clara