Re: [PATCH v6 21/21] docs: gunyah: Document Gunyah VM Manager

[Bagas Sanjaya]

On Wed, Oct 26, 2022 at 11:58:46AM -0700, Elliot Berman wrote:
> 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

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