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

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On 11/2/2022 6:05 AM, Bagas Sanjaya wrote:
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.

One side question -- before, you asked that I add newline between the list entries. Here, you've removed them. When do I need the extra newline vs not?

https://lore.kernel.org/all/YzUUaIx+azyzFDNX@xxxxxxxxx/

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.


Thanks for reviewing and providing all the suggestions. I've applied all of them.






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