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Date:   Wed, 2 Nov 2022 20:05:07 +0700
From:   Bagas Sanjaya <bagasdotme@gmail.com>
To:     Elliot Berman <quic_eberman@quicinc.com>
Cc:     Bjorn Andersson <quic_bjorande@quicinc.com>,
        Jonathan Corbet <corbet@lwn.net>,
        Murali Nalajala <quic_mnalajal@quicinc.com>,
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        Andy Gross <agross@kernel.org>,
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        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
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        Amol Maheshwari <amahesh@qti.qualcomm.com>,
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        linux-doc@vger.kernel.org, linux-arm-msm@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v6 21/21] docs: gunyah: Document Gunyah VM Manager
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On Wed, Oct 26, 2022 at 11:58:46AM -0700, Elliot Berman wrote:
> diff --git a/Documentation/virt/gunyah/vm-manager.rst b/Documentation/vir=
t/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
> +
> +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> +Virtual Machine Manager
> +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> +
> +The Gunyah Virtual Machine Manager is a Linux driver to support launchin=
g virtual machines.
> +
> +Summary
> +=3D=3D=3D=3D=3D=3D=3D
> +
> +Gunyah VMM presently supports launching non-proxy scheduled Linux-like v=
irtual machines.
> +
> +Sample Userspace VMM
> +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> +
> +A sample userspace VMM is included in samples/gunyah/ along with a sampl=
e 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
> +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D
> +
> +The kernel exposes a char device interface at /dev/gunyah.
> +
> +To create a VM, use the GH_CREATE_VM ioctl. A successful call will retur=
n 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 gue=
st
> +virtual machine. Each memory region is uniquely identified by a label;
> +attempting to create two memory regions with the same label is not allow=
ed.
> +
> +While VMM is guest-agnostic and allows runtime addition of memory region=
s,
> +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=
=2E All
> +other bits must be 0 and are reserved for future use. The ioctl will ret=
urn
> +-EINVAL if an unsupported bit is detected.
> +
> +  - GH_MEM_ALLOW_READ/GH_MEM_ALLOW_WRITE/GH_MEM_ALLOW_EXEC sets read/wri=
te/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
 =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
=20
-The Gunyah Virtual Machine Manager is a Linux driver to support launching =
virtual machines.
-
-Summary
-=3D=3D=3D=3D=3D=3D=3D
-
-Gunyah VMM presently supports launching non-proxy scheduled Linux-like vir=
tual 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.
=20
 Sample Userspace VMM
 =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
=20
-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 b=
uild 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.
=20
 IOCTLs and userspace VMM flows
@@ -23,7 +20,8 @@ IOCTLs and userspace VMM flows
=20
 The kernel exposes a char device interface at /dev/gunyah.
=20
-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.
=20
 /dev/gunyah API Descriptions
 ----------------------------
@@ -51,29 +49,28 @@ GH_VM_SET_USER_MEM_REGION
=20
 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.
=20
 While VMM is guest-agnostic and allows runtime addition of memory regions,
 Linux guest virtual machines do not support accepting memory regions at ru=
ntime.
-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.
=20
-The guest physical address is used by Linux to check the requested user re=
gions
-do not overlap and to help find a corresponding memory region for calls li=
ke
-GH_VM_SET_DTB_CONFIG.
+The guest physical address is used by Linux kernel to check that the reque=
sted
+user regions do not overlap and to help find the corresponding memory regi=
on
+for calls like GH_VM_SET_DTB_CONFIG.
=20
 To delete a memory region, call GH_VM_SET_USER_MEM_REGION with label set t=
o the
-memory region of interest and memory_size set to 0.
+desired region and memory_size set to 0.
=20
-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.
=20
-  - 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 b=
e 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.
=20
 GH_VM_SET_DTB_CONFIG
 ~~~~~~~~~~~~~~~~~~~~
@@ -91,4 +88,4 @@ Resource Manager to allocate resources.
 GH_VM_START
 ~~~~~~~~~~~
=20
-This ioctl starts the virtual machine.
+This ioctl starts the VM.

Thanks.=20

--=20
An old man doll... just what I always wanted! - Clara

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