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[v4,2/2] docs/designs/launch: Hyperlaunch device tree

Message ID 20210514034101.3683-3-christopher.w.clark@gmail.com (mailing list archive)
State New
Headers show
Series Introducing Hyperlaunch capability design (formerly: DomB mode of dom0less) | expand

Commit Message

Christopher Clark May 14, 2021, 3:41 a.m. UTC
From: "Daniel P. Smith" <dpsmith@apertussolutions.com>

Adds a design document for Hyperlaunch device tree structure.

Signed-off-by: Christopher Clark <christopher.clark@starlab.io>
Signed-off by: Daniel P. Smith <dpsmith@apertussolutions.com>
---
 .../designs/launch/hyperlaunch-devicetree.rst | 343 ++++++++++++++++++
 1 file changed, 343 insertions(+)
 create mode 100644 docs/designs/launch/hyperlaunch-devicetree.rst
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diff --git a/docs/designs/launch/hyperlaunch-devicetree.rst b/docs/designs/launch/hyperlaunch-devicetree.rst
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+-------------------------------------
+Xen Hyperlaunch Device Tree Bindings
+-------------------------------------
+
+The Xen Hyperlaunch device tree adopts the dom0less device tree structure and
+extends it to meet the requirements for the Hyperlaunch capability. The primary
+difference is the introduction of the ``hypervisor`` node that is under the
+``/chosen`` node. The move to a dedicated node was driven by:
+
+1. Reduces the need to walk over nodes that are not of interest, e.g. only
+   nodes of interest should be in ``/chosen/hypervisor``
+
+2. Allows for the domain construction information to easily be sanitized by
+   simple removing the ``/chosen/hypervisor`` node.
+
+Example Configuration
+---------------------
+
+Below are two example device tree definitions for the hypervisor node. The
+first is an example of a multiboot-based configuration for x86 and the second
+is a module-based configuration for Arm.
+
+Multiboot x86 Configuration:
+""""""""""""""""""""""""""""
+
+::
+
+    hypervisor {
+        #address-cells = <1>;
+        #size-cells = <0>;
+        compatible = “hypervisor,xen”
+ 
+        // Configuration container
+        config {
+            compatible = "xen,config";
+ 
+            module {
+                compatible = "module,microcode", "multiboot,module";
+                mb-index = <1>;
+            };
+ 
+            module {
+                compatible = "module,xsm-policy", "multiboot,module";
+                mb-index = <2>;
+            };
+        };
+ 
+        // Boot Domain definition
+        domain {
+            compatible = "xen,domain";
+ 
+            domid = <0x7FF5>;
+ 
+            // FUNCTION_NONE            (0)
+            // FUNCTION_BOOT            (1 << 0)
+            // FUNCTION_CRASH           (1 << 1)
+            // FUNCTION_CONSOLE         (1 << 2)
+            // FUNCTION_XENSTORE        (1 << 30)
+            // FUNCTION_LEGACY_DOM0     (1 << 31)
+            functions = <0x00000001>;
+ 
+            memory = <0x0 0x20000>;
+            cpus = <1>;
+            module {
+                compatible = "module,kernel", "multiboot,module";
+                mb-index = <3>;
+            };
+ 
+            module {
+                compatible = "module,ramdisk", "multiboot,module";
+                mb-index = <4>;
+            };
+            module {
+                compatible = "module,config", "multiboot,module";
+                mb-index = <5>;
+            };
+ 
+        // Classic Dom0 definition
+        domain {
+            compatible = "xen,domain";
+ 
+            domid = <0>;
+ 
+            // PERMISSION_NONE          (0)
+            // PERMISSION_CONTROL       (1 << 0)
+            // PERMISSION_HARDWARE      (1 << 1)
+            permissions = <3>;
+ 
+            // FUNCTION_NONE            (0)
+            // FUNCTION_BOOT            (1 << 0)
+            // FUNCTION_CRASH           (1 << 1)
+            // FUNCTION_CONSOLE         (1 << 2)
+            // FUNCTION_XENSTORE        (1 << 30)
+            // FUNCTION_LEGACY_DOM0     (1 << 31)
+            functions = <0xC0000006>;
+ 
+            // MODE_PARAVIRTUALIZED     (1 << 0) /* PV | PVH/HVM */
+            // MODE_ENABLE_DEVICE_MODEL (1 << 1) /* HVM | PVH */
+            // MODE_LONG                (1 << 2) /* 64 BIT | 32 BIT */
+            mode = <5>; /* 64 BIT, PV */
+ 
+            // UUID
+            domain-uuid = [B3 FB 98 FB 8F 9F 67 A3];
+ 
+            cpus = <1>;
+            memory = <0x0 0x20000>;
+            security-id = “dom0_t;
+ 
+            module {
+                compatible = "module,kernel", "multiboot,module";
+                mb-index = <6>;
+                bootargs = "console=hvc0";
+            };
+            module {
+                compatible = "module,ramdisk", "multiboot,module";
+                mb-index = <7>;
+            };
+    };
+
+The multiboot modules supplied when using the above config would be, in order:
+
+* (the above config, compiled)
+* CPU microcode
+* XSM policy
+* kernel for boot domain
+* ramdisk for boot domain
+* boot domain configuration file
+* kernel for the classic dom0 domain
+* ramdisk for the classic dom0 domain
+
+Module Arm Configuration:
+"""""""""""""""""""""""""
+
+::
+
+    hypervisor {
+        compatible = “hypervisor,xen”
+ 
+        // Configuration container
+        config {
+            compatible = "xen,config";
+ 
+            module {
+                compatible = "module,microcode”;
+                module-addr = <0x0000ff00 0x80>;
+            };
+ 
+            module {
+                compatible = "module,xsm-policy";
+                module-addr = <0x0000ff00 0x80>;
+ 
+            };
+        };
+ 
+        // Boot Domain definition
+        domain {
+            compatible = "xen,domain";
+ 
+            domid = <0x7FF5>;
+ 
+            // FUNCTION_NONE            (0)
+            // FUNCTION_BOOT            (1 << 0)
+            // FUNCTION_CRASH           (1 << 1)
+            // FUNCTION_CONSOLE         (1 << 2)
+            // FUNCTION_XENSTORE        (1 << 30)
+            // FUNCTION_LEGACY_DOM0     (1 << 31)
+            functions = <0x00000001>;
+ 
+            memory = <0x0 0x20000>;
+            cpus = <1>;
+            module {
+                compatible = "module,kernel";
+                module-addr = <0x0000ff00 0x80>;
+            };
+ 
+            module {
+                compatible = "module,ramdisk";
+                module-addr = <0x0000ff00 0x80>;
+            };
+            module {
+                compatible = "module,config";
+                module-addr = <0x0000ff00 0x80>;
+            };
+ 
+        // Classic Dom0 definition
+        domain@0 {
+            compatible = "xen,domain";
+ 
+            domid = <0>;
+ 
+            // PERMISSION_NONE          (0)
+            // PERMISSION_CONTROL       (1 << 0)
+            // PERMISSION_HARDWARE      (1 << 1)
+            permissions = <3>;
+ 
+            // FUNCTION_NONE            (0)
+            // FUNCTION_BOOT            (1 << 0)
+            // FUNCTION_CRASH           (1 << 1)
+            // FUNCTION_CONSOLE         (1 << 2)
+            // FUNCTION_XENSTORE        (1 << 30)
+            // FUNCTION_LEGACY_DOM0     (1 << 31)
+            functions = <0xC0000006>;
+ 
+            // MODE_PARAVIRTUALIZED     (1 << 0) /* PV | PVH/HVM */
+            // MODE_ENABLE_DEVICE_MODEL (1 << 1) /* HVM | PVH */
+            // MODE_LONG                (1 << 2) /* 64 BIT | 32 BIT */
+            mode = <5>; /* 64 BIT, PV */
+ 
+            // UUID
+            domain-uuid = [B3 FB 98 FB 8F 9F 67 A3];
+ 
+            cpus = <1>;
+            memory = <0x0 0x20000>;
+            security-id = “dom0_t”;
+ 
+            module {
+                compatible = "module,kernel";
+                module-addr = <0x0000ff00 0x80>;
+                bootargs = "console=hvc0";
+            };
+            module {
+                compatible = "module,ramdisk";
+                module-addr = <0x0000ff00 0x80>;
+            };
+    };
+
+The modules that would be supplied when using the above config would be:
+
+* (the above config, compiled into hardware tree)
+* CPU microcode
+* XSM policy
+* kernel for boot domain
+* ramdisk for boot domain
+* boot domain configuration file
+* kernel for the classic dom0 domain
+* ramdisk for the classic dom0 domain
+
+The hypervisor device tree would be compiled into the hardware device tree and
+provided to Xen using the standard method currently in use. The remaining
+modules would need to be loaded in the respective addresses specified in the
+`module-addr` property.
+
+
+The Hypervisor node
+-------------------
+
+The hypervisor node is a top level container for the domains that will be built
+by hypervisor on start up. On the ``hypervisor`` node the ``compatible``
+property is used to identify the type of hypervisor node present..
+
+compatible
+  Identifies the type of node. Required.
+
+The Config node
+---------------
+
+A config node is for detailing any modules that are of interest to Xen itself.
+For example this would be where Xen would be informed of microcode or XSM
+policy locations. If the modules are multiboot modules and are able to be
+located by index within the module chain, the ``mb-index`` property should be
+used to specify the index in the multiboot module chain.. If the module will be
+located by physical memory address, then the ``module-addr`` property should be
+used to identify the location and size of the module.
+
+compatible
+  Identifies the type of node. Required.
+
+The Domain node
+---------------
+
+A domain node is for describing the construction of a domain. It may provide a
+domid property which will be used as the requested domain id for the domain
+with a value of “0” signifying to use the next available domain id, which is
+the default behavior if omitted. A domain configuration is not able to request
+a domid of “0”. After that a domain node may have any of the following
+parameters,
+
+compatible
+  Identifies the type of node. Required.
+
+domid
+  Identifies the domid requested to assign to the domain. Required.
+
+permissions
+  This sets what Discretionary Access Control permissions 
+  a domain is assigned. Optional, default is none.
+
+functions
+  This identifies what system functions a domain will fulfill.
+  Optional, the default is none.
+
+.. note::  The `functions` bits that have been selected to indicate
+   ``FUNCTION_XENSTORE`` and ``FUNCTION_LEGACY_DOM0`` are the last two bits
+   (30, 31) such that should these features ever be fully retired, the flags may
+   be dropped without leaving a gap in the flag set.
+
+mode
+  The mode the domain will be executed under. Required.
+
+domain-uuid
+  A globally unique identifier for the domain. Optional,
+  the default is NULL.
+
+cpus
+  The number of vCPUs to be assigned to the domain. Optional,
+  the default is “1”.
+
+memory
+  The amount of memory to assign to the domain, in KBs.
+  Required.
+
+security-id
+  The security identity to be assigned to the domain when XSM
+  is the access control mechanism being used. Optional,
+  the default is “domu_t”.
+
+The Module node
+---------------
+
+This node describes a boot module loaded by the boot loader. The required
+compatible property follows the format: module,<type> where type can be
+“kernel”, “ramdisk”, “device-tree”, “microcode”, “xsm-policy” or “config”. In
+the case the module is a multiboot module, the additional property string
+“multiboot,module” may be present. One of two properties is required and
+identifies how to locate the module. They are the mb-index, used for multiboot
+modules, and the module-addr for memory address based location.
+
+compatible
+  This identifies what the module is and thus what the hypervisor
+  should use the module for during domain construction. Required.
+
+mb-index
+  This identifies the index for this module in the multiboot module chain.
+  Required for multiboot environments.
+
+module-addr
+  This identifies where in memory this module is located. Required for
+  non-multiboot environments.
+
+bootargs
+  This is used to provide the boot params to kernel modules.
+
+.. note::  The bootargs property is intended for situations where the same kernel multiboot module is used for more than one domain.