Re: [PATCH v3 1/2] qom: new object to associate device to numa node

[Markus Armbruster]

<ankita@nvidia.com> writes:

> From: Ankit Agrawal <ankita@nvidia.com>
>
> NVIDIA GPU's support MIG (Mult-Instance GPUs) feature [1], which allows
> partitioning of the GPU device resources (including device memory) into
> several (upto 8) isolated instances. Each of the partitioned memory needs
> a dedicated NUMA node to operate. The partitions are not fixed and they
> can be created/deleted at runtime.
>
> Unfortunately Linux OS does not provide a means to dynamically create/destroy
> NUMA nodes and such feature implementation is not expected to be trivial. The
> nodes that OS discovers at the boot time while parsing SRAT remains fixed. So
> we utilize the Generic Initiator Affinity structures that allows association
> between nodes and devices. Multiple GI structures per BDF is possible,
> allowing creation of multiple nodes by exposing unique PXM in each of these
> structures.
>
> Introduce a new acpi-generic-initiator object to allow host admin provide the
> device and the corresponding NUMA nodes. Qemu maintain this association and
> use this object to build the requisite GI Affinity Structure.
>
> An admin can provide the range of nodes using a ':' delimited numalist and

Please don't create special-purpose syntax, use existing general-purpose
syntax.  See also review of qom.json below.

> link it to a device by providing its id. The node ids are extracted from
> numalist and stores as a uint16List. The following sample creates 8 nodes
> and link them to the device dev0:
>
> -numa node,nodeid=2 \
> -numa node,nodeid=3 \
> -numa node,nodeid=4 \
> -numa node,nodeid=5 \
> -numa node,nodeid=6 \
> -numa node,nodeid=7 \
> -numa node,nodeid=8 \
> -numa node,nodeid=9 \
> -device 
> vfio-pci-nohotplug,host=0009:01:00.0,bus=pcie.0,addr=04.0,rombar=0,id=dev0 \
> -object acpi-generic-initiator,id=gi0,device=dev0,numalist=2:3:4:5:6:7:8:9 \
>
> [1] https://www.nvidia.com/en-in/technologies/multi-instance-gpu
>
> Signed-off-by: Ankit Agrawal <ankita@nvidia.com>
> ---
>  hw/acpi/acpi-generic-initiator.c         | 80 ++++++++++++++++++++++++
>  hw/acpi/meson.build                      |  1 +
>  include/hw/acpi/acpi-generic-initiator.h | 29 +++++++++
>  qapi/qom.json                            | 16 +++++
>  4 files changed, 126 insertions(+)
>  create mode 100644 hw/acpi/acpi-generic-initiator.c
>  create mode 100644 include/hw/acpi/acpi-generic-initiator.h
>
> diff --git a/hw/acpi/acpi-generic-initiator.c 
> b/hw/acpi/acpi-generic-initiator.c
> new file mode 100644
> index 0000000000..0699c878e2
> --- /dev/null
> +++ b/hw/acpi/acpi-generic-initiator.c
> @@ -0,0 +1,80 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (c) 2023, NVIDIA CORPORATION & AFFILIATES. All rights reserved
> + */
> +
> +#include "qemu/osdep.h"
> +#include "hw/qdev-properties.h"
> +#include "qapi/error.h"
> +#include "qapi/visitor.h"
> +#include "qom/object_interfaces.h"
> +#include "qom/object.h"
> +#include "hw/qdev-core.h"
> +#include "hw/vfio/vfio-common.h"
> +#include "hw/vfio/pci.h"
> +#include "hw/pci/pci_device.h"
> +#include "sysemu/numa.h"
> +#include "hw/acpi/acpi-generic-initiator.h"
> +
> +OBJECT_DEFINE_TYPE_WITH_INTERFACES(AcpiGenericInitiator, 
> acpi_generic_initiator,
> +                   ACPI_GENERIC_INITIATOR, OBJECT,
> +                   { TYPE_USER_CREATABLE },
> +                   { NULL })
> +
> +OBJECT_DECLARE_SIMPLE_TYPE(AcpiGenericInitiator, ACPI_GENERIC_INITIATOR)
> +
> +static void acpi_generic_initiator_init(Object *obj)
> +{
> +    AcpiGenericInitiator *gi = ACPI_GENERIC_INITIATOR(obj);
> +    gi->device = NULL;
> +    gi->nodelist = NULL;
> +}
> +
> +static void acpi_generic_initiator_finalize(Object *obj)
> +{
> +    AcpiGenericInitiator *gi = ACPI_GENERIC_INITIATOR(obj);
> +
> +    g_free(gi->device);
> +    qapi_free_uint16List(gi->nodelist);
> +}
> +
> +static void acpi_generic_initiator_set_device(Object *obj, const char *val,
> +                                              Error **errp)
> +{
> +    AcpiGenericInitiator *gi = ACPI_GENERIC_INITIATOR(obj);
> +
> +    gi->device = g_strdup(val);
> +}
> +
> +static void acpi_generic_initiator_set_nodelist(Object *obj, const char *val,
> +                                            Error **errp)
> +{
> +    AcpiGenericInitiator *gi = ACPI_GENERIC_INITIATOR(obj);
> +    char *value = g_strdup(val);
> +    uint16_t node;
> +    uint16List **tail = &(gi->nodelist);
> +    char *nodestr = value ? strtok(value, ":") : NULL;
> +
> +    while (nodestr) {
> +        if (sscanf(nodestr, "%hu", &node) != 1) {
> +            error_setg(errp, "failed to read node-id");
> +            return;
> +        }
> +
> +        if (node >= MAX_NODES) {
> +            error_setg(errp, "invalid node-id");
> +            return;
> +        }
> +
> +        QAPI_LIST_APPEND(tail, node);
> +        nodestr = strtok(NULL, ":");
> +    }
> +}
> +
> +static void acpi_generic_initiator_class_init(ObjectClass *oc, void *data)
> +{
> +    object_class_property_add_str(oc, ACPI_GENERIC_INITIATOR_DEVICE_PROP, 
> NULL,
> +                                  acpi_generic_initiator_set_device);
> +    object_class_property_add_str(oc, ACPI_GENERIC_INITIATOR_NODELIST_PROP,
> +                                  NULL, acpi_generic_initiator_set_nodelist);
> +}
> diff --git a/hw/acpi/meson.build b/hw/acpi/meson.build
> index fc1b952379..2268589519 100644
> --- a/hw/acpi/meson.build
> +++ b/hw/acpi/meson.build
> @@ -1,5 +1,6 @@
>  acpi_ss = ss.source_set()
>  acpi_ss.add(files(
> +  'acpi-generic-initiator.c',
>    'acpi_interface.c',
>    'aml-build.c',
>    'bios-linker-loader.c',
> diff --git a/include/hw/acpi/acpi-generic-initiator.h 
> b/include/hw/acpi/acpi-generic-initiator.h
> new file mode 100644
> index 0000000000..bb127b2541
> --- /dev/null
> +++ b/include/hw/acpi/acpi-generic-initiator.h
> @@ -0,0 +1,29 @@
> +#ifndef ACPI_GENERIC_INITIATOR_H
> +#define ACPI_GENERIC_INITIATOR_H
> +
> +#include "hw/mem/pc-dimm.h"
> +#include "hw/acpi/bios-linker-loader.h"
> +#include "qemu/uuid.h"
> +#include "hw/acpi/aml-build.h"
> +#include "qom/object.h"
> +#include "qom/object_interfaces.h"
> +
> +#define TYPE_ACPI_GENERIC_INITIATOR "acpi-generic-initiator"
> +
> +#define ACPI_GENERIC_INITIATOR_DEVICE_PROP "device"
> +#define ACPI_GENERIC_INITIATOR_NODELIST_PROP "nodelist"
> +
> +typedef struct AcpiGenericInitiator {
> +    /* private */
> +    Object parent;
> +
> +    /* public */
> +    char *device;
> +    uint16List *nodelist;
> +} AcpiGenericInitiator;
> +
> +typedef struct AcpiGenericInitiatorClass {
> +        ObjectClass parent_class;
> +} AcpiGenericInitiatorClass;
> +
> +#endif
> diff --git a/qapi/qom.json b/qapi/qom.json
> index fa3e88c8e6..66d2bffdcc 100644
> --- a/qapi/qom.json
> +++ b/qapi/qom.json
> @@ -779,6 +779,20 @@
>  { 'struct': 'VfioUserServerProperties',
>    'data': { 'socket': 'SocketAddress', 'device': 'str' } }
>  
> +##
> +# @AcpiGenericInitiatorProperties:
> +#
> +# Properties for acpi-generic-initiator objects.
> +#
> +# @device: the ID of the device to be associated with the node
> +#
> +# @nodelist: delimited numa node list
> +#
> +# Since: 8.2
> +##
> +{ 'struct': 'AcpiGenericInitiatorProperties',
> +  'data': { 'device': 'str', 'nodelist': 'str' } }

Do not encode structured data in strings.  Instead:

    'nodes': ['uint16']

This matches MemoryBackendProperties member @host-nodes.

Check out host_memory_backend_get_host_nodes() and
host_memory_backend_set_host_nodes() to see how to work with such a
member.

> +
>  ##
>  # @RngProperties:
>  #
> @@ -896,6 +910,7 @@
>  ##
>  { 'enum': 'ObjectType',
>    'data': [
> +    'acpi-generic-initiator',
>      'authz-list',
>      'authz-listfile',
>      'authz-pam',
> @@ -966,6 +981,7 @@
>              'id': 'str' },
>    'discriminator': 'qom-type',
>    'data': {
> +      'acpi-generic-initiator':     'AcpiGenericInitiatorProperties',
>        'authz-list':                 'AuthZListProperties',
>        'authz-listfile':             'AuthZListFileProperties',
>        'authz-pam':                  'AuthZPAMProperties',