Re: [PATCH v2 3/3] qom: Link multiple numa nodes to device using a new object

[Alex Williamson]

On Mon, 9 Oct 2023 13:30:48 +0100
Jonathan Cameron <Jonathan.Cameron@Huawei.com> wrote:

> On Sun, 8 Oct 2023 01:47:40 +0530
> <ankita@nvidia.com> wrote:
> 
> > 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 GI 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.
> > 
> > Introducing a new nvidia-acpi-generic-initiator object, which inherits from
> > the generic acpi-generic-initiator object to allow a BDF to be associated 
> > with
> > more than 1 nodes.
> > 
> > An admin can provide the range of nodes using numa-node-start and
> > numa-node-count and link it to a device by providing its id. 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 
> > nvidia-acpi-generic-initiator,id=gi0,device=dev0,numa-node-start=2,numa-node-count=8
> >  \  
> 
> If you go this way, use an array of references to the numa nodes instead of a 
> start and number.
> There is no obvious reason why they should be contiguous that I can see.

Yup, I was looking for other places we allow a list syntax, I only
found fds=a:b:...:z, which is also used for vhostfds=.  I didn't find a
property beyond the string type to hold this though.

> I think it is simpler the other way around though - so have the numa nodes 
> point at the
> vfio-pci-nohotplug device. 

Do you have a syntax you'd propose for this?  I'm having trouble seeing
how it makes things simpler.  Thanks,

Alex

> > [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         | 61 ++++++++++++++++++++++++
> >  include/hw/acpi/acpi-generic-initiator.h | 12 +++++
> >  qapi/qom.json                            | 24 +++++++++-
> >  3 files changed, 95 insertions(+), 2 deletions(-)
> > 
> > diff --git a/hw/acpi/acpi-generic-initiator.c 
> > b/hw/acpi/acpi-generic-initiator.c
> > index 1ae79639be..8ef887c3a4 100644
> > --- a/hw/acpi/acpi-generic-initiator.c
> > +++ b/hw/acpi/acpi-generic-initiator.c
> > @@ -150,3 +150,64 @@ void build_srat_generic_initiator(GArray *table_data)
> >      }
> >      g_slist_free(list);
> >  }
> > +
> > +static void
> > +nvidia_acpi_generic_initiator_set_node_start(Object *obj, Visitor *v,
> > +                                             const char *name, void 
> > *opaque,
> > +                                             Error **errp)
> > +{
> > +    AcpiGenericInitiator *gi = ACPI_GENERIC_INITIATOR(obj);
> > +    uint32_t value;
> > +
> > +    if (!visit_type_uint32(v, name, &value, errp)) {
> > +        return;
> > +    }
> > +
> > +    if (value >= MAX_NODES) {
> > +        return;
> > +    }
> > +
> > +    gi->node = value;
> > +}
> > +
> > +static void
> > +nvidia_acpi_generic_initiator_set_node_count(Object *obj, Visitor *v,
> > +                                             const char *name, void 
> > *opaque,
> > +                                             Error **errp)
> > +{
> > +    AcpiGenericInitiator *gi = ACPI_GENERIC_INITIATOR(obj);
> > +    uint32_t value;
> > +
> > +    if (!visit_type_uint32(v, name, &value, errp)) {
> > +        return;
> > +    }
> > +
> > +    gi->node_count = value;
> > +}
> > +
> > +static void nvidia_acpi_generic_initiator_class_init(ObjectClass *oc, void 
> > *data)
> > +{
> > +    object_class_property_add(oc, 
> > NVIDIA_ACPI_GENERIC_INITIATOR_NODE_START_PROP,
> > +                              "uint32", NULL,
> > +                              nvidia_acpi_generic_initiator_set_node_start,
> > +                              NULL, NULL);
> > +    object_class_property_add(oc, 
> > NVIDIA_ACPI_GENERIC_INITIATOR_NODE_COUNT_PROP,
> > +                              "uint32", NULL,
> > +                              nvidia_acpi_generic_initiator_set_node_count,
> > +                              NULL, NULL);
> > +}
> > +
> > +static const TypeInfo nvidia_acpi_generic_initiator_info = {
> > +    .parent = TYPE_ACPI_GENERIC_INITIATOR,
> > +    .name = TYPE_NVIDIA_ACPI_GENERIC_INITIATOR,
> > +    .instance_size = sizeof(NvidiaAcpiGenericInitiator),
> > +    .class_size = sizeof(NvidiaAcpiGenericInitiatorClass),
> > +    .class_init = nvidia_acpi_generic_initiator_class_init,
> > +};
> > +
> > +static void
> > +nvidia_acpi_generic_initiator_register_types(void)
> > +{
> > +    type_register_static(&nvidia_acpi_generic_initiator_info);
> > +}
> > +type_init(nvidia_acpi_generic_initiator_register_types);
> > diff --git a/include/hw/acpi/acpi-generic-initiator.h 
> > b/include/hw/acpi/acpi-generic-initiator.h
> > index e8e2670309..3e4cf42064 100644
> > --- a/include/hw/acpi/acpi-generic-initiator.h
> > +++ b/include/hw/acpi/acpi-generic-initiator.h
> > @@ -9,10 +9,14 @@
> >  #include "qom/object_interfaces.h"
> >  
> >  #define TYPE_ACPI_GENERIC_INITIATOR "acpi-generic-initiator"
> > +#define TYPE_NVIDIA_ACPI_GENERIC_INITIATOR "nvidia-acpi-generic-initiator"
> >  
> >  #define ACPI_GENERIC_INITIATOR_DEVICE_PROP "device"
> >  #define ACPI_GENERIC_INITIATOR_NODE_PROP "node"
> >  
> > +#define NVIDIA_ACPI_GENERIC_INITIATOR_NODE_START_PROP "numa-node-start"
> > +#define NVIDIA_ACPI_GENERIC_INITIATOR_NODE_COUNT_PROP "numa-node-count"
> > +
> >  typedef struct AcpiGenericInitiator {
> >      /* private */
> >      Object parent;
> > @@ -47,6 +51,14 @@ typedef struct PCIDeviceHandle {
> >      uint64_t res1;
> >  } PCIDeviceHandle;
> >  
> > +typedef struct NvidiaAcpiGenericInitiator {
> > +    AcpiGenericInitiator parent;
> > +} NvidiaAcpiGenericInitiator;
> > +
> > +typedef struct NvidiaAcpiGenericInitiatorClass {
> > +        AcpiGenericInitiatorClass parent_class;
> > +} NvidiaAcpiGenericInitiatorClass;
> > +
> >  void build_srat_generic_initiator(GArray *table_data);
> >  
> >  #endif
> > diff --git a/qapi/qom.json b/qapi/qom.json
> > index 86c87a161c..c29ad1388d 100644
> > --- a/qapi/qom.json
> > +++ b/qapi/qom.json
> > @@ -793,6 +793,24 @@
> >  { 'struct': 'AcpiGenericInitiatorProperties',
> >    'data': { 'device': 'str', 'node': 'uint32' } }
> >  
> > +##
> > +# @NvidiaAcpiGenericInitiatorProperties:
> > +#
> > +# Properties for nvidia-acpi-generic-initiator objects.
> > +#
> > +# @device: the ID of the device to be associated with the nodes
> > +#
> > +# @numa-node-start: the ID of the numa node
> > +#
> > +# @numa-node-count: count of the numa nodes assocuated with the device
> > +#
> > +# Since: 8.0
> > +##
> > +{ 'struct': 'NvidiaAcpiGenericInitiatorProperties',
> > +  'data': { 'device': 'str',
> > +            'numa-node-start': 'uint32',
> > +            'numa-node-count': 'uint32' } }
> > +
> >  ##
> >  # @RngProperties:
> >  #
> > @@ -962,7 +980,8 @@
> >      'tls-cipher-suites',
> >      { 'name': 'x-remote-object', 'features': [ 'unstable' ] },
> >      { 'name': 'x-vfio-user-server', 'features': [ 'unstable' ] },
> > -    'acpi-generic-initiator'
> > +    'acpi-generic-initiator',
> > +    'nvidia-acpi-generic-initiator'
> >    ] }
> >  
> >  ##
> > @@ -1030,7 +1049,8 @@
> >        'tls-cipher-suites':          'TlsCredsProperties',
> >        'x-remote-object':            'RemoteObjectProperties',
> >        'x-vfio-user-server':         'VfioUserServerProperties',
> > -      'acpi-generic-initiator':     'AcpiGenericInitiatorProperties'
> > +      'acpi-generic-initiator':     'AcpiGenericInitiatorProperties',
> > +      'nvidia-acpi-generic-initiator':     
> > 'NvidiaAcpiGenericInitiatorProperties'
> >    } }
> >  
> >  ##  
>