Re: [PATCH v7 09/12] hw/cxl/events: Add qmp interfaces to add/release dynamic capacity extents

[Jonathan Cameron via <qemu-devel@nongnu.org>]

On Tue, 21 May 2024 16:32:52 -0700
fan <nifan.cxl@gmail.com> wrote:

> From 9d6d774ec973d22c0f662b32385345a88b14cc55 Mon Sep 17 00:00:00 2001
> From: Fan Ni <fan.ni@samsung.com>
> Date: Tue, 20 Feb 2024 09:48:31 -0800
> Subject: [PATCH 11/14] hw/cxl/events: Add qmp interfaces to add/release
>  dynamic capacity extents
> 
> To simulate FM functionalities for initiating Dynamic Capacity Add
> (Opcode 5604h) and Dynamic Capacity Release (Opcode 5605h) as in CXL spec
> r3.1 7.6.7.6.5 and 7.6.7.6.6, we implemented two QMP interfaces to issue
> add/release dynamic capacity extents requests.
> 
> With the change, we allow to release an extent only when its DPA range
> is contained by a single accepted extent in the device. That is to say,
> extent superset release is not supported yet.
> 
> 1. Add dynamic capacity extents:
> 
> For example, the command to add two continuous extents (each 128MiB long)
> to region 0 (starting at DPA offset 0) looks like below:
> 
> { "execute": "qmp_capabilities" }
> 
> { "execute": "cxl-add-dynamic-capacity",
>   "arguments": {
>       "path": "/machine/peripheral/cxl-dcd0",
>       "host-id": 0,
>       "selection-policy": "prescriptive",
>       "region": 0,
>       "tag": "",
As below, should we make the tag optional? (prefix it with * and
the callback will gain a has_x bool.)
>       "extents": [
>       {
>           "offset": 0,
>           "len": 134217728
>       },
>       {
>           "offset": 134217728,
>           "len": 134217728
>       }
>       ]
>   }
> }
> 
> 2. Release dynamic capacity extents:
> 
> For example, the command to release an extent of size 128MiB from region 0
> (DPA offset 128MiB) looks like below:
> 
> { "execute": "cxl-release-dynamic-capacity",
>   "arguments": {
>       "path": "/machine/peripheral/cxl-dcd0",
>       "host-id": 0,
>       "removal-policy":"prescriptive",
>       "forced-removal": false,
>       "sanitize-on-release": false,
>       "region": 0,
>       "tag": "",
This suggests to me we should use some optional parameters with
sensible defaults (off and not present) for
tag, sanitize-on-release and forced-removal.


>       "extents": [
>       {
>           "offset": 134217728,
>           "len": 134217728
>       }
>       ]
>   }
> }


> diff --git a/qapi/cxl.json b/qapi/cxl.json
> index 4281726dec..a3a900eb2e 100644
> --- a/qapi/cxl.json
> +++ b/qapi/cxl.json
> @@ -361,3 +361,146 @@
>  ##
>  {'command': 'cxl-inject-correctable-error',
>   'data': {'path': 'str', 'type': 'CxlCorErrorType'}}
> +
> +##
> +# @CXLDynamicCapacityExtent:
> +#
> +# A single dynamic capacity extent
> +#
> +# @offset: The offset (in bytes) to the start of the region
> +#     where the extent belongs to.
> +#
> +# @len: The length of the extent in bytes.
> +#
> +# Since: 9.1
> +##
> +{ 'struct': 'CXLDynamicCapacityExtent',
> +  'data': {
> +      'offset':'uint64',
> +      'len': 'uint64'
> +  }
> +}
> +
> +##
> +# @CXLExtSelPolicy:
> +#
> +# The policy to use for selecting which extents comprise the added
> +# capacity, as defined in cxl spec r3.1 Table 7-70.
> +#
> +# @free: 0h = Free
> +#
> +# @contiguous: 1h = Continuous
> +#
> +# @prescriptive: 2h = Prescriptive
> +#
> +# @enable-shared-access: 3h = Enable Shared Access
> +#
> +# Since: 9.1
> +##
> +{ 'enum': 'CXLExtSelPolicy',
> +  'data': ['free',
> +           'contiguous',
> +           'prescriptive',
> +           'enable-shared-access']
> +}
> +
> +##
> +# @cxl-add-dynamic-capacity:
> +#
> +# Command to initiate to add dynamic capacity extents to a host.  It
> +# simulates operations defined in cxl spec r3.1 7.6.7.6.5.
> +#
> +# @path: CXL DCD canonical QOM path.
> +#
> +# @host-id: The "Host ID" field as defined in cxl spec r3.1
> +#     Table 7-70.
> +#
> +# @selection-policy: The "Selection Policy" bits as defined in
> +#     cxl spec r3.1 Table 7-70.  It specifies the policy to use for
> +#     selecting which extents comprise the added capacity.
> +#
> +# @region: The "Region Number" field as defined in cxl spec r3.1
> +#     Table 7-70.  The dynamic capacity region where the capacity
> +#     is being added.  Valid range is from 0-7.
> +#
> +# @tag: The "Tag" field as defined in cxl spec r3.1 Table 7-70.
> +#
> +# @extents: The "Extent List" field as defined in cxl spec r3.1
> +#     Table 7-70.
> +#
> +# Since : 9.1
> +##
> +{ 'command': 'cxl-add-dynamic-capacity',
> +  'data': { 'path': 'str',
> +            'host-id': 'uint16',
> +            'selection-policy': 'CXLExtSelPolicy',
> +            'region': 'uint8',
> +            'tag': 'str',
> +            'extents': [ 'CXLDynamicCapacityExtent' ]
> +           }
> +}
> +
> +##
> +# @CXLExtRemovalPolicy:
> +#
> +# The policy to use for selecting which extents comprise the released
> +# capacity, defined in the "Flags" field in cxl spec r3.1 Table 7-71.
> +#
> +# @tag-based: value = 0h.  Extents are selected by the device based
> +#     on tag, with no requirement for contiguous extents.
> +#
> +# @prescriptive: value = 1h.  Extent list of capacity to release is
> +#     included in the request payload.
> +#
> +# Since: 9.1
> +##
> +{ 'enum': 'CXLExtRemovalPolicy',
> +  'data': ['tag-based',
> +           'prescriptive']
> +}
> +
> +##
> +# @cxl-release-dynamic-capacity:
> +#
> +# Command to initiate to release dynamic capacity extents from a
> +# host.  It simulates operations defined in cxl spec r3.1 7.6.7.6.6.
> +#
> +# @path: CXL DCD canonical QOM path.
> +#
> +# @host-id: The "Host ID" field as defined in cxl spec r3.1
> +#     Table 7-71.
> +#
> +# @removal-policy: Bit[3:0] of the "Flags" field as defined in cxl
> +#     spec r3.1 Table 7-71.
> +#
> +# @forced-removal: Bit[4] of the "Flags" field in cxl spec r3.1
> +#     Table 7-71.  When set, device does not wait for a Release
> +#     Dynamic Capacity command from the host.  Host immediately
> +#     loses access to released capacity.
> +#
> +# @sanitize-on-release: Bit[5] of the "Flags" field in cxl spec r3.1
> +#     Table 7-71.  When set, device should sanitize all released
> +#     capacity as a result of this request.
> +#
> +# @region: The "Region Number" field as defined in cxl spec r3.1
> +#     Table 7-71.  The dynamic capacity region where the capacity
> +#     is being added.  Valid range is from 0-7.
> +#
> +# @tag: The "Tag" field as defined in cxl spec r3.1 Table 7-71.
> +#
> +# @extents: The "Extent List" field as defined in cxl spec r3.1
> +#     Table 7-71.
> +#
> +# Since : 9.1
> +##
> +{ 'command': 'cxl-release-dynamic-capacity',
> +  'data': { 'path': 'str',
> +            'host-id': 'uint16',
> +            'removal-policy': 'CXLExtRemovalPolicy',
> +            'forced-removal': 'bool',
> +            'sanitize-on-release': 'bool',
> +            'region': 'uint8',
> +            'tag': 'str',
> +            'extents': [ 'CXLDynamicCapacityExtent' ]
> +           }
> +}