[RFC PATCH 0/3] QEMU ACPI generic port support

[Dave Jiang]

s small RFC patch series is really a hack on what I need from qemu rather
than a proper implementation. I'm hoping to get some guidance from the list on
how to implement this correctly for qemu upstream. Thank you!

The patch series provides support for the ACPI Generic Port support that's
defined by ACPI spec 6.5 5.2.16.7 (Generic Port Affinity Structure). The
series also adds a genport object that allows locality data to be injected via
qemu commandline to the HMAT tables. The generic port support is to allow a hot
plugged CXL memory device to calculate the locality data from the CPU to
the CXL device. The generic port related data provides the locality data from
the CPU to the CXL host bridge (latency and bandwidth). These data in
addition to the PCIe link data, CDAT from device, and CXL switch CDAT if switch
exist, provides the locality data for the entire path.

Patch1: Adds Generic Port Affinity Structure sub-tables to the SRAT. For
each CXL Host Bridge (HB) a GPAS entry is created with a unique proximity
domain. For example, if the system is created with 4 proximity domains (PXM) for
system memory, then the next GPAS will get PXM 4 and so on.

Patch2: Add the json support for generic port. Split out because
clang-format really clobbers the json files.

Patch3: Add a generic port object. The intention here is to allow setup of
numa nodes, add hmat-lb data and node distance for the generic targets. I had to
add a hack in qemu_create_cli_devices() to realize the genport objects. I need
guidance on where and how to do this properly so the genport objects
realize at the correct place and time.

Example of genport setup:
-object genport,id=$X -numa node,genport=genport$X,nodeid=$Y,initiator=$Z
-numa 
hmat-lb,initiator=$Z,target=$X,hierarchy=memory,data-type=access-latency,latency=$latency
-numa 
hmat-lb,initiator=$Z,target=$X,hierarchy=memory,data-type=access-bandwidth,bandwidth=$bandwidthM
for ((i = 0; i < total_nodes; i++)); do
        for ((j = 0; j < cxl_hbs; j++ )); do        # 2 CXL HBs
                -numa dist,src=$i,dst=$X,val=$dist
        done
done
Linux kernel support:
https://lore.kernel.org/linux-cxl/168088732996.1441063.10107817505475386072.stgit@djiang5-mobl3/T/#t

---

Dave Jiang (3):
      hw/acpi: Add support for Generic Port Affinity Structure to SRAT
      genport: Add json support for generic port
      acpi: add generic port device object


 hw/acpi/aml-build.c         | 21 +++++++++++++
 hw/acpi/genport.c           | 61 +++++++++++++++++++++++++++++++++++++
 hw/acpi/meson.build         |  1 +
 hw/i386/acpi-build.c        | 45 +++++++++++++++++++++++++++
 include/hw/acpi/aml-build.h | 27 ++++++++++++++++
 qapi/machine.json           |  3 +-
 qapi/qom.json               | 12 ++++++++
 softmmu/vl.c                | 26 ++++++++++++++++
 8 files changed, 195 insertions(+), 1 deletion(-)
 create mode 100644 hw/acpi/genport.c

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