Re: [PATCH v7 2/2] hw/acpi: Implement the SRAT GI affinity structure

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

On Mon, 26 Feb 2024 16:42:29 +0000
Jonathan Cameron via <qemu-devel@nongnu.org> wrote:

> On Fri, 23 Feb 2024 12:42:23 +0000
> <ankita@nvidia.com> wrote:
> 
> > From: Ankit Agrawal <ankita@nvidia.com>
> > 
> > ACPI spec provides a scheme to associate "Generic Initiators" [1]
> > (e.g. heterogeneous processors and accelerators, GPUs, and I/O devices with
> > integrated compute or DMA engines GPUs) with Proximity Domains. This is
> > achieved using Generic Initiator Affinity Structure in SRAT. During bootup,
> > Linux kernel parse the ACPI SRAT to determine the PXM ids and create a NUMA
> > node for each unique PXM ID encountered. Qemu currently do not implement
> > these structures while building SRAT.
> > 
> > Add GI structures while building VM ACPI SRAT. The association between
> > device and node are stored using acpi-generic-initiator object. Lookup
> > presence of all such objects and use them to build these structures.
> > 
> > The structure needs a PCI device handle [2] that consists of the device BDF.
> > The vfio-pci device corresponding to the acpi-generic-initiator object is
> > located to determine the BDF.
> > 
> > [1] ACPI Spec 6.3, Section 5.2.16.6
> > [2] ACPI Spec 6.3, Table 5.80
> > 
> > Signed-off-by: Ankit Agrawal <ankita@nvidia.com>  
> 
> One thing I forgot.
And another :)

It might be nice to also support x86 from the start (apparently people still
care about that old architecture)

https://gitlab.com/jic23/qemu/-/commit/ccfb4fe22167e035173390cf147d9c226951b9b6
is what I'm carrying for this (see below)

We could do this later as part of the generic ports series (which is also on
that tree if you are curious).

diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index 2d2bb0a325b83f5e3fb4666a462a693aea1a2220..54462d3a46c379a4159b4d71d7689a107745fa4c 100644
--- a/hw/i386/acpi-build.c
+++ b/hw/i386/acpi-build.c
@@ -68,6 +68,7 @@
 #include "hw/acpi/utils.h"
 #include "hw/acpi/pci.h"
 #include "hw/acpi/cxl.h"
+#include "hw/acpi/acpi-generic-initiator.h"
 
 #include "qom/qom-qobject.h"
 #include "hw/i386/amd_iommu.h"
@@ -2097,6 +2098,7 @@ build_srat(GArray *table_data, BIOSLinker *linker, MachineState *machine)
         }
     }
 
+    build_srat_generic_pci_initiator(table_data);
     if (machine->nvdimms_state->is_enabled) {
         nvdimm_build_srat(table_data);
     }




> 
> Please add a test.  tests/qtest/bios-tables-test.c
> + relevant table dumps.
> 
> Could also hook this up for x86 with a oneline addition and improve
> test coverage.  If not, I'll do it when I add Generic Ports as annoyingly
> people still care about x86 for some reason.
>