[PATCH v4 8/9] i386/pc: Support cache topology in -machine for PC machine

Zhao Liu
2024-10-22T13:36:52Z

Allow user to configure l1d, l1i, l2 and l3 cache topologies for PC
machine.

Additionally, add the document of "-machine smp-cache" in
qemu-options.hx.

Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
Tested-by: Yongwei Ma <yongwei.ma@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
---
Changes since Patch v3:
* Described the omitting cache will use "default" level and described
the default cache topology model of i386 PC machine. (Daniel)
---
hw/i386/pc.c | 4 ++++
qemu-options.hx | 31 ++++++++++++++++++++++++++++++-
2 files changed, 34 insertions(+), 1 deletion(-)

diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 2047633e4cf7..8aea2308dcb9 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -1791,6 +1791,10 @@ static void pc_machine_class_init(ObjectClass *oc, void *data)
mc->nvdimm_supported = true;
mc->smp_props.dies_supported = true;
mc->smp_props.modules_supported = true;
+ mc->smp_props.cache_supported[CACHE_LEVEL_AND_TYPE_L1D] = true;
+ mc->smp_props.cache_supported[CACHE_LEVEL_AND_TYPE_L1I] = true;
+ mc->smp_props.cache_supported[CACHE_LEVEL_AND_TYPE_L2] = true;
+ mc->smp_props.cache_supported[CACHE_LEVEL_AND_TYPE_L3] = true;
mc->default_ram_id = "pc.ram";
pcmc->default_smbios_ep_type = SMBIOS_ENTRY_POINT_TYPE_AUTO;

diff --git a/qemu-options.hx b/qemu-options.hx
index daae49414740..fe39973d97a5 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -39,7 +39,8 @@ DEF("machine", HAS_ARG, QEMU_OPTION_machine, \
" memory-encryption=@var{} memory encryption object to use (default=none)\n"
" hmat=on|off controls ACPI HMAT support (default=off)\n"
" memory-backend='backend-id' specifies explicitly provided backend for main RAM (default=none)\n"
- " cxl-fmw.0.targets.0=firsttarget,cxl-fmw.0.targets.1=secondtarget,cxl-fmw.0.size=size[,cxl-fmw.0.interleave-granularity=granularity]\n",
+ " cxl-fmw.0.targets.0=firsttarget,cxl-fmw.0.targets.1=secondtarget,cxl-fmw.0.size=size[,cxl-fmw.0.interleave-granularity=granularity]\n"
+ " smp-cache.0.cache=cachename,smp-cache.0.topology=topologylevel\n",
QEMU_ARCH_ALL)
SRST
``-machine [type=]name[,prop=value[,...]]``
@@ -159,6 +160,34 @@ SRST
::

-machine cxl-fmw.0.targets.0=cxl.0,cxl-fmw.0.targets.1=cxl.1,cxl-fmw.0.size=128G,cxl-fmw.0.interleave-granularity=512
+
+ ``smp-cache.0.cache=cachename,smp-cache.0.topology=topologylevel``
+ Define cache properties for SMP system.
+
+ ``cache=cachename`` specifies the cache that the properties will be
+ applied on. This field is the combination of cache level and cache
+ type. It supports ``l1d`` (L1 data cache), ``l1i`` (L1 instruction
+ cache), ``l2`` (L2 unified cache) and ``l3`` (L3 unified cache).
+
+ ``topology=topologylevel`` sets the cache topology level. It accepts
+ CPU topology levels including ``thread``, ``core``, ``module``,
+ ``cluster``, ``die``, ``socket``, ``book``, ``drawer`` and a special
+ value ``default``. If ``default`` is set, then the cache topology will
+ follow the architecture's default cache topology model. If another
+ topology level is set, the cache will be shared at corresponding CPU
+ topology level. For example, ``topology=core`` makes the cache shared
+ by all threads within a core. The omitting cache will default to using
+ the ``default`` level.
+
+ The default cache topology model for an i386 PC machine is as follows:
+ ``l1d``, ``l1i``, and ``l2`` caches are per ``core``, while the ``l3``
+ cache is per ``die``.
+
+ Example:
+
+ ::
+
+ -machine smp-cache.0.cache=l1d,smp-cache.0.topology=core,smp-cache.1.cache=l1i,smp-cache.1.topology=core
ERST

DEF("M", HAS_ARG, QEMU_OPTION_M,
--
2.34.1