[v6,3/4] i386/pc: Support cache topology in -machine for PC machine

Commit Message

Zhao Liu Dec. 19, 2024, 8:32 a.m. UTC

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 <[e-mail]>
Tested-by: Yongwei Ma <[e-mail]>
Reviewed-by: Jonathan Cameron <[e-mail]>
---
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(-)

Patch

diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 92047ce8c9df..7804991229f1 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -1797,6 +1797,10 @@  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 cc694d3b890c..257563437c05 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,