[Qemu-devel] [PATCH 2.1 15/28] numa: add -numa node, memdev= option

[Paolo Bonzini <pbonzini@redhat.com>]

This option provides the infrastructure for binding guest NUMA nodes
to host NUMA nodes.  For example:

 -object memory-ram,size=1024M,policy=membind,host-nodes=0,id=ram-node0 \
 -numa node,nodeid=0,cpus=0,memdev=ram-node0 \
 -object memory-ram,size=1024M,policy=interleave,host-nodes=1-3,id=ram-node1 \
 -numa node,nodeid=1,cpus=1,memdev=ram-node1

The option replaces "-numa node,mem=".

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 include/sysemu/sysemu.h |  1 +
 numa.c                  | 63 +++++++++++++++++++++++++++++++++++++++++++++++--
 qapi-schema.json        |  8 ++++++-
 qemu-options.hx         | 12 ++++++----
 4 files changed, 77 insertions(+), 7 deletions(-)

diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h
index 54a6f28..4870129 100644
--- a/include/sysemu/sysemu.h
+++ b/include/sysemu/sysemu.h
@@ -139,6 +139,7 @@ extern int nb_numa_nodes;
 typedef struct node_info {
     uint64_t node_mem;
     DECLARE_BITMAP(node_cpu, MAX_CPUMASK_BITS);
+    struct HostMemoryBackend *node_memdev;
 } NodeInfo;
 extern NodeInfo numa_info[MAX_NODES];
 void set_numa_nodes(void);
diff --git a/numa.c b/numa.c
index 930f49d..b00ef90 100644
--- a/numa.c
+++ b/numa.c
@@ -32,6 +32,7 @@
 #include "qapi/dealloc-visitor.h"
 #include "qapi/qmp/qerror.h"
 #include "hw/boards.h"
+#include "sysemu/hostmem.h"
 
 QemuOptsList qemu_numa_opts = {
     .name = "numa",
@@ -40,6 +41,8 @@ QemuOptsList qemu_numa_opts = {
     .desc = { { 0 } } /* validated with OptsVisitor */
 };
 
+static int have_memdevs = -1;
+
 static void numa_node_parse(NumaNodeOptions *node, QemuOpts *opts, Error **errp)
 {
     uint16_t nodenr;
@@ -66,6 +69,20 @@ static void numa_node_parse(NumaNodeOptions *node, QemuOpts *opts, Error **errp)
         bitmap_set(numa_info[nodenr].node_cpu, cpus->value, 1);
     }
 
+    if (node->has_mem && node->has_memdev) {
+        error_setg(errp, "qemu: cannot specify both mem= and memdev=\n");
+        return;
+    }
+
+    if (have_memdevs == -1) {
+        have_memdevs = node->has_memdev;
+    }
+    if (node->has_memdev != have_memdevs) {
+        error_setg(errp, "qemu: memdev option must be specified for either "
+                   "all or no nodes\n");
+        return;
+    }
+
     if (node->has_mem) {
         uint64_t mem_size = node->mem;
         const char *mem_str = qemu_opt_get(opts, "mem");
@@ -75,6 +92,18 @@ static void numa_node_parse(NumaNodeOptions *node, QemuOpts *opts, Error **errp)
         }
         numa_info[nodenr].node_mem = mem_size;
     }
+    if (node->has_memdev) {
+        Object *o;
+        o = object_resolve_path_type(node->memdev, TYPE_MEMORY_BACKEND, NULL);
+        if (!o) {
+            error_setg(errp, "memdev=%s is ambiguous", node->memdev);
+            return;
+        }
+
+        object_ref(o);
+        numa_info[nodenr].node_mem = object_property_get_int(o, "size", NULL);
+        numa_info[nodenr].node_memdev = MEMORY_BACKEND(o);
+    }
 }
 
 int numa_init_func(QemuOpts *opts, void *opaque)
@@ -193,12 +222,42 @@ void set_numa_modes(void)
     }
 }
 
+static void allocate_system_memory_nonnuma(MemoryRegion *mr, Object *owner,
+                                           const char *name,
+                                           QEMUMachineInitArgs *args)
+{
+    uint64_t ram_size = args->ram_size;
+
+    memory_region_init_ram(mr, owner, name, ram_size);
+    vmstate_register_ram_global(mr);
+}
+
 void memory_region_allocate_system_memory(MemoryRegion *mr, Object *owner,
                                           const char *name,
                                           QEMUMachineInitArgs *args)
 {
     uint64_t ram_size = args->ram_size;
+    uint64_t addr = 0;
+    int i;
 
-    memory_region_init_ram(mr, owner, name, ram_size);
-    vmstate_register_ram_global(mr);
+    if (nb_numa_nodes == 0 || !have_memdevs) {
+        allocate_system_memory_nonnuma(mr, owner, name, args);
+        return;
+    }
+
+    memory_region_init(mr, owner, name, ram_size);
+    for (i = 0; i < nb_numa_nodes; i++) {
+        Error *local_err = NULL;
+        uint64_t size = numa_info[i].node_mem;
+        HostMemoryBackend *backend = numa_info[i].node_memdev;
+        MemoryRegion *seg = host_memory_backend_get_memory(backend, &local_err);
+        if (local_err) {
+            qerror_report_err(local_err);
+            exit(1);
+        }
+
+        memory_region_add_subregion(mr, addr, seg);
+        vmstate_register_ram_global(seg);
+        addr += size;
+    }
 }
diff --git a/qapi-schema.json b/qapi-schema.json
index ca8c11e..8bd84da 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -4543,10 +4543,16 @@
 # @mem: #optional memory size of this node (equally divide total memory among
 #        nodes if omitted)
 #
+# @memdev: #optional memory backend object.  If specified for one node,
+#          it must be specified for all nodes.
+#
+# @mem: #optional memory size of this node; mutually exclusive with @memdev.
+#
 # Since: 2.1
 ##
 { 'type': 'NumaNodeOptions',
   'data': {
    '*nodeid': 'uint16',
    '*cpus':   ['uint16'],
-   '*mem':    'size' }}
+   '*mem':    'size',
+   '*memdev': 'str' }}
diff --git a/qemu-options.hx b/qemu-options.hx
index 98e78ca..f3bf291 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -95,16 +95,20 @@ specifies the maximum number of hotpluggable CPUs.
 ETEXI
 
 DEF("numa", HAS_ARG, QEMU_OPTION_numa,
-    "-numa node[,mem=size][,cpus=cpu[-cpu]][,nodeid=node]\n", QEMU_ARCH_ALL)
+    "-numa node[,mem=size][,memdev=id][,cpus=cpu[-cpu]][,nodeid=node]\n", QEMU_ARCH_ALL)
 STEXI
-@item -numa node[,mem=@var{size}][,cpus=@var{cpu[-cpu]}][,nodeid=@var{node}]
+@item -numa node[,mem=@var{size}][,memdev=@var{id}][,cpus=@var{cpu[-cpu]}][,nodeid=@var{node}]
 @findex -numa
-Simulate a multi node NUMA system. If @samp{mem}
+Simulate a multi node NUMA system. If @samp{mem}, @samp{memdev}
 and @samp{cpus} are omitted, resources are split equally. Also, note
 that the -@option{numa} option doesn't allocate any of the specified
 resources. That is, it just assigns existing resources to NUMA nodes. This
 means that one still has to use the @option{-m}, @option{-smp} options
-to respectively allocate RAM and vCPUs.
+to respectively allocate RAM and vCPUs, and possibly @option{-object}
+to specify the memory backend for the @samp{memdev} suboption.
+
+@samp{mem} and @samp{memdev} are mutually exclusive.  Furthermore, if one
+node uses @samp{memdev}, all of them have to use it.
 ETEXI
 
 DEF("add-fd", HAS_ARG, QEMU_OPTION_add_fd,
-- 
1.8.5.3