{"id":2216048,"url":"http://patchwork.ozlabs.org/api/patches/2216048/?format=json","web_url":"http://patchwork.ozlabs.org/project/qemu-devel/patch/20260325184259.366-2-alireza.sanaee@huawei.com/","project":{"id":14,"url":"http://patchwork.ozlabs.org/api/projects/14/?format=json","name":"QEMU Development","link_name":"qemu-devel","list_id":"qemu-devel.nongnu.org","list_email":"qemu-devel@nongnu.org","web_url":"","scm_url":"","webscm_url":"","list_archive_url":"","list_archive_url_format":"","commit_url_format":""},"msgid":"<20260325184259.366-2-alireza.sanaee@huawei.com>","list_archive_url":null,"date":"2026-03-25T18:42:49","name":"[1/9] hw/mem: Add tag support to generic host memory backends","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"87d2741c18aee42478eabe99ac40095e47830698","submitter":{"id":90159,"url":"http://patchwork.ozlabs.org/api/people/90159/?format=json","name":"Alireza Sanaee","email":"alireza.sanaee@huawei.com"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/qemu-devel/patch/20260325184259.366-2-alireza.sanaee@huawei.com/mbox/","series":[{"id":497484,"url":"http://patchwork.ozlabs.org/api/series/497484/?format=json","web_url":"http://patchwork.ozlabs.org/project/qemu-devel/list/?series=497484","date":"2026-03-25T18:42:48","name":"Application Specific Tagged Memory Support in CXL Type 3 Devices","version":1,"mbox":"http://patchwork.ozlabs.org/series/497484/mbox/"}],"comments":"http://patchwork.ozlabs.org/api/patches/2216048/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2216048/checks/","tags":{},"related":[],"headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":"legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org\n (client-ip=209.51.188.17; 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Wed, 25 Mar 2026 14:43:42 -0400","from mail.maildlp.com (unknown [172.18.224.83])\n by frasgout.his.huawei.com (SkyGuard) with ESMTPS id 4fgwlB5KS0zHnGhl;\n Thu, 26 Mar 2026 02:43:02 +0800 (CST)","from dubpeml500005.china.huawei.com (unknown [7.214.145.207])\n by mail.maildlp.com (Postfix) with ESMTPS id 8F53240086;\n Thu, 26 Mar 2026 02:43:38 +0800 (CST)","from a2303103017.china.huawei.com (10.47.66.203) by\n dubpeml500005.china.huawei.com (7.214.145.207) with Microsoft SMTP Server\n (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id\n 15.2.1544.11; Wed, 25 Mar 2026 18:43:37 +0000"],"To":"","CC":", , ,\n , ,\n , , ,\n , , ,\n , ","Subject":"[PATCH 1/9] hw/mem: Add tag support to generic host memory backends","Date":"Wed, 25 Mar 2026 18:42:49 +0000","Message-ID":"<20260325184259.366-2-alireza.sanaee@huawei.com>","X-Mailer":"git-send-email 2.51.0.windows.2","In-Reply-To":"<20260325184259.366-1-alireza.sanaee@huawei.com>","References":"<20260325184259.366-1-alireza.sanaee@huawei.com>","MIME-Version":"1.0","Content-Transfer-Encoding":"8bit","Content-Type":"text/plain","X-Originating-IP":"[10.47.66.203]","X-ClientProxiedBy":"lhrpeml500011.china.huawei.com (7.191.174.215) To\n dubpeml500005.china.huawei.com (7.214.145.207)","Received-SPF":"pass client-ip=185.176.79.56;\n envelope-from=alireza.sanaee@huawei.com; helo=frasgout.his.huawei.com","X-Spam_score_int":"-41","X-Spam_score":"-4.2","X-Spam_bar":"----","X-Spam_report":"(-4.2 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_MED=-2.3,\n RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001,\n RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001,\n SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no","X-Spam_action":"no action","X-BeenThere":"qemu-devel@nongnu.org","X-Mailman-Version":"2.1.29","Precedence":"list","List-Id":"qemu development ","List-Unsubscribe":",\n ","List-Archive":"","List-Post":"","List-Help":"","List-Subscribe":",\n ","Reply-to":"Alireza Sanaee ","From":"Alireza Sanaee via qemu development ","Errors-To":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org","Sender":"qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org"},"content":"Add a string tag property to HostMemoryBackend so that backends can be\nidentified by a user-assigned name at runtime. Expose the property through\nQOM and add a host_memory_backend_find_by_tag() helper that walks the\nobject tree to locate a backend by its tag.\n\nThis is used by the following CXL patches to resolve a named backend for a\npending DC extent and attach it to the accepted extent when the host\nacknowledges the add request.\n\nSigned-off-by: Alireza Sanaee \n---\n backends/hostmem.c | 72 ++++++++++++++++++++++++++++++++++++++++\n include/system/hostmem.h | 2 ++\n qapi/qom.json | 3 ++\n tests/qtest/qom-test.c | 8 +++--\n 4 files changed, 83 insertions(+), 2 deletions(-)","diff":"diff --git a/backends/hostmem.c b/backends/hostmem.c\nindex 15d4365b69..270cae9569 100644\n--- a/backends/hostmem.c\n+++ b/backends/hostmem.c\n@@ -47,6 +47,50 @@ host_memory_backend_get_name(HostMemoryBackend *backend)\n return object_get_canonical_path(OBJECT(backend));\n }\n \n+typedef struct HostMemoryBackendTagSearch {\n+ const char *tag;\n+ HostMemoryBackend *backend;\n+} HostMemoryBackendTagSearch;\n+\n+static int host_memory_backend_find_by_tag_cb(Object *obj, void *opaque)\n+{\n+ HostMemoryBackendTagSearch *ctx = opaque;\n+ HostMemoryBackend *backend;\n+\n+ if (!object_dynamic_cast(obj, TYPE_MEMORY_BACKEND)) {\n+ return 0;\n+ }\n+\n+ backend = MEMORY_BACKEND(obj);\n+ if (!backend->tag) {\n+ return 0;\n+ }\n+\n+ if (strcmp(backend->tag, ctx->tag) == 0) {\n+ ctx->backend = backend;\n+ return 1;\n+ }\n+\n+ return 0;\n+}\n+\n+HostMemoryBackend *host_memory_backend_find_by_tag(const char *tag)\n+{\n+ HostMemoryBackendTagSearch ctx = {\n+ .tag = tag,\n+ .backend = NULL,\n+ };\n+\n+ if (!tag) {\n+ return NULL;\n+ }\n+\n+ object_child_foreach_recursive(object_get_objects_root(),\n+ host_memory_backend_find_by_tag_cb, &ctx);\n+\n+ return ctx.backend;\n+}\n+\n static void\n host_memory_backend_get_size(Object *obj, Visitor *v, const char *name,\n void *opaque, Error **errp)\n@@ -460,6 +504,22 @@ static void host_memory_backend_set_share(Object *o, bool value, Error **errp)\n backend->share = value;\n }\n \n+static void\n+host_memory_backend_set_tag(Object *obj, const char *value, Error **errp)\n+{\n+ HostMemoryBackend *backend = MEMORY_BACKEND(obj);\n+\n+ g_free(backend->tag);\n+ backend->tag = g_strdup(value);\n+}\n+\n+static char *host_memory_backend_get_tag(Object *obj, Error **errp)\n+{\n+ HostMemoryBackend *backend = MEMORY_BACKEND(obj);\n+\n+ return g_strdup(backend->tag);\n+}\n+\n #ifdef CONFIG_LINUX\n static bool host_memory_backend_get_reserve(Object *o, Error **errp)\n {\n@@ -501,6 +561,13 @@ host_memory_backend_set_use_canonical_path(Object *obj, bool value,\n backend->use_canonical_path = value;\n }\n \n+static void host_memory_backend_finalize(Object *obj)\n+{\n+ HostMemoryBackend *backend = MEMORY_BACKEND(obj);\n+\n+ g_free(backend->tag);\n+}\n+\n static void\n host_memory_backend_class_init(ObjectClass *oc, const void *data)\n {\n@@ -557,6 +624,10 @@ host_memory_backend_class_init(ObjectClass *oc, const void *data)\n host_memory_backend_get_share, host_memory_backend_set_share);\n object_class_property_set_description(oc, \"share\",\n \"Mark the memory as private to QEMU or shared\");\n+ object_class_property_add_str(oc, \"tag\",\n+ host_memory_backend_get_tag, host_memory_backend_set_tag);\n+ object_class_property_set_description(oc, \"tag\",\n+ \"A user-defined tag to identify this memory backend\");\n #ifdef CONFIG_LINUX\n object_class_property_add_bool(oc, \"reserve\",\n host_memory_backend_get_reserve, host_memory_backend_set_reserve);\n@@ -586,6 +657,7 @@ static const TypeInfo host_memory_backend_info = {\n .class_init = host_memory_backend_class_init,\n .instance_size = sizeof(HostMemoryBackend),\n .instance_init = host_memory_backend_init,\n+ .instance_finalize = host_memory_backend_finalize,\n .instance_post_init = host_memory_backend_post_init,\n .interfaces = (const InterfaceInfo[]) {\n { TYPE_USER_CREATABLE },\ndiff --git a/include/system/hostmem.h b/include/system/hostmem.h\nindex 88fa791ac7..a02e173d48 100644\n--- a/include/system/hostmem.h\n+++ b/include/system/hostmem.h\n@@ -81,12 +81,14 @@ struct HostMemoryBackend {\n ThreadContext *prealloc_context;\n DECLARE_BITMAP(host_nodes, MAX_NODES + 1);\n HostMemPolicy policy;\n+ char *tag;\n \n MemoryRegion mr;\n };\n \n bool host_memory_backend_mr_inited(HostMemoryBackend *backend);\n MemoryRegion *host_memory_backend_get_memory(HostMemoryBackend *backend);\n+HostMemoryBackend *host_memory_backend_find_by_tag(const char *tag);\n \n void host_memory_backend_set_mapped(HostMemoryBackend *backend, bool mapped);\n bool host_memory_backend_is_mapped(HostMemoryBackend *backend);\ndiff --git a/qapi/qom.json b/qapi/qom.json\nindex c653248f85..e6feeb324a 100644\n--- a/qapi/qom.json\n+++ b/qapi/qom.json\n@@ -658,6 +658,8 @@\n # @reserve: if true, reserve swap space (or huge pages) if applicable\n # (default: true) (since 6.1)\n #\n+# @tag: user-defined memory backend tag (since 11.1)\n+#\n # @size: size of the memory region in bytes\n #\n # @x-use-canonical-path-for-ramblock-id: if true, the canonical path\n@@ -683,6 +685,7 @@\n '*prealloc-context': 'str',\n '*share': 'bool',\n '*reserve': 'bool',\n+ '*tag': 'str',\n 'size': 'size',\n '*x-use-canonical-path-for-ramblock-id': 'bool' } }\n \ndiff --git a/tests/qtest/qom-test.c b/tests/qtest/qom-test.c\nindex 6421f2d9d9..3109b47cca 100644\n--- a/tests/qtest/qom-test.c\n+++ b/tests/qtest/qom-test.c\n@@ -17,6 +17,7 @@\n \n #define RAM_NAME \"node0\"\n #define RAM_SIZE 65536\n+#define RAM_TAG \"ramtag0\"\n \n static int verbosity_level;\n \n@@ -59,6 +60,8 @@ static void test_list_get_value(QTestState *qts)\n \n } else if (!strcmp(prop_name, \"size\")) {\n g_assert_cmpint(qdict_get_int(prop, \"value\"), ==, RAM_SIZE);\n+ } else if (!strcmp(prop_name, \"tag\")) {\n+ g_assert_cmpstr(qdict_get_str(prop, \"value\"), ==, RAM_TAG);\n }\n }\n }\n@@ -195,8 +198,9 @@ static void test_machine(gconstpointer data)\n QTestState *qts;\n g_autoptr(QList) paths = qlist_new();\n \n- qts = qtest_initf(\"-machine %s -object memory-backend-ram,id=%s,size=%d\",\n- machine, RAM_NAME, RAM_SIZE);\n+ qts = qtest_initf(\"-machine %s -object memory-backend-ram,id=%s,size=%d\"\n+ \",tag=%s\",\n+ machine, RAM_NAME, RAM_SIZE, RAM_TAG);\n \n if (g_test_slow()) {\n /* Make sure we can get the machine class properties: */\n","prefixes":["1/9"]}