[PATCH v5 08/13] migration/multifd: Add new migration option for multifd DSA offloading.

[Yichen Wang]

From: Hao Xiang <hao.xiang@linux.dev>

Intel DSA offloading is an optional feature that turns on if
proper hardware and software stack is available. To turn on
DSA offloading in multifd live migration:

dsa-accel-path="[dsa_dev_path1] [dsa_dev_path2] ... [dsa_dev_pathX]"

This feature is turned off by default.

Signed-off-by: Hao Xiang <hao.xiang@linux.dev>
Signed-off-by: Yichen Wang <yichen.wang@bytedance.com>
---
 migration/migration-hmp-cmds.c | 15 ++++++++++-
 migration/options.c            | 47 ++++++++++++++++++++++++++++++++++
 migration/options.h            |  1 +
 qapi/migration.json            | 32 ++++++++++++++++++++---
 4 files changed, 90 insertions(+), 5 deletions(-)

diff --git a/migration/migration-hmp-cmds.c b/migration/migration-hmp-cmds.c
index 7d608d26e1..c422db4ecd 100644
--- a/migration/migration-hmp-cmds.c
+++ b/migration/migration-hmp-cmds.c
@@ -312,7 +312,16 @@ void hmp_info_migrate_parameters(Monitor *mon, const QDict 
*qdict)
         monitor_printf(mon, "%s: '%s'\n",
             MigrationParameter_str(MIGRATION_PARAMETER_TLS_AUTHZ),
             params->tls_authz);
-
+        if (params->has_dsa_accel_path) {
+            strList *dsa_accel_path = params->dsa_accel_path;
+            monitor_printf(mon, "%s:",
+                MigrationParameter_str(MIGRATION_PARAMETER_DSA_ACCEL_PATH));
+            while (dsa_accel_path) {
+                monitor_printf(mon, " %s", dsa_accel_path->value);
+                dsa_accel_path = dsa_accel_path->next;
+            }
+            monitor_printf(mon, "\n");
+        }
         if (params->has_block_bitmap_mapping) {
             const BitmapMigrationNodeAliasList *bmnal;
 
@@ -563,6 +572,10 @@ void hmp_migrate_set_parameter(Monitor *mon, const QDict 
*qdict)
         p->has_x_checkpoint_delay = true;
         visit_type_uint32(v, param, &p->x_checkpoint_delay, &err);
         break;
+    case MIGRATION_PARAMETER_DSA_ACCEL_PATH:
+        p->has_dsa_accel_path = true;
+        visit_type_strList(v, param, &p->dsa_accel_path, &err);
+        break;
     case MIGRATION_PARAMETER_MULTIFD_CHANNELS:
         p->has_multifd_channels = true;
         visit_type_uint8(v, param, &p->multifd_channels, &err);
diff --git a/migration/options.c b/migration/options.c
index 645f55003d..f839493016 100644
--- a/migration/options.c
+++ b/migration/options.c
@@ -29,6 +29,7 @@
 #include "ram.h"
 #include "options.h"
 #include "sysemu/kvm.h"
+#include <cpuid.h>
 
 /* Maximum migrate downtime set to 2000 seconds */
 #define MAX_MIGRATE_DOWNTIME_SECONDS 2000
@@ -162,6 +163,10 @@ Property migration_properties[] = {
     DEFINE_PROP_ZERO_PAGE_DETECTION("zero-page-detection", MigrationState,
                        parameters.zero_page_detection,
                        ZERO_PAGE_DETECTION_MULTIFD),
+    /* DEFINE_PROP_ARRAY("dsa-accel-path", MigrationState, x, */
+    /*                    parameters.dsa_accel_path, qdev_prop_string, char 
*), */
+    /* DEFINE_PROP_STRING("dsa-accel-path", MigrationState, */
+    /*                    parameters.dsa_accel_path), */
 
     /* Migration capabilities */
     DEFINE_PROP_MIG_CAP("x-xbzrle", MIGRATION_CAPABILITY_XBZRLE),
@@ -815,6 +820,13 @@ const char *migrate_tls_creds(void)
     return s->parameters.tls_creds;
 }
 
+const strList *migrate_dsa_accel_path(void)
+{
+    MigrationState *s = migrate_get_current();
+
+    return s->parameters.dsa_accel_path;
+}
+
 const char *migrate_tls_hostname(void)
 {
     MigrationState *s = migrate_get_current();
@@ -926,6 +938,7 @@ MigrationParameters *qmp_query_migrate_parameters(Error 
**errp)
     params->zero_page_detection = s->parameters.zero_page_detection;
     params->has_direct_io = true;
     params->direct_io = s->parameters.direct_io;
+    params->dsa_accel_path = QAPI_CLONE(strList, s->parameters.dsa_accel_path);
 
     return params;
 }
@@ -934,6 +947,7 @@ void migrate_params_init(MigrationParameters *params)
 {
     params->tls_hostname = g_strdup("");
     params->tls_creds = g_strdup("");
+    params->dsa_accel_path = NULL;
 
     /* Set has_* up only for parameter checks */
     params->has_throttle_trigger_threshold = true;
@@ -1137,6 +1151,22 @@ bool migrate_params_check(MigrationParameters *params, 
Error **errp)
         return false;
     }
 
+    if (params->has_zero_page_detection &&
+        params->zero_page_detection == ZERO_PAGE_DETECTION_DSA_ACCEL) {
+#ifdef CONFIG_DSA_OPT
+        unsigned int eax, ebx, ecx, edx;
+        /* ENQCMD is indicated by bit 29 of ecx in CPUID leaf 7, subleaf 0. */
+        if (!__get_cpuid_count(7, 0, &eax, &ebx, &ecx, &edx) ||
+            !(ecx & (1 << 29))) {
+            error_setg(errp, "DSA acceleration is not supported by CPU");
+            return false;
+        }
+#else
+        error_setg(errp, "DSA acceleration is not enabled");
+        return false;
+#endif
+    }
+
     return true;
 }
 
@@ -1247,6 +1277,11 @@ static void 
migrate_params_test_apply(MigrateSetParameters *params,
     if (params->has_direct_io) {
         dest->direct_io = params->direct_io;
     }
+
+    if (params->has_dsa_accel_path) {
+        dest->has_dsa_accel_path = true;
+        dest->dsa_accel_path = params->dsa_accel_path;
+    }
 }
 
 static void migrate_params_apply(MigrateSetParameters *params, Error **errp)
@@ -1376,6 +1411,12 @@ static void migrate_params_apply(MigrateSetParameters 
*params, Error **errp)
     if (params->has_direct_io) {
         s->parameters.direct_io = params->direct_io;
     }
+    if (params->has_dsa_accel_path) {
+        qapi_free_strList(s->parameters.dsa_accel_path);
+        s->parameters.has_dsa_accel_path = true;
+        s->parameters.dsa_accel_path =
+            QAPI_CLONE(strList, params->dsa_accel_path);
+    }
 }
 
 void qmp_migrate_set_parameters(MigrateSetParameters *params, Error **errp)
@@ -1401,6 +1442,12 @@ void qmp_migrate_set_parameters(MigrateSetParameters 
*params, Error **errp)
         params->tls_authz->type = QTYPE_QSTRING;
         params->tls_authz->u.s = strdup("");
     }
+    /* if (params->dsa_accel_path */
+    /*     && params->dsa_accel_path->type == QTYPE_QNULL) { */
+    /*     qobject_unref(params->dsa_accel_path->u.n); */
+    /*     params->dsa_accel_path->type = QTYPE_QLIST; */
+    /*     params->dsa_accel_path->u.s = strdup(""); */
+    /* } */
 
     migrate_params_test_apply(params, &tmp);
 
diff --git a/migration/options.h b/migration/options.h
index a2397026db..78b9e4080b 100644
--- a/migration/options.h
+++ b/migration/options.h
@@ -85,6 +85,7 @@ const char *migrate_tls_creds(void);
 const char *migrate_tls_hostname(void);
 uint64_t migrate_xbzrle_cache_size(void);
 ZeroPageDetection migrate_zero_page_detection(void);
+const strList *migrate_dsa_accel_path(void);
 
 /* parameters helpers */
 
diff --git a/qapi/migration.json b/qapi/migration.json
index 1234bef888..ff41780347 100644
--- a/qapi/migration.json
+++ b/qapi/migration.json
@@ -619,10 +619,14 @@
 #     multifd migration is enabled, else in the main migration thread
 #     as for @legacy.
 #
+# @dsa-accel: Perform zero page checking with the DSA accelerator
+#     offloading in multifd sender thread if multifd migration is
+#     enabled, else in the main migration thread as for @legacy.
+#
 # Since: 9.0
 ##
 { 'enum': 'ZeroPageDetection',
-  'data': [ 'none', 'legacy', 'multifd' ] }
+  'data': [ 'none', 'legacy', 'multifd', 'dsa-accel' ] }
 
 ##
 # @BitmapMigrationBitmapAliasTransform:
@@ -825,6 +829,12 @@
 #     See description in @ZeroPageDetection.  Default is 'multifd'.
 #     (since 9.0)
 #
+# @dsa-accel-path: If enabled, use DSA accelerator offloading for
+#     certain memory operations. Enable DSA accelerator for zero
+#     page detection offloading by setting the @zero-page-detection
+#     to dsa-accel. This parameter defines the dsa device path, and
+#     defaults to an empty list. (since 9.2)
+#
 # @direct-io: Open migration files with O_DIRECT when possible.  This
 #     only has effect if the @mapped-ram capability is enabled.
 #     (Since 9.1)
@@ -843,7 +853,7 @@
            'cpu-throttle-initial', 'cpu-throttle-increment',
            'cpu-throttle-tailslow',
            'tls-creds', 'tls-hostname', 'tls-authz', 'max-bandwidth',
-           'avail-switchover-bandwidth', 'downtime-limit',
+           'avail-switchover-bandwidth', 'downtime-limit', 'dsa-accel-path',
            { 'name': 'x-checkpoint-delay', 'features': [ 'unstable' ] },
            'multifd-channels',
            'xbzrle-cache-size', 'max-postcopy-bandwidth',
@@ -1000,6 +1010,12 @@
 #     See description in @ZeroPageDetection.  Default is 'multifd'.
 #     (since 9.0)
 #
+# @dsa-accel-path: If enabled, use DSA accelerator offloading for
+#     certain memory operations. Enable DSA accelerator for zero
+#     page detection offloading by setting the @zero-page-detection
+#     to dsa-accel. This parameter defines the dsa device path, and
+#     defaults to an empty list. (since 9.2)
+#
 # @direct-io: Open migration files with O_DIRECT when possible.  This
 #     only has effect if the @mapped-ram capability is enabled.
 #     (Since 9.1)
@@ -1044,7 +1060,8 @@
             '*vcpu-dirty-limit': 'uint64',
             '*mode': 'MigMode',
             '*zero-page-detection': 'ZeroPageDetection',
-            '*direct-io': 'bool' } }
+            '*direct-io': 'bool',
+            '*dsa-accel-path': ['str'] } }
 
 ##
 # @migrate-set-parameters:
@@ -1204,6 +1221,12 @@
 #     See description in @ZeroPageDetection.  Default is 'multifd'.
 #     (since 9.0)
 #
+# @dsa-accel-path: If enabled, use DSA accelerator offloading for
+#     certain memory operations. Enable DSA accelerator for zero
+#     page detection offloading by setting the @zero-page-detection
+#     to dsa-accel. This parameter defines the dsa device path, and
+#     defaults to an empty list. (since 9.2)
+#
 # @direct-io: Open migration files with O_DIRECT when possible.  This
 #     only has effect if the @mapped-ram capability is enabled.
 #     (Since 9.1)
@@ -1245,7 +1268,8 @@
             '*vcpu-dirty-limit': 'uint64',
             '*mode': 'MigMode',
             '*zero-page-detection': 'ZeroPageDetection',
-            '*direct-io': 'bool' } }
+            '*direct-io': 'bool',
+            '*dsa-accel-path': ['str'] } }
 
 ##
 # @query-migrate-parameters:
-- 
Yichen Wang