migration: Add qtest for migration over RDMA

This qtest requires there is a RDMA(RoCE) link in the host.
In order to make the test work smoothly, introduce a
scripts/rdma-migration-helper.sh to detect existing RoCE link before
running the test.

Test will be skipped if there is no available RoCE link.
 # Start of rdma tests
 # Running /x86_64/migration/precopy/rdma/plain
 ok 1 /x86_64/migration/precopy/rdma/plain # SKIP No rdma link available
 # To enable the test:
 # Run 'scripts/rdma-migration-helper.sh setup' with root to setup a new rdma/rxe link and rerun the test
 # Optional: run 'scripts/rdma-migration-helper.sh clean' to revert the 'setup'

 # End of rdma tests

Cc: Philippe Mathieu-Daudé <philmd@linaro.org>
Cc: Stefan Hajnoczi <stefanha@gmail.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Li Zhijian <lizhijian@fujitsu.com>
Message-ID: <20250311024221.363421-1-lizhijian@fujitsu.com>
[add 'head -1' to script, reformat test message]
Signed-off-by: Fabiano Rosas <farosas@suse.de>

MAINTAINERS

@@ -3538,6 +3538,7 @@ R: Li Zhijian <lizhijian@fujitsu.com>
 R: Peter Xu <peterx@redhat.com>
 S: Odd Fixes
 F: migration/rdma*
+F: scripts/rdma-migration-helper.sh
 
 Migration dirty limit and dirty page rate
 M: Hyman Huang <yong.huang@smartx.com>

scripts/rdma-migration-helper.sh

@@ -0,0 +1,70 @@
+#!/bin/bash
+
+# Copied from blktests
+get_ipv4_addr()
+{
+    ip -4 -o addr show dev "$1" |
+        sed -n 's/.*[[:blank:]]inet[[:blank:]]*\([^[:blank:]/]*\).*/\1/p' |
+        head -1 | tr -d '\n'
+}
+
+# existing rdma interfaces
+rdma_interfaces()
+{
+    rdma link show | sed -nE 's/^link .* netdev ([^ ]+).*$/\1 /p'
+}
+
+# existing valid ipv4 interfaces
+ipv4_interfaces()
+{
+    ip -o addr show | awk '/inet / {print $2}' | grep -v -w lo
+}
+
+rdma_rxe_detect()
+{
+    for r in $(rdma_interfaces)
+    do
+        ipv4_interfaces | grep -qw $r && get_ipv4_addr $r && return
+    done
+
+    return 1
+}
+
+rdma_rxe_setup()
+{
+    for i in $(ipv4_interfaces)
+    do
+        rdma_interfaces | grep -qw $i && continue
+        rdma link add "${i}_rxe" type rxe netdev "$i" && {
+            echo "Setup new rdma/rxe ${i}_rxe for $i with $(get_ipv4_addr $i)"
+            return
+        }
+    done
+
+    echo "Failed to setup any new rdma/rxe link" >&2
+    return 1
+}
+
+rdma_rxe_clean()
+{
+    modprobe -r rdma_rxe
+}
+
+operation=${1:-detect}
+
+command -v rdma >/dev/null || {
+    echo "Command 'rdma' is not available, please install it first." >&2
+    exit 1
+}
+
+if [ "$operation" == "setup" ] || [ "$operation" == "clean" ]; then
+    [ "$UID" == 0 ] || {
+        echo "Root privilege is required to setup/clean a rdma/rxe link" >&2
+        exit 1
+    }
+    rdma_rxe_"$operation"
+elif [ "$operation" == "detect" ]; then
+    rdma_rxe_detect
+else
+    echo "Usage: $0 [setup | detect | clean]"
+fi

tests/qtest/migration/precopy-tests.c

@@ -99,6 +99,68 @@ static void test_precopy_unix_dirty_ring(void)
     test_precopy_common(&args);
 }
 
+#ifdef CONFIG_RDMA
+
+#define RDMA_MIGRATION_HELPER "scripts/rdma-migration-helper.sh"
+static int new_rdma_link(char *buffer)
+{
+    char cmd[256];
+    bool verbose = g_getenv("QTEST_LOG");
+
+    snprintf(cmd, sizeof(cmd), "%s detect %s", RDMA_MIGRATION_HELPER,
+             verbose ? "" : "2>/dev/null");
+
+    FILE *pipe = popen(cmd, "r");
+    if (pipe == NULL) {
+        perror("Failed to run script");
+        return -1;
+    }
+
+    int idx = 0;
+    while (fgets(buffer + idx, 128 - idx, pipe) != NULL) {
+        idx += strlen(buffer);
+    }
+
+    int status = pclose(pipe);
+    if (status == -1) {
+        perror("Error reported by pclose()");
+        return -1;
+    } else if (WIFEXITED(status)) {
+        return WEXITSTATUS(status);
+    }
+
+    return -1;
+}
+
+static void test_precopy_rdma_plain(void)
+{
+    char buffer[128] = {};
+
+    if (new_rdma_link(buffer)) {
+        g_test_skip("No rdma link available\n"
+                    "# To enable the test:\n"
+                    "# Run \'" RDMA_MIGRATION_HELPER " setup\' with root to "
+                    "setup a new rdma/rxe link and rerun the test\n"
+                    "# Optional: run 'scripts/rdma-migration-helper.sh clean' "
+                    "to revert the 'setup'");
+        return;
+    }
+
+    /*
+     * TODO: query a free port instead of hard code.
+     * 29200=('R'+'D'+'M'+'A')*100
+     **/
+    g_autofree char *uri = g_strdup_printf("rdma:%s:29200", buffer);
+
+    MigrateCommon args = {
+        .listen_uri = uri,
+        .connect_uri = uri,
+    };
+
+    test_precopy_common(&args);
+}
+#endif
+
 static void test_precopy_tcp_plain(void)
 {
     MigrateCommon args = {
@@ -1124,6 +1186,10 @@ static void migration_test_add_precopy_smoke(MigrationTestEnv *env)
                        test_multifd_tcp_uri_none);
     migration_test_add("/migration/multifd/tcp/plain/cancel",
                        test_multifd_tcp_cancel);
+#ifdef CONFIG_RDMA
+    migration_test_add("/migration/precopy/rdma/plain",
+                       test_precopy_rdma_plain);
+#endif
 }
 
 void migration_test_add_precopy(MigrationTestEnv *env)