qemu: Implement support for locking domain's memory pages

src/qemu/qemu_capabilities.c

@@ -230,6 +230,7 @@ VIR_ENUM_IMPL(virQEMUCaps, QEMU_CAPS_LAST,
               "mem-merge",
               "vnc-websocket",
               "drive-discard",
+              "mlock",
     );
 
 struct _virQEMUCaps {
@@ -2246,6 +2247,7 @@ struct virQEMUCapsCommandLineProps {
 static struct virQEMUCapsCommandLineProps virQEMUCapsCommandLine[] = {
     { "machine", "mem-merge", QEMU_CAPS_MEM_MERGE },
     { "drive", "discard", QEMU_CAPS_DRIVE_DISCARD },
+    { "realtime", "mlock", QEMU_CAPS_MLOCK },
 };
 
 static int

src/qemu/qemu_capabilities.h

@@ -187,6 +187,7 @@ enum virQEMUCapsFlags {
     QEMU_CAPS_MEM_MERGE          = 146, /* -machine mem-merge */
     QEMU_CAPS_VNC_WEBSOCKET      = 147, /* -vnc x:y,websocket */
     QEMU_CAPS_DRIVE_DISCARD      = 148, /* -drive discard=off(ignore)|on(unmap) */
+    QEMU_CAPS_MLOCK              = 149, /* -realtime mlock=on|off */
 
     QEMU_CAPS_LAST,                   /* this must always be the last item */
 };

src/qemu/qemu_command.c

@@ -6541,6 +6541,17 @@ qemuBuildCommandLine(virConnectPtr conn,
                              cfg->hugepagePath, NULL);
     }
 
+    if (def->mem.locked && !virQEMUCapsGet(qemuCaps, QEMU_CAPS_MLOCK)) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                       _("memory locking not supported by QEMU binary"));
+        goto error;
+    }
+    if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_MLOCK)) {
+        virCommandAddArg(cmd, "-realtime");
+        virCommandAddArgFormat(cmd, "mlock=%s",
+                               def->mem.locked ? "on" : "off");
+    }
+
     virCommandAddArg(cmd, "-smp");
     if (!(smp = qemuBuildSmpArgStr(def, qemuCaps)))
         goto error;

tests/qemuxml2argvdata/qemuxml2argv-mlock-off.args

+LC_ALL=C PATH=/bin HOME=/home/test USER=test LOGNAME=test \
+/usr/bin/qemu -S -M pc -m 214 -realtime mlock=off \
+-smp 1 -nographic -monitor unix:/tmp/test-monitor,server,nowait \
+-no-acpi -boot c -usb -net none -serial none -parallel none

tests/qemuxml2argvdata/qemuxml2argv-mlock-off.xml

+<domain type='qemu'>
+  <name>QEMUGuest1</name>
+  <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
+  <memory unit='KiB'>219136</memory>
+  <currentMemory unit='KiB'>219136</currentMemory>
+  <vcpu placement='static'>1</vcpu>
+  <os>
+    <type arch='i686' machine='pc'>hvm</type>
+    <boot dev='hd'/>
+  </os>
+  <devices>
+    <emulator>/usr/bin/qemu</emulator>
+    <memballoon model='none'/>
+  </devices>
+</domain>

tests/qemuxml2argvdata/qemuxml2argv-mlock-on.args

+LC_ALL=C PATH=/bin HOME=/home/test USER=test LOGNAME=test \
+/usr/bin/qemu -S -M pc -m 214 -realtime mlock=on \
+-smp 1 -nographic -monitor unix:/tmp/test-monitor,server,nowait \
+-no-acpi -boot c -usb -net none -serial none -parallel none

tests/qemuxml2argvdata/qemuxml2argv-mlock-on.xml

+<domain type='qemu'>
+  <name>QEMUGuest1</name>
+  <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
+  <memory unit='KiB'>219136</memory>
+  <currentMemory unit='KiB'>219136</currentMemory>
+  <memoryBacking>
+    <locked/>
+  </memoryBacking>
+  <vcpu placement='static'>1</vcpu>
+  <os>
+    <type arch='i686' machine='pc'>hvm</type>
+    <boot dev='hd'/>
+  </os>
+  <devices>
+    <emulator>/usr/bin/qemu</emulator>
+    <memballoon model='none'/>
+  </devices>
+</domain>

tests/qemuxml2argvdata/qemuxml2argv-mlock-unsupported.args

+LC_ALL=C PATH=/bin HOME=/home/test USER=test LOGNAME=test \
+/usr/bin/qemu -S -M pc -m 214 \
+-smp 1 -nographic -monitor unix:/tmp/test-monitor,server,nowait \
+-no-acpi -boot c -usb -net none -serial none -parallel none

tests/qemuxml2argvdata/qemuxml2argv-mlock-unsupported.xml

+<domain type='qemu'>
+  <name>QEMUGuest1</name>
+  <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
+  <memory unit='KiB'>219136</memory>
+  <currentMemory unit='KiB'>219136</currentMemory>
+  <vcpu placement='static'>1</vcpu>
+  <os>
+    <type arch='i686' machine='pc'>hvm</type>
+    <boot dev='hd'/>
+  </os>
+  <devices>
+    <emulator>/usr/bin/qemu</emulator>
+    <memballoon model='none'/>
+  </devices>
+</domain>

tests/qemuxml2argvtest.c

@@ -1007,6 +1007,11 @@ mymain(void)
             QEMU_CAPS_DEVICE_SCSI_GENERIC,
             QEMU_CAPS_DEVICE_SCSI_GENERIC_BOOTINDEX);
 
+    DO_TEST("mlock-on", QEMU_CAPS_MLOCK);
+    DO_TEST_FAILURE("mlock-on", NONE);
+    DO_TEST("mlock-off", QEMU_CAPS_MLOCK);
+    DO_TEST("mlock-unsupported", NONE);
+
     virObjectUnref(driver.config);
     virObjectUnref(driver.caps);
     virObjectUnref(driver.xmlopt);