[PATCH v2 3/3] qemu: command: support for virtio-blk-pci discard option

[<yuxiating@xxxxxxxxxx>]

From: yuxiating <yuxiating@xxxxxxxxxx>

This patch introduces a new attribute "discard". An example of
the XML:

<disk type='file' device='disk'>
  <driver name='qemu' type='qcow2' discard_enable='4'/>

The corresponding QEMU command line:

-device virtio-blk-pci,scsi=off,discard=off,id=virtio-disk0

Signed-off-by: yuxiating <yuxiating@xxxxxxxxxx>
---
 src/qemu/qemu_command.c                       |  5 +++
 .../qemuxml2argvdata/disk-virtio-discard.args | 29 +++++++++++++++
 .../qemuxml2argvdata/disk-virtio-discard.xml  | 35 +++++++++++++++++++
 tests/qemuxml2argvtest.c                      |  2 ++
 4 files changed, 71 insertions(+)
 create mode 100644 tests/qemuxml2argvdata/disk-virtio-discard.args
 create mode 100644 tests/qemuxml2argvdata/disk-virtio-discard.xml

diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
index b230314f7f..cf5a4ca7cf 100644
--- a/src/qemu/qemu_command.c
+++ b/src/qemu/qemu_command.c
@@ -1739,6 +1739,11 @@ qemuBuildDiskDeviceStr(const virDomainDef *def,
             virBufferAsprintf(&opt, ",num-queues=%u", disk->queues);
         }
 
+        if (disk->discard_enable) {
+            virBufferAsprintf(&opt, ",discard=%s",
+                              virTristateSwitchTypeToString(disk->discard_enable));
+        }
+
         qemuBuildVirtioOptionsStr(&opt, disk->virtio);
 
         if (qemuBuildDeviceAddressStr(&opt, def, &disk->info) < 0)
diff --git a/tests/qemuxml2argvdata/disk-virtio-discard.args b/tests/qemuxml2argvdata/disk-virtio-discard.args
new file mode 100644
index 0000000000..0e952ca81a
--- /dev/null
+++ b/tests/qemuxml2argvdata/disk-virtio-discard.args
@@ -0,0 +1,29 @@
+LC_ALL=C \
+PATH=/bin \
+HOME=/tmp/lib/domain--1-QEMUGuest1 \
+USER=test \
+LOGNAME=test \
+XDG_DATA_HOME=/tmp/lib/domain--1-QEMUGuest1/.local/share \
+XDG_CACHE_HOME=/tmp/lib/domain--1-QEMUGuest1/.cache \
+XDG_CONFIG_HOME=/tmp/lib/domain--1-QEMUGuest1/.config \
+QEMU_AUDIO_DRV=none \
+/usr/bin/qemu-system-i386 \
+-name guest=QEMUGuest1,debug-threads=on \
+-S \
+-machine pc,accel=tcg,usb=off,dump-guest-core=off \
+-m 214 \
+-realtime mlock=off \
+-smp 1,sockets=1,cores=1,threads=1 \
+-uuid c7a5fdbd-edaf-9455-926a-d65c16db1809 \
+-display none \
+-no-user-config \
+-nodefaults \
+-chardev socket,id=charmonitor,path=/tmp/lib/domain--1-QEMUGuest1/monitor.sock,server=on,wait=off \
+-mon chardev=charmonitor,id=monitor,mode=control \
+-rtc base=utc \
+-no-shutdown \
+-no-acpi \
+-usb \
+-drive file=/tmp/data.img,format=raw,if=none,id=drive-virtio-disk0 \
+-device virtio-blk-pci,discard=off,bus=pci.0,addr=0x3,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1 \
+-msg timestamp=on
diff --git a/tests/qemuxml2argvdata/disk-virtio-discard.xml b/tests/qemuxml2argvdata/disk-virtio-discard.xml
new file mode 100644
index 0000000000..37450f0bfc
--- /dev/null
+++ b/tests/qemuxml2argvdata/disk-virtio-discard.xml
@@ -0,0 +1,35 @@
+<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>
+  <clock offset='utc'/>
+  <on_poweroff>destroy</on_poweroff>
+  <on_reboot>restart</on_reboot>
+  <on_crash>destroy</on_crash>
+  <devices>
+    <emulator>/usr/bin/qemu-system-i386</emulator>
+    <disk type='file' device='disk'>
+      <driver name='qemu' type='raw' discard_enable='off'/>
+      <source file='/tmp/data.img'/>
+      <target dev='vda' bus='virtio'/>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
+    </disk>
+    <controller type='usb' index='0'>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x2'/>
+    </controller>
+    <controller type='ide' index='0'>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/>
+    </controller>
+    <controller type='pci' index='0' model='pci-root'/>
+    <input type='mouse' bus='ps2'/>
+    <input type='keyboard' bus='ps2'/>
+    <audio id='1' type='none'/>
+    <memballoon model='none'/>
+  </devices>
+</domain>
diff --git a/tests/qemuxml2argvtest.c b/tests/qemuxml2argvtest.c
index 3b331d5fd4..4375b06d40 100644
--- a/tests/qemuxml2argvtest.c
+++ b/tests/qemuxml2argvtest.c
@@ -1341,6 +1341,8 @@ mymain(void)
     DO_TEST("disk-order", QEMU_CAPS_VIRTIO_BLK_SCSI);
     DO_TEST("disk-virtio-queues",
             QEMU_CAPS_VIRTIO_BLK_NUM_QUEUES);
+    DO_TEST("disk-virtio-discard",
+            QEMU_CAPS_DEVICE_DISCARD);
     DO_TEST_NOCAPS("disk-boot-disk");
     DO_TEST_NOCAPS("disk-boot-cdrom");
     DO_TEST_NOCAPS("floppy-drive-fat");
-- 
2.27.0