From: Peter Krempa <pkrempa@redhat.com>

The 'migration' attribute for the '<reservations>' element allows to
control the persistent reservation migration feature independently of
the machine type default.

Add the XML plumbing and qemu support.

We consider it ABI for now since it influences qemu migration protocol.

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
---
 docs/formatdomain.rst                         |  3 +++
 src/conf/domain_conf.c                        | 21 +++++++++++++++++++
 src/conf/schemas/storagecommon.rng            |  5 +++++
 src/conf/storage_source_conf.c                | 10 +++++++++
 src/conf/storage_source_conf.h                |  2 ++
 src/qemu/qemu_command.c                       |  4 ++++
 src/qemu/qemu_validate.c                      | 16 ++++++++++++++
 ...irtio-scsi-reservations.x86_64-latest.args |  2 +-
 .../disk-virtio-scsi-reservations.xml         |  2 +-
 9 files changed, 63 insertions(+), 2 deletions(-)

diff --git a/docs/formatdomain.rst b/docs/formatdomain.rst
index 87644ad42a..dfc0e94ec3 100644
--- a/docs/formatdomain.rst
+++ b/docs/formatdomain.rst
@@ -3186,6 +3186,9 @@ paravirtualized driver is specified via the ``disk`` element.
       the socket, and finally ``mode`` which accepts one value ``client``
       specifying the role of hypervisor. It's recommended to allow libvirt
       manage the persistent reservations.
+      :since:`Since 12.1.0` the ``migration`` (values ``yes``, ``no``) controls
+      whether the hypervisor should attempt to migrate persistent reservations
+      during migration.
    ``initiator``
       :since:`Since 4.7.0`, the ``initiator`` element is supported for
       a disk ``type`` "network" that is using a ``source`` element with the
diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
index e88dc62520..09cd562d3a 100644
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -20999,6 +20999,27 @@ virDomainDiskDefCheckABIStability(virDomainDiskDef *src,
         return false;
     }

+    /* While not guest visible it influences the qemu migration stream so
+     * we need to keep it identical */
+    if (src->src->pr || dst->src->pr) {
+        virTristateBool srcmig = VIR_TRISTATE_BOOL_ABSENT;
+        virTristateBool dstmig = VIR_TRISTATE_BOOL_ABSENT;
+
+        if (src->src->pr)
+            srcmig = src->src->pr->migration;
+
+        if (dst->src->pr)
+            dstmig = dst->src->pr->migration;
+
+        if (srcmig != dstmig) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                           _("Target disk reservations 'migration' property %1$s does not match source %2$s"),
+                           virTristateBoolTypeToString(dstmig),
+                           virTristateBoolTypeToString(srcmig));
+            return false;
+        }
+    }
+
     if (!virDomainVirtioOptionsCheckABIStability(src->virtio, dst->virtio))
         return false;

diff --git a/src/conf/schemas/storagecommon.rng b/src/conf/schemas/storagecommon.rng
index 14704c737e..450d53131f 100644
--- a/src/conf/schemas/storagecommon.rng
+++ b/src/conf/schemas/storagecommon.rng
@@ -104,6 +104,11 @@
           <ref name="virYesNo"/>
         </attribute>
       </optional>
+      <optional>
+        <attribute name="migration">
+          <ref name="virYesNo"/>
+        </attribute>
+      </optional>
       <optional>
         <ref name="unixSocketSource"/>
       </optional>
diff --git a/src/conf/storage_source_conf.c b/src/conf/storage_source_conf.c
index d7b9bdfecb..e5f20fba80 100644
--- a/src/conf/storage_source_conf.c
+++ b/src/conf/storage_source_conf.c
@@ -331,6 +331,11 @@ virStoragePRDefParseXML(xmlXPathContextPtr ctxt)
                                &prd->managed) < 0)
         goto cleanup;

+    if (virXMLPropTristateBool(ctxt->node, "migration",
+                               VIR_XML_PROP_NONZERO,
+                               &prd->migration) < 0)
+        goto cleanup;
+
     type = virXPathString("string(./source[1]/@type)", ctxt);
     path = virXPathString("string(./source[1]/@path)", ctxt);
     mode = virXPathString("string(./source[1]/@mode)", ctxt);
@@ -385,6 +390,11 @@ virStoragePRDefFormat(virBuffer *buf,
 {
     virBufferAsprintf(buf, "<reservations managed='%s'",
                       virTristateBoolTypeToString(prd->managed));
+
+    if (prd->migration != VIR_TRISTATE_BOOL_ABSENT)
+        virBufferAsprintf(buf, " migration='%s'",
+                          virTristateBoolTypeToString(prd->migration));
+
     if (prd->path &&
         (prd->managed == VIR_TRISTATE_BOOL_NO || !migratable)) {
         virBufferAddLit(buf, ">\n");
diff --git a/src/conf/storage_source_conf.h b/src/conf/storage_source_conf.h
index 22c35d420d..d3a9b0e7a2 100644
--- a/src/conf/storage_source_conf.h
+++ b/src/conf/storage_source_conf.h
@@ -236,6 +236,8 @@ struct _virStoragePRDef {
     virTristateBool managed;
     char *path;

+    virTristateBool migration;
+
     /* manager object alias */
     char *mgralias;
 };
diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
index 069211e139..c09c883a28 100644
--- a/src/qemu/qemu_command.c
+++ b/src/qemu/qemu_command.c
@@ -1692,6 +1692,7 @@ qemuBuildDiskDeviceProps(const virDomainDef *def,
     g_autofree char *usbdiskalias = NULL;
     const virDomainDeviceInfo *deviceinfo = &disk->info;
     g_autoptr(virJSONValue) statistics = NULL;
+    virTristateBool migrate_pr = VIR_TRISTATE_BOOL_ABSENT;
     virDomainDeviceInfo usbSCSIinfo = {
         .type = VIR_DOMAIN_DEVICE_ADDRESS_TYPE_DRIVE,
         .addr.drive = { .diskbus = VIR_DOMAIN_DISK_BUS_USB },
@@ -1717,6 +1718,8 @@ qemuBuildDiskDeviceProps(const virDomainDef *def,
     case VIR_DOMAIN_DISK_BUS_SCSI:
         if (disk->device == VIR_DOMAIN_DISK_DEVICE_LUN) {
             driver = "scsi-block";
+            if (disk->src->pr)
+                migrate_pr = disk->src->pr->migration;
         } else {
             if (disk->device == VIR_DOMAIN_DISK_DEVICE_CDROM) {
                 driver = "scsi-cd";
@@ -1938,6 +1941,7 @@ qemuBuildDiskDeviceProps(const virDomainDef *def,
                               "S:rerror", rpolicy,
                               "A:stats-intervals", &statistics,
                               "T:dpofua", disk->dpofua, /* SCSI-only, ensured by validation */
+                              "T:migrate-pr", migrate_pr, /* 'scsi-block' only, ensured by validation */
                               NULL) < 0)
         return NULL;

diff --git a/src/qemu/qemu_validate.c b/src/qemu/qemu_validate.c
index 0bad299996..2ca38db9f1 100644
--- a/src/qemu/qemu_validate.c
+++ b/src/qemu/qemu_validate.c
@@ -3226,6 +3226,22 @@ qemuValidateDomainDeviceDefDiskFrontend(const virDomainDiskDef *disk,
         }
     }

+    if (disk->src->pr &&
+        disk->src->pr->migration != VIR_TRISTATE_BOOL_ABSENT) {
+        if (disk->device != VIR_DOMAIN_DISK_DEVICE_LUN ||
+            disk->bus != VIR_DOMAIN_DISK_BUS_SCSI) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                           _("persistent reservation migration supported only with 'lun' disks on 'scsi' bus"));
+            return -1;
+        }
+
+        if (!virQEMUCapsGet(qemuCaps, QEMU_CAPS_DEVICE_SCSI_BLOCK_MIGRATE_PR)) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                           _("persistent reservation migration not supported by this qemu"));
+            return -1;
+        }
+    }
+
     if (disk->rotation_rate) {
         if (disk->bus != VIR_DOMAIN_DISK_BUS_SCSI &&
             disk->bus != VIR_DOMAIN_DISK_BUS_IDE &&
diff --git a/tests/qemuxmlconfdata/disk-virtio-scsi-reservations.x86_64-latest.args b/tests/qemuxmlconfdata/disk-virtio-scsi-reservations.x86_64-latest.args
index cbc2a0f398..f1d7a450ee 100644
--- a/tests/qemuxmlconfdata/disk-virtio-scsi-reservations.x86_64-latest.args
+++ b/tests/qemuxmlconfdata/disk-virtio-scsi-reservations.x86_64-latest.args
@@ -33,7 +33,7 @@ XDG_CONFIG_HOME=/var/lib/libvirt/qemu/domain--1-QEMUGuest1/.config \
 -device '{"driver":"scsi-block","bus":"scsi0.0","channel":0,"scsi-id":0,"lun":0,"drive":"libvirt-2-storage","id":"scsi0-0-0-0","bootindex":1}' \
 -object '{"qom-type":"pr-manager-helper","id":"pr-helper-libvirt-1-storage","path":"/path/to/qemu-pr-helper.sock"}' \
 -blockdev '{"driver":"host_device","filename":"/dev/HostVG/QEMUGuest2","pr-manager":"pr-helper-libvirt-1-storage","node-name":"libvirt-1-storage","read-only":false}' \
--device '{"driver":"scsi-block","bus":"scsi0.0","channel":0,"scsi-id":0,"lun":1,"drive":"libvirt-1-storage","id":"scsi0-0-0-1"}' \
+-device '{"driver":"scsi-block","bus":"scsi0.0","channel":0,"scsi-id":0,"lun":1,"drive":"libvirt-1-storage","id":"scsi0-0-0-1","migrate-pr":true}' \
 -audiodev '{"id":"audio1","driver":"none"}' \
 -device '{"driver":"virtio-balloon-pci","id":"balloon0","bus":"pci.0","addr":"0x4"}' \
 -sandbox on,obsolete=deny,elevateprivileges=deny,spawn=deny,resourcecontrol=deny \
diff --git a/tests/qemuxmlconfdata/disk-virtio-scsi-reservations.xml b/tests/qemuxmlconfdata/disk-virtio-scsi-reservations.xml
index 9c55d6ec3e..7f9160ff3a 100644
--- a/tests/qemuxmlconfdata/disk-virtio-scsi-reservations.xml
+++ b/tests/qemuxmlconfdata/disk-virtio-scsi-reservations.xml
@@ -28,7 +28,7 @@
     <disk type='block' device='lun'>
       <driver name='qemu' type='raw'/>
       <source dev='/dev/HostVG/QEMUGuest2'>
-        <reservations managed='no'>
+        <reservations managed='no' migration='yes'>
           <source type='unix' path='/path/to/qemu-pr-helper.sock' mode='client'/>
         </reservations>
       </source>
-- 
2.53.0