qemu: Report disk bus as reported by agent in virDomainGetGuestInfo

KubeVirt decided to report this to the users. In order to allow them to
use proper APIs expose the field as well.

Resolves: https://issues.redhat.com/browse/RHEL-80688
Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>

docs/manpages/virsh.rst

@@ -2999,6 +2999,7 @@ returned:
 * ``disk.<num>.serial`` -  optional disk serial number
 * ``disk.<num>.alias`` - the device alias of the disk (e.g. sda)
 * ``disk.<num>.guest_alias`` - optional alias assigned to the disk
+* ``disk.<num>.guest_bus`` - bus type as reported by the guest
 
 *--interface* returns:
 * ``if.count`` - the number of interfaces defined on this domain

src/libvirt-domain.c

@@ -13273,6 +13273,7 @@ virDomainSetVcpu(virDomainPtr domain,
  *      "disk.<num>.alias" - the device alias of the disk (e.g. sda)
  *      "disk.<num>.guest_alias" - optional alias assigned to the disk, on Linux
  *                      this is a name assigned by device mapper
+ *      "disk.<num>.guest_bus" - disk bus as reported by the guest OS
  *
  * VIR_DOMAIN_GUEST_INFO_HOSTNAME:
  *  Returns information about the hostname of the domain. The typed

src/qemu/qemu_driver.c

@@ -19278,6 +19278,15 @@ qemuAgentDiskInfoFormatParams(qemuAgentDiskInfo **info,
                                             param_name, diskdef->dst) < 0)
                     return;
             }
+
+            if (address->bus_type) {
+                g_snprintf(param_name, VIR_TYPED_PARAM_FIELD_LENGTH,
+                           "disk.%zu.guest_bus", i);
+
+                if (virTypedParamsAddString(params, nparams, maxparams,
+                                            param_name, address->bus_type) < 0)
+                    return;
+            }
         }
 
         if (info[i]->alias) {