Support default block interfaces per QEMUMachine

There are QEMUMachines that have neither IF_IDE nor IF_SCSI as a
default/standard interface to their block devices / drives. Therefore,
this patch introduces a new field default_block_type per QEMUMachine
struct. The prior use_scsi field becomes thereby obsolete and is
replaced through .default_block_type = IF_SCSI.

This patch also changes the default for s390x to IF_VIRTIO and
removes an early hack that converts IF_IDE drives.
Other parties have already claimed interest (e.g. IF_SD for exynos)

To create a sane default, for machines that dont specify a
default_block_type, this patch makes IF_IDE = 0 and IF_NONE = 1.
I checked all users of IF_NONE (blockdev.c and ww/device-hotplug.c)
as well as IF_IDE and it seems that it is ok to change the defines -
in other words, I found no obvious (to me) assumption in the code
regarding IF_NONE==0. IF_NONE is only set if there is an
explicit if=none. Without if=* the interface becomes IF_DEFAULT.

I would suggest to have some additional care, e.g. by letting
this patch sit some days in the block tree.

Based on an initial patch from Einar Lueck <elelueck@de.ibm.com>

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
CC: Igor Mitsyanko <i.mitsyanko@samsung.com>
CC: Markus Armbruster <armbru@redhat.com>
CC: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Alexander Graf <agraf@suse.de>
Acked-by: Igor Mitsyanko <i.mitsyanko@samsung.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

1 files changed, 12 insertions, 9 deletions

diff --git a/vl.c b/vl.c
index a3ab3841a7..ee10d21c78 100644
--- a/vl.c
+++ b/vl.c
@@ -886,9 +886,9 @@ static int cleanup_add_fd(QemuOpts *opts, void *opaque)
 
 static int drive_init_func(QemuOpts *opts, void *opaque)
 {
-    int *use_scsi = opaque;
+    BlockInterfaceType *block_default_type = opaque;
 
-    return drive_init(opts, *use_scsi) == NULL;
+    return drive_init(opts, *block_default_type) == NULL;
 }
 
 static int drive_enable_snapshot(QemuOpts *opts, void *opaque)
@@ -899,14 +899,15 @@ static int drive_enable_snapshot(QemuOpts *opts, void *opaque)
     return 0;
 }
 
-static void default_drive(int enable, int snapshot, int use_scsi,
+static void default_drive(int enable, int snapshot,
+                          BlockInterfaceType block_default_type,
                           BlockInterfaceType type, int index,
                           const char *optstr)
 {
     QemuOpts *opts;
 
     if (type == IF_DEFAULT) {
-        type = use_scsi ? IF_SCSI : IF_IDE;
+        type = block_default_type;
     }
 
     if (!enable || drive_get_by_index(type, index)) {
@@ -917,7 +918,7 @@ static void default_drive(int enable, int snapshot, int use_scsi,
     if (snapshot) {
         drive_enable_snapshot(opts, NULL);
     }
-    if (!drive_init(opts, use_scsi)) {
+    if (!drive_init(opts, type)) {
         exit(1);
     }
 }
@@ -3770,14 +3771,16 @@ int main(int argc, char **argv, char **envp)
     /* open the virtual block devices */
     if (snapshot)
         qemu_opts_foreach(qemu_find_opts("drive"), drive_enable_snapshot, NULL, 0);
-    if (qemu_opts_foreach(qemu_find_opts("drive"), drive_init_func, &machine->use_scsi, 1) != 0)
+    if (qemu_opts_foreach(qemu_find_opts("drive"), drive_init_func,
+                          &machine->block_default_type, 1) != 0) {
         exit(1);
+    }
 
-    default_drive(default_cdrom, snapshot, machine->use_scsi,
+    default_drive(default_cdrom, snapshot, machine->block_default_type,
                   IF_DEFAULT, 2, CDROM_OPTS);
-    default_drive(default_floppy, snapshot, machine->use_scsi,
+    default_drive(default_floppy, snapshot, machine->block_default_type,
                   IF_FLOPPY, 0, FD_OPTS);
-    default_drive(default_sdcard, snapshot, machine->use_scsi,
+    default_drive(default_sdcard, snapshot, machine->block_default_type,
                   IF_SD, 0, SD_OPTS);
 
     register_savevm_live(NULL, "ram", 0, 4, &savevm_ram_handlers, NULL);