Re: [Qemu-devel] [PATCH 2/3] migration: Allow "device add" options to only add migratable devices

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Ashijeet Acharya (ashijeetacharya@gmail.com) wrote:
> On Thu, Dec 15, 2016 at 9:35 PM, Dr. David Alan Gilbert
> <dgilbert@redhat.com> wrote:
> > * Ashijeet Acharya (ashijeetacharya@gmail.com) wrote:
> >> Introduce checks for the unmigratable flag in the VMStateDescription
> >> structs of respective devices when user attempts to add them. If the
> >> "--only-migratable" was specified, all unmigratable devices will
> >> rightly fail to add. This feature is made compatible for both "-device"
> >> and "-usbdevice" command line options and covers their hmp and qmp
> >> counterparts as well.
> >>
> >> Signed-off-by: Ashijeet Acharya <ashijeetacharya@gmail.com>
> >> ---
> >>  hw/usb/bus.c   | 15 +++++++++++++++
> >>  qdev-monitor.c |  9 +++++++++
> >>  2 files changed, 24 insertions(+)
> >>
> >> diff --git a/hw/usb/bus.c b/hw/usb/bus.c
> >> index 25913ad..8796788 100644
> >> --- a/hw/usb/bus.c
> >> +++ b/hw/usb/bus.c
> >> @@ -8,6 +8,7 @@
> >>  #include "monitor/monitor.h"
> >>  #include "trace.h"
> >>  #include "qemu/cutils.h"
> >> +#include "migration/migration.h"
> >>
> >>  static void usb_bus_dev_print(Monitor *mon, DeviceState *qdev, int indent);
> >>
> >> @@ -686,6 +687,8 @@ USBDevice *usbdevice_create(const char *cmdline)
> >>      const char *params;
> >>      int len;
> >>      USBDevice *dev;
> >> +    ObjectClass *klass;
> >> +    DeviceClass *dc;
> >>
> >>      params = strchr(cmdline,':');
> >>      if (params) {
> >> @@ -720,6 +723,18 @@ USBDevice *usbdevice_create(const char *cmdline)
> >>          return NULL;
> >>      }
> >>
> >> +    klass = object_class_by_name(f->name);
> >
> >> +    dc = DEVICE_CLASS(klass);
> >
> > Would qdev_get_device_class work here instead of that pair?
> 
> No, because I believe that is defined as static in qdev_monitor.c
> which was one of the reasons I faced a difficulty with this one.

Hmm, I wonder if Markus can suggest a better way; qdev_get_device_class
seems a lot more complex dealing iwth aliases and stuff, if we need that
type of stuff.

Dave

> > (I was thinking you needed to check klass to make sure it wasn't null)
> 
> Right. I will include the check in v2.
> 
> Ashijeet
> >
> >> +    if (only_migratable) {
> >> +        if (dc->vmsd->unmigratable) {
> >> +            error_report("Device %s is not migratable, but --only-migratable "
> >> +                         "was specified", f->name);
> >> +            return NULL;
> >> +        }
> >> +    }
> >> +
> >>      if (f->usbdevice_init) {
> >>          dev = f->usbdevice_init(bus, params);
> >>      } else {
> >> diff --git a/qdev-monitor.c b/qdev-monitor.c
> >> index c73410c..81d01df 100644
> >> --- a/qdev-monitor.c
> >> +++ b/qdev-monitor.c
> >> @@ -29,6 +29,7 @@
> >>  #include "qemu/error-report.h"
> >>  #include "qemu/help_option.h"
> >>  #include "sysemu/block-backend.h"
> >> +#include "migration/migration.h"
> >>
> >>  /*
> >>   * Aliases were a bad idea from the start.  Let's keep them
> >> @@ -577,6 +578,14 @@ DeviceState *qdev_device_add(QemuOpts *opts, Error **errp)
> >>          return NULL;
> >>      }
> >>
> >> +    if (only_migratable) {
> >> +        if (dc->vmsd->unmigratable) {
> >> +            error_setg(errp, "Device %s is not migratable, but "
> >> +                       "--only-migratable was specified", driver);
> >> +            return NULL;
> >> +        }
> >> +    }
> >> +
> >>      /* find bus */
> >>      path = qemu_opt_get(opts, "bus");
> >>      if (path != NULL) {
> >> --
> >> 2.6.2
> >>
> > --
> > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK