Re: [Qemu-devel] [PATCH v3 10/19] pc: register created initial and hotpluged CPUs in one place pc_cpu_plug()

[Eduardo Habkost]

On Wed, Jul 13, 2016 at 06:59:21PM -0400, Bandan Das wrote:
> Eduardo Habkost <address@hidden> writes:
> 
> > On Wed, Jul 13, 2016 at 06:32:27PM -0400, Bandan Das wrote:
> >> Igor Mammedov <address@hidden> writes:
> >> 
> >> > consolidate possible_cpus array management in pc_cpu_plug()
> >> > for smp_cpus, coldplugged with -device and hotplugged with
> >> > device_add.
> >> 
> >> So, this takes care of the hotplug case and 09/19 took care of the
> >> coldplug case, right ? If yes, we should probably modify this commit
> >> message a little.
> >
> > This makes pc_cpu_plug() take care of both: now it will handle
> > the coldplug case also (in addition to the hotplug case, that it
> > already handled). I don't understand what you mean.
> >
> > Are you talking about the rtc_set_memory() call, only? This seems
> > to be the only hotplug-specific code that still remains, in this
> 
> Right, I thought the rtc_set_memory() call in 09/19 takes care of the
> case when the user boots with "-device" and this takes care of the case
> when user invokes device_add, no ?

Yes for rtc_set_memory(). But the main purpose of this patch is
to reuse all the rest of pc_cpu_plug() (i.e. everything except
for the rtc_set_memory() call) for the coldplug CPUs too.

Note that I didn't review the patch completely, yet. The
replacement for the possible_cpus code looks OK, but I didn't
check if it is safe to call
HOTPLUG_HANDLER_GET_CLASS(pcms->acpi_dev)->plug() for coldplugged
CPUs too.

> 
> > patch.
> >
> >> 
> >> Bandan
> >> > Signed-off-by: Igor Mammedov <address@hidden>
> >> > ---
> >> >  hw/i386/pc.c | 25 +++++++++----------------
> >> >  1 file changed, 9 insertions(+), 16 deletions(-)
> >> >
> >> > diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> >> > index 3206572..0f85b56 100644
> >> > --- a/hw/i386/pc.c
> >> > +++ b/hw/i386/pc.c
> >> > @@ -1142,7 +1142,6 @@ void pc_cpus_init(PCMachineState *pcms)
> >> >          if (i < smp_cpus) {
> >> >              cpu = pc_new_cpu(typename, x86_cpu_apic_id_from_index(i),
> >> >                               &error_fatal);
> >> > -            pcms->possible_cpus->cpus[i].cpu = CPU(cpu);
> >> >              object_unref(OBJECT(cpu));
> >> >          }
> >> >      }
> >> > @@ -1697,25 +1696,19 @@ static void pc_cpu_plug(HotplugHandler 
> >> > *hotplug_dev,
> >> >      Error *local_err = NULL;
> >> >      PCMachineState *pcms = PC_MACHINE(hotplug_dev);
> >> >  
> >> > -    if (!dev->hotplugged) {
> >> > -        goto out;
> >> > -    }
> >> > -
> >> > -    if (!pcms->acpi_dev) {
> >> > -        error_setg(&local_err,
> >> > -                   "cpu hotplug is not enabled: missing acpi device");
> >> > -        goto out;
> >> > +    if (pcms->acpi_dev) {
> >> > +        hhc = HOTPLUG_HANDLER_GET_CLASS(pcms->acpi_dev);
> >> > +        hhc->plug(HOTPLUG_HANDLER(pcms->acpi_dev), dev, &local_err);
> >> > +        if (local_err) {
> >> > +            goto out;
> >> > +        }
> >> >      }
> >> >  
> >> > -    hhc = HOTPLUG_HANDLER_GET_CLASS(pcms->acpi_dev);
> >> > -    hhc->plug(HOTPLUG_HANDLER(pcms->acpi_dev), dev, &local_err);
> >> > -    if (local_err) {
> >> > -        goto out;
> >> > +    if (dev->hotplugged) {
> >> > +        /* increment the number of CPUs */
> >> > +        rtc_set_memory(pcms->rtc, 0x5f, rtc_get_memory(pcms->rtc, 0x5f) 
> >> > + 1);
> >> >      }
> >> >  
> >> > -    /* increment the number of CPUs */
> >> > -    rtc_set_memory(pcms->rtc, 0x5f, rtc_get_memory(pcms->rtc, 0x5f) + 
> >> > 1);
> >> > -
> >> >      found_cpu = pc_find_cpu_slot(pcms, CPU(dev), NULL);
> >> >      found_cpu->cpu = CPU(dev);
> >> >  out:

-- 
Eduardo