[libvirt] [PATCH 7/7] qemu: Allow making vcpus hotpluggable with virDomainSetVcpusFlags

[Peter Krempa]

On Thu, Sep 29, 2016 at 17:37:53 +0530, Shivaprasad G Bhat wrote:
> 
> 
> On 09/29/2016 05:32 PM, Peter Krempa wrote:
> > On Thu, Sep 29, 2016 at 16:29:13 +0530, Shivaprasad G Bhat wrote:
> >> On 09/21/2016 05:19 PM, Peter Krempa wrote:
> >>> Implement support for VIR_DOMAIN_VCPU_HOTPLUGGABLE so that users can
> >>> choose to make vcpus added by the API removable.
> >>> ---
> >>>    src/qemu/qemu_driver.c | 22 ++++++++++++++++------
> >>>    1 file changed, 16 insertions(+), 6 deletions(-)
> >>>
> >>> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> >>> index 357be4e..8453628 100644
> >>> --- a/src/qemu/qemu_driver.c
> >>> +++ b/src/qemu/qemu_driver.c
> >>> @@ -4912,7 +4912,8 @@ qemuDomainSetVcpusLive(virQEMUDriverPtr driver,
> >>>     */
> >>>    static void
> >>>    qemuDomainSetVcpusConfig(virDomainDefPtr def,
> >>> -                         unsigned int nvcpus)
> >>> +                         unsigned int nvcpus,
> >>> +                         bool hotpluggable)
> >>>    {
> >>>        virDomainVcpuDefPtr vcpu;
> >> Here  if (curvcpus == nvcpus)
> >>
> >>                       return
> >>      we still need to allow if someone wants to switch from hotpluggable
> >> = yes to no/ vice versa.
> > No. As no new vcpus were added there's nothing to turn to hotpluggable.
> > The flag turns only the newly added vcpus as hotpluggable.
> 
> What if someone had the hotplug = yes. And He wants to make it "no".  ? 
> With no changes to the vcpus.

You can make two calls to the API, decreasing and re-increasing the
count. Or edit the XML directly since its a non-simple change. If the
API call would change existing vcpus to either hotpluggable or not it
would break configurations. Eg. as PPC requires first 8 vcpus to be non
hotpluggable vs. just one on intel.