Re: [Qemu-devel] [PATCH v2 13/15] qmp: Expose manual_dirty_log_protect via "query-kvm"

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

* Paolo Bonzini (pbonzini@redhat.com) wrote:
> On 20/05/19 05:08, Peter Xu wrote:
> > Expose the new capability via "query-kvm" QMP command too so we know
> > whether that's turned on on the source VM when we want.
> > 
> > Signed-off-by: Peter Xu <peterx@redhat.com>
> 
> Is this useful?  We could I guess make a migration capability in order
> to benchmark with the old code, but otherwise I would just make this a
> "hidden" optimization just like many others (same for patch 14).
> 
> In other words, there are many other capabilities that we could inform
> the user about, I don't see what makes manual_dirty_log_protect special.

Yes agreed, if your kernel has it then just use it.

Dave

> Paolo
> 
> > ---
> >  accel/kvm/kvm-all.c  | 5 +++++
> >  include/sysemu/kvm.h | 2 ++
> >  qapi/misc.json       | 6 +++++-
> >  qmp.c                | 1 +
> >  4 files changed, 13 insertions(+), 1 deletion(-)
> > 
> > diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
> > index 062bf8b5b0..c79d6b51e2 100644
> > --- a/accel/kvm/kvm-all.c
> > +++ b/accel/kvm/kvm-all.c
> > @@ -169,6 +169,11 @@ int kvm_memcrypt_encrypt_data(uint8_t *ptr, uint64_t len)
> >      return 1;
> >  }
> >  
> > +bool kvm_manual_dirty_log_protect_enabled(void)
> > +{
> > +    return kvm_state && kvm_state->manual_dirty_log_protect;
> > +}
> > +
> >  /* Must be with slots_lock held */
> >  static KVMSlot *kvm_get_free_slot(KVMMemoryListener *kml)
> >  {
> > diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h
> > index a6d1cd190f..30757f1425 100644
> > --- a/include/sysemu/kvm.h
> > +++ b/include/sysemu/kvm.h
> > @@ -547,4 +547,6 @@ int kvm_set_one_reg(CPUState *cs, uint64_t id, void *source);
> >  int kvm_get_one_reg(CPUState *cs, uint64_t id, void *target);
> >  struct ppc_radix_page_info *kvm_get_radix_page_info(void);
> >  int kvm_get_max_memslots(void);
> > +bool kvm_manual_dirty_log_protect_enabled(void);
> > +
> >  #endif
> > diff --git a/qapi/misc.json b/qapi/misc.json
> > index 8b3ca4fdd3..ce7a76755a 100644
> > --- a/qapi/misc.json
> > +++ b/qapi/misc.json
> > @@ -253,9 +253,13 @@
> >  #
> >  # @present: true if KVM acceleration is built into this executable
> >  #
> > +# @manual-dirty-log-protect: true if manual dirty log protect is enabled
> > +#
> >  # Since: 0.14.0
> >  ##
> > -{ 'struct': 'KvmInfo', 'data': {'enabled': 'bool', 'present': 'bool'} }
> > +{ 'struct': 'KvmInfo', 'data':
> > +  {'enabled': 'bool', 'present': 'bool',
> > +   'manual-dirty-log-protect': 'bool' } }
> >  
> >  ##
> >  # @query-kvm:
> > diff --git a/qmp.c b/qmp.c
> > index b92d62cd5f..047bef032e 100644
> > --- a/qmp.c
> > +++ b/qmp.c
> > @@ -73,6 +73,7 @@ KvmInfo *qmp_query_kvm(Error **errp)
> >  
> >      info->enabled = kvm_enabled();
> >      info->present = kvm_available();
> > +    info->manual_dirty_log_protect = kvm_manual_dirty_log_protect_enabled();
> >  
> >      return info;
> >  }
> > 
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK