Re: [Qemu-devel] [PATCH] kvm: don't register smram_listener when smm is off

[Gonglei (Arei)]

> -----Original Message-----
> From: Paolo Bonzini [mailto:address@hidden
> Sent: Thursday, June 01, 2017 6:04 PM
> To: Gonglei (Arei); address@hidden
> Cc: Yechuan
> Subject: Re: [PATCH] kvm: don't register smram_listener when smm is off
> 
> 
> 
> On 27/05/2017 08:10, Gonglei wrote:
> > If the user set disable smm by '-machine smm=off', we
> > should not register smram_listener so that we can
> > avoid waster memory in kvm since the added sencond
> > address space.
> >
> > Meanwhile we should assign value of the global kvm_state
> > before invoking the kvm_arch_init(), because
> > pc_machine_is_smm_enabled() may use it by kvm_has_mm().
> >
> > Signed-off-by: Gonglei <address@hidden>
> > ---
> >  kvm-all.c         | 4 ++--
> >  target/i386/kvm.c | 3 ++-
> >  2 files changed, 4 insertions(+), 3 deletions(-)
> >
> > diff --git a/kvm-all.c b/kvm-all.c
> > index 90b8573..92bdf2c 100644
> > --- a/kvm-all.c
> > +++ b/kvm-all.c
> > @@ -1746,6 +1746,8 @@ static int kvm_init(MachineState *ms)
> >      kvm_ioeventfd_any_length_allowed =
> >          (kvm_check_extension(s, KVM_CAP_IOEVENTFD_ANY_LENGTH) >
> 0);
> >
> > +    kvm_state = s;
> > +
> >      ret = kvm_arch_init(ms, s);
> >      if (ret < 0) {
> >          goto err;
> > @@ -1755,8 +1757,6 @@ static int kvm_init(MachineState *ms)
> >          kvm_irqchip_create(ms, s);
> >      }
> >
> > -    kvm_state = s;
> > -
> >      if (kvm_eventfds_allowed) {
> >          s->memory_listener.listener.eventfd_add =
> kvm_mem_ioeventfd_add;
> >          s->memory_listener.listener.eventfd_del =
> kvm_mem_ioeventfd_del;
> > diff --git a/target/i386/kvm.c b/target/i386/kvm.c
> > index 011d4a5..cb5b47e 100644
> > --- a/target/i386/kvm.c
> > +++ b/target/i386/kvm.c
> > @@ -1254,7 +1254,8 @@ int kvm_arch_init(MachineState *ms, KVMState
> *s)
> >          }
> >      }
> >
> > -    if (kvm_check_extension(s, KVM_CAP_X86_SMM)) {
> > +    if (kvm_check_extension(s, KVM_CAP_X86_SMM) &&
> > +            pc_machine_is_smm_enabled(PC_MACHINE(ms))) {
> >          smram_machine_done.notify = register_smram_listener;
> >
> qemu_add_machine_init_done_notifier(&smram_machine_done);
> >      }
> >
> 
> I think this breaks
> 
>     x86_64-softmmu/qemu-system-x86_64 -M none -S --enable-kvm
> 
> You need to do a object_dynamic_cast before invoking PC_MACHINE(ms).
> 
Good catch! V2 will be posted soon.

Thanks,
-Gonglei