Re: [Qemu-devel] [PATCH 2/9] kvm: add kvm_enable_cap_{vm,vcpu}

[Cornelia Huck]

On Wed, 16 Apr 2014 13:58:31 +0200
Cornelia Huck <address@hidden> wrote:

> On Wed, 16 Apr 2014 13:38:27 +0200
> Alexander Graf <address@hidden> wrote:
> 
> > 
> > On 16.04.2014, at 13:22, Alexander Graf <address@hidden> wrote:
> > 
> > > 
> > > On 14.04.14 18:48, Cornelia Huck wrote:
> > >> Provide helper functions for enabling capabilities (on a vcpu and on a 
> > >> vm).
> > >> 
> > >> Reviewed-by: Thomas Huth <address@hidden>
> > >> Signed-off-by: Cornelia Huck <address@hidden>
> > >> ---
> > >>  include/sysemu/kvm.h |    4 ++++
> > >>  kvm-all.c            |   33 ++++++++++++++++++++++++++++++++-
> > >>  2 files changed, 36 insertions(+), 1 deletion(-)
> > >> 
> > >> diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h
> > >> index 0bee1e8..2ff5ad3 100644
> > >> --- a/include/sysemu/kvm.h
> > >> +++ b/include/sysemu/kvm.h
> > >> @@ -294,6 +294,10 @@ bool kvm_arch_stop_on_emulation_error(CPUState 
> > >> *cpu);
> > >>    int kvm_check_extension(KVMState *s, unsigned int extension);
> > >>  +int kvm_enable_cap_vm(KVMState *s, unsigned int capability, ...);
> > >> +
> > >> +int kvm_enable_cap_vcpu(CPUState *cpu, unsigned int capability, ...);
> > >> +
> > >>  uint32_t kvm_arch_get_supported_cpuid(KVMState *env, uint32_t function,
> > >>                                        uint32_t index, int reg);
> > >>  diff --git a/kvm-all.c b/kvm-all.c
> > >> index cd4111d..658e50c 100644
> > >> --- a/kvm-all.c
> > >> +++ b/kvm-all.c
> > >> @@ -501,7 +501,38 @@ int kvm_check_extension(KVMState *s, unsigned int 
> > >> extension)
> > >>      return ret;
> > >>  }
> > >>  -static int kvm_set_ioeventfd_mmio(int fd, hwaddr addr, uint32_t val,
> > >> +int kvm_enable_cap_vm(KVMState *s, unsigned int capability, ...)
> > >> +{
> > >> +    struct kvm_enable_cap cap = {};
> > >> +    va_list ap;
> > >> +    int i;
> > >> +
> > >> +    cap.cap = capability;
> > >> +    va_start(ap, capability);
> > >> +    for (i = 0; i < 4; i++) {
> > >> +        cap.args[i] = va_arg(ap, uint64_t);
> > > 
> > > Is this legit? Can we just pull items off the stack without running 
> > > beyond?
> > 
> > For inspiration on how to know the number of arguments that got passed in, 
> > check out
> > 
> >   http://git.qemu.org/?p=qemu.git;a=blob;f=include/sysemu/device_tree.h#l40
> 
> Ah, that is probably better than splattering args with random stuff.
> Will try.
>  
Huh, how does

<integer type> array[] = { __VA_ARGS__ };

even compile? On both i386 and s390, I get "initialization makes
integer from pointer without a cast" - is arm different?