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

[Cornelia Huck]

On Wed, 16 Apr 2014 16:26:30 +0200
Alexander Graf <address@hidden> wrote:

> 
> On 16.04.14 16:25, Cornelia Huck wrote:
> > 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?
> 
> This only works when used inside a #define, since then the preprocessor 
> resolves __VA_ARGS__ :).

Obviously. That's where I got the error :)