Re: [PATCH v2] KVM: Don't fail KVM_GET_SUPPORTED_CPUID if nent is just right

[Avi Kivity <avi@redhat.com>]

On 11/24/2011 01:53 PM, Sasha Levin wrote:
> On Thu, 2011-11-24 at 12:48 +0200, Avi Kivity wrote:
> > On 11/24/2011 12:45 PM, Sasha Levin wrote:
> > > If we pass just enough entries to KVM_GET_SUPPORTED_CPUID, we would still
> > > fail with -E2BIG due to wrong comparisons.
> > >
> > > Cc: Avi Kivity <avi@redhat.com>
> > > Cc: Marcelo Tosatti <mtosatti@redhat.com>
> > > Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
> > > ---
> > >  arch/x86/kvm/x86.c |    2 +-
> > >  1 files changed, 1 insertions(+), 1 deletions(-)
> > >
> > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> > > index 9eff4af..83fef71 100644
> > > --- a/arch/x86/kvm/x86.c
> > > +++ b/arch/x86/kvm/x86.c
> > > @@ -2710,7 +2710,7 @@ static int kvm_dev_ioctl_get_supported_cpuid(struct kvm_cpuid2 *cpuid,
> > >  		     cpuid->nent);
> > >  
> > >  	r = -E2BIG;
> > > -	if (nent >= cpuid->nent)
> > > +	if (nent > cpuid->nent)
> > >  		goto out_free;
> > >  
> > >
> > 
> > This is just a landmine for the next entry to be added there; surely
> > whoever adds it will forget to correct the > back to >=.
> > 
>
> Slapping a big warning before that should do the trick? Or maybe add
> something similar to 'final_nent = nent - 1;'?

Refactor the whole thing so all the repetitive code goes away.  Maybe
make it table driven.

But after my cpuid.c patch please, I'd hate to redo it.

-- 
error compiling committee.c: too many arguments to function