Re: [Xen-devel] [PATCH] x86/HVM: improve a few state load checks

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

> -----Original Message-----
> From: Andrew Cooper
> Sent: 16 July 2018 15:08
> To: Paul Durrant <Paul.Durrant@xxxxxxxxxx>; 'Jan Beulich'
> <JBeulich@xxxxxxxx>; xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxxx>
> Subject: Re: [PATCH] x86/HVM: improve a few state load checks
> 
> On 16/07/18 15:05, Paul Durrant wrote:
> >> --- a/xen/arch/x86/hvm/hvm.c
> >> +++ b/xen/arch/x86/hvm/hvm.c
> >> @@ -976,14 +976,13 @@ unsigned long hvm_cr4_guest_valid_bits(c
> >>
> >>  static int hvm_load_cpu_ctxt(struct domain *d, hvm_domain_context_t
> *h)
> >>  {
> >> -    int vcpuid;
> >> +    unsigned int vcpuid = hvm_load_instance(h);
> >>      struct vcpu *v;
> >>      struct hvm_hw_cpu ctxt;
> >>      struct segment_register seg;
> >>      const char *errstr;
> >>
> >>      /* Which vcpu is this? */
> >> -    vcpuid = hvm_load_instance(h);
> >>      if ( vcpuid >= d->max_vcpus || (v = d->vcpu[vcpuid]) == NULL )
> > This open coded pattern:
> >
> > vcpuid = hvm_load_instance(h);
> > if ( vcpuid >= d->max_vcpus || (v = d->vcpu[vcpuid]) == NULL )
> > { ...
> >
> > seems to be repeated an awful lot. Is it time, perhaps, to introduce a
> helper function that incorporates the check?
> 
> In some copious free time when I can post v2 of my "fix max_vcpus"
> series, all of this logic (and much more) will become redundant and get
> culled.
> 
> I really wouldn't waste time re-factoring it at this point.

Ok. If that's the case then...

Reviewed-by: Paul Durrant <paul.durrant@xxxxxxxxxx>

> 
> ~Andrew
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