Re: [Xen-devel] [PATCH v8 15/19] x86/VPMU: Merge vpmu_rdmsr and vpmu_wrmsr

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

On 07/29/2014 03:46 AM, Jan Beulich wrote:
> > > > On 01.07.14 at 16:37, <boris.ostrovsky@xxxxxxxxxx> wrote:
> > @@ -99,13 +99,21 @@ int vpmu_do_wrmsr(unsigned int msr, uint64_t msr_content)
> >       if ( !(vpmu_mode & XENPMU_MODE_ON) )
> >           return 0;
> >   
> > -    if ( vpmu->arch_vpmu_ops && vpmu->arch_vpmu_ops->do_wrmsr )
> > +    ASSERT((rw == VPMU_MSR_READ) || (rw == VPMU_MSR_WRITE));
> > +
> > +    if ( vpmu->arch_vpmu_ops )
> >       {
> > -        int ret = vpmu->arch_vpmu_ops->do_wrmsr(msr, msr_content);
> > +        int ret;
> >   
> > +        if ( (rw == VPMU_MSR_READ) && vpmu->arch_vpmu_ops->do_rdmsr )
> > +            ret = vpmu->arch_vpmu_ops->do_rdmsr(msr, msr_content);
> > +        else if ( vpmu->arch_vpmu_ops->do_wrmsr )
> > +            ret = vpmu->arch_vpmu_ops->do_wrmsr(msr, *msr_content);
> This won't do what you intend if rw == VPMU_MSR_READ but there's
> no ->do_rdmsr handler.
Right.

I was actually thinking about dropping checks for ops altogether 
(everywhere) and adding nop ops when needed (I think cpuid is the only one).
But if I do this it will be sometime later.


-boris


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