Re: [Qemu-devel] [PATCH 07/13] target/arm/kvm: max cpu: Allow sve max vector length setting

[Andrew Jones]

On Mon, May 13, 2019 at 10:19:25AM -0700, Richard Henderson wrote:
> On 5/12/19 1:36 AM, Andrew Jones wrote:
> > @@ -292,7 +292,7 @@ static void aarch64_max_initfn(Object *obj)
> >  
> >      if (kvm_enabled()) {
> >          kvm_arm_set_cpu_features_from_host(cpu);
> > -        cpu->sve_max_vq = ARM_MAX_VQ;
> > +        cpu->sve_max_vq = -1; /* set in kvm_arch_init_vcpu() */
> 
> Perhaps a better comment is "unspecified, to be finalized in ..."

OK

> 
> > +    object_property_add(obj, "sve-max-vq", "uint32", cpu_max_get_sve_vq,
> > +                        cpu_max_set_sve_vq, NULL, NULL, &error_fatal);
> 
> as one can set it here, via the command-line.
> 
> > @@ -644,6 +702,24 @@ int kvm_arch_init_vcpu(CPUState *cs)
> >      }
> >  
> >      if (cpu->sve_max_vq) {
> > +        uint64_t sve_vls[KVM_ARM64_SVE_VLS_WORDS];
> > +        ret = kvm_arm_get_sve_vls(cs, sve_vls);
> > +        if (ret < 0) {
> > +            return ret;
> > +        }
> > +        if (cpu->sve_max_vq == -1) {
> > +            cpu->sve_max_vq = ret;
> 
> You still cannot set a value larger than ARM_MAX_VQ, as that is the fixed
> amount of space allocated within the cpu structure.
>

Good point. I should check against ARM_MAX_VQ here.

Thanks,
drew