Re: [Xen-devel] [PATCH v15 17/21] x86/VPMU: Handle PMU interrupts for PV guests

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 17.11.14 at 00:07, <boris.ostrovsky@xxxxxxxxxx> wrote:
> +            if ( (vpmu_mode & XENPMU_MODE_SELF) )
> +                cur_regs = guest_cpu_user_regs();
> +            else if ( !guest_mode(regs) && 
> is_hardware_domain(sampling->domain) )
> +            {
> +                cur_regs = regs;
> +                domid = DOMID_XEN;
> +            }
> +            else
> +                cur_regs = guest_cpu_user_regs();

Of course it would be nice to do this with a single if/else pair.

> +            else
> +            {
> +                struct segment_register seg;
> +
> +                hvm_get_segment_register(sampled, x86_seg_cs, &seg);
> +                r->cs = seg.sel;
> +                hvm_get_segment_register(sampled, x86_seg_ss, &seg);
> +                r->ss = seg.sel;
> +                if ( seg.attr.fields.dpl != 0 )
> +                    *flags |= PMU_SAMPLE_USER;

Is that how hardware treats it (CPL != 0 meaning user, rather
than CPL == 3)? Maybe you should surface CPL instead of a
boolean flag?

Anyway, with or without the adjustments (unless you go a 3rd
way)
Acked-by: Jan Beulich <jbeulich@xxxxxxxx>

Jan


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