Re: [PATCH 27/27] KVM: PPC: Add Documentation about PV interface

Benjamin Herrenschmidt
2010-07-03T22:41:49Z

On Fri, 2010-07-02 at 18:27 +0200, Segher Boessenkool wrote:
> > +To find out if we're running on KVM or not, we overlay the PVR
> > register. Usually
> > +the PVR register contains an id that identifies your CPU type. If,
> > however, you
> > +pass KVM_PVR_PARA in the register that you want the PVR result in,
> > the register
> > +still contains KVM_PVR_PARA after the mfpvr call.
> > +
> > + LOAD_REG_IMM(r5, KVM_PVR_PARA)
> > + mfpvr r5
> > + [r5 still contains KVM_PVR_PARA]
>
> I love this part :-)

Me not :-)

It should be in the device-tree instead, or something like that. Enough
games with PVR...

Ben.

> > + __u64 scratch3;
> > + __u64 critical; /* Guest may not get interrupts if == r1 */
> > + __u64 sprg0;
> > + __u64 sprg1;
> > + __u64 sprg2;
> > + __u64 sprg3;
> > + __u64 srr0;
> > + __u64 srr1;
> > + __u64 dar;
> > + __u64 msr;
> > + __u32 dsisr;
> > + __u32 int_pending; /* Tells the guest if we have an interrupt */
> > +};
> > +
> > +Additions to the page must only occur at the end. Struct fields
> > are always 32
> > +bit aligned.
>
> The u64s are 64-bit aligned, should they always be?
>
> > +The "ld" and "std" instructions are transormed to "lwz" and "stw"
> > instructions
> > +respectively on 32 bit systems with an added offset of 4 to
> > accomodate for big
> > +endianness.
>
> Will this add never overflow? Is there anything that checks for it?
>
> > +mtmsrd rX, 0 b <special mtmsr section>
> > +mtmsr b <special mtmsr section>
>
> mtmsr rX
>
>
> Segher
>
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