Re: [Xen-devel] [PATCH v8a 5/6] xen/arm: split vgic driver into generic and vgic-v2 driver

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Thu, 2014-07-03 at 13:57 +0100, Julien Grall wrote:

> > +struct vgic_ops {
> > +    /* Initialize vGIC */
> > +    int (*vcpu_init)(struct vcpu *v);
> > +    /* Domain specific initialization of vGIC */
> > +    int (*domain_init)(struct domain *d);
> > +    /* SGI handler of vGIC */
> > +    int (*send_sgi)(struct vcpu *v, register_t sgir);
> 
> By reviewing the VGIC-v3 support, I still don't think this is the right
> callback to add. You bypass the VGIC common emulation with your
> vgic_emulate...
> 
> I would introduce a callback to emulate_sysreg rather than this send_sgi.

Why? The vgic will either be v2 or v3, so either MMIO or sysreg, once
the thing has been decoded then you want to send an SGI I think, hence
the callback. Passing a register_t does seem odd though, I'd have
thought it would take an SGI number and any other flags which would then
be interpreted for either v2 or v3 as appropriate.

Although thinking about it now: Given that a guest can't mix gic v2 and
v3 why is the send sgi exposed outside of the respective files at all? I
suppose it's because it goes via the core gic code?

Ian.


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