Re: [Xen-devel] [PATCH v2 12/15] xen/arm: gic: Store the necessary HW information per vGIC ...

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

On Tue, 2015-06-30 at 14:38 +0100, Julien Grall wrote:
> Hi Ian,
> 
> On 30/06/15 13:56, Ian Campbell wrote:
> > On Fri, 2015-06-26 at 10:34 +0100, Julien Grall wrote:
> >> ... in order to decouple the vGIC driver from the GIC driver.
> >>
> >> Each vGIC HW structure contains a boolean to indicate if the current GIC is
> >> able to support this specific version of virtual GIC.
> >>
> >> Helpers have been introduced in order to help the GIC to setup correctly
> >> the vGIC. The GIC will have to call them to announce the support of this
> >> specific version.
> >>
> > 
> > "...to help the GIC correctly setup the vGIC"
> > 
> > "...to announce support for this specific version"
> > 
> > 
> >> Also drop fields that become unecessary in each global state.
> > 
> > "unnecessary"
> 
> I will fix it in the next version.
> 
> >> @@ -228,6 +232,55 @@ static inline int vgic_allocate_spi(struct domain *d)
> >>  
> >>  extern void vgic_free_virq(struct domain *d, unsigned int virq);
> >>  
> >> +struct vgic_v2_hw_config
> >> +{
> >> +    bool_t enabled;
> >> +    /* Distributor interface address */
> >> +    paddr_t dbase;
> >> +    /* CPU interface address */
> >> +    paddr_t cbase;
> >> +    /* Virtual CPU interface address */
> >> +    paddr_t vbase;
> >> +};
> >> +
> >> +extern struct vgic_v2_hw_config vgic_v2_hw;
> > 
> > My inclination is to call this either vgic_v2_hwdom(_config) (since it
> > is vgic config for the hw dom) or to call it gic_v2_hw_config (since it
> > contains config info of the physical gic which we happen to be going to
> > use for vgic).
> > 
> > I think given the expected usage the former makes more sense.
> 
> I think that the 2 names don't work for the usage of the structure:
>       - vgic_v2_hwdom: vbase is used to map the guest CPU interface into the
> virtual CPU interface
>       - gic_v2_hw_config: it gives the impression to be physical GIC specific
> rather the virtual GIC.
> 
> I would prefer to stick in vgic_v2_hw_config which show that we use it
> for the virtual GIC.

OK.


> >> +
> >> +static inline void vgic_v2_setup_hw(paddr_t dbase, paddr_t cbase,
> >> +                                    paddr_t vbase)
> >> +{
> >> +    vgic_v2_hw.enabled = 1;
> >> +    vgic_v2_hw.dbase = dbase;
> >> +    vgic_v2_hw.cbase = cbase;
> >> +    vgic_v2_hw.vbase = vbase;
> >> +}
> > 
> > If you were to move this out of line into vgic-v2.c would that mean that
> > vgic_v2_hw_config etc could be static to that file?
> 
> No, we have to access the field enabled in domain_vgic_init to verify
> the GIC is supporting the version of the vGIC.

That's a shame.

vgic_vN_init would have been the ideal place to test for this, which
would have kept everything in one place, but you've just nuked that and
I suppose don't want it coming back.

It was the inclusion of <asm/gic_v3_defs.h> into vgic.h which took me
down the line of thinking of wanting to make this self contained, and in
particular exposing struct rdist_region.

Ian.


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