Re: [Xen-devel] [RFC PATCH 27/49] ARM: new VGIC: Add MMIO handling framework

[Julien Grall <julien.grall@xxxxxxx>]

Hi Andre,

On 13/02/18 18:17, Andre Przywara wrote:
> On 13/02/18 16:52, Julien Grall wrote:
> > > +struct vgic_register_region {
> > > +    unsigned int reg_offset;
> > > +    unsigned int len;
> > > +    unsigned int bits_per_irq;
> > > +    unsigned int access_flags;
> > > +    union
> > > +    {
> > > +        unsigned long (*read)(struct vcpu *vcpu, paddr_t addr,
> > > +                              unsigned int len);
> > > +        unsigned long (*its_read)(struct domain *d, struct vgic_its
> > > *its,
> > > +                                  paddr_t addr, unsigned int len);
> > > +    };
> > > +    union
> > > +    {
> > > +        void (*write)(struct vcpu *vcpu, paddr_t addr,
> > > +                      unsigned int len, unsigned long val);
> > > +        void (*its_write)(struct domain *d, struct vgic_its *its,
> > > +                          paddr_t addr, unsigned int len,
> > > +                          unsigned long val);
> > > +    };
> > > +    unsigned long (*uaccess_read)(struct vcpu *vcpu, paddr_t addr,
> > > +                                  unsigned int len);
> > > +    union
> > > +    {
> > > +        void (*uaccess_write)(struct vcpu *vcpu, paddr_t addr,
> > > +                              unsigned int len, unsigned long val);
> > > +        int (*uaccess_its_write)(struct domain *d, struct vgic_its *its,
> > > +                                 paddr_t addr, unsigned int len,
> > > +                                 unsigned long val);
> > > +    };
> > I don't think uaccess helpers makes sense for Xen.
> True, I was unsure about whether to keep them. I have the gut feeling we
> need it later when we want to suspend/resume the VGIC, so removing
> everything and then simplifying the code afterwards might bite us in the
> future.
> So as long as it doesn't really hurt, I am tempted to keep that code in,
> which also keeps it closer the the KVM implementation.
I don't want to see code that is going to potentially rot. If we really 
need it, we can add it afterwards.
Cheers,

--
Julien Grall

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