Re: [Xen-devel] [PATCH v5 20/21] xen/arm: add SGI handling for GICv3

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Thu, 12 Jun 2014, Stefano Stabellini wrote:
> On Thu, 12 Jun 2014, vijay.kilari@xxxxxxxxx wrote:
> > +static int vgicv3_to_sgi(struct vcpu *v, register_t sgir)
> > +{
> > +    int virq;
> > +    int irqmode;
> > +    enum gic_sgi_mode sgi_mode;
> > +    unsigned long vcpu_mask = 0;
> > +
> > +    irqmode = (sgir >> ICH_SGI_IRQMODE_SHIFT) & ICH_SGI_IRQMODE_MASK;
> > +    virq = (sgir >> ICH_SGI_IRQ_SHIFT ) & ICH_SGI_IRQ_MASK;
> > +    vcpu_mask = sgir & ICH_SGI_TARGETLIST_MASK;
> > +
> > +    /* Map GIC sgi value to enum value */
> > +    switch ( irqmode )
> > +    {
> > +    case ICH_SGI_TARGET_LIST:
> > +        sgi_mode = SGI_TARGET_LIST;
> > +        break;
> > +    case ICH_SGI_TARGET_OTHERS:
> > +        sgi_mode = SGI_TARGET_OTHERS;
> > +        break;
> > +    default:
> > +        BUG();
> 
> If this field can be written by the guest than a BUG is a mistake (a
> guest could crash the hypervisor).
> 

It would be nice to add a comment to the code like:

/* XXX: ignoring affinity 1, 2, 3 */


> > +    }
> > +
> > +    return vgic_to_sgi(v, sgir, sgi_mode, virq, vcpu_mask);
> > +}
> > +
> > +int vgic_emulate(struct cpu_user_regs *regs, union hsr hsr)
> > +{
> > +    struct vcpu *v = current;
> > +    struct hsr_sysreg sysreg = hsr.sysreg;
> > +    register_t *r = select_user_reg(regs, sysreg.reg);
> > +
> > +    ASSERT (hsr.ec == HSR_EC_SYSREG);
> > +
> > +    switch ( hsr.bits & HSR_SYSREG_REGS_MASK )
> > +    {
> > +    case HSR_SYSREG_ICC_SGI1R_EL1:
> > +        /* WO */
> > +        if ( !sysreg.read )
> > +            return vgicv3_to_sgi(v, *r);
> > +        else
> > +        {
> > +            gdprintk(XENLOG_WARNING, "Reading SGI1R_EL1 - WO register\n");
> > +            return 0;
> > +        }
> > +    default:
> > +        return 0;
> > +    }
> > +}
> > +
> >  static const struct mmio_handler_ops vgic_rdistr_mmio_handler = {
> >      .read_handler  = vgic_v3_rdistr_mmio_read,
> >      .write_handler = vgic_v3_rdistr_mmio_write,
> 

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