Re: [Xen-devel] [PATCH v2] ignore writes to GICD_ICACTIVER ... GICD_ICACTIVERN

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Fri, 4 Dec 2015, Julien Grall wrote:
> Hi Stefano:
> 
> Can you please add xen/arm in the commit title?
> 
> On 04/12/2015 12:36, Stefano Stabellini wrote:
> > Injecting a fault to the guest just because it is writing to one of the
> > GICD_ICACTIVER registers, which are part of the GICv2 and GICv3 specs,
> > is harsh. Additionally it causes recent linux kernels to fail to boot on
> > Xen.
> > 
> > Ignore writes to GICD_ICACTIVER ... GICD_ICACTIVERN instead, to solve
> > the boot issue and for backportability. However implementing the
> > registers properly might a better long term solution.
> > 
> > Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> > 
> > ---
> > 
> > Changes in v2:
> > - rebase on staging
> > 
> > diff --git a/xen/arch/arm/vgic-v2.c b/xen/arch/arm/vgic-v2.c
> > index 2c73133..3079901 100644
> > --- a/xen/arch/arm/vgic-v2.c
> > +++ b/xen/arch/arm/vgic-v2.c
> > @@ -494,11 +494,10 @@ static int vgic_v2_distr_mmio_write(struct vcpu *v,
> > mmio_info_t *info,
> >           return 0;
> > 
> >       case VRANGE32(GICD_ICACTIVER, GICD_ICACTIVERN):
> > -        if ( dabt.size != DABT_WORD ) goto bad_width;
> > -        printk(XENLOG_G_ERR
> > +        gdprintk(XENLOG_DEBUG,
> 
> Why did you  move to gdprintk? The vCPU is already printed using %pv in the
> string.

Because this is a log message which is directly caused by guest
behaviour, so it makes more sense to be to be a gdprintk


> >                  "%pv: vGICD: unhandled word write %#"PRIregister" to
> > ICACTIVER%d\n",
> >                  v, r, gicd_reg - GICD_ICACTIVER);
> > -        return 0;
> > +        goto write_ignore_32;
> > 
> >       case VRANGE32(GICD_IPRIORITYR, GICD_IPRIORITYRN):
> >       {
> > diff --git a/xen/arch/arm/vgic-v3.c b/xen/arch/arm/vgic-v3.c
> > index 985e866..6011e9e 100644
> > --- a/xen/arch/arm/vgic-v3.c
> > +++ b/xen/arch/arm/vgic-v3.c
> > @@ -621,11 +621,10 @@ static int __vgic_v3_distr_common_mmio_write(const
> > char *name, struct vcpu *v,
> >           return 0;
> > 
> >       case VRANGE32(GICD_ICACTIVER, GICD_ICACTIVERN):
> > -        if ( dabt.size != DABT_WORD ) goto bad_width;
> > -        printk(XENLOG_G_ERR
> > +        gdprintk(XENLOG_DEBUG,
> 
> Ditto
> 
> >                  "%pv: %s: unhandled word write %#"PRIregister" to
> > ICACTIVER%d\n",
> >                  v, name, r, reg - GICD_ICACTIVER);
> > -        return 0;
> > +        goto write_ignore_32;
> > 
> >       case VRANGE32(GICD_IPRIORITYR, GICD_IPRIORITYRN):
> >       {
> > 
> 
> Regards,
> 
> -- 
> Julien Grall
> 

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