Re: [PATCH v5 01/10] hw/intc: GICv3 ITS initial framework

[Peter Maydell <peter.maydell@linaro.org>]

On Wed, 30 Jun 2021 at 16:32, Shashi Mallela <shashi.mallela@linaro.org> wrote:
>
> Added register definitions relevant to ITS,implemented overall
> ITS device framework with stubs for ITS control and translater
> regions read/write,extended ITS common to handle mmio init between
> existing kvm device and newer qemu device.
>
> Signed-off-by: Shashi Mallela <shashi.mallela@linaro.org>
> Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
> +static void gicv3_arm_its_realize(DeviceState *dev, Error **errp)
> +{
> +    GICv3ITSState *s = ARM_GICV3_ITS_COMMON(dev);
> +
> +    gicv3_its_init_mmio(s, &gicv3_its_control_ops, &gicv3_its_translation_ops);
> +
> +    if (s->gicv3->cpu->gicr_typer & GICR_TYPER_PLPIS) {

Can you remind me why we make this check, please? When would we
have created an ITS device but not have a GICv3 with LPI support?

Maybe it would be better to either
(a) simply create the ITS and assume that the board connected it up
to a GICv3 that supports it
(b) check every CPU for whether PLPIS is set, and if one of them does
not have it set then return an error from the ITS realize

?

(Found this by looking for code where we do s->gicv3->cpu->something...)

> +        /* set the ITS default features supported */
> +        s->typer = FIELD_DP64(s->typer, GITS_TYPER, PHYSICAL,
> +                              GITS_TYPE_PHYSICAL);
> +        s->typer = FIELD_DP64(s->typer, GITS_TYPER, ITT_ENTRY_SIZE,
> +                              ITS_ITT_ENTRY_SIZE - 1);
> +        s->typer = FIELD_DP64(s->typer, GITS_TYPER, IDBITS, ITS_IDBITS);
> +        s->typer = FIELD_DP64(s->typer, GITS_TYPER, DEVBITS, ITS_DEVBITS);
> +        s->typer = FIELD_DP64(s->typer, GITS_TYPER, CIL, 1);
> +        s->typer = FIELD_DP64(s->typer, GITS_TYPER, CIDBITS, ITS_CIDBITS);
> +    }
> +}
> +
> +static void gicv3_its_reset(DeviceState *dev)
> +{
> +    GICv3ITSState *s = ARM_GICV3_ITS_COMMON(dev);
> +    GICv3ITSClass *c = ARM_GICV3_ITS_GET_CLASS(s);
> +
> +    if (s->gicv3->cpu->gicr_typer & GICR_TYPER_PLPIS) {

Similarly here.

> +        c->parent_reset(dev);
> +
> +        /* Quiescent bit reset to 1 */
> +        s->ctlr = FIELD_DP32(s->ctlr, GITS_CTLR, QUIESCENT, 1);
> +
> +        /*
> +         * setting GITS_BASER0.Type = 0b001 (Device)
> +         *         GITS_BASER1.Type = 0b100 (Collection Table)
> +         *         GITS_BASER<n>.Type,where n = 3 to 7 are 0b00 (Unimplemented)
> +         *         GITS_BASER<0,1>.Page_Size = 64KB
> +         * and default translation table entry size to 16 bytes
> +         */
> +        s->baser[0] = FIELD_DP64(s->baser[0], GITS_BASER, TYPE,
> +                                 GITS_ITT_TYPE_DEVICE);
> +        s->baser[0] = FIELD_DP64(s->baser[0], GITS_BASER, PAGESIZE,
> +                                 GITS_BASER_PAGESIZE_64K);
> +        s->baser[0] = FIELD_DP64(s->baser[0], GITS_BASER, ENTRYSIZE,
> +                                 GITS_DTE_SIZE - 1);
> +
> +        s->baser[1] = FIELD_DP64(s->baser[1], GITS_BASER, TYPE,
> +                                 GITS_ITT_TYPE_COLLECTION);
> +        s->baser[1] = FIELD_DP64(s->baser[1], GITS_BASER, PAGESIZE,
> +                                 GITS_BASER_PAGESIZE_64K);
> +        s->baser[1] = FIELD_DP64(s->baser[1], GITS_BASER, ENTRYSIZE,
> +                                 GITS_CTE_SIZE - 1);
> +    }
> +}

thanks
-- PMM