Re: [PATCH v5 14/32] hw/arm/smmuv3-accel: Install SMMUv3 GBPA based hwpt

[Zhangfei Gao <zhangfei.gao@linaro.org>]

Hi, Shameer

On Fri, 31 Oct 2025 at 18:53, Shameer Kolothum <skolothumtho@nvidia.com> wrote:
>
> When the Guest reboots or updates the GBPA we need to attach a nested HWPT
> based on the GBPA register values.
>
> Signed-off-by: Shameer Kolothum <skolothumtho@nvidia.com>
> ---
>  hw/arm/smmuv3-accel.c | 42 ++++++++++++++++++++++++++++++++++++++++++
>  hw/arm/smmuv3-accel.h |  8 ++++++++
>  hw/arm/smmuv3.c       |  2 ++
>  3 files changed, 52 insertions(+)
>
> diff --git a/hw/arm/smmuv3-accel.c b/hw/arm/smmuv3-accel.c
> index c74e95a0ea..0573ae3772 100644
> --- a/hw/arm/smmuv3-accel.c
> +++ b/hw/arm/smmuv3-accel.c
> @@ -479,6 +479,48 @@ static const PCIIOMMUOps smmuv3_accel_ops = {
>      .unset_iommu_device = smmuv3_accel_unset_iommu_device,
>  };
>
> +
> +/* Based on SMUUv3 GBPA configuration, attach a corresponding HWPT */
> +void smmuv3_accel_gbpa_update(SMMUv3State *s)
> +{
> +    SMMUv3AccelDevice *accel_dev;
> +    Error *local_err = NULL;
> +    SMMUViommu *vsmmu;
> +    uint32_t hwpt_id;
> +
> +    if (!s->accel || !s->s_accel->vsmmu) {
> +        return;
> +    }
> +
> +    vsmmu = s->s_accel->vsmmu;
> +    /*
> +     * The Linux kernel does not allow configuring GBPA MemAttr, MTCFG,
> +     * ALLOCCFG, SHCFG, PRIVCFG, or INSTCFG fields for a vSTE. Host kernel
> +     * has final control over these parameters. Hence, use one of the
> +     * pre-allocated HWPTs depending on GBPA.ABORT value.
> +     */
> +    if (s->gbpa & SMMU_GBPA_ABORT) {
> +        hwpt_id = vsmmu->abort_hwpt_id;
> +    } else {
> +        hwpt_id = vsmmu->bypass_hwpt_id;
> +    }
> +
> +    QLIST_FOREACH(accel_dev, &vsmmu->device_list, next) {
v4 has this, while v5 removes it.
             if (!accel_dev->vdev)
                continue;

So I got a warning when accel_dev->vdev = NULL in the beginning.
"Failed to attach GBPA hwpt id xx for dev id xx"

Thanks