[PATCH 1/3] iommu/qcom: Invalidate the TLB in flush_iotlb_all

[Rob Clark]

On Fri, Oct 30, 2026 at 3:05 PM Dmitry Baryshkov
<dmitry.baryshkov at oss.qualcomm.com> wrote:
>
> qcom_iommu_flush_iotlb_all() only waits for a TLB sync and never
> invalidates anything. iommu_unmap() users do not notice, since
> io-pgtable invalidates each page through the gather, but drm/msm unmaps
> with a NULL gather and relies on flush_iotlb_all. On db410c the GPU then
> hangs on stale TLB entries as soon as another process reuses the IOVAs.
>
> Invalidate the whole context, as arm-smmu does, and keep iotlb_sync a
> plain sync.
>
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov at oss.qualcomm.com>

Reviewed-by: Rob Clark <rob.clark at oss.qualcomm.com>

> ---
>  drivers/iommu/arm/arm-smmu/qcom_iommu.c | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/iommu/arm/arm-smmu/qcom_iommu.c b/drivers/iommu/arm/arm-smmu/qcom_iommu.c
> index 21d18ce67b98..54130c32056a 100644
> --- a/drivers/iommu/arm/arm-smmu/qcom_iommu.c
> +++ b/drivers/iommu/arm/arm-smmu/qcom_iommu.c
> @@ -479,14 +479,22 @@ static void qcom_iommu_flush_iotlb_all(struct iommu_domain *domain)
>                 return;
>
>         pm_runtime_get_sync(qcom_domain->iommu->dev);
> -       qcom_iommu_tlb_sync(pgtable->cookie);
> +       qcom_iommu_tlb_inv_context(pgtable->cookie);
>         pm_runtime_put_sync(qcom_domain->iommu->dev);
>  }
>
>  static void qcom_iommu_iotlb_sync(struct iommu_domain *domain,
>                                   struct iommu_iotlb_gather *gather)
>  {
> -       qcom_iommu_flush_iotlb_all(domain);
> +       struct qcom_iommu_domain *qcom_domain = to_qcom_iommu_domain(domain);
> +       struct io_pgtable *pgtable = container_of(qcom_domain->pgtbl_ops,
> +                                                 struct io_pgtable, ops);
> +       if (!qcom_domain->pgtbl_ops)
> +               return;
> +
> +       pm_runtime_get_sync(qcom_domain->iommu->dev);
> +       qcom_iommu_tlb_sync(pgtable->cookie);
> +       pm_runtime_put_sync(qcom_domain->iommu->dev);
>  }
>
>  static phys_addr_t qcom_iommu_iova_to_phys(struct iommu_domain *domain,
>
> --
> 2.47.3
>