On Thu, Jun 22, 2023 at 11:27:40AM +0200, AngeloGioacchino Del Regno wrote:
> This driver was indexing the contexts by asid-1, which is probably
> done under the assumption that the first ASID is always 1.
> Unfortunately this is not always true: at least for MSM8956 and
> MSM8976's GPU IOMMU, the gpu_user context's ASID number is zero.
> To allow using a zero asid number, index the contexts by `asid`
> instead of by `asid - 1`.
>
> While at it, also enhance human readability by renaming the
> `num_ctxs` member of struct qcom_iommu_dev to `max_asid`.
>
> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>
> ---
> drivers/iommu/arm/arm-smmu/qcom_iommu.c | 22 ++++++++++------------
> 1 file changed, 10 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/iommu/arm/arm-smmu/qcom_iommu.c b/drivers/iommu/arm/arm-smmu/qcom_iommu.c
> index f1bd7c035db8..9786fd094e7d 100644
> --- a/drivers/iommu/arm/arm-smmu/qcom_iommu.c
> +++ b/drivers/iommu/arm/arm-smmu/qcom_iommu.c
> @@ -51,8 +51,8 @@ struct qcom_iommu_dev {
> struct clk_bulk_data clks[CLK_NUM];
> void __iomem *local_base;
> u32 sec_id;
> - u8 num_ctxs;
> - struct qcom_iommu_ctx *ctxs[]; /* indexed by asid-1 */
> + u8 max_asid;
> + struct qcom_iommu_ctx *ctxs[]; /* indexed by asid */
> };
>
> struct qcom_iommu_ctx {
> @@ -94,7 +94,7 @@ static struct qcom_iommu_ctx * to_ctx(struct qcom_iommu_domain *d, unsigned asid
> struct qcom_iommu_dev *qcom_iommu = d->iommu;
> if (!qcom_iommu)
> return NULL;
> - return qcom_iommu->ctxs[asid - 1];
> + return qcom_iommu->ctxs[asid];
> }
>
> static inline void
> @@ -534,12 +534,10 @@ static int qcom_iommu_of_xlate(struct device *dev, struct of_phandle_args *args)
> qcom_iommu = platform_get_drvdata(iommu_pdev);
>
> /* make sure the asid specified in dt is valid, so we don't have
> - * to sanity check this elsewhere, since 'asid - 1' is used to
> - * index into qcom_iommu->ctxs:
> + * to sanity check this elsewhere:
> */
> - if (WARN_ON(asid < 1) ||
> - WARN_ON(asid > qcom_iommu->num_ctxs) ||
> - WARN_ON(qcom_iommu->ctxs[asid - 1] == NULL)) {
> + if (WARN_ON(asid > qcom_iommu->max_asid) ||
> + WARN_ON(qcom_iommu->ctxs[asid] == NULL)) {
> put_device(&iommu_pdev->dev);
> return -EINVAL;
> }
> @@ -696,7 +694,7 @@ static int qcom_iommu_ctx_probe(struct platform_device *pdev)
>
> dev_dbg(dev, "found asid %u\n", ctx->asid);
>
> - qcom_iommu->ctxs[ctx->asid - 1] = ctx;
> + qcom_iommu->ctxs[ctx->asid] = ctx;
>
> return 0;
> }
> @@ -708,7 +706,7 @@ static void qcom_iommu_ctx_remove(struct platform_device *pdev)
>
> platform_set_drvdata(pdev, NULL);
>
> - qcom_iommu->ctxs[ctx->asid - 1] = NULL;
> + qcom_iommu->ctxs[ctx->asid] = NULL;
> }
>
> static const struct of_device_id ctx_of_match[] = {
> @@ -755,11 +753,11 @@ static int qcom_iommu_device_probe(struct platform_device *pdev)
> for_each_child_of_node(dev->of_node, child)
> max_asid = max(max_asid, get_asid(child));
>
> - qcom_iommu = devm_kzalloc(dev, struct_size(qcom_iommu, ctxs, max_asid),
> + qcom_iommu = devm_kzalloc(dev, struct_size(qcom_iommu, ctxs, max_asid + 1),
> GFP_KERNEL);
So is this '+ 1' there to handle the case where ASIDs are indexed from 1? If
so, please add a comment because this isn't obvious at all.
Will
