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Subject[PATCH v3 4/6] iommu/qcom: Index contexts by asid number to allow asid 0
Date
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`.

Signed-off-by: Marijn Suijten <marijn.suijten@somainline.org>
[Marijn: Rebased over next-20221111]
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
---
drivers/iommu/arm/arm-smmu/qcom_iommu.c | 24 ++++++++++++------------
1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/drivers/iommu/arm/arm-smmu/qcom_iommu.c b/drivers/iommu/arm/arm-smmu/qcom_iommu.c
index 49f4308f1bd2..94f51cafee17 100644
--- a/drivers/iommu/arm/arm-smmu/qcom_iommu.c
+++ b/drivers/iommu/arm/arm-smmu/qcom_iommu.c
@@ -52,7 +52,7 @@ struct qcom_iommu_dev {
void __iomem *local_base;
u32 sec_id;
u8 num_ctxs;
- struct qcom_iommu_ctx *ctxs[]; /* indexed by asid-1 */
+ 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
@@ -563,12 +563,10 @@ 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->num_ctxs) ||
+ WARN_ON(qcom_iommu->ctxs[asid] == NULL)) {
put_device(&iommu_pdev->dev);
return -EINVAL;
}
@@ -726,7 +724,7 @@ 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;
}
@@ -738,7 +736,7 @@ static int 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;

return 0;
}
@@ -779,7 +777,7 @@ static int qcom_iommu_device_probe(struct platform_device *pdev)
struct device *dev = &pdev->dev;
struct resource *res;
struct clk *clk;
- int ret, max_asid = 0;
+ int ret, num_ctxs, max_asid = 0;

/* find the max asid (which is 1:1 to ctx bank idx), so we know how
* many child ctx devices we have:
@@ -787,11 +785,13 @@ 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),
+ num_ctxs = max_asid + 1;
+
+ qcom_iommu = devm_kzalloc(dev, struct_size(qcom_iommu, ctxs, num_ctxs),
GFP_KERNEL);
if (!qcom_iommu)
return -ENOMEM;
- qcom_iommu->num_ctxs = max_asid;
+ qcom_iommu->num_ctxs = num_ctxs;
qcom_iommu->dev = dev;

res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
--
2.38.1
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