[PATCH 5/6] iommu/qcom: Index contexts by asid number to allow asid 0

Konrad Dybcio
2022-05-27T21:39:02Z

From: AngeloGioacchino Del Regno <angelogioacchino.delregno@somainline.org>

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 entirely true: at least in the MSM8956
and MSM8976 GPU IOMMU, the gpu_user context's ASID number is zero.
To allow using an asid number of zero, stop indexing the contexts
by asid-1 and rather index them by asid.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@somainline.org>
Signed-off-by: Marijn Suijten <marijn.suijten@somainline.org>
Signed-off-by: Konrad Dybcio <konrad.dybcio@somainline.org>
---
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 530aa92bf6a1..4fefbab15b71 100644
--- a/drivers/iommu/arm/arm-smmu/qcom_iommu.c
+++ b/drivers/iommu/arm/arm-smmu/qcom_iommu.c
@@ -53,7 +53,7 @@ struct qcom_iommu_dev {
u32 sec_id;
u8 num_ctxs;
bool use_aarch64_pt;
- struct qcom_iommu_ctx *ctxs[]; /* indexed by asid-1 */
+ struct qcom_iommu_ctx *ctxs[]; /* indexed by asid */
};

struct qcom_iommu_ctx {
@@ -95,7 +95,7 @@ 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
@@ -614,12 +614,10 @@ 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;
}
@@ -778,7 +776,7 @@ 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;
}
@@ -790,7 +788,7 @@ 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;
}
@@ -828,7 +826,7 @@ 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:
@@ -836,11 +834,13 @@ 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);
--
2.36.1