iommu/arm-smmu: Allow client devices to select identity mapping

From: Jordan Crouse <[email protected]>

Some client devices want to directly map the IOMMU themselves instead of using the DMA domain. Allow those devices to opt in to direct mapping by way of a list of compatible strings.

Signed-off-by Jordan Crouse <[email protected]>

Co-developed-by Sai Prakash Ranjan <[email protected]>

Signed-off-by Sai Prakash Ranjan <[email protected]>

---
  drivers/iommu/arm-smmu-qcom.c | 19 +++++++++++++++++++
  drivers/iommu/arm-smmu.h      |  1 +
  2 files changed, 20 insertions(+)

drivers/iommu/arm-smmu-qcom.c +19 -0

index 64a4ab270ab7..5bedf21587a5 100644
@@ -3,6 +3,7 @@
   * Copyright (c) 2019, The Linux Foundation. All rights reserved.
   */
 
+#include <linux/of_device.h>
  #include <linux/qcom_scm.h>
 
  #include "arm-smmu.h"

@@ -11,6 +12,23 @@ struct qcom_smmu {
  	struct arm_smmu_device smmu;
  };
 
+static const struct of_device_id qcom_smmu_client_of_match[] = {
+	{ .compatible = "qcom,adreno" },
+	{ .compatible = "qcom,mdp4" },
+	{ .compatible = "qcom,mdss" },
+	{ .compatible = "qcom,sc7180-mdss" },
+	{ .compatible = "qcom,sdm845-mdss" },
+	{ }
+};
+
+static int qcom_smmu_def_domain_type(struct device *dev)
+{
+	const struct of_device_id *match =
+		of_match_device(qcom_smmu_client_of_match, dev);
+
+	return match ? IOMMU_DOMAIN_IDENTITY : 0;
+}
+
  static int qcom_sdm845_smmu500_reset(struct arm_smmu_device *smmu)
  {
  	int ret;

@@ -41,6 +59,7 @@ static int qcom_smmu500_reset(struct arm_smmu_device *smmu)
  }
 
  static const struct arm_smmu_impl qcom_smmu_impl = {
+	.def_domain_type = qcom_smmu_def_domain_type,
  	.reset = qcom_smmu500_reset,
  };
 

drivers/iommu/arm-smmu.h +1 -0

index 8d1cd54d82a6..d172c024be61 100644
@@ -386,6 +386,7 @@ struct arm_smmu_impl {
  	int (*init_context)(struct arm_smmu_domain *smmu_domain);
  	void (*tlb_sync)(struct arm_smmu_device *smmu, int page, int sync,
  			 int status);
+	int (*def_domain_type)(struct device *dev);
  };
 
  static inline void __iomem *arm_smmu_page(struct arm_smmu_device *smmu, int n)

Quoted 5 lines · Sai Prakash Ranjan

From: Jordan Crouse <[email protected]>

Some client devices want to directly map the IOMMU themselves instead of using the DMA domain. Allow those devices to opt in to direct mapping by way of a list of compatible strings.

Neat and tidy :)

Reviewed-by Robin Murphy <[email protected]>

Strictly, I think patch #3/6 should really have come before this one (with the header change moved accordingly), but don't bother resending just for that.

Implement the new def_domain_type call-back for the ARM SMMU driver. We need this to support requesting the domain type by the client devices.

Signed-off-by Sai Prakash Ranjan <[email protected]>

---
  drivers/iommu/arm-smmu.c | 12 ++++++++++++
  1 file changed, 12 insertions(+)

drivers/iommu/arm-smmu.c +12 -0

index e622f4e33379..b345a86085ce 100644
@@ -1609,6 +1609,17 @@ static void arm_smmu_get_resv_regions(struct device *dev,
  	iommu_dma_get_resv_regions(dev, head);
  }
 
+static int arm_smmu_def_domain_type(struct device *dev)
+{
+	struct arm_smmu_master_cfg *cfg = dev_iommu_priv_get(dev);
+	const struct arm_smmu_impl *impl = cfg->smmu->impl;
+
+	if (impl && impl->def_domain_type)
+		return impl->def_domain_type(dev);
+
+	return 0;
+}
+
  static struct iommu_ops arm_smmu_ops = {
  	.capable		= arm_smmu_capable,
  	.domain_alloc		= arm_smmu_domain_alloc,

@@ -1627,6 +1638,7 @@ static struct iommu_ops arm_smmu_ops = {
  	.of_xlate		= arm_smmu_of_xlate,
  	.get_resv_regions	= arm_smmu_get_resv_regions,
  	.put_resv_regions	= generic_iommu_put_resv_regions,
+	.def_domain_type	= arm_smmu_def_domain_type,
  	.pgsize_bitmap		= -1UL, /* Restricted during device attach */
  };
 

From: Sibi Sankar <[email protected]>

Request direct mapping for modem on platforms which don't have TrustZone (which programs the modem SIDs) to prevent the following global faults seen on Cheza/Trogdor:

arm-smmu 15000000.iommu: Unexpected global fault, this could be serious arm-smmu 15000000.iommu: GFSR 0x80000002, GFSYNR0 0x00000000,

			 GFSYNR1 0x00000781, GFSYNR2 0x00000000

arm-smmu 15000000.iommu: Unexpected global fault, this could be serious arm-smmu 15000000.iommu: GFSR 0x80000002, GFSYNR0 0x00000000,

			 GFSYNR1 0x00000461, GFSYNR2 0x00000000

Signed-off-by Sibi Sankar <[email protected]>

Signed-off-by Sai Prakash Ranjan <[email protected]>

---
  drivers/iommu/arm-smmu-qcom.c | 2 ++
  1 file changed, 2 insertions(+)

drivers/iommu/arm-smmu-qcom.c +2 -0

index 5bedf21587a5..cf01d0215a39 100644
@@ -17,7 +17,9 @@ static const struct of_device_id qcom_smmu_client_of_match[] = {
  	{ .compatible = "qcom,mdp4" },
  	{ .compatible = "qcom,mdss" },
  	{ .compatible = "qcom,sc7180-mdss" },
+	{ .compatible = "qcom,sc7180-mss-pil" },
  	{ .compatible = "qcom,sdm845-mdss" },
+	{ .compatible = "qcom,sdm845-mss-pil" },
  	{ }
  };
 

Quoted 5 lines · Sai Prakash Ranjan

From: Sibi Sankar <[email protected]>

Request direct mapping for modem on platforms which don't have TrustZone (which programs the modem SIDs) to prevent the following global faults seen on Cheza/Trogdor:

Not strictly true - it's patch #6/6 that prevents *those* faults (and these days the driver should be reporting unmatched streams a little more helpfully). This change would resolve the context faults and/or weird memory corruption that might result from applying patch #6 alone
- this is the crazy thing where transactions sometimes go directly to DRAM round the side of the SMMU so we can never safely remap anything, right?