remoteproc: qcom: pas: Enable Secure PAS support with IOMMU managed by Linux

Most Qualcomm platforms feature Gunyah hypervisor, which typically
handles IOMMU configuration. This includes mapping memory regions and
device memory resources for remote processors by intercepting
qcom_scm_pas_auth_and_reset() calls. These mappings are later removed
during teardown. Additionally, SHM bridge setup is required to enable
memory protection for both remoteproc metadata and its memory regions.
When the aforementioned hypervisor is absent, the operating system must
perform these configurations instead.

When Linux runs as the hypervisor (@ EL2) on a SoC, it will have its
own device tree overlay file that specifies the firmware stream ID now
managed by Linux for a particular remote processor. If the iommus
property is specified in the remoteproc device tree node, it indicates
that IOMMU configuration must be handled by Linux. In this case, the
has_iommu flag is set for the remote processor, which ensures that the
resource table, carveouts, and SHM bridge are properly configured before
memory is passed to TrustZone for authentication. Otherwise, the
has_iommu flag remains unset, which indicates default behavior.

Enables Secure PAS support for remote processors when IOMMU configuration
is managed by Linux.

Signed-off-by: Mukesh Ojha <mukesh.ojha@oss.qualcomm.com>
Link: https://lore.kernel.org/r/20260105-kvmrprocv10-v10-13-022e96815380@oss.qualcomm.com
Signed-off-by: Bjorn Andersson <andersson@kernel.org>

Author: mukeshojha-linux

drivers/remoteproc/qcom_q6v5_pas.c

@@ -11,6 +11,7 @@
 #include <linux/delay.h>
 #include <linux/firmware.h>
 #include <linux/interrupt.h>
+#include <linux/iommu.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/of.h>
@@ -255,6 +256,22 @@ static int qcom_pas_load(struct rproc *rproc, const struct firmware *fw)
 	return ret;
 }
 
+static void qcom_pas_unmap_carveout(struct rproc *rproc, phys_addr_t mem_phys, size_t size)
+{
+	if (rproc->has_iommu)
+		iommu_unmap(rproc->domain, mem_phys, size);
+}
+
+static int qcom_pas_map_carveout(struct rproc *rproc, phys_addr_t mem_phys, size_t size)
+{
+	int ret = 0;
+
+	if (rproc->has_iommu)
+		ret = iommu_map(rproc->domain, mem_phys, mem_phys, size,
+				IOMMU_READ | IOMMU_WRITE, GFP_KERNEL);
+	return ret;
+}
+
 static int qcom_pas_start(struct rproc *rproc)
 {
 	struct qcom_pas *pas = rproc->priv;
@@ -289,11 +306,15 @@ static int qcom_pas_start(struct rproc *rproc)
 	}
 
 	if (pas->dtb_pas_id) {
-		ret = qcom_scm_pas_auth_and_reset(pas->dtb_pas_id);
+		ret = qcom_pas_map_carveout(rproc, pas->dtb_mem_phys, pas->dtb_mem_size);
+		if (ret)
+			goto disable_px_supply;
+
+		ret = qcom_scm_pas_prepare_and_auth_reset(pas->dtb_pas_ctx);
 		if (ret) {
 			dev_err(pas->dev,
 				"failed to authenticate dtb image and release reset\n");
-			goto disable_px_supply;
+			goto unmap_dtb_carveout;
 		}
 	}
 
@@ -304,18 +325,22 @@ static int qcom_pas_start(struct rproc *rproc)
 
 	qcom_pil_info_store(pas->info_name, pas->mem_phys, pas->mem_size);
 
-	ret = qcom_scm_pas_auth_and_reset(pas->pas_id);
+	ret = qcom_pas_map_carveout(rproc, pas->mem_phys, pas->mem_size);
+	if (ret)
+		goto release_pas_metadata;
+
+	ret = qcom_scm_pas_prepare_and_auth_reset(pas->pas_ctx);
 	if (ret) {
 		dev_err(pas->dev,
 			"failed to authenticate image and release reset\n");
-		goto release_pas_metadata;
+		goto unmap_carveout;
 	}
 
 	ret = qcom_q6v5_wait_for_start(&pas->q6v5, msecs_to_jiffies(5000));
 	if (ret == -ETIMEDOUT) {
 		dev_err(pas->dev, "start timed out\n");
 		qcom_scm_pas_shutdown(pas->pas_id);
-		goto release_pas_metadata;
+		goto unmap_carveout;
 	}
 
 	qcom_scm_pas_metadata_release(pas->pas_ctx);
@@ -327,10 +352,16 @@ static int qcom_pas_start(struct rproc *rproc)
 
 	return 0;
 
+unmap_carveout:
+	qcom_pas_unmap_carveout(rproc, pas->mem_phys, pas->mem_size);
 release_pas_metadata:
 	qcom_scm_pas_metadata_release(pas->pas_ctx);
 	if (pas->dtb_pas_id)
 		qcom_scm_pas_metadata_release(pas->dtb_pas_ctx);
+
+unmap_dtb_carveout:
+	if (pas->dtb_pas_id)
+		qcom_pas_unmap_carveout(rproc, pas->dtb_mem_phys, pas->dtb_mem_size);
 disable_px_supply:
 	if (pas->px_supply)
 		regulator_disable(pas->px_supply);
@@ -386,8 +417,12 @@ static int qcom_pas_stop(struct rproc *rproc)
 		ret = qcom_scm_pas_shutdown(pas->dtb_pas_id);
 		if (ret)
 			dev_err(pas->dev, "failed to shutdown dtb: %d\n", ret);
+
+		qcom_pas_unmap_carveout(rproc, pas->dtb_mem_phys, pas->dtb_mem_size);
 	}
 
+	qcom_pas_unmap_carveout(rproc, pas->mem_phys, pas->mem_size);
+
 	handover = qcom_q6v5_unprepare(&pas->q6v5);
 	if (handover)
 		qcom_pas_handover(&pas->q6v5);
@@ -738,6 +773,7 @@ static int qcom_pas_probe(struct platform_device *pdev)
 		return -ENOMEM;
 	}
 
+	rproc->has_iommu = of_property_present(pdev->dev.of_node, "iommus");
 	rproc->auto_boot = desc->auto_boot;
 	rproc_coredump_set_elf_info(rproc, ELFCLASS32, EM_NONE);
 
@@ -817,6 +853,8 @@ static int qcom_pas_probe(struct platform_device *pdev)
 		goto remove_ssr_sysmon;
 	}
 
+	pas->pas_ctx->use_tzmem = rproc->has_iommu;
+	pas->dtb_pas_ctx->use_tzmem = rproc->has_iommu;
 	ret = rproc_add(rproc);
 	if (ret)
 		goto remove_ssr_sysmon;