iommu/arm-smmu-v3: Add stall support for platform devices

The SMMU provides a Stall model for handling page faults in platform
devices. It is similar to PCIe PRI, but doesn't require devices to have
their own translation cache. Instead, faulting transactions are parked
and the OS is given a chance to fix the page tables and retry the
transaction.

Enable stall for devices that support it (opt-in by firmware). When an
event corresponds to a translation error, call the IOMMU fault handler.
If the fault is recoverable, it will call us back to terminate or
continue the stall.

To use stall device drivers need to enable IOMMU_DEV_FEAT_IOPF, which
initializes the fault queue for the device.
Tested-by: Zhangfei Gao <zhangfei.gao@linaro.org>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Link: https://lore.kernel.org/r/20210526161927.24268-4-jean-philippe@linaro.orgSigned-off-by: Will Deacon <will@kernel.org>

drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c

@@ -435,9 +435,13 @@ bool arm_smmu_sva_supported(struct arm_smmu_device *smmu)
 	return true;
 }
 
-static bool arm_smmu_iopf_supported(struct arm_smmu_master *master)
+bool arm_smmu_master_iopf_supported(struct arm_smmu_master *master)
 {
-	return false;
+	/* We're not keeping track of SIDs in fault events */
+	if (master->num_streams != 1)
+		return false;
+
+	return master->stall_enabled;
 }
 
 bool arm_smmu_master_sva_supported(struct arm_smmu_master *master)
@@ -445,8 +449,8 @@ bool arm_smmu_master_sva_supported(struct arm_smmu_master *master)
 	if (!(master->smmu->features & ARM_SMMU_FEAT_SVA))
 		return false;
 
-	/* SSID and IOPF support are mandatory for the moment */
-	return master->ssid_bits && arm_smmu_iopf_supported(master);
+	/* SSID support is mandatory for the moment */
+	return master->ssid_bits;
 }
 
 bool arm_smmu_master_sva_enabled(struct arm_smmu_master *master)
@@ -459,13 +463,55 @@ bool arm_smmu_master_sva_enabled(struct arm_smmu_master *master)
 	return enabled;
 }
 
+static int arm_smmu_master_sva_enable_iopf(struct arm_smmu_master *master)
+{
+	int ret;
+	struct device *dev = master->dev;
+
+	/*
+	 * Drivers for devices supporting PRI or stall should enable IOPF first.
+	 * Others have device-specific fault handlers and don't need IOPF.
+	 */
+	if (!arm_smmu_master_iopf_supported(master))
+		return 0;
+
+	if (!master->iopf_enabled)
+		return -EINVAL;
+
+	ret = iopf_queue_add_device(master->smmu->evtq.iopf, dev);
+	if (ret)
+		return ret;
+
+	ret = iommu_register_device_fault_handler(dev, iommu_queue_iopf, dev);
+	if (ret) {
+		iopf_queue_remove_device(master->smmu->evtq.iopf, dev);
+		return ret;
+	}
+	return 0;
+}
+
+static void arm_smmu_master_sva_disable_iopf(struct arm_smmu_master *master)
+{
+	struct device *dev = master->dev;
+
+	if (!master->iopf_enabled)
+		return;
+
+	iommu_unregister_device_fault_handler(dev);
+	iopf_queue_remove_device(master->smmu->evtq.iopf, dev);
+}
+
 int arm_smmu_master_enable_sva(struct arm_smmu_master *master)
 {
+	int ret;
+
 	mutex_lock(&sva_lock);
-	master->sva_enabled = true;
+	ret = arm_smmu_master_sva_enable_iopf(master);
+	if (!ret)
+		master->sva_enabled = true;
 	mutex_unlock(&sva_lock);
 
-	return 0;
+	return ret;
 }
 
 int arm_smmu_master_disable_sva(struct arm_smmu_master *master)
@@ -476,6 +522,7 @@ int arm_smmu_master_disable_sva(struct arm_smmu_master *master)
 		mutex_unlock(&sva_lock);
 		return -EBUSY;
 	}
+	arm_smmu_master_sva_disable_iopf(master);
 	master->sva_enabled = false;
 	mutex_unlock(&sva_lock);
 

drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h

@@ -354,6 +354,13 @@
 #define CMDQ_PRI_1_GRPID		GENMASK_ULL(8, 0)
 #define CMDQ_PRI_1_RESP			GENMASK_ULL(13, 12)
 
+#define CMDQ_RESUME_0_RESP_TERM		0UL
+#define CMDQ_RESUME_0_RESP_RETRY	1UL
+#define CMDQ_RESUME_0_RESP_ABORT	2UL
+#define CMDQ_RESUME_0_RESP		GENMASK_ULL(13, 12)
+#define CMDQ_RESUME_0_SID		GENMASK_ULL(63, 32)
+#define CMDQ_RESUME_1_STAG		GENMASK_ULL(15, 0)
+
 #define CMDQ_SYNC_0_CS			GENMASK_ULL(13, 12)
 #define CMDQ_SYNC_0_CS_NONE		0
 #define CMDQ_SYNC_0_CS_IRQ		1
@@ -370,6 +377,25 @@
 
 #define EVTQ_0_ID			GENMASK_ULL(7, 0)
 
+#define EVT_ID_TRANSLATION_FAULT	0x10
+#define EVT_ID_ADDR_SIZE_FAULT		0x11
+#define EVT_ID_ACCESS_FAULT		0x12
+#define EVT_ID_PERMISSION_FAULT		0x13
+
+#define EVTQ_0_SSV			(1UL << 11)
+#define EVTQ_0_SSID			GENMASK_ULL(31, 12)
+#define EVTQ_0_SID			GENMASK_ULL(63, 32)
+#define EVTQ_1_STAG			GENMASK_ULL(15, 0)
+#define EVTQ_1_STALL			(1UL << 31)
+#define EVTQ_1_PnU			(1UL << 33)
+#define EVTQ_1_InD			(1UL << 34)
+#define EVTQ_1_RnW			(1UL << 35)
+#define EVTQ_1_S2			(1UL << 39)
+#define EVTQ_1_CLASS			GENMASK_ULL(41, 40)
+#define EVTQ_1_TT_READ			(1UL << 44)
+#define EVTQ_2_ADDR			GENMASK_ULL(63, 0)
+#define EVTQ_3_IPA			GENMASK_ULL(51, 12)
+
 /* PRI queue */
 #define PRIQ_ENT_SZ_SHIFT		4
 #define PRIQ_ENT_DWORDS			((1 << PRIQ_ENT_SZ_SHIFT) >> 3)
@@ -462,6 +488,13 @@ struct arm_smmu_cmdq_ent {
 			enum pri_resp		resp;
 		} pri;
 
+		#define CMDQ_OP_RESUME		0x44
+		struct {
+			u32			sid;
+			u16			stag;
+			u8			resp;
+		} resume;
+
 		#define CMDQ_OP_CMD_SYNC	0x46
 		struct {
 			u64			msiaddr;
@@ -520,6 +553,7 @@ struct arm_smmu_cmdq_batch {
 
 struct arm_smmu_evtq {
 	struct arm_smmu_queue		q;
+	struct iopf_queue		*iopf;
 	u32				max_stalls;
 };
 
@@ -657,7 +691,9 @@ struct arm_smmu_master {
 	struct arm_smmu_stream		*streams;
 	unsigned int			num_streams;
 	bool				ats_enabled;
+	bool				stall_enabled;
 	bool				sva_enabled;
+	bool				iopf_enabled;
 	struct list_head		bonds;
 	unsigned int			ssid_bits;
 };
@@ -675,6 +711,7 @@ struct arm_smmu_domain {
 	struct mutex			init_mutex; /* Protects smmu pointer */
 
 	struct io_pgtable_ops		*pgtbl_ops;
+	bool				stall_enabled;
 	atomic_t			nr_ats_masters;
 
 	enum arm_smmu_domain_stage	stage;
@@ -716,6 +753,7 @@ bool arm_smmu_master_sva_supported(struct arm_smmu_master *master);
 bool arm_smmu_master_sva_enabled(struct arm_smmu_master *master);
 int arm_smmu_master_enable_sva(struct arm_smmu_master *master);
 int arm_smmu_master_disable_sva(struct arm_smmu_master *master);
+bool arm_smmu_master_iopf_supported(struct arm_smmu_master *master);
 struct iommu_sva *arm_smmu_sva_bind(struct device *dev, struct mm_struct *mm,
 				    void *drvdata);
 void arm_smmu_sva_unbind(struct iommu_sva *handle);
@@ -747,6 +785,11 @@ static inline int arm_smmu_master_disable_sva(struct arm_smmu_master *master)
 	return -ENODEV;
 }
 
+static inline bool arm_smmu_master_iopf_supported(struct arm_smmu_master *master)
+{
+	return false;
+}
+
 static inline struct iommu_sva *
 arm_smmu_sva_bind(struct device *dev, struct mm_struct *mm, void *drvdata)
 {