[PATCH 5/8] iommu/arm-smmu-v3: Add second level of context descriptor table

[Jean-Philippe Brucker]

The SMMU can support up to 20 bits of SSID. Add a second level of page
tables to accommodate this. Devices that support more than 1024 SSIDs now
have a table of 1024 L1 entries (8kB), pointing to tables of 1024 context
descriptors (64kB), allocated on demand.

Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@xxxxxxx>
---
 drivers/iommu/arm-smmu-v3.c | 136 +++++++++++++++++++++++++++++++++---
 1 file changed, 128 insertions(+), 8 deletions(-)

diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
index d90eb604b65d..326b71793336 100644
--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c
@@ -216,6 +216,8 @@
 
 #define STRTAB_STE_0_S1FMT		GENMASK_ULL(5, 4)
 #define STRTAB_STE_0_S1FMT_LINEAR	0
+#define STRTAB_STE_0_S1FMT_4K_L2	1
+#define STRTAB_STE_0_S1FMT_64K_L2	2
 #define STRTAB_STE_0_S1CTXPTR_MASK	GENMASK_ULL(51, 6)
 #define STRTAB_STE_0_S1CDMAX		GENMASK_ULL(63, 59)
 
@@ -255,6 +257,18 @@
 
 #define STRTAB_STE_3_S2TTB_MASK		GENMASK_ULL(51, 4)
 
+/*
+ * Linear: when less than 1024 SSIDs are supported
+ * 2lvl: at most 1024 L1 entrie,
+ *      1024 lazy entries per table.
+ */
+#define CTXDESC_SPLIT			10
+#define CTXDESC_NUM_L2_ENTRIES		(1 << CTXDESC_SPLIT)
+
+#define CTXDESC_L1_DESC_DWORD		1
+#define CTXDESC_L1_DESC_VALID		1
+#define CTXDESC_L1_DESC_L2PTR_MASK	GENMASK_ULL(51, 12)
+
 /* Context descriptor (stage-1 only) */
 #define CTXDESC_CD_DWORDS		8
 #define CTXDESC_CD_0_TCR_T0SZ		GENMASK_ULL(5, 0)
@@ -530,7 +544,10 @@ struct arm_smmu_ctx_desc {
 struct arm_smmu_s1_cfg {
 	u8				s1fmt;
 	u8				s1cdmax;
-	struct arm_smmu_cd_table	table;
+	struct arm_smmu_cd_table	*tables;
+	size_t				num_tables;
+	__le64				*l1ptr;
+	dma_addr_t			l1ptr_dma;
 
 	/* Context descriptor 0, when substreams are disabled or s1dss = 0b10 */
 	struct arm_smmu_ctx_desc	cd;
@@ -1118,12 +1135,51 @@ static void arm_smmu_free_cd_leaf_table(struct arm_smmu_device *smmu,
 {
 	size_t size = num_entries * (CTXDESC_CD_DWORDS << 3);
 
+	if (!table->ptr)
+		return;
 	dmam_free_coherent(smmu->dev, size, table->ptr, table->ptr_dma);
 }
 
-static __le64 *arm_smmu_get_cd_ptr(struct arm_smmu_s1_cfg *cfg, u32 ssid)
+static void arm_smmu_write_cd_l1_desc(__le64 *dst,
+				      struct arm_smmu_cd_table *table)
 {
-	return cfg->table.ptr + ssid * CTXDESC_CD_DWORDS;
+	u64 val = (table->ptr_dma & CTXDESC_L1_DESC_L2PTR_MASK) |
+		  CTXDESC_L1_DESC_VALID;
+
+	*dst = cpu_to_le64(val);
+}
+
+static __le64 *arm_smmu_get_cd_ptr(struct arm_smmu_domain *smmu_domain,
+				   u32 ssid)
+{
+	unsigned int idx;
+	struct arm_smmu_cd_table *table;
+	struct arm_smmu_device *smmu = smmu_domain->smmu;
+	struct arm_smmu_s1_cfg *cfg = &smmu_domain->s1_cfg;
+
+	if (cfg->s1fmt == STRTAB_STE_0_S1FMT_LINEAR) {
+		table = &cfg->tables[0];
+		idx = ssid;
+	} else {
+		idx = ssid >> CTXDESC_SPLIT;
+		if (idx >= cfg->num_tables)
+			return NULL;
+
+		table = &cfg->tables[idx];
+		if (!table->ptr) {
+			__le64 *l1ptr = cfg->l1ptr + idx * CTXDESC_L1_DESC_DWORD;
+
+			if (arm_smmu_alloc_cd_leaf_table(smmu, table,
+							 CTXDESC_NUM_L2_ENTRIES))
+				return NULL;
+
+			arm_smmu_write_cd_l1_desc(l1ptr, table);
+			/* An invalid L1 entry is allowed to be cached */
+			arm_smmu_sync_cd(smmu_domain, ssid, false);
+		}
+		idx = ssid & (CTXDESC_NUM_L2_ENTRIES - 1);
+	}
+	return table->ptr + idx * CTXDESC_CD_DWORDS;
 }
 
 static u64 arm_smmu_cpu_tcr_to_cd(u64 tcr)
@@ -1149,7 +1205,7 @@ static int arm_smmu_write_ctx_desc(struct arm_smmu_domain *smmu_domain,
 	u64 val;
 	bool cd_live;
 	struct arm_smmu_device *smmu = smmu_domain->smmu;
-	__le64 *cdptr = arm_smmu_get_cd_ptr(&smmu_domain->s1_cfg, ssid);
+	__le64 *cdptr = arm_smmu_get_cd_ptr(smmu_domain, ssid);
 
 	/*
 	 * This function handles the following cases:
@@ -1213,20 +1269,81 @@ static int arm_smmu_write_ctx_desc(struct arm_smmu_domain *smmu_domain,
 static int arm_smmu_alloc_cd_tables(struct arm_smmu_domain *smmu_domain,
 				    struct arm_smmu_master *master)
 {
+	int ret;
+	size_t size = 0;
+	size_t max_contexts, num_leaf_entries;
 	struct arm_smmu_device *smmu = smmu_domain->smmu;
 	struct arm_smmu_s1_cfg *cfg = &smmu_domain->s1_cfg;
 
 	cfg->s1fmt = STRTAB_STE_0_S1FMT_LINEAR;
 	cfg->s1cdmax = master->ssid_bits;
-	return arm_smmu_alloc_cd_leaf_table(smmu, &cfg->table, 1 << cfg->s1cdmax);
+
+	max_contexts = 1 << cfg->s1cdmax;
+	if (!(smmu->features & ARM_SMMU_FEAT_2_LVL_CDTAB) ||
+	    max_contexts <= CTXDESC_NUM_L2_ENTRIES) {
+		cfg->s1fmt = STRTAB_STE_0_S1FMT_LINEAR;
+		cfg->num_tables = 1;
+		num_leaf_entries = max_contexts;
+	} else {
+		cfg->s1fmt = STRTAB_STE_0_S1FMT_64K_L2;
+		/*
+		 * SSID[S1CDmax-1:10] indexes 1st-level table, SSID[9:0] indexes
+		 * 2nd-level
+		 */
+		cfg->num_tables = max_contexts / CTXDESC_NUM_L2_ENTRIES;
+
+		size = cfg->num_tables * (CTXDESC_L1_DESC_DWORD << 3);
+		cfg->l1ptr = dmam_alloc_coherent(smmu->dev, size,
+						 &cfg->l1ptr_dma,
+						 GFP_KERNEL | __GFP_ZERO);
+		if (!cfg->l1ptr) {
+			dev_warn(smmu->dev, "failed to allocate L1 context table\n");
+			return -ENOMEM;
+		}
+
+		num_leaf_entries = CTXDESC_NUM_L2_ENTRIES;
+	}
+
+	cfg->tables = devm_kzalloc(smmu->dev, sizeof(struct arm_smmu_cd_table) *
+				   cfg->num_tables, GFP_KERNEL);
+	if (!cfg->tables)
+		return -ENOMEM;
+
+	ret = arm_smmu_alloc_cd_leaf_table(smmu, &cfg->tables[0], num_leaf_entries);
+	if (ret)
+		goto err_free_l1;
+
+	if (cfg->l1ptr)
+		arm_smmu_write_cd_l1_desc(cfg->l1ptr, &cfg->tables[0]);
+
+	return 0;
+
+err_free_l1:
+	if (cfg->l1ptr)
+		dmam_free_coherent(smmu->dev, size, cfg->l1ptr, cfg->l1ptr_dma);
+	devm_kfree(smmu->dev, cfg->tables);
+	return ret;
 }
 
 static void arm_smmu_free_cd_tables(struct arm_smmu_domain *smmu_domain)
 {
+	int i;
 	struct arm_smmu_device *smmu = smmu_domain->smmu;
 	struct arm_smmu_s1_cfg *cfg = &smmu_domain->s1_cfg;
+	size_t num_leaf_entries = 1 << cfg->s1cdmax;
+	struct arm_smmu_cd_table *table = cfg->tables;
+
+	if (cfg->l1ptr) {
+		size_t size = cfg->num_tables * (CTXDESC_L1_DESC_DWORD << 3);
 
-	arm_smmu_free_cd_leaf_table(smmu, &cfg->table, 1 << cfg->s1cdmax);
+		dmam_free_coherent(smmu->dev, size, cfg->l1ptr,
+				   cfg->l1ptr_dma);
+		num_leaf_entries = CTXDESC_NUM_L2_ENTRIES;
+	}
+
+	for (i = 0; i < cfg->num_tables; i++, table++)
+		arm_smmu_free_cd_leaf_table(smmu, table, num_leaf_entries);
+	devm_kfree(smmu->dev, cfg->tables);
 }
 
 /* Stream table manipulation functions */
@@ -1346,6 +1463,9 @@ static void arm_smmu_write_strtab_ent(struct arm_smmu_master *master, u32 sid,
 	}
 
 	if (s1_cfg) {
+		dma_addr_t ptr_dma = s1_cfg->l1ptr ? s1_cfg->l1ptr_dma :
+			             s1_cfg->tables[0].ptr_dma;
+
 		BUG_ON(ste_live);
 		dst[1] = cpu_to_le64(
 			 FIELD_PREP(STRTAB_STE_1_S1DSS, STRTAB_STE_1_S1DSS_SSID0) |
@@ -1358,7 +1478,7 @@ static void arm_smmu_write_strtab_ent(struct arm_smmu_master *master, u32 sid,
 		   !(smmu->features & ARM_SMMU_FEAT_STALL_FORCE))
 			dst[1] |= cpu_to_le64(STRTAB_STE_1_S1STALLD);
 
-		val |= (s1_cfg->table.ptr_dma & STRTAB_STE_0_S1CTXPTR_MASK) |
+		val |= (ptr_dma & STRTAB_STE_0_S1CTXPTR_MASK) |
 			FIELD_PREP(STRTAB_STE_0_CFG, STRTAB_STE_0_CFG_S1_TRANS) |
 			FIELD_PREP(STRTAB_STE_0_S1CDMAX, s1_cfg->s1cdmax) |
 			FIELD_PREP(STRTAB_STE_0_S1FMT, s1_cfg->s1fmt);
@@ -1815,7 +1935,7 @@ static void arm_smmu_domain_free(struct iommu_domain *domain)
 	if (smmu_domain->stage == ARM_SMMU_DOMAIN_S1) {
 		struct arm_smmu_s1_cfg *cfg = &smmu_domain->s1_cfg;
 
-		if (cfg->table.ptr) {
+		if (cfg->tables) {
 			arm_smmu_free_cd_tables(smmu_domain);
 			arm_smmu_bitmap_free(smmu->asid_map, cfg->cd.asid);
 		}
-- 
2.21.0