Re: [RFC PATCH 07/30] iommu/arm-smmu-v3: Add second level of context descriptor table

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Hi Jean,

On 27.02.2017 20:54, Jean-Philippe Brucker wrote:
@@ -1213,17 +1356,59 @@ static void arm_smmu_free_cd_tables(struct arm_smmu_master_data *master)
 __maybe_unused
 static int arm_smmu_alloc_cd(struct arm_smmu_master_data *master)
 {
+	int ssid;
+	int i, ret;
 	struct arm_smmu_cd_cfg *cfg = &master->ste.cd_cfg;

-	return arm_smmu_bitmap_alloc(cfg->context_map, ilog2(cfg->num_entries));
+	if (cfg->linear)
+		return arm_smmu_bitmap_alloc(cfg->table.context_map,
+					     ilog2(cfg->num_entries));
+
+	/* Find first leaf table with an empty slot, or allocate a new leaf */
+	for (i = cfg->l1.cur_table; i < cfg->num_entries; i++) {
+		struct arm_smmu_cd_table *table = &cfg->l1.tables[i];
+
+		if (!table->cdptr) {
+			__le64 *l1ptr = cfg->l1.ptr + i * CTXDESC_L1_DESC_DWORD;
+
+			ret = arm_smmu_alloc_cd_leaf_table(master->smmu, table,
+							   CTXDESC_NUM_L2_ENTRIES);
+			if (ret)
+				return ret;
+
+			arm_smmu_write_cd_l1_desc(l1ptr, table);
+			arm_smmu_sync_cd(master, i << CTXDESC_SPLIT, false);
+		}
+
+		ssid = arm_smmu_bitmap_alloc(table->context_map, CTXDESC_SPLIT);
+		if (ssid < 0)
+			continue;
+
+		cfg->l1.cur_table = i;
+		return i << CTXDESC_SPLIT | ssid;
+	}
+
+	return -ENOSPC;
 }

 __maybe_unused
 static void arm_smmu_free_cd(struct arm_smmu_master_data *master, u32 ssid)
 {
+	unsigned long l1_idx, idx;
 	struct arm_smmu_cd_cfg *cfg = &master->ste.cd_cfg;

-	arm_smmu_bitmap_free(cfg->context_map, ssid);
+	if (cfg->linear) {
+		arm_smmu_bitmap_free(cfg->table.context_map, ssid);
+		return;
+	}
+
+	l1_idx = ssid >> CTXDESC_SPLIT;
+	idx = ssid & ((1 << CTXDESC_SPLIT) - 1);
+	arm_smmu_bitmap_free(cfg->l1.tables[l1_idx].context_map, idx);
+
+	/* Prepare next allocation */
+	if (cfg->l1.cur_table > idx)
+		cfg->l1.cur_table = idx;
 }

I am not sure what is the logic here. idx becomes index of l1.tables in arm_smmu_alloc_cd() which in turn may be out of allocated memory. I may miss something. Can you please elaborate on this?

Thanks,
Tomasz



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