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

Tomasz Nowicki
2017-05-15T12:47:25Z

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