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Subject[PATCH 5/8] iommu/arm-smmu-v3: Add second level of context descriptor table
Date
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@arm.com>
---
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
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