Subject: [PATCH v6 2/5] iommu/arm-smmu: Add support for TTBR1

From: Jordan Crouse <[email-masked]>
Date: Thu, 9 Apr 2020 17:33:47 -0600

Add support to enable TTBR1 if the domain requests it via the
DOMAIN_ATTR_SPLIT_TABLES attribute. If enabled by the hardware
and pagetable configuration the driver will configure the TTBR1 region
and program the domain pagetable on TTBR1. TTBR0 will be disabled.

After attaching the device the value of he domain attribute can
be queried to see if the split pagetables were successfully programmed.
The domain geometry will be updated as well so that the caller can
determine the active region for the pagetable that was programmed.

Signed-off-by: Jordan Crouse <[email-masked]>
---

 drivers/iommu/arm-smmu.c | 48 ++++++++++++++++++++++++++++++++++------
 drivers/iommu/arm-smmu.h | 24 +++++++++++++++-----
 2 files changed, 59 insertions(+), 13 deletions(-)

diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index a6a5796e9c41..db6d503c1673 100644
--- a/drivers/iommu/arm-smmu.c
+++ b/drivers/iommu/arm-smmu.c
@@ -555,11 +555,16 @@ static void arm_smmu_init_context_bank(struct arm_smmu_domain *smmu_domain,
 			cb->ttbr[0] = pgtbl_cfg->arm_v7s_cfg.ttbr;
 			cb->ttbr[1] = 0;
 		} else {
-			cb->ttbr[0] = pgtbl_cfg->arm_lpae_s1_cfg.ttbr;
-			cb->ttbr[0] |= FIELD_PREP(ARM_SMMU_TTBRn_ASID,
-						  cfg->asid);
-			cb->ttbr[1] = FIELD_PREP(ARM_SMMU_TTBRn_ASID,
-						 cfg->asid);
+			cb->ttbr[0] = FIELD_PREP(ARM_SMMU_TTBRn_ASID,
+				cfg->asid);
+
+			if (pgtbl_cfg->quirks & IO_PGTABLE_QUIRK_ARM_TTBR1) {
+				cb->ttbr[1] = pgtbl_cfg->arm_lpae_s1_cfg.ttbr;
+			} else {
+				cb->ttbr[0] |= pgtbl_cfg->arm_lpae_s1_cfg.ttbr;
+				cb->ttbr[1] = FIELD_PREP(ARM_SMMU_TTBRn_ASID,
+							 cfg->asid);
+			}
 		}
 	} else {
 		cb->ttbr[0] = pgtbl_cfg->arm_lpae_s2_cfg.vttbr;
@@ -673,6 +678,7 @@ static int arm_smmu_init_domain_context(struct iommu_domain *domain,
 	enum io_pgtable_fmt fmt;
 	struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
 	struct arm_smmu_cfg *cfg = &smmu_domain->cfg;
+	unsigned long quirks = 0;
 
 	mutex_lock(&smmu_domain->init_mutex);
 	if (smmu_domain->smmu)
@@ -741,6 +747,14 @@ static int arm_smmu_init_domain_context(struct iommu_domain *domain,
 		oas = smmu->ipa_size;
 		if (cfg->fmt == ARM_SMMU_CTX_FMT_AARCH64) {
 			fmt = ARM_64_LPAE_S1;
+
+			/*
+			 * We are assuming that split pagetables will always use
+			 * SEP_UPSTREAM so we don't need to reduce the size of
+			 * the ias to account for the sign extension bit
+			 */
+			if (smmu_domain->split_pagetables)
+				quirks |= IO_PGTABLE_QUIRK_ARM_TTBR1;
 		} else if (cfg->fmt == ARM_SMMU_CTX_FMT_AARCH32_L) {
 			fmt = ARM_32_LPAE_S1;
 			ias = min(ias, 32UL);
@@ -810,6 +824,7 @@ static int arm_smmu_init_domain_context(struct iommu_domain *domain,
 		.coherent_walk	= smmu->features & ARM_SMMU_FEAT_COHERENT_WALK,
 		.tlb		= smmu_domain->flush_ops,
 		.iommu_dev	= smmu->dev,
+		.quirks		= quirks,
 	};
 
 	if (smmu_domain->non_strict)
@@ -823,8 +838,16 @@ static int arm_smmu_init_domain_context(struct iommu_domain *domain,
 
 	/* Update the domain's page sizes to reflect the page table format */
 	domain->pgsize_bitmap = pgtbl_cfg.pgsize_bitmap;
-	domain->geometry.aperture_end = (1UL << ias) - 1;
-	domain->geometry.force_aperture = true;
+
+	if (pgtbl_cfg.quirks & IO_PGTABLE_QUIRK_ARM_TTBR1) {
+		domain->geometry.aperture_start = ~0UL << ias;
+		domain->geometry.aperture_end = ~0UL;
+		domain->geometry.force_aperture = true;
+	} else {
+		domain->geometry.aperture_end = (1UL << ias) - 1;
+		domain->geometry.force_aperture = true;
+		smmu_domain->split_pagetables = false;
+	}
 
 	/* Initialise the context bank with our page table cfg */
 	arm_smmu_init_context_bank(smmu_domain, &pgtbl_cfg);
@@ -1526,6 +1549,9 @@ static int arm_smmu_domain_get_attr(struct iommu_domain *domain,
 		case DOMAIN_ATTR_NESTING:
 			*(int *)data = (smmu_domain->stage == ARM_SMMU_DOMAIN_NESTED);
 			return 0;
+		case DOMAIN_ATTR_SPLIT_TABLES:
+			*(int *)data = smmu_domain->split_pagetables;
+			return 0;
 		default:
 			return -ENODEV;
 		}
@@ -1566,6 +1592,14 @@ static int arm_smmu_domain_set_attr(struct iommu_domain *domain,
 			else
 				smmu_domain->stage = ARM_SMMU_DOMAIN_S1;
 			break;
+		case DOMAIN_ATTR_SPLIT_TABLES:
+			if (smmu_domain->smmu) {
+				ret = -EPERM;
+				goto out_unlock;
+			}
+			if (*(int *)data)
+				smmu_domain->split_pagetables = true;
+			break;
 		default:
 			ret = -ENODEV;
 		}
diff --git a/drivers/iommu/arm-smmu.h b/drivers/iommu/arm-smmu.h
index 8d1cd54d82a6..5f6d0af7c8c8 100644
--- a/drivers/iommu/arm-smmu.h
+++ b/drivers/iommu/arm-smmu.h
@@ -172,6 +172,7 @@ enum arm_smmu_cbar_type {
 #define ARM_SMMU_TCR_SH0		GENMASK(13, 12)
 #define ARM_SMMU_TCR_ORGN0		GENMASK(11, 10)
 #define ARM_SMMU_TCR_IRGN0		GENMASK(9, 8)
+#define ARM_SMMU_TCR_EPD0		BIT(7)
 #define ARM_SMMU_TCR_T0SZ		GENMASK(5, 0)
 
 #define ARM_SMMU_VTCR_RES1		BIT(31)
@@ -343,16 +344,27 @@ struct arm_smmu_domain {
 	struct mutex			init_mutex; /* Protects smmu pointer */
 	spinlock_t			cb_lock; /* Serialises ATS1* ops and TLB syncs */
 	struct iommu_domain		domain;
+	bool				split_pagetables;
 };
 
 static inline u32 arm_smmu_lpae_tcr(struct io_pgtable_cfg *cfg)
 {
-	return ARM_SMMU_TCR_EPD1 |
-	       FIELD_PREP(ARM_SMMU_TCR_TG0, cfg->arm_lpae_s1_cfg.tcr.tg) |
-	       FIELD_PREP(ARM_SMMU_TCR_SH0, cfg->arm_lpae_s1_cfg.tcr.sh) |
-	       FIELD_PREP(ARM_SMMU_TCR_ORGN0, cfg->arm_lpae_s1_cfg.tcr.orgn) |
-	       FIELD_PREP(ARM_SMMU_TCR_IRGN0, cfg->arm_lpae_s1_cfg.tcr.irgn) |
-	       FIELD_PREP(ARM_SMMU_TCR_T0SZ, cfg->arm_lpae_s1_cfg.tcr.tsz);
+	u32 tcr = FIELD_PREP(ARM_SMMU_TCR_TG0, cfg->arm_lpae_s1_cfg.tcr.tg) |
+		FIELD_PREP(ARM_SMMU_TCR_SH0, cfg->arm_lpae_s1_cfg.tcr.sh) |
+		FIELD_PREP(ARM_SMMU_TCR_ORGN0, cfg->arm_lpae_s1_cfg.tcr.orgn) |
+		FIELD_PREP(ARM_SMMU_TCR_IRGN0, cfg->arm_lpae_s1_cfg.tcr.irgn) |
+		FIELD_PREP(ARM_SMMU_TCR_T0SZ, cfg->arm_lpae_s1_cfg.tcr.tsz);
+
+       /*
+	* When TTBR1 is selected shift the TCR fields by 16 bits and disable
+	* translation in TTBR0
+	*/
+	if (cfg->quirks & IO_PGTABLE_QUIRK_ARM_TTBR1)
+		tcr = (tcr << 16) | ARM_SMMU_TCR_EPD0;
+	else
+		tcr |= ARM_SMMU_TCR_EPD1;
+
+	return tcr;
 }
 
 static inline u32 arm_smmu_lpae_tcr2(struct io_pgtable_cfg *cfg)
-- 
2.17.1

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