iommu/arm-smmu-v3: Move the CD generation for SVA into a function

Pull all the calculations for building the CD table entry for a mmu_struct
into arm_smmu_make_sva_cd().

Call it in the two places installing the SVA CD table entry.

Open code the last caller of arm_smmu_update_ctx_desc_devices() and remove
the function.

Remove arm_smmu_write_ctx_desc() since all callers are gone. Add the
locking assertions to arm_smmu_alloc_cd_ptr() since
arm_smmu_update_ctx_desc_devices() was the last problematic caller.

Remove quiet_cd since all users are gone, arm_smmu_make_sva_cd() creates
the same value.

The behavior of quiet_cd changes slightly, the old implementation edited
the CD in place to set CTXDESC_CD_0_TCR_EPD0 assuming it was a SVA CD
entry. This version generates a full CD entry with a 0 TTB0 and relies on
arm_smmu_write_cd_entry() to install it hitlessly.

Tested-by: Nicolin Chen <[email protected]>
Tested-by: Shameer Kolothum <[email protected]>
Reviewed-by: Nicolin Chen <[email protected]>
Signed-off-by: Jason Gunthorpe <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Will Deacon <[email protected]>

Author: jgunthorpe

drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c

@@ -34,25 +34,6 @@ struct arm_smmu_bond {
 
 static DEFINE_MUTEX(sva_lock);
 
-/*
- * Write the CD to the CD tables for all masters that this domain is attached
- * to. Note that this is only used to update existing CD entries in the target
- * CD table, for which it's assumed that arm_smmu_write_ctx_desc can't fail.
- */
-static void arm_smmu_update_ctx_desc_devices(struct arm_smmu_domain *smmu_domain,
-					   int ssid,
-					   struct arm_smmu_ctx_desc *cd)
-{
-	struct arm_smmu_master *master;
-	unsigned long flags;
-
-	spin_lock_irqsave(&smmu_domain->devices_lock, flags);
-	list_for_each_entry(master, &smmu_domain->devices, domain_head) {
-		arm_smmu_write_ctx_desc(master, ssid, cd);
-	}
-	spin_unlock_irqrestore(&smmu_domain->devices_lock, flags);
-}
-
 static void
 arm_smmu_update_s1_domain_cd_entry(struct arm_smmu_domain *smmu_domain)
 {
@@ -128,11 +109,85 @@ arm_smmu_share_asid(struct mm_struct *mm, u16 asid)
 	return NULL;
 }
 
+static u64 page_size_to_cd(void)
+{
+	static_assert(PAGE_SIZE == SZ_4K || PAGE_SIZE == SZ_16K ||
+		      PAGE_SIZE == SZ_64K);
+	if (PAGE_SIZE == SZ_64K)
+		return ARM_LPAE_TCR_TG0_64K;
+	if (PAGE_SIZE == SZ_16K)
+		return ARM_LPAE_TCR_TG0_16K;
+	return ARM_LPAE_TCR_TG0_4K;
+}
+
+static void arm_smmu_make_sva_cd(struct arm_smmu_cd *target,
+				 struct arm_smmu_master *master,
+				 struct mm_struct *mm, u16 asid)
+{
+	u64 par;
+
+	memset(target, 0, sizeof(*target));
+
+	par = cpuid_feature_extract_unsigned_field(
+		read_sanitised_ftr_reg(SYS_ID_AA64MMFR0_EL1),
+		ID_AA64MMFR0_EL1_PARANGE_SHIFT);
+
+	target->data[0] = cpu_to_le64(
+		CTXDESC_CD_0_TCR_EPD1 |
+#ifdef __BIG_ENDIAN
+		CTXDESC_CD_0_ENDI |
+#endif
+		CTXDESC_CD_0_V |
+		FIELD_PREP(CTXDESC_CD_0_TCR_IPS, par) |
+		CTXDESC_CD_0_AA64 |
+		(master->stall_enabled ? CTXDESC_CD_0_S : 0) |
+		CTXDESC_CD_0_R |
+		CTXDESC_CD_0_A |
+		CTXDESC_CD_0_ASET |
+		FIELD_PREP(CTXDESC_CD_0_ASID, asid));
+
+	/*
+	 * If no MM is passed then this creates a SVA entry that faults
+	 * everything. arm_smmu_write_cd_entry() can hitlessly go between these
+	 * two entries types since TTB0 is ignored by HW when EPD0 is set.
+	 */
+	if (mm) {
+		target->data[0] |= cpu_to_le64(
+			FIELD_PREP(CTXDESC_CD_0_TCR_T0SZ,
+				   64ULL - vabits_actual) |
+			FIELD_PREP(CTXDESC_CD_0_TCR_TG0, page_size_to_cd()) |
+			FIELD_PREP(CTXDESC_CD_0_TCR_IRGN0,
+				   ARM_LPAE_TCR_RGN_WBWA) |
+			FIELD_PREP(CTXDESC_CD_0_TCR_ORGN0,
+				   ARM_LPAE_TCR_RGN_WBWA) |
+			FIELD_PREP(CTXDESC_CD_0_TCR_SH0, ARM_LPAE_TCR_SH_IS));
+
+		target->data[1] = cpu_to_le64(virt_to_phys(mm->pgd) &
+					      CTXDESC_CD_1_TTB0_MASK);
+	} else {
+		target->data[0] |= cpu_to_le64(CTXDESC_CD_0_TCR_EPD0);
+
+		/*
+		 * Disable stall and immediately generate an abort if stall
+		 * disable is permitted. This speeds up cleanup for an unclean
+		 * exit if the device is still doing a lot of DMA.
+		 */
+		if (!(master->smmu->features & ARM_SMMU_FEAT_STALL_FORCE))
+			target->data[0] &=
+				cpu_to_le64(~(CTXDESC_CD_0_S | CTXDESC_CD_0_R));
+	}
+
+	/*
+	 * MAIR value is pretty much constant and global, so we can just get it
+	 * from the current CPU register
+	 */
+	target->data[3] = cpu_to_le64(read_sysreg(mair_el1));
+}
+
 static struct arm_smmu_ctx_desc *arm_smmu_alloc_shared_cd(struct mm_struct *mm)
 {
 	u16 asid;
 	int err = 0;
-	u64 tcr, par, reg;
 	struct arm_smmu_ctx_desc *cd;
 	struct arm_smmu_ctx_desc *ret = NULL;
 
@@ -166,39 +221,6 @@ static struct arm_smmu_ctx_desc *arm_smmu_alloc_shared_cd(struct mm_struct *mm)
 	if (err)
 		goto out_free_asid;
 
-	tcr = FIELD_PREP(CTXDESC_CD_0_TCR_T0SZ, 64ULL - vabits_actual) |
-	      FIELD_PREP(CTXDESC_CD_0_TCR_IRGN0, ARM_LPAE_TCR_RGN_WBWA) |
-	      FIELD_PREP(CTXDESC_CD_0_TCR_ORGN0, ARM_LPAE_TCR_RGN_WBWA) |
-	      FIELD_PREP(CTXDESC_CD_0_TCR_SH0, ARM_LPAE_TCR_SH_IS) |
-	      CTXDESC_CD_0_TCR_EPD1 | CTXDESC_CD_0_AA64;
-
-	switch (PAGE_SIZE) {
-	case SZ_4K:
-		tcr |= FIELD_PREP(CTXDESC_CD_0_TCR_TG0, ARM_LPAE_TCR_TG0_4K);
-		break;
-	case SZ_16K:
-		tcr |= FIELD_PREP(CTXDESC_CD_0_TCR_TG0, ARM_LPAE_TCR_TG0_16K);
-		break;
-	case SZ_64K:
-		tcr |= FIELD_PREP(CTXDESC_CD_0_TCR_TG0, ARM_LPAE_TCR_TG0_64K);
-		break;
-	default:
-		WARN_ON(1);
-		err = -EINVAL;
-		goto out_free_asid;
-	}
-
-	reg = read_sanitised_ftr_reg(SYS_ID_AA64MMFR0_EL1);
-	par = cpuid_feature_extract_unsigned_field(reg, ID_AA64MMFR0_EL1_PARANGE_SHIFT);
-	tcr |= FIELD_PREP(CTXDESC_CD_0_TCR_IPS, par);
-
-	cd->ttbr = virt_to_phys(mm->pgd);
-	cd->tcr = tcr;
-	/*
-	 * MAIR value is pretty much constant and global, so we can just get it
-	 * from the current CPU register
-	 */
-	cd->mair = read_sysreg(mair_el1);
 	cd->asid = asid;
 	cd->mm = mm;
 
@@ -276,6 +298,8 @@ static void arm_smmu_mm_release(struct mmu_notifier *mn, struct mm_struct *mm)
 {
 	struct arm_smmu_mmu_notifier *smmu_mn = mn_to_smmu(mn);
 	struct arm_smmu_domain *smmu_domain = smmu_mn->domain;
+	struct arm_smmu_master *master;
+	unsigned long flags;
 
 	mutex_lock(&sva_lock);
 	if (smmu_mn->cleared) {
@@ -287,8 +311,19 @@ static void arm_smmu_mm_release(struct mmu_notifier *mn, struct mm_struct *mm)
 	 * DMA may still be running. Keep the cd valid to avoid C_BAD_CD events,
 	 * but disable translation.
 	 */
-	arm_smmu_update_ctx_desc_devices(smmu_domain, mm_get_enqcmd_pasid(mm),
-					 &quiet_cd);
+	spin_lock_irqsave(&smmu_domain->devices_lock, flags);
+	list_for_each_entry(master, &smmu_domain->devices, domain_head) {
+		struct arm_smmu_cd target;
+		struct arm_smmu_cd *cdptr;
+
+		cdptr = arm_smmu_get_cd_ptr(master, mm_get_enqcmd_pasid(mm));
+		if (WARN_ON(!cdptr))
+			continue;
+		arm_smmu_make_sva_cd(&target, master, NULL, smmu_mn->cd->asid);
+		arm_smmu_write_cd_entry(master, mm_get_enqcmd_pasid(mm), cdptr,
+					&target);
+	}
+	spin_unlock_irqrestore(&smmu_domain->devices_lock, flags);
 
 	arm_smmu_tlb_inv_asid(smmu_domain->smmu, smmu_mn->cd->asid);
 	arm_smmu_atc_inv_domain(smmu_domain, mm_get_enqcmd_pasid(mm), 0, 0);
@@ -383,6 +418,8 @@ static int __arm_smmu_sva_bind(struct device *dev, ioasid_t pasid,
 			       struct mm_struct *mm)
 {
 	int ret;
+	struct arm_smmu_cd target;
+	struct arm_smmu_cd *cdptr;
 	struct arm_smmu_bond *bond;
 	struct arm_smmu_master *master = dev_iommu_priv_get(dev);
 	struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
@@ -409,9 +446,13 @@ static int __arm_smmu_sva_bind(struct device *dev, ioasid_t pasid,
 		goto err_free_bond;
 	}
 
-	ret = arm_smmu_write_ctx_desc(master, pasid, bond->smmu_mn->cd);
-	if (ret)
+	cdptr = arm_smmu_alloc_cd_ptr(master, mm_get_enqcmd_pasid(mm));
+	if (!cdptr) {
+		ret = -ENOMEM;
 		goto err_put_notifier;
+	}
+	arm_smmu_make_sva_cd(&target, master, mm, bond->smmu_mn->cd->asid);
+	arm_smmu_write_cd_entry(master, pasid, cdptr, &target);
 
 	list_add(&bond->list, &master->bonds);
 	return 0;

drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c

@@ -83,12 +83,6 @@ struct arm_smmu_option_prop {
 DEFINE_XARRAY_ALLOC1(arm_smmu_asid_xa);
 DEFINE_MUTEX(arm_smmu_asid_lock);
 
-/*
- * Special value used by SVA when a process dies, to quiesce a CD without
- * disabling it.
- */
-struct arm_smmu_ctx_desc quiet_cd = { 0 };
-
 static struct arm_smmu_option_prop arm_smmu_options[] = {
 	{ ARM_SMMU_OPT_SKIP_PREFETCH, "hisilicon,broken-prefetch-cmd" },
 	{ ARM_SMMU_OPT_PAGE0_REGS_ONLY, "cavium,cn9900-broken-page1-regspace"},
@@ -1200,7 +1194,7 @@ static void arm_smmu_write_cd_l1_desc(__le64 *dst,
 	u64 val = (l1_desc->l2ptr_dma & CTXDESC_L1_DESC_L2PTR_MASK) |
 		  CTXDESC_L1_DESC_V;
 
-	/* See comment in arm_smmu_write_ctx_desc() */
+	/* The HW has 64 bit atomicity with stores to the L2 CD table */
 	WRITE_ONCE(*dst, cpu_to_le64(val));
 }
 
@@ -1223,12 +1217,15 @@ struct arm_smmu_cd *arm_smmu_get_cd_ptr(struct arm_smmu_master *master,
 	return &l1_desc->l2ptr[ssid % CTXDESC_L2_ENTRIES];
 }
 
-static struct arm_smmu_cd *arm_smmu_alloc_cd_ptr(struct arm_smmu_master *master,
-						 u32 ssid)
+struct arm_smmu_cd *arm_smmu_alloc_cd_ptr(struct arm_smmu_master *master,
+					  u32 ssid)
 {
 	struct arm_smmu_ctx_desc_cfg *cd_table = &master->cd_table;
 	struct arm_smmu_device *smmu = master->smmu;
 
+	might_sleep();
+	iommu_group_mutex_assert(master->dev);
+
 	if (!cd_table->cdtab) {
 		if (arm_smmu_alloc_cd_tables(master))
 			return NULL;
@@ -1346,65 +1343,6 @@ void arm_smmu_clear_cd(struct arm_smmu_master *master, ioasid_t ssid)
 	arm_smmu_write_cd_entry(master, ssid, cdptr, &target);
 }
 
-int arm_smmu_write_ctx_desc(struct arm_smmu_master *master, int ssid,
-			    struct arm_smmu_ctx_desc *cd)
-{
-	/*
-	 * This function handles the following cases:
-	 *
-	 * (1) Install primary CD, for normal DMA traffic (SSID = IOMMU_NO_PASID = 0).
-	 * (2) Install a secondary CD, for SID+SSID traffic.
-	 * (4) Quiesce the context without clearing the valid bit. Disable
-	 *     translation, and ignore any translation fault.
-	 */
-	u64 val;
-	struct arm_smmu_cd target;
-	struct arm_smmu_cd *cdptr = ⌖
-	struct arm_smmu_cd *cd_table_entry;
-	struct arm_smmu_ctx_desc_cfg *cd_table = &master->cd_table;
-	struct arm_smmu_device *smmu = master->smmu;
-
-	if (WARN_ON(ssid >= (1 << cd_table->s1cdmax)))
-		return -E2BIG;
-
-	cd_table_entry = arm_smmu_alloc_cd_ptr(master, ssid);
-	if (!cd_table_entry)
-		return -ENOMEM;
-
-	target = *cd_table_entry;
-	val = le64_to_cpu(cdptr->data[0]);
-
-	if (cd == &quiet_cd) { /* (4) */
-		val &= ~(CTXDESC_CD_0_TCR_T0SZ | CTXDESC_CD_0_TCR_TG0 |
-			 CTXDESC_CD_0_TCR_IRGN0 | CTXDESC_CD_0_TCR_ORGN0 |
-			 CTXDESC_CD_0_TCR_SH0);
-		if (!(smmu->features & ARM_SMMU_FEAT_STALL_FORCE))
-			val &= ~(CTXDESC_CD_0_S | CTXDESC_CD_0_R);
-		val |= CTXDESC_CD_0_TCR_EPD0;
-		cdptr->data[1] &= ~cpu_to_le64(CTXDESC_CD_1_TTB0_MASK);
-	} else { /* (1) and (2) */
-		cdptr->data[1] = cpu_to_le64(cd->ttbr & CTXDESC_CD_1_TTB0_MASK);
-		cdptr->data[2] = 0;
-		cdptr->data[3] = cpu_to_le64(cd->mair);
-
-		val = cd->tcr |
-#ifdef __BIG_ENDIAN
-			CTXDESC_CD_0_ENDI |
-#endif
-			CTXDESC_CD_0_R | CTXDESC_CD_0_A |
-			(cd->mm ? 0 : CTXDESC_CD_0_ASET) |
-			CTXDESC_CD_0_AA64 |
-			FIELD_PREP(CTXDESC_CD_0_ASID, cd->asid) |
-			CTXDESC_CD_0_V;
-
-		if (cd_table->stall_enabled)
-			val |= CTXDESC_CD_0_S;
-	}
-	cdptr->data[0] = cpu_to_le64(val);
-	arm_smmu_write_cd_entry(master, ssid, cd_table_entry, &target);
-	return 0;
-}
-
 static int arm_smmu_alloc_cd_tables(struct arm_smmu_master *master)
 {
 	int ret;
@@ -1413,7 +1351,6 @@ static int arm_smmu_alloc_cd_tables(struct arm_smmu_master *master)
 	struct arm_smmu_device *smmu = master->smmu;
 	struct arm_smmu_ctx_desc_cfg *cd_table = &master->cd_table;
 
-	cd_table->stall_enabled = master->stall_enabled;
 	cd_table->s1cdmax = master->ssid_bits;
 	max_contexts = 1 << cd_table->s1cdmax;
 
@@ -1511,7 +1448,7 @@ arm_smmu_write_strtab_l1_desc(__le64 *dst, struct arm_smmu_strtab_l1_desc *desc)
 	val |= FIELD_PREP(STRTAB_L1_DESC_SPAN, desc->span);
 	val |= desc->l2ptr_dma & STRTAB_L1_DESC_L2PTR_MASK;
 
-	/* See comment in arm_smmu_write_ctx_desc() */
+	/* The HW has 64 bit atomicity with stores to the L2 STE table */
 	WRITE_ONCE(*dst, cpu_to_le64(val));
 }
 

drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h

@@ -608,8 +608,6 @@ struct arm_smmu_ctx_desc_cfg {
 	u8				s1fmt;
 	/* log2 of the maximum number of CDs supported by this table */
 	u8				s1cdmax;
-	/* Whether CD entries in this table have the stall bit set. */
-	u8				stall_enabled:1;
 };
 
 struct arm_smmu_s2_cfg {
@@ -748,20 +746,19 @@ static inline struct arm_smmu_domain *to_smmu_domain(struct iommu_domain *dom)
 
 extern struct xarray arm_smmu_asid_xa;
 extern struct mutex arm_smmu_asid_lock;
-extern struct arm_smmu_ctx_desc quiet_cd;
 
 void arm_smmu_clear_cd(struct arm_smmu_master *master, ioasid_t ssid);
 struct arm_smmu_cd *arm_smmu_get_cd_ptr(struct arm_smmu_master *master,
 					u32 ssid);
+struct arm_smmu_cd *arm_smmu_alloc_cd_ptr(struct arm_smmu_master *master,
+					  u32 ssid);
 void arm_smmu_make_s1_cd(struct arm_smmu_cd *target,
 			 struct arm_smmu_master *master,
 			 struct arm_smmu_domain *smmu_domain);
 void arm_smmu_write_cd_entry(struct arm_smmu_master *master, int ssid,
 			     struct arm_smmu_cd *cdptr,
 			     const struct arm_smmu_cd *target);
 
-int arm_smmu_write_ctx_desc(struct arm_smmu_master *smmu_master, int ssid,
-			    struct arm_smmu_ctx_desc *cd);
 void arm_smmu_tlb_inv_asid(struct arm_smmu_device *smmu, u16 asid);
 void arm_smmu_tlb_inv_range_asid(unsigned long iova, size_t size, int asid,
 				 size_t granule, bool leaf,