iommu/arm-smmu-v3: Make the kunit into a module

It turns out kconfig has problems ensuring the SMMU module and the KUNIT
module are consistently y/m to allow linking. It will permit KUNIT to be a
module while SMMU is built in.

Also, Fedora apparently enables kunit on production kernels.

So, put the entire kunit in its own module using the
VISIBLE_IF_KUNIT/EXPORT_SYMBOL_IF_KUNIT machinery. This keeps it out of
vmlinus on Fedora and makes the kconfig work in the normal way. There is
no cost if kunit is disabled.

Fixes: 56e1a4cc25 ("iommu/arm-smmu-v3: Add unit tests for arm_smmu_write_entry")
Reported-by: Thorsten Leemhuis <linux@leemhuis.info>
Link: https://lore.kernel.org/all/aeea8546-5bce-4c51-b506-5d2008e52fef@leemhuis.info
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Tested-by: Thorsten Leemhuis <linux@leemhuis.info>
Acked-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/0-v1-24cba6c0f404+2ae-smmu_kunit_module_jgg@nvidia.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/Kconfig

@@ -415,7 +415,7 @@ config ARM_SMMU_V3_SVA
 	  and PRI.
 
 config ARM_SMMU_V3_KUNIT_TEST
-	bool "KUnit tests for arm-smmu-v3 driver"  if !KUNIT_ALL_TESTS
+	tristate "KUnit tests for arm-smmu-v3 driver"  if !KUNIT_ALL_TESTS
 	depends on KUNIT
 	depends on ARM_SMMU_V3_SVA
 	default KUNIT_ALL_TESTS

drivers/iommu/arm/arm-smmu-v3/Makefile

@@ -2,5 +2,6 @@
 obj-$(CONFIG_ARM_SMMU_V3) += arm_smmu_v3.o
 arm_smmu_v3-objs-y += arm-smmu-v3.o
 arm_smmu_v3-objs-$(CONFIG_ARM_SMMU_V3_SVA) += arm-smmu-v3-sva.o
-arm_smmu_v3-objs-$(CONFIG_ARM_SMMU_V3_KUNIT_TEST) += arm-smmu-v3-test.o
 arm_smmu_v3-objs := $(arm_smmu_v3-objs-y)
+
+obj-$(CONFIG_ARM_SMMU_V3_KUNIT_TEST) += arm-smmu-v3-test.o

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

@@ -185,6 +185,7 @@ void arm_smmu_make_sva_cd(struct arm_smmu_cd *target,
 	 */
 	target->data[3] = cpu_to_le64(read_sysreg(mair_el1));
 }
+EXPORT_SYMBOL_IF_KUNIT(arm_smmu_make_sva_cd);
 
 static struct arm_smmu_ctx_desc *arm_smmu_alloc_shared_cd(struct mm_struct *mm)
 {

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

@@ -463,3 +463,6 @@ static struct kunit_suite arm_smmu_v3_test_module = {
 	.test_cases = arm_smmu_v3_test_cases,
 };
 kunit_test_suites(&arm_smmu_v3_test_module);
+
+MODULE_IMPORT_NS(EXPORTED_FOR_KUNIT_TESTING);
+MODULE_LICENSE("GPL v2");

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

@@ -1007,6 +1007,7 @@ void arm_smmu_get_ste_used(const __le64 *ent, __le64 *used_bits)
 	if (cfg == STRTAB_STE_0_CFG_BYPASS)
 		used_bits[1] |= cpu_to_le64(STRTAB_STE_1_SHCFG);
 }
+EXPORT_SYMBOL_IF_KUNIT(arm_smmu_get_ste_used);
 
 /*
  * Figure out if we can do a hitless update of entry to become target. Returns a
@@ -1141,6 +1142,7 @@ void arm_smmu_write_entry(struct arm_smmu_entry_writer *writer, __le64 *entry,
 			entry_set(writer, entry, target, 0, NUM_ENTRY_QWORDS));
 	}
 }
+EXPORT_SYMBOL_IF_KUNIT(arm_smmu_write_entry);
 
 static void arm_smmu_sync_cd(struct arm_smmu_master *master,
 			     int ssid, bool leaf)
@@ -1268,6 +1270,7 @@ void arm_smmu_get_cd_used(const __le64 *ent, __le64 *used_bits)
 		used_bits[1] &= ~cpu_to_le64(CTXDESC_CD_1_TTB0_MASK);
 	}
 }
+EXPORT_SYMBOL_IF_KUNIT(arm_smmu_get_cd_used);
 
 static void arm_smmu_cd_writer_sync_entry(struct arm_smmu_entry_writer *writer)
 {
@@ -1332,6 +1335,7 @@ void arm_smmu_make_s1_cd(struct arm_smmu_cd *target,
 				      CTXDESC_CD_1_TTB0_MASK);
 	target->data[3] = cpu_to_le64(pgtbl_cfg->arm_lpae_s1_cfg.mair);
 }
+EXPORT_SYMBOL_IF_KUNIT(arm_smmu_make_s1_cd);
 
 void arm_smmu_clear_cd(struct arm_smmu_master *master, ioasid_t ssid)
 {
@@ -1515,6 +1519,7 @@ void arm_smmu_make_abort_ste(struct arm_smmu_ste *target)
 		STRTAB_STE_0_V |
 		FIELD_PREP(STRTAB_STE_0_CFG, STRTAB_STE_0_CFG_ABORT));
 }
+EXPORT_SYMBOL_IF_KUNIT(arm_smmu_make_abort_ste);
 
 VISIBLE_IF_KUNIT
 void arm_smmu_make_bypass_ste(struct arm_smmu_device *smmu,
@@ -1529,6 +1534,7 @@ void arm_smmu_make_bypass_ste(struct arm_smmu_device *smmu,
 		target->data[1] = cpu_to_le64(FIELD_PREP(STRTAB_STE_1_SHCFG,
 							 STRTAB_STE_1_SHCFG_INCOMING));
 }
+EXPORT_SYMBOL_IF_KUNIT(arm_smmu_make_bypass_ste);
 
 VISIBLE_IF_KUNIT
 void arm_smmu_make_cdtable_ste(struct arm_smmu_ste *target,
@@ -1580,6 +1586,7 @@ void arm_smmu_make_cdtable_ste(struct arm_smmu_ste *target,
 			cpu_to_le64(FIELD_PREP(STRTAB_STE_2_S2VMID, 0));
 	}
 }
+EXPORT_SYMBOL_IF_KUNIT(arm_smmu_make_cdtable_ste);
 
 VISIBLE_IF_KUNIT
 void arm_smmu_make_s2_domain_ste(struct arm_smmu_ste *target,
@@ -1627,6 +1634,7 @@ void arm_smmu_make_s2_domain_ste(struct arm_smmu_ste *target,
 	target->data[3] = cpu_to_le64(pgtbl_cfg->arm_lpae_s2_cfg.vttbr &
 				      STRTAB_STE_3_S2TTB_MASK);
 }
+EXPORT_SYMBOL_IF_KUNIT(arm_smmu_make_s2_domain_ste);
 
 /*
  * This can safely directly manipulate the STE memory without a sync sequence