iommu/arm-smmu-v3: Add unit tests for arm_smmu_write_entry

Add tests for some of the more common STE update operations that we expect
to see, as well as some artificial STE updates to test the edges of
arm_smmu_write_entry. These also serve as a record of which common
operation is expected to be hitless, and how many syncs they require.

arm_smmu_write_entry implements a generic algorithm that updates an STE/CD
to any other abritrary STE/CD configuration. The update requires a
sequence of write+sync operations with some invariants that must be held
true after each sync. arm_smmu_write_entry lends itself well to
unit-testing since the function's interaction with the STE/CD is already
abstracted by input callbacks that we can hook to introspect into the
sequence of operations. We can use these hooks to guarantee that
invariants are held throughout the entire update operation.

Link: https://lore.kernel.org/r/20240106083617.1173871-3-mshavit@google.com
Tested-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Michael Shavit <mshavit@google.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/9-v9-5040dc602008+177d7-smmuv3_newapi_p2_jgg@nvidia.com
Signed-off-by: Will Deacon <will@kernel.org>

1 files changed, 465 insertions, 0 deletions

diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-test.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-test.c
new file mode 100644
index 000000000000..417804392ff0
--- /dev/null
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-test.c
@@ -0,0 +1,465 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2024 Google LLC.
+ */
+#include <kunit/test.h>
+#include <linux/io-pgtable.h>
+
+#include "arm-smmu-v3.h"
+
+struct arm_smmu_test_writer {
+	struct arm_smmu_entry_writer writer;
+	struct kunit *test;
+	const __le64 *init_entry;
+	const __le64 *target_entry;
+	__le64 *entry;
+
+	bool invalid_entry_written;
+	unsigned int num_syncs;
+};
+
+#define NUM_ENTRY_QWORDS 8
+#define NUM_EXPECTED_SYNCS(x) x
+
+static struct arm_smmu_ste bypass_ste;
+static struct arm_smmu_ste abort_ste;
+static struct arm_smmu_device smmu = {
+	.features = ARM_SMMU_FEAT_STALLS | ARM_SMMU_FEAT_ATTR_TYPES_OVR
+};
+static struct mm_struct sva_mm = {
+	.pgd = (void *)0xdaedbeefdeadbeefULL,
+};
+
+static bool arm_smmu_entry_differs_in_used_bits(const __le64 *entry,
+						const __le64 *used_bits,
+						const __le64 *target,
+						unsigned int length)
+{
+	bool differs = false;
+	unsigned int i;
+
+	for (i = 0; i < length; i++) {
+		if ((entry[i] & used_bits[i]) != target[i])
+			differs = true;
+	}
+	return differs;
+}
+
+static void
+arm_smmu_test_writer_record_syncs(struct arm_smmu_entry_writer *writer)
+{
+	struct arm_smmu_test_writer *test_writer =
+		container_of(writer, struct arm_smmu_test_writer, writer);
+	__le64 *entry_used_bits;
+
+	entry_used_bits = kunit_kzalloc(
+		test_writer->test, sizeof(*entry_used_bits) * NUM_ENTRY_QWORDS,
+		GFP_KERNEL);
+	KUNIT_ASSERT_NOT_NULL(test_writer->test, entry_used_bits);
+
+	pr_debug("STE value is now set to: ");
+	print_hex_dump_debug("    ", DUMP_PREFIX_NONE, 16, 8,
+			     test_writer->entry,
+			     NUM_ENTRY_QWORDS * sizeof(*test_writer->entry),
+			     false);
+
+	test_writer->num_syncs += 1;
+	if (!test_writer->entry[0]) {
+		test_writer->invalid_entry_written = true;
+	} else {
+		/*
+		 * At any stage in a hitless transition, the entry must be
+		 * equivalent to either the initial entry or the target entry
+		 * when only considering the bits used by the current
+		 * configuration.
+		 */
+		writer->ops->get_used(test_writer->entry, entry_used_bits);
+		KUNIT_EXPECT_FALSE(
+			test_writer->test,
+			arm_smmu_entry_differs_in_used_bits(
+				test_writer->entry, entry_used_bits,
+				test_writer->init_entry, NUM_ENTRY_QWORDS) &&
+				arm_smmu_entry_differs_in_used_bits(
+					test_writer->entry, entry_used_bits,
+					test_writer->target_entry,
+					NUM_ENTRY_QWORDS));
+	}
+}
+
+static void
+arm_smmu_v3_test_debug_print_used_bits(struct arm_smmu_entry_writer *writer,
+				       const __le64 *ste)
+{
+	__le64 used_bits[NUM_ENTRY_QWORDS] = {};
+
+	arm_smmu_get_ste_used(ste, used_bits);
+	pr_debug("STE used bits: ");
+	print_hex_dump_debug("    ", DUMP_PREFIX_NONE, 16, 8, used_bits,
+			     sizeof(used_bits), false);
+}
+
+static const struct arm_smmu_entry_writer_ops test_ste_ops = {
+	.sync = arm_smmu_test_writer_record_syncs,
+	.get_used = arm_smmu_get_ste_used,
+};
+
+static const struct arm_smmu_entry_writer_ops test_cd_ops = {
+	.sync = arm_smmu_test_writer_record_syncs,
+	.get_used = arm_smmu_get_cd_used,
+};
+
+static void arm_smmu_v3_test_ste_expect_transition(
+	struct kunit *test, const struct arm_smmu_ste *cur,
+	const struct arm_smmu_ste *target, unsigned int num_syncs_expected,
+	bool hitless)
+{
+	struct arm_smmu_ste cur_copy = *cur;
+	struct arm_smmu_test_writer test_writer = {
+		.writer = {
+			.ops = &test_ste_ops,
+		},
+		.test = test,
+		.init_entry = cur->data,
+		.target_entry = target->data,
+		.entry = cur_copy.data,
+		.num_syncs = 0,
+		.invalid_entry_written = false,
+
+	};
+
+	pr_debug("STE initial value: ");
+	print_hex_dump_debug("    ", DUMP_PREFIX_NONE, 16, 8, cur_copy.data,
+			     sizeof(cur_copy), false);
+	arm_smmu_v3_test_debug_print_used_bits(&test_writer.writer, cur->data);
+	pr_debug("STE target value: ");
+	print_hex_dump_debug("    ", DUMP_PREFIX_NONE, 16, 8, target->data,
+			     sizeof(cur_copy), false);
+	arm_smmu_v3_test_debug_print_used_bits(&test_writer.writer,
+					       target->data);
+
+	arm_smmu_write_entry(&test_writer.writer, cur_copy.data, target->data);
+
+	KUNIT_EXPECT_EQ(test, test_writer.invalid_entry_written, !hitless);
+	KUNIT_EXPECT_EQ(test, test_writer.num_syncs, num_syncs_expected);
+	KUNIT_EXPECT_MEMEQ(test, target->data, cur_copy.data, sizeof(cur_copy));
+}
+
+static void arm_smmu_v3_test_ste_expect_hitless_transition(
+	struct kunit *test, const struct arm_smmu_ste *cur,
+	const struct arm_smmu_ste *target, unsigned int num_syncs_expected)
+{
+	arm_smmu_v3_test_ste_expect_transition(test, cur, target,
+					       num_syncs_expected, true);
+}
+
+static const dma_addr_t fake_cdtab_dma_addr = 0xF0F0F0F0F0F0;
+
+static void arm_smmu_test_make_cdtable_ste(struct arm_smmu_ste *ste,
+					   const dma_addr_t dma_addr)
+{
+	struct arm_smmu_master master = {
+		.cd_table.cdtab_dma = dma_addr,
+		.cd_table.s1cdmax = 0xFF,
+		.cd_table.s1fmt = STRTAB_STE_0_S1FMT_64K_L2,
+		.smmu = &smmu,
+	};
+
+	arm_smmu_make_cdtable_ste(ste, &master);
+}
+
+static void arm_smmu_v3_write_ste_test_bypass_to_abort(struct kunit *test)
+{
+	/*
+	 * Bypass STEs has used bits in the first two Qwords, while abort STEs
+	 * only have used bits in the first QWord. Transitioning from bypass to
+	 * abort requires two syncs: the first to set the first qword and make
+	 * the STE into an abort, the second to clean up the second qword.
+	 */
+	arm_smmu_v3_test_ste_expect_hitless_transition(
+		test, &bypass_ste, &abort_ste, NUM_EXPECTED_SYNCS(2));
+}
+
+static void arm_smmu_v3_write_ste_test_abort_to_bypass(struct kunit *test)
+{
+	/*
+	 * Transitioning from abort to bypass also requires two syncs: the first
+	 * to set the second qword data required by the bypass STE, and the
+	 * second to set the first qword and switch to bypass.
+	 */
+	arm_smmu_v3_test_ste_expect_hitless_transition(
+		test, &abort_ste, &bypass_ste, NUM_EXPECTED_SYNCS(2));
+}
+
+static void arm_smmu_v3_write_ste_test_cdtable_to_abort(struct kunit *test)
+{
+	struct arm_smmu_ste ste;
+
+	arm_smmu_test_make_cdtable_ste(&ste, fake_cdtab_dma_addr);
+	arm_smmu_v3_test_ste_expect_hitless_transition(test, &ste, &abort_ste,
+						       NUM_EXPECTED_SYNCS(2));
+}
+
+static void arm_smmu_v3_write_ste_test_abort_to_cdtable(struct kunit *test)
+{
+	struct arm_smmu_ste ste;
+
+	arm_smmu_test_make_cdtable_ste(&ste, fake_cdtab_dma_addr);
+	arm_smmu_v3_test_ste_expect_hitless_transition(test, &abort_ste, &ste,
+						       NUM_EXPECTED_SYNCS(2));
+}
+
+static void arm_smmu_v3_write_ste_test_cdtable_to_bypass(struct kunit *test)
+{
+	struct arm_smmu_ste ste;
+
+	arm_smmu_test_make_cdtable_ste(&ste, fake_cdtab_dma_addr);
+	arm_smmu_v3_test_ste_expect_hitless_transition(test, &ste, &bypass_ste,
+						       NUM_EXPECTED_SYNCS(3));
+}
+
+static void arm_smmu_v3_write_ste_test_bypass_to_cdtable(struct kunit *test)
+{
+	struct arm_smmu_ste ste;
+
+	arm_smmu_test_make_cdtable_ste(&ste, fake_cdtab_dma_addr);
+	arm_smmu_v3_test_ste_expect_hitless_transition(test, &bypass_ste, &ste,
+						       NUM_EXPECTED_SYNCS(3));
+}
+
+static void arm_smmu_test_make_s2_ste(struct arm_smmu_ste *ste,
+				      bool ats_enabled)
+{
+	struct arm_smmu_master master = {
+		.smmu = &smmu,
+		.ats_enabled = ats_enabled,
+	};
+	struct io_pgtable io_pgtable = {};
+	struct arm_smmu_domain smmu_domain = {
+		.pgtbl_ops = &io_pgtable.ops,
+	};
+
+	io_pgtable.cfg.arm_lpae_s2_cfg.vttbr = 0xdaedbeefdeadbeefULL;
+	io_pgtable.cfg.arm_lpae_s2_cfg.vtcr.ps = 1;
+	io_pgtable.cfg.arm_lpae_s2_cfg.vtcr.tg = 2;
+	io_pgtable.cfg.arm_lpae_s2_cfg.vtcr.sh = 3;
+	io_pgtable.cfg.arm_lpae_s2_cfg.vtcr.orgn = 1;
+	io_pgtable.cfg.arm_lpae_s2_cfg.vtcr.irgn = 2;
+	io_pgtable.cfg.arm_lpae_s2_cfg.vtcr.sl = 3;
+	io_pgtable.cfg.arm_lpae_s2_cfg.vtcr.tsz = 4;
+
+	arm_smmu_make_s2_domain_ste(ste, &master, &smmu_domain);
+}
+
+static void arm_smmu_v3_write_ste_test_s2_to_abort(struct kunit *test)
+{
+	struct arm_smmu_ste ste;
+
+	arm_smmu_test_make_s2_ste(&ste, true);
+	arm_smmu_v3_test_ste_expect_hitless_transition(test, &ste, &abort_ste,
+						       NUM_EXPECTED_SYNCS(2));
+}
+
+static void arm_smmu_v3_write_ste_test_abort_to_s2(struct kunit *test)
+{
+	struct arm_smmu_ste ste;
+
+	arm_smmu_test_make_s2_ste(&ste, true);
+	arm_smmu_v3_test_ste_expect_hitless_transition(test, &abort_ste, &ste,
+						       NUM_EXPECTED_SYNCS(2));
+}
+
+static void arm_smmu_v3_write_ste_test_s2_to_bypass(struct kunit *test)
+{
+	struct arm_smmu_ste ste;
+
+	arm_smmu_test_make_s2_ste(&ste, true);
+	arm_smmu_v3_test_ste_expect_hitless_transition(test, &ste, &bypass_ste,
+						       NUM_EXPECTED_SYNCS(2));
+}
+
+static void arm_smmu_v3_write_ste_test_bypass_to_s2(struct kunit *test)
+{
+	struct arm_smmu_ste ste;
+
+	arm_smmu_test_make_s2_ste(&ste, true);
+	arm_smmu_v3_test_ste_expect_hitless_transition(test, &bypass_ste, &ste,
+						       NUM_EXPECTED_SYNCS(2));
+}
+
+static void arm_smmu_v3_test_cd_expect_transition(
+	struct kunit *test, const struct arm_smmu_cd *cur,
+	const struct arm_smmu_cd *target, unsigned int num_syncs_expected,
+	bool hitless)
+{
+	struct arm_smmu_cd cur_copy = *cur;
+	struct arm_smmu_test_writer test_writer = {
+		.writer = {
+			.ops = &test_cd_ops,
+		},
+		.test = test,
+		.init_entry = cur->data,
+		.target_entry = target->data,
+		.entry = cur_copy.data,
+		.num_syncs = 0,
+		.invalid_entry_written = false,
+
+	};
+
+	pr_debug("CD initial value: ");
+	print_hex_dump_debug("    ", DUMP_PREFIX_NONE, 16, 8, cur_copy.data,
+			     sizeof(cur_copy), false);
+	arm_smmu_v3_test_debug_print_used_bits(&test_writer.writer, cur->data);
+	pr_debug("CD target value: ");
+	print_hex_dump_debug("    ", DUMP_PREFIX_NONE, 16, 8, target->data,
+			     sizeof(cur_copy), false);
+	arm_smmu_v3_test_debug_print_used_bits(&test_writer.writer,
+					       target->data);
+
+	arm_smmu_write_entry(&test_writer.writer, cur_copy.data, target->data);
+
+	KUNIT_EXPECT_EQ(test, test_writer.invalid_entry_written, !hitless);
+	KUNIT_EXPECT_EQ(test, test_writer.num_syncs, num_syncs_expected);
+	KUNIT_EXPECT_MEMEQ(test, target->data, cur_copy.data, sizeof(cur_copy));
+}
+
+static void arm_smmu_v3_test_cd_expect_non_hitless_transition(
+	struct kunit *test, const struct arm_smmu_cd *cur,
+	const struct arm_smmu_cd *target, unsigned int num_syncs_expected)
+{
+	arm_smmu_v3_test_cd_expect_transition(test, cur, target,
+					      num_syncs_expected, false);
+}
+
+static void arm_smmu_v3_test_cd_expect_hitless_transition(
+	struct kunit *test, const struct arm_smmu_cd *cur,
+	const struct arm_smmu_cd *target, unsigned int num_syncs_expected)
+{
+	arm_smmu_v3_test_cd_expect_transition(test, cur, target,
+					      num_syncs_expected, true);
+}
+
+static void arm_smmu_test_make_s1_cd(struct arm_smmu_cd *cd, unsigned int asid)
+{
+	struct arm_smmu_master master = {
+		.smmu = &smmu,
+	};
+	struct io_pgtable io_pgtable = {};
+	struct arm_smmu_domain smmu_domain = {
+		.pgtbl_ops = &io_pgtable.ops,
+		.cd = {
+			.asid = asid,
+		},
+	};
+
+	io_pgtable.cfg.arm_lpae_s1_cfg.ttbr = 0xdaedbeefdeadbeefULL;
+	io_pgtable.cfg.arm_lpae_s1_cfg.tcr.ips = 1;
+	io_pgtable.cfg.arm_lpae_s1_cfg.tcr.tg = 2;
+	io_pgtable.cfg.arm_lpae_s1_cfg.tcr.sh = 3;
+	io_pgtable.cfg.arm_lpae_s1_cfg.tcr.orgn = 1;
+	io_pgtable.cfg.arm_lpae_s1_cfg.tcr.irgn = 2;
+	io_pgtable.cfg.arm_lpae_s1_cfg.tcr.tsz = 4;
+	io_pgtable.cfg.arm_lpae_s1_cfg.mair = 0xabcdef012345678ULL;
+
+	arm_smmu_make_s1_cd(cd, &master, &smmu_domain);
+}
+
+static void arm_smmu_v3_write_cd_test_s1_clear(struct kunit *test)
+{
+	struct arm_smmu_cd cd = {};
+	struct arm_smmu_cd cd_2;
+
+	arm_smmu_test_make_s1_cd(&cd_2, 1997);
+	arm_smmu_v3_test_cd_expect_non_hitless_transition(
+		test, &cd, &cd_2, NUM_EXPECTED_SYNCS(2));
+	arm_smmu_v3_test_cd_expect_non_hitless_transition(
+		test, &cd_2, &cd, NUM_EXPECTED_SYNCS(2));
+}
+
+static void arm_smmu_v3_write_cd_test_s1_change_asid(struct kunit *test)
+{
+	struct arm_smmu_cd cd = {};
+	struct arm_smmu_cd cd_2;
+
+	arm_smmu_test_make_s1_cd(&cd, 778);
+	arm_smmu_test_make_s1_cd(&cd_2, 1997);
+	arm_smmu_v3_test_cd_expect_hitless_transition(test, &cd, &cd_2,
+						      NUM_EXPECTED_SYNCS(1));
+	arm_smmu_v3_test_cd_expect_hitless_transition(test, &cd_2, &cd,
+						      NUM_EXPECTED_SYNCS(1));
+}
+
+static void arm_smmu_test_make_sva_cd(struct arm_smmu_cd *cd, unsigned int asid)
+{
+	struct arm_smmu_master master = {
+		.smmu = &smmu,
+	};
+
+	arm_smmu_make_sva_cd(cd, &master, &sva_mm, asid);
+}
+
+static void arm_smmu_test_make_sva_release_cd(struct arm_smmu_cd *cd,
+					      unsigned int asid)
+{
+	struct arm_smmu_master master = {
+		.smmu = &smmu,
+	};
+
+	arm_smmu_make_sva_cd(cd, &master, NULL, asid);
+}
+
+static void arm_smmu_v3_write_cd_test_sva_clear(struct kunit *test)
+{
+	struct arm_smmu_cd cd = {};
+	struct arm_smmu_cd cd_2;
+
+	arm_smmu_test_make_sva_cd(&cd_2, 1997);
+	arm_smmu_v3_test_cd_expect_non_hitless_transition(
+		test, &cd, &cd_2, NUM_EXPECTED_SYNCS(2));
+	arm_smmu_v3_test_cd_expect_non_hitless_transition(
+		test, &cd_2, &cd, NUM_EXPECTED_SYNCS(2));
+}
+
+static void arm_smmu_v3_write_cd_test_sva_release(struct kunit *test)
+{
+	struct arm_smmu_cd cd;
+	struct arm_smmu_cd cd_2;
+
+	arm_smmu_test_make_sva_cd(&cd, 1997);
+	arm_smmu_test_make_sva_release_cd(&cd_2, 1997);
+	arm_smmu_v3_test_cd_expect_hitless_transition(test, &cd, &cd_2,
+						      NUM_EXPECTED_SYNCS(2));
+	arm_smmu_v3_test_cd_expect_hitless_transition(test, &cd_2, &cd,
+						      NUM_EXPECTED_SYNCS(2));
+}
+
+static struct kunit_case arm_smmu_v3_test_cases[] = {
+	KUNIT_CASE(arm_smmu_v3_write_ste_test_bypass_to_abort),
+	KUNIT_CASE(arm_smmu_v3_write_ste_test_abort_to_bypass),
+	KUNIT_CASE(arm_smmu_v3_write_ste_test_cdtable_to_abort),
+	KUNIT_CASE(arm_smmu_v3_write_ste_test_abort_to_cdtable),
+	KUNIT_CASE(arm_smmu_v3_write_ste_test_cdtable_to_bypass),
+	KUNIT_CASE(arm_smmu_v3_write_ste_test_bypass_to_cdtable),
+	KUNIT_CASE(arm_smmu_v3_write_ste_test_s2_to_abort),
+	KUNIT_CASE(arm_smmu_v3_write_ste_test_abort_to_s2),
+	KUNIT_CASE(arm_smmu_v3_write_ste_test_s2_to_bypass),
+	KUNIT_CASE(arm_smmu_v3_write_ste_test_bypass_to_s2),
+	KUNIT_CASE(arm_smmu_v3_write_cd_test_s1_clear),
+	KUNIT_CASE(arm_smmu_v3_write_cd_test_s1_change_asid),
+	KUNIT_CASE(arm_smmu_v3_write_cd_test_sva_clear),
+	KUNIT_CASE(arm_smmu_v3_write_cd_test_sva_release),
+	{},
+};
+
+static int arm_smmu_v3_test_suite_init(struct kunit_suite *test)
+{
+	arm_smmu_make_bypass_ste(&smmu, &bypass_ste);
+	arm_smmu_make_abort_ste(&abort_ste);
+	return 0;
+}
+
+static struct kunit_suite arm_smmu_v3_test_module = {
+	.name = "arm-smmu-v3-kunit-test",
+	.suite_init = arm_smmu_v3_test_suite_init,
+	.test_cases = arm_smmu_v3_test_cases,
+};
+kunit_test_suites(&arm_smmu_v3_test_module);