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Tue, 08 Sep 2026 10:17:49 -0700 (PDT) Date: Tue, 8 Sep 2026 17:17:11 +0000 In-Reply-To: <20260908171712.356645-1-praan@google.com> Mime-Version: 1.0 References: <20260908171712.356645-1-praan@google.com> X-Mailer: git-send-email 2.55.0.979.g7e5102b832-goog Message-ID: <20260908171712.356645-16-praan@google.com> Subject: [PATCH v10 15/15] iommu/arm-smmu-v3: Add KUnit unit tests for Runtime PM From: Pranjal Shrivastava To: iommu@lists.linux.dev Cc: Will Deacon , Joerg Roedel , Robin Murphy , Jason Gunthorpe , Mostafa Saleh , Nicolin Chen , Daniel Mentz , Ashish Mhetre , linux-arm-kernel@lists.infradead.org, Greg Kroah-Hartman , rafael@kernel.org, Danilo Krummrich , Thomas Gleixner , driver-core@lists.linux.dev, Pranjal Shrivastava Content-Type: text/plain; charset="UTF-8" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260908_181753_157608_C944AE05 X-CRM114-Status: GOOD ( 21.07 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Introduce kunit selftests to verify the Runtime PM elision gating, post-suspend elisions and progress on resumption under active invalidation load. Simulate concurrent HW suspension using a timer. Mock all HW registers and CMDQ buffers by allocating them on RAM. Make the mock CMDQ self-consuming to avoid hitting queue_full scenarios. Signed-off-by: Pranjal Shrivastava --- .../iommu/arm/arm-smmu-v3/arm-smmu-v3-test.c | 215 ++++++++++++++++++ drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 1 + 2 files changed, 216 insertions(+) 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 index add671363c82..97c1e907717d 100644 --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-test.c +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-test.c @@ -3,6 +3,10 @@ * Copyright 2024 Google LLC. */ #include +#include +#include +#include +#include #include #include "arm-smmu-v3.h" @@ -771,6 +775,215 @@ static void arm_smmu_v3_invs_test(struct kunit *test) kfree(test_b); } +struct arm_smmu_mock_cmdq { + /* + * Mock register in RAM. Typed as __le32 to match writel_relaxed() + * endianness without calling readl_* accessors directly on RAM. + */ + __le32 mock_prod_reg; +}; + +/* Helper to allocate a self-consuming mock cmdq */ +static void arm_smmu_v3_test_init_mock_cmdq(struct kunit *test, + struct arm_smmu_device *smmu, + struct arm_smmu_mock_cmdq *mock) +{ + struct arm_smmu_cmdq *cmdq = &smmu->cmdq; + unsigned long *mock_valid_map; + u64 *mock_base; + + mock_base = kunit_kzalloc(test, 1024 * sizeof(struct arm_smmu_cmd), GFP_KERNEL); + mock_valid_map = kunit_kzalloc(test, BITS_TO_LONGS(1024) * sizeof(long), GFP_KERNEL); + + KUNIT_ASSERT_NOT_NULL(test, mock_base); + KUNIT_ASSERT_NOT_NULL(test, mock_valid_map); + + smmu->features = 0; + /* 1024 entries */ + cmdq->q.llq.max_n_shift = 10; + cmdq->q.ent_dwords = CMDQ_ENT_DWORDS; + cmdq->q.base = (__le64 *)mock_base; + cmdq->valid_map = (atomic_long_t *)mock_valid_map; + + /* Self-Consuming, prod == cons always ensures queue empty */ + cmdq->q.prod_reg = (__force void __iomem *)&mock->mock_prod_reg; + cmdq->q.cons_reg = (__force void __iomem *)&mock->mock_prod_reg; + + atomic_set(&cmdq->q.llq.atomic.prod, 0); + atomic_set(&cmdq->q.llq.atomic.cons, 0); + atomic_set(&cmdq->owner_prod, 0); + mock->mock_prod_reg = cpu_to_le32(0); +} + +struct arm_smmu_test_timer_context { + struct arm_smmu_device *smmu; + struct timer_list timer; + bool suspended; +}; + +static void arm_smmu_v3_test_rpm_timer_callback(struct timer_list *t) +{ + struct arm_smmu_test_timer_context *ctx = + timer_container_of(ctx, t, timer); + struct arm_smmu_cmdq *cmdq = &ctx->smmu->cmdq; + + /* Simulate a concurrent suspend event interrupting the invalidations */ + atomic_or(CMDQ_PROD_STOP_FLAG, &cmdq->q.llq.atomic.prod); + WRITE_ONCE(ctx->suspended, true); +} + +/* + * Verify SMMU PM Runtime gating, elision, and post-suspend resumption + * safety sequentially under active stress. + */ +static void arm_smmu_v3_rpm_test_stress_race(struct kunit *test) +{ + struct arm_smmu_cmd cmd = arm_smmu_make_cmd_cfgi_all(); + struct arm_smmu_test_timer_context timer_ctx = {0}; + struct arm_smmu_device mock_smmu = smmu; + struct arm_smmu_cmdq *cmdq = &mock_smmu.cmdq; + struct arm_smmu_mock_cmdq mock = {0}; + u32 stopped_prod; + int i; + + arm_smmu_v3_test_init_mock_cmdq(test, &mock_smmu, &mock); + + timer_ctx.smmu = &mock_smmu; + + timer_setup_on_stack(&timer_ctx.timer, arm_smmu_v3_test_rpm_timer_callback, 0); + mod_timer(&timer_ctx.timer, jiffies + msecs_to_jiffies(10)); + + /* Execute the unmap storm until the timer triggers */ + while (!READ_ONCE(timer_ctx.suspended)) { + if (arm_smmu_cmdq_issue_cmdlist(&mock_smmu, cmdq, &cmd, 1, false)) + break; + usleep_range(50, 100); + } + + timer_shutdown_sync(&timer_ctx.timer); + timer_destroy_on_stack(&timer_ctx.timer); + + /* Establish the post-storm prod_reg index */ + stopped_prod = le32_to_cpu(mock.mock_prod_reg); + + /* + * Attempt multiple unmaps while the SMMU is disabled (STOP_GATE is set) + * Every single invalidation must get elided and return 0. The prod_reg + * shall remain completely frozen after all of these submissions. + */ + for (i = 0; i < 1000; i++) { + if (arm_smmu_cmdq_issue_cmdlist(&mock_smmu, cmdq, &cmd, 1, false)) + break; + } + KUNIT_EXPECT_EQ(test, stopped_prod, le32_to_cpu(mock.mock_prod_reg)); + + /* + * Clear the STOP_FLAG (resume the SMMU). A new invalidation must + * now successfully commit prod_idx & move the prod_reg by exactly 1. + */ + atomic_andnot(CMDQ_PROD_STOP_FLAG, &cmdq->q.llq.atomic.prod); + KUNIT_EXPECT_EQ(test, 0, arm_smmu_cmdq_issue_cmdlist(&mock_smmu, cmdq, &cmd, 1, false)); + KUNIT_EXPECT_EQ(test, Q_POS(&cmdq->q.llq, stopped_prod + 1), + le32_to_cpu(mock.mock_prod_reg)); +} + +struct arm_smmu_test_kthread_context { + struct arm_smmu_device *smmu; + int error; +}; + +static int arm_smmu_v3_test_kthread_worker(void *data) +{ + struct arm_smmu_cmd cmd = arm_smmu_make_cmd_cfgi_all(); + struct arm_smmu_test_kthread_context *ctx = data; + struct arm_smmu_cmdq *cmdq = &ctx->smmu->cmdq; + + while (!kthread_should_stop()) { + if (arm_smmu_cmdq_issue_cmdlist(ctx->smmu, cmdq, &cmd, 1, false)) + WRITE_ONCE(ctx->error, 1); + usleep_range(50, 100); + } + return 0; +} + +KUNIT_DEFINE_ACTION_WRAPPER(kunit_action_kthread_stop, kthread_stop, struct task_struct *); + +static void arm_smmu_v3_rpm_test_kthread_race(struct kunit *test) +{ + struct arm_smmu_test_kthread_context *ctx; + struct arm_smmu_device *mock_smmu; + struct arm_smmu_mock_cmdq *mock; + struct task_struct *thread1, *thread2; + u32 stopped_prod; + int i; + + ctx = kunit_kzalloc(test, sizeof(*ctx), GFP_KERNEL); + mock_smmu = kunit_kzalloc(test, sizeof(*mock_smmu), GFP_KERNEL); + mock = kunit_kzalloc(test, sizeof(*mock), GFP_KERNEL); + KUNIT_ASSERT_NOT_NULL(test, ctx); + KUNIT_ASSERT_NOT_NULL(test, mock_smmu); + KUNIT_ASSERT_NOT_NULL(test, mock); + + *mock_smmu = smmu; + ctx->smmu = mock_smmu; + arm_smmu_v3_test_init_mock_cmdq(test, mock_smmu, mock); + + thread1 = kthread_run(arm_smmu_v3_test_kthread_worker, ctx, "smmu_w1"); + if (IS_ERR(thread1)) { + KUNIT_FAIL(test, "Failed to spawn kthread 1\n"); + return; + } + if (kunit_add_action_or_reset(test, kunit_action_kthread_stop, thread1)) { + KUNIT_FAIL(test, "Failed to register cleanup for kthread 1\n"); + return; + } + + thread2 = kthread_run(arm_smmu_v3_test_kthread_worker, ctx, "smmu_w2"); + if (IS_ERR(thread2)) { + KUNIT_FAIL(test, "Failed to spawn kthread 2\n"); + return; + } + if (kunit_add_action_or_reset(test, kunit_action_kthread_stop, thread2)) { + KUNIT_FAIL(test, "Failed to register cleanup for kthread 2\n"); + return; + } + + /* Wait for worker threads to start and issue initial commands */ + for (i = 0; i < 20; i++) { + if (le32_to_cpu(READ_ONCE(mock->mock_prod_reg)) > 0) + break; + usleep_range(1000, 2000); + } + KUNIT_EXPECT_GT(test, le32_to_cpu(READ_ONCE(mock->mock_prod_reg)), 0); + + /* Gate the CMDQ */ + atomic_or(CMDQ_PROD_STOP_FLAG, &mock_smmu->cmdq.q.llq.atomic.prod); + + /* Wait for in-flight submissions to settle */ + for (i = 0; i < 50; i++) { + stopped_prod = le32_to_cpu(READ_ONCE(mock->mock_prod_reg)); + usleep_range(1000, 2000); + if (stopped_prod == le32_to_cpu(READ_ONCE(mock->mock_prod_reg))) + break; + } + + usleep_range(1000, 2000); + KUNIT_EXPECT_EQ(test, stopped_prod, le32_to_cpu(READ_ONCE(mock->mock_prod_reg))); + + /* Open the gate and wait for worker threads to resume */ + atomic_andnot(CMDQ_PROD_STOP_FLAG, &mock_smmu->cmdq.q.llq.atomic.prod); + for (i = 0; i < 20; i++) { + if (le32_to_cpu(READ_ONCE(mock->mock_prod_reg)) != stopped_prod) + break; + usleep_range(1000, 2000); + } + KUNIT_EXPECT_NE(test, stopped_prod, le32_to_cpu(READ_ONCE(mock->mock_prod_reg))); + + kunit_release_action(test, kunit_action_kthread_stop, thread2); + kunit_release_action(test, kunit_action_kthread_stop, thread1); + KUNIT_EXPECT_EQ(test, 0, READ_ONCE(ctx->error)); +} + 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), @@ -797,6 +1010,8 @@ static struct kunit_case arm_smmu_v3_test_cases[] = { KUNIT_CASE(arm_smmu_v3_write_cd_test_sva_clear), KUNIT_CASE(arm_smmu_v3_write_cd_test_sva_release), KUNIT_CASE(arm_smmu_v3_invs_test), + KUNIT_CASE(arm_smmu_v3_rpm_test_stress_race), + KUNIT_CASE(arm_smmu_v3_rpm_test_kthread_race), {}, }; diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c index 8e4ce5eb2228..12d191fe57ed 100644 --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c @@ -991,6 +991,7 @@ int arm_smmu_cmdq_issue_cmdlist(struct arm_smmu_device *smmu, return ret; } +EXPORT_SYMBOL_IF_KUNIT(arm_smmu_cmdq_issue_cmdlist); static int arm_smmu_cmdq_issue_cmd_p(struct arm_smmu_device *smmu, struct arm_smmu_cmd *cmd, bool sync) -- 2.55.0.979.g7e5102b832-goog