[PATCH v5 15/18] PCI: Add KUnit coverage for ACS isolation checks

@@ -3578,7 +3578,8 @@ void pci_configure_ari(struct pci_dev *dev)
 	}
 }
 
-static bool pci_acs_flags_enabled(struct pci_dev *pdev, u16 acs_flags)
+VISIBLE_IF_KUNIT
+bool pci_acs_flags_enabled(struct pci_dev *pdev, u16 acs_flags)
 {
 	int pos;
 	u16 ctrl;

@@ -3598,6 +3599,7 @@ static bool pci_acs_flags_enabled(struct pci_dev *pdev, u16 acs_flags)
 		return false;
 	return (ctrl & acs_flags) == acs_flags;
 }
+EXPORT_SYMBOL_IF_KUNIT(pci_acs_flags_enabled);
 
 /**
  * pci_acs_enabled - test ACS against required flags for a given device

@@ -1104,6 +1104,7 @@ enum pci_acs_p2pdma_state {
 };
 
 #if IS_ENABLED(CONFIG_KUNIT)
+bool pci_acs_flags_enabled(struct pci_dev *pdev, u16 acs_flags);
 enum pci_acs_p2pdma_state pci_acs_p2pdma_request(u16 ctrl,
 						unsigned int tlp_flags);
 enum pci_acs_p2pdma_state pci_acs_p2pdma_completion(u16 ctrl,

@@ -102,6 +102,140 @@ static void pci_acs_p2pdma_completion_test(struct kunit *test)
 			c->expect);
 }
 
+/* Flags an IOMMU asks for; see REQ_ACS_FLAGS in drivers/iommu/iommu.c. */
+#define ACS_REQ_FLAGS	(PCI_ACS_SV | PCI_ACS_RR | PCI_ACS_CR | PCI_ACS_UF)
+#define ACS_ALL_CAPS	(PCI_ACS_SV | PCI_ACS_TB | PCI_ACS_RR | PCI_ACS_CR | \
+			 PCI_ACS_UF | PCI_ACS_DT)
+#define ACS_TEST_CAP	0x100
+
+struct acs_ctrl_cfg {
+	unsigned int devfn;
+	u16 cap;	/* Offset where the ACS capability responds */
+	u16 ctrl;
+	bool fail_read;
+};
+
+static int acs_ctrl_read(struct pci_bus *bus, unsigned int devfn,
+			 int where, int size, u32 *val)
+{
+	struct acs_ctrl_cfg *cfg = bus->sysdata;
+
+	*val = 0;
+	if (cfg->fail_read)
+		return PCIBIOS_DEVICE_NOT_FOUND;
+
+	if (devfn == cfg->devfn && size == 2 &&
+	    where == cfg->cap + PCI_ACS_CTRL)
+		*val = cfg->ctrl;
+	return PCIBIOS_SUCCESSFUL;
+}
+
+static int acs_ctrl_write(struct pci_bus *bus, unsigned int devfn,
+			  int where, int size, u32 val)
+{
+	return PCIBIOS_SUCCESSFUL;
+}
+
+static struct pci_ops acs_ctrl_ops = {
+	.read	= acs_ctrl_read,
+	.write	= acs_ctrl_write,
+};
+
+struct acs_isolation_case {
+	const char *desc;
+	u16 ctrl;
+	u16 req;
+	bool expect;
+};
+
+static const struct acs_isolation_case acs_isolation_cases[] = {
+	{ "all_enabled", ACS_REQ_FLAGS, ACS_REQ_FLAGS, true },
+	/* Translated Requests remain isolated by their IOMMU translation. */
+	{ "dt", ACS_REQ_FLAGS | PCI_ACS_DT, ACS_REQ_FLAGS, true },
+	{ "rr_not_enabled", PCI_ACS_SV | PCI_ACS_CR | PCI_ACS_UF,
+	  ACS_REQ_FLAGS, false },
+	{ "rr_not_required", PCI_ACS_SV | PCI_ACS_CR | PCI_ACS_UF,
+	  PCI_ACS_SV | PCI_ACS_CR | PCI_ACS_UF, true },
+};
+
+static void acs_isolation_desc(const struct acs_isolation_case *c, char *desc)
+{
+	strscpy(desc, c->desc, KUNIT_PARAM_DESC_SIZE);
+}
+
+KUNIT_ARRAY_PARAM(acs_isolation, acs_isolation_cases, acs_isolation_desc);
+
+static void pci_acs_flags_enabled_test(struct kunit *test)
+{
+	const struct acs_isolation_case *c = test->param_value;
+	struct acs_ctrl_cfg cfg = {
+		.devfn = PCI_DEVFN(0, 0),
+		.cap = ACS_TEST_CAP,
+		.ctrl = c->ctrl,
+	};
+	struct pci_bus *bus = kunit_kzalloc(test, sizeof(*bus), GFP_KERNEL);
+	struct pci_dev *pdev = kunit_kzalloc(test, sizeof(*pdev), GFP_KERNEL);
+
+	KUNIT_ASSERT_NOT_NULL(test, bus);
+	KUNIT_ASSERT_NOT_NULL(test, pdev);
+
+	bus->ops = &acs_ctrl_ops;
+	bus->sysdata = &cfg;
+
+	pdev->bus = bus;
+	pdev->devfn = cfg.devfn;
+	pdev->acs_cap = ACS_TEST_CAP;
+	pdev->acs_capabilities = ACS_ALL_CAPS;
+
+	KUNIT_EXPECT_EQ(test, pci_acs_flags_enabled(pdev, c->req), c->expect);
+}
+
+static bool acs_isolated(struct kunit *test, struct acs_ctrl_cfg *cfg,
+			 u16 acs_cap, u16 acs_flags)
+{
+	struct pci_bus *bus = kunit_kzalloc(test, sizeof(*bus), GFP_KERNEL);
+	struct pci_dev *pdev = kunit_kzalloc(test, sizeof(*pdev), GFP_KERNEL);
+
+	KUNIT_ASSERT_NOT_NULL(test, bus);
+	KUNIT_ASSERT_NOT_NULL(test, pdev);
+
+	bus->ops = &acs_ctrl_ops;
+	bus->sysdata = cfg;
+
+	pdev->bus = bus;
+	pdev->devfn = cfg->devfn;
+	pdev->acs_cap = acs_cap;
+	pdev->acs_capabilities = ACS_ALL_CAPS;
+
+	return pci_acs_flags_enabled(pdev, acs_flags);
+}
+
+static void pci_acs_flags_no_cap_test(struct kunit *test)
+{
+	struct acs_ctrl_cfg cfg = {
+		.devfn = PCI_DEVFN(0, 0),
+		.cap = 0,
+		.ctrl = ACS_REQ_FLAGS,
+	};
+
+	KUNIT_EXPECT_FALSE(test, acs_isolated(test, &cfg, 0, ACS_REQ_FLAGS));
+}
+
+static void pci_acs_flags_read_fails_test(struct kunit *test)
+{
+	u16 no_rr = ACS_REQ_FLAGS & ~PCI_ACS_RR;
+	struct acs_ctrl_cfg cfg = {
+		.devfn = PCI_DEVFN(0, 0),
+		.cap = ACS_TEST_CAP,
+		.ctrl = ACS_REQ_FLAGS,
+	};
+
+	KUNIT_EXPECT_TRUE(test, acs_isolated(test, &cfg, ACS_TEST_CAP, no_rr));
+
+	cfg.fail_read = true;
+	KUNIT_EXPECT_FALSE(test, acs_isolated(test, &cfg, ACS_TEST_CAP, no_rr));
+}
+
 /*
  * Drive calc_map_type_and_dist() over a fabricated PCIe fabric matching the
  * canonical topology of two devices below one switch:

@@ -445,6 +579,10 @@ static struct kunit_case pci_acs_test_cases[] = {
 			 acs_request_gen_params),
 	KUNIT_CASE_PARAM(pci_acs_p2pdma_completion_test,
 			 acs_completion_gen_params),
+	KUNIT_CASE_PARAM(pci_acs_flags_enabled_test,
+			 acs_isolation_gen_params),
+	KUNIT_CASE(pci_acs_flags_no_cap_test),
+	KUNIT_CASE(pci_acs_flags_read_fails_test),
 	KUNIT_CASE(acs_walk_bus_addr_test),
 	KUNIT_CASE(acs_walk_request_redirect_test),
 	KUNIT_CASE(acs_walk_completion_redirect_test),