cxl: Introduce implementation-specific API

The backend API (in cxl.h) lists some low-level functions whose
implementation is different on bare-metal and in a guest. Each
environment implements its own functions, and the common code uses
them through function pointers, defined in cxl_backend_ops

Co-authored-by: Christophe Lombard <clombard@linux.vnet.ibm.com>
Signed-off-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>
Signed-off-by: Christophe Lombard <clombard@linux.vnet.ibm.com>
Reviewed-by: Manoj Kumar <manoj@linux.vnet.ibm.com>
Acked-by: Ian Munsie <imunsie@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

11 files changed, 185 insertions, 120 deletions

diff --git a/drivers/misc/cxl/api.c b/drivers/misc/cxl/api.c
index b45d857..31eb842 100644
--- a/drivers/misc/cxl/api.c
+++ b/drivers/misc/cxl/api.c
@@ -100,7 +100,7 @@ EXPORT_SYMBOL_GPL(cxl_allocate_afu_irqs);
 void cxl_free_afu_irqs(struct cxl_context *ctx)
 {
 	afu_irq_name_free(ctx);
-	cxl_release_irq_ranges(&ctx->irqs, ctx->afu->adapter);
+	cxl_ops->release_irq_ranges(&ctx->irqs, ctx->afu->adapter);
 }
 EXPORT_SYMBOL_GPL(cxl_free_afu_irqs);
 
@@ -176,7 +176,7 @@ int cxl_start_context(struct cxl_context *ctx, u64 wed,
 
 	cxl_ctx_get();
 
-	if ((rc = cxl_attach_process(ctx, kernel, wed , 0))) {
+	if ((rc = cxl_ops->attach_process(ctx, kernel, wed, 0))) {
 		put_pid(ctx->pid);
 		cxl_ctx_put();
 		goto out;
@@ -342,11 +342,11 @@ int cxl_afu_reset(struct cxl_context *ctx)
 	struct cxl_afu *afu = ctx->afu;
 	int rc;
 
-	rc = __cxl_afu_reset(afu);
+	rc = cxl_ops->afu_reset(afu);
 	if (rc)
 		return rc;
 
-	return cxl_afu_check_and_enable(afu);
+	return cxl_ops->afu_check_and_enable(afu);
 }
 EXPORT_SYMBOL_GPL(cxl_afu_reset);
 
diff --git a/drivers/misc/cxl/context.c b/drivers/misc/cxl/context.c
index 262b88e..aa65262 100644
--- a/drivers/misc/cxl/context.c
+++ b/drivers/misc/cxl/context.c
@@ -214,8 +214,8 @@ int __detach_context(struct cxl_context *ctx)
 	/* Only warn if we detached while the link was OK.
 	 * If detach fails when hw is down, we don't care.
 	 */
-	WARN_ON(cxl_detach_process(ctx) &&
-		cxl_adapter_link_ok(ctx->afu->adapter));
+	WARN_ON(cxl_ops->detach_process(ctx) &&
+		cxl_ops->link_ok(ctx->afu->adapter));
 	flush_work(&ctx->fault_work); /* Only needed for dedicated process */
 
 	/* release the reference to the group leader and mm handling pid */
diff --git a/drivers/misc/cxl/cxl.h b/drivers/misc/cxl/cxl.h
index 3b824e3..8233af3 100644
--- a/drivers/misc/cxl/cxl.h
+++ b/drivers/misc/cxl/cxl.h
@@ -623,11 +623,6 @@ static inline u64 cxl_p2n_read(struct cxl_afu *afu, cxl_p2n_reg_t reg)
 		return ~0ULL;
 }
 
-u64 cxl_afu_cr_read64(struct cxl_afu *afu, int cr, u64 off);
-u32 cxl_afu_cr_read32(struct cxl_afu *afu, int cr, u64 off);
-u16 cxl_afu_cr_read16(struct cxl_afu *afu, int cr, u64 off);
-u8 cxl_afu_cr_read8(struct cxl_afu *afu, int cr, u64 off);
-
 ssize_t cxl_afu_read_err_buffer(struct cxl_afu *afu, char *buf,
 				loff_t off, size_t count);
 
@@ -666,10 +661,6 @@ void cxl_sysfs_afu_m_remove(struct cxl_afu *afu);
 
 struct cxl *cxl_alloc_adapter(void);
 struct cxl_afu *cxl_alloc_afu(struct cxl *adapter, int slice);
-
-int cxl_afu_activate_mode(struct cxl_afu *afu, int mode);
-int _cxl_afu_deactivate_mode(struct cxl_afu *afu, int mode);
-int cxl_afu_deactivate_mode(struct cxl_afu *afu);
 int cxl_afu_select_best_mode(struct cxl_afu *afu);
 
 int cxl_register_psl_irq(struct cxl_afu *afu);
@@ -681,8 +672,6 @@ void cxl_release_serr_irq(struct cxl_afu *afu);
 int afu_register_irqs(struct cxl_context *ctx, u32 count);
 void afu_release_irqs(struct cxl_context *ctx, void *cookie);
 void afu_irq_name_free(struct cxl_context *ctx);
-irqreturn_t handle_psl_slice_error(struct cxl_context *ctx, u64 dsisr,
-				u64 errstat);
 
 int cxl_debugfs_init(void);
 void cxl_debugfs_exit(void);
@@ -727,18 +716,10 @@ int cxl_register_one_irq(struct cxl *adapter, irq_handler_t handler,
 			void *cookie, irq_hw_number_t *dest_hwirq,
 			unsigned int *dest_virq, const char *name);
 
-int cxl_attach_process(struct cxl_context *ctx, bool kernel, u64 wed,
-			    u64 amr);
-int cxl_detach_process(struct cxl_context *ctx);
-
-int cxl_ack_irq(struct cxl_context *ctx, u64 tfc, u64 psl_reset_mask);
-
 int cxl_check_error(struct cxl_afu *afu);
 int cxl_afu_slbia(struct cxl_afu *afu);
 int cxl_tlb_slb_invalidate(struct cxl *adapter);
 int cxl_afu_disable(struct cxl_afu *afu);
-int __cxl_afu_reset(struct cxl_afu *afu);
-int cxl_afu_check_and_enable(struct cxl_afu *afu);
 int cxl_psl_purge(struct cxl_afu *afu);
 
 void cxl_stop_trace(struct cxl *cxl);
@@ -757,4 +738,38 @@ unsigned int afu_poll(struct file *file, struct poll_table_struct *poll);
 ssize_t afu_read(struct file *file, char __user *buf, size_t count, loff_t *off);
 extern const struct file_operations afu_fops;
 
+struct cxl_backend_ops {
+	struct module *module;
+	int (*adapter_reset)(struct cxl *adapter);
+	int (*alloc_one_irq)(struct cxl *adapter);
+	void (*release_one_irq)(struct cxl *adapter, int hwirq);
+	int (*alloc_irq_ranges)(struct cxl_irq_ranges *irqs,
+				struct cxl *adapter, unsigned int num);
+	void (*release_irq_ranges)(struct cxl_irq_ranges *irqs,
+				struct cxl *adapter);
+	int (*setup_irq)(struct cxl *adapter, unsigned int hwirq,
+			unsigned int virq);
+	irqreturn_t (*handle_psl_slice_error)(struct cxl_context *ctx,
+					u64 dsisr, u64 errstat);
+	irqreturn_t (*psl_interrupt)(int irq, void *data);
+	int (*ack_irq)(struct cxl_context *ctx, u64 tfc, u64 psl_reset_mask);
+	int (*attach_process)(struct cxl_context *ctx, bool kernel,
+			u64 wed, u64 amr);
+	int (*detach_process)(struct cxl_context *ctx);
+	bool (*link_ok)(struct cxl *cxl);
+	void (*release_afu)(struct device *dev);
+	ssize_t (*afu_read_err_buffer)(struct cxl_afu *afu, char *buf,
+				loff_t off, size_t count);
+	int (*afu_check_and_enable)(struct cxl_afu *afu);
+	int (*afu_activate_mode)(struct cxl_afu *afu, int mode);
+	int (*afu_deactivate_mode)(struct cxl_afu *afu, int mode);
+	int (*afu_reset)(struct cxl_afu *afu);
+	int (*afu_cr_read8)(struct cxl_afu *afu, int cr_idx, u64 offset, u8 *val);
+	int (*afu_cr_read16)(struct cxl_afu *afu, int cr_idx, u64 offset, u16 *val);
+	int (*afu_cr_read32)(struct cxl_afu *afu, int cr_idx, u64 offset, u32 *val);
+	int (*afu_cr_read64)(struct cxl_afu *afu, int cr_idx, u64 offset, u64 *val);
+};
+extern const struct cxl_backend_ops cxl_native_ops;
+extern const struct cxl_backend_ops *cxl_ops;
+
 #endif
diff --git a/drivers/misc/cxl/fault.c b/drivers/misc/cxl/fault.c
index 81c3f75..ab740a1 100644
--- a/drivers/misc/cxl/fault.c
+++ b/drivers/misc/cxl/fault.c
@@ -101,7 +101,7 @@ static void cxl_ack_ae(struct cxl_context *ctx)
 {
 	unsigned long flags;
 
-	cxl_ack_irq(ctx, CXL_PSL_TFC_An_AE, 0);
+	cxl_ops->ack_irq(ctx, CXL_PSL_TFC_An_AE, 0);
 
 	spin_lock_irqsave(&ctx->lock, flags);
 	ctx->pending_fault = true;
@@ -125,7 +125,7 @@ static int cxl_handle_segment_miss(struct cxl_context *ctx,
 	else {
 
 		mb(); /* Order seg table write to TFC MMIO write */
-		cxl_ack_irq(ctx, CXL_PSL_TFC_An_R, 0);
+		cxl_ops->ack_irq(ctx, CXL_PSL_TFC_An_R, 0);
 	}
 
 	return IRQ_HANDLED;
@@ -163,7 +163,7 @@ static void cxl_handle_page_fault(struct cxl_context *ctx,
 	local_irq_restore(flags);
 
 	pr_devel("Page fault successfully handled for pe: %i!\n", ctx->pe);
-	cxl_ack_irq(ctx, CXL_PSL_TFC_An_R, 0);
+	cxl_ops->ack_irq(ctx, CXL_PSL_TFC_An_R, 0);
 }
 
 /*
diff --git a/drivers/misc/cxl/file.c b/drivers/misc/cxl/file.c
index 783337d..b8ce29b 100644
--- a/drivers/misc/cxl/file.c
+++ b/drivers/misc/cxl/file.c
@@ -79,7 +79,7 @@ static int __afu_open(struct inode *inode, struct file *file, bool master)
 	if (!afu->current_mode)
 		goto err_put_afu;
 
-	if (!cxl_adapter_link_ok(adapter)) {
+	if (!cxl_ops->link_ok(adapter)) {
 		rc = -EIO;
 		goto err_put_afu;
 	}
@@ -210,8 +210,8 @@ static long afu_ioctl_start_work(struct cxl_context *ctx,
 
 	trace_cxl_attach(ctx, work.work_element_descriptor, work.num_interrupts, amr);
 
-	if ((rc = cxl_attach_process(ctx, false, work.work_element_descriptor,
-				     amr))) {
+	if ((rc = cxl_ops->attach_process(ctx, false, work.work_element_descriptor,
+							amr))) {
 		afu_release_irqs(ctx, ctx);
 		goto out;
 	}
@@ -222,6 +222,7 @@ out:
 	mutex_unlock(&ctx->status_mutex);
 	return rc;
 }
+
 static long afu_ioctl_process_element(struct cxl_context *ctx,
 				      int __user *upe)
 {
@@ -259,7 +260,7 @@ long afu_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 	if (ctx->status == CLOSED)
 		return -EIO;
 
-	if (!cxl_adapter_link_ok(ctx->afu->adapter))
+	if (!cxl_ops->link_ok(ctx->afu->adapter))
 		return -EIO;
 
 	pr_devel("afu_ioctl\n");
@@ -289,7 +290,7 @@ int afu_mmap(struct file *file, struct vm_area_struct *vm)
 	if (ctx->status != STARTED)
 		return -EIO;
 
-	if (!cxl_adapter_link_ok(ctx->afu->adapter))
+	if (!cxl_ops->link_ok(ctx->afu->adapter))
 		return -EIO;
 
 	return cxl_context_iomap(ctx, vm);
@@ -336,7 +337,7 @@ ssize_t afu_read(struct file *file, char __user *buf, size_t count,
 	int rc;
 	DEFINE_WAIT(wait);
 
-	if (!cxl_adapter_link_ok(ctx->afu->adapter))
+	if (!cxl_ops->link_ok(ctx->afu->adapter))
 		return -EIO;
 
 	if (count < CXL_READ_MIN_SIZE)
@@ -349,7 +350,7 @@ ssize_t afu_read(struct file *file, char __user *buf, size_t count,
 		if (ctx_event_pending(ctx))
 			break;
 
-		if (!cxl_adapter_link_ok(ctx->afu->adapter)) {
+		if (!cxl_ops->link_ok(ctx->afu->adapter)) {
 			rc = -EIO;
 			goto out;
 		}
diff --git a/drivers/misc/cxl/irq.c b/drivers/misc/cxl/irq.c
index 16fd67f..56ad301 100644
--- a/drivers/misc/cxl/irq.c
+++ b/drivers/misc/cxl/irq.c
@@ -79,7 +79,8 @@ irqreturn_t cxl_irq(int irq, void *data, struct cxl_irq_info *irq_info)
 	if (dsisr & CXL_PSL_DSISR_An_UR)
 		pr_devel("CXL interrupt: AURP PTE not found\n");
 	if (dsisr & CXL_PSL_DSISR_An_PE)
-		return handle_psl_slice_error(ctx, dsisr, irq_info->errstat);
+		return cxl_ops->handle_psl_slice_error(ctx, dsisr,
+						irq_info->errstat);
 	if (dsisr & CXL_PSL_DSISR_An_AE) {
 		pr_devel("CXL interrupt: AFU Error 0x%016llx\n", irq_info->afu_err);
 
@@ -103,7 +104,7 @@ irqreturn_t cxl_irq(int irq, void *data, struct cxl_irq_info *irq_info)
 			wake_up_all(&ctx->wq);
 		}
 
-		cxl_ack_irq(ctx, CXL_PSL_TFC_An_A, 0);
+		cxl_ops->ack_irq(ctx, CXL_PSL_TFC_An_A, 0);
 		return IRQ_HANDLED;
 	}
 	if (dsisr & CXL_PSL_DSISR_An_OC)
@@ -167,7 +168,8 @@ unsigned int cxl_map_irq(struct cxl *adapter, irq_hw_number_t hwirq,
 		return 0;
 	}
 
-	cxl_setup_irq(adapter, hwirq, virq);
+	if (cxl_ops->setup_irq)
+		cxl_ops->setup_irq(adapter, hwirq, virq);
 
 	pr_devel("hwirq %#lx mapped to virq %u\n", hwirq, virq);
 
@@ -195,7 +197,7 @@ int cxl_register_one_irq(struct cxl *adapter,
 {
 	int hwirq, virq;
 
-	if ((hwirq = cxl_alloc_one_irq(adapter)) < 0)
+	if ((hwirq = cxl_ops->alloc_one_irq(adapter)) < 0)
 		return hwirq;
 
 	if (!(virq = cxl_map_irq(adapter, hwirq, handler, cookie, name)))
@@ -207,7 +209,7 @@ int cxl_register_one_irq(struct cxl *adapter,
 	return 0;
 
 err:
-	cxl_release_one_irq(adapter, hwirq);
+	cxl_ops->release_one_irq(adapter, hwirq);
 	return -ENOMEM;
 }
 
@@ -230,7 +232,8 @@ int afu_allocate_irqs(struct cxl_context *ctx, u32 count)
 	/* Initialize the list head to hold irq names */
 	INIT_LIST_HEAD(&ctx->irq_names);
 
-	if ((rc = cxl_alloc_irq_ranges(&ctx->irqs, ctx->afu->adapter, count)))
+	if ((rc = cxl_ops->alloc_irq_ranges(&ctx->irqs, ctx->afu->adapter,
+							count)))
 		return rc;
 
 	/* Multiplexed PSL Interrupt */
@@ -268,7 +271,7 @@ int afu_allocate_irqs(struct cxl_context *ctx, u32 count)
 	return 0;
 
 out:
-	cxl_release_irq_ranges(&ctx->irqs, ctx->afu->adapter);
+	cxl_ops->release_irq_ranges(&ctx->irqs, ctx->afu->adapter);
 	afu_irq_name_free(ctx);
 	return -ENOMEM;
 }
@@ -319,7 +322,7 @@ void afu_release_irqs(struct cxl_context *ctx, void *cookie)
 	}
 
 	afu_irq_name_free(ctx);
-	cxl_release_irq_ranges(&ctx->irqs, ctx->afu->adapter);
+	cxl_ops->release_irq_ranges(&ctx->irqs, ctx->afu->adapter);
 
 	ctx->irq_count = 0;
 }
diff --git a/drivers/misc/cxl/main.c b/drivers/misc/cxl/main.c
index 90933eb..a9051512 100644
--- a/drivers/misc/cxl/main.c
+++ b/drivers/misc/cxl/main.c
@@ -32,6 +32,8 @@ uint cxl_verbose;
 module_param_named(verbose, cxl_verbose, uint, 0600);
 MODULE_PARM_DESC(verbose, "Enable verbose dmesg output");
 
+const struct cxl_backend_ops *cxl_ops;
+
 int cxl_afu_slbia(struct cxl_afu *afu)
 {
 	unsigned long timeout = jiffies + (HZ * CXL_TIMEOUT);
@@ -46,7 +48,7 @@ int cxl_afu_slbia(struct cxl_afu *afu)
 		/* If the adapter has gone down, we can assume that we
 		 * will PERST it and that will invalidate everything.
 		 */
-		if (!cxl_adapter_link_ok(afu->adapter))
+		if (!cxl_ops->link_ok(afu->adapter))
 			return -EIO;
 		cpu_relax();
 	}
@@ -228,7 +230,7 @@ struct cxl_afu *cxl_alloc_afu(struct cxl *adapter, int slice)
 
 	afu->adapter = adapter;
 	afu->dev.parent = &adapter->dev;
-	afu->dev.release = cxl_release_afu;
+	afu->dev.release = cxl_ops->release_afu;
 	afu->slice = slice;
 	idr_init(&afu->contexts_idr);
 	mutex_init(&afu->contexts_lock);
@@ -244,10 +246,10 @@ struct cxl_afu *cxl_alloc_afu(struct cxl *adapter, int slice)
 int cxl_afu_select_best_mode(struct cxl_afu *afu)
 {
 	if (afu->modes_supported & CXL_MODE_DIRECTED)
-		return cxl_afu_activate_mode(afu, CXL_MODE_DIRECTED);
+		return cxl_ops->afu_activate_mode(afu, CXL_MODE_DIRECTED);
 
 	if (afu->modes_supported & CXL_MODE_DEDICATED)
-		return cxl_afu_activate_mode(afu, CXL_MODE_DEDICATED);
+		return cxl_ops->afu_activate_mode(afu, CXL_MODE_DEDICATED);
 
 	dev_warn(&afu->dev, "No supported programming modes available\n");
 	/* We don't fail this so the user can inspect sysfs */
@@ -269,6 +271,7 @@ static int __init init_cxl(void)
 	if ((rc = register_cxl_calls(&cxl_calls)))
 		goto err;
 
+	cxl_ops = &cxl_native_ops;
 	if ((rc = pci_register_driver(&cxl_pci_driver)))
 		goto err1;
 
diff --git a/drivers/misc/cxl/native.c b/drivers/misc/cxl/native.c
index 3103e33..16d3b1a 100644
--- a/drivers/misc/cxl/native.c
+++ b/drivers/misc/cxl/native.c
@@ -42,7 +42,7 @@ static int afu_control(struct cxl_afu *afu, u64 command,
 			goto out;
 		}
 
-		if (!cxl_adapter_link_ok(afu->adapter)) {
+		if (!cxl_ops->link_ok(afu->adapter)) {
 			afu->enabled = enabled;
 			rc = -EIO;
 			goto out;
@@ -80,7 +80,7 @@ int cxl_afu_disable(struct cxl_afu *afu)
 }
 
 /* This will disable as well as reset */
-int __cxl_afu_reset(struct cxl_afu *afu)
+static int __cxl_afu_reset(struct cxl_afu *afu)
 {
 	pr_devel("AFU reset request\n");
 
@@ -90,9 +90,9 @@ int __cxl_afu_reset(struct cxl_afu *afu)
 			   false);
 }
 
-int cxl_afu_check_and_enable(struct cxl_afu *afu)
+static int cxl_afu_check_and_enable(struct cxl_afu *afu)
 {
-	if (!cxl_adapter_link_ok(afu->adapter)) {
+	if (!cxl_ops->link_ok(afu->adapter)) {
 		WARN(1, "Refusing to enable afu while link down!\n");
 		return -EIO;
 	}
@@ -114,7 +114,7 @@ int cxl_psl_purge(struct cxl_afu *afu)
 
 	pr_devel("PSL purge request\n");
 
-	if (!cxl_adapter_link_ok(afu->adapter)) {
+	if (!cxl_ops->link_ok(afu->adapter)) {
 		dev_warn(&afu->dev, "PSL Purge called with link down, ignoring\n");
 		rc = -EIO;
 		goto out;
@@ -136,7 +136,7 @@ int cxl_psl_purge(struct cxl_afu *afu)
 			rc = -EBUSY;
 			goto out;
 		}
-		if (!cxl_adapter_link_ok(afu->adapter)) {
+		if (!cxl_ops->link_ok(afu->adapter)) {
 			rc = -EIO;
 			goto out;
 		}
@@ -247,7 +247,7 @@ int cxl_tlb_slb_invalidate(struct cxl *adapter)
 			dev_warn(&adapter->dev, "WARNING: CXL adapter wide TLBIA timed out!\n");
 			return -EBUSY;
 		}
-		if (!cxl_adapter_link_ok(adapter))
+		if (!cxl_ops->link_ok(adapter))
 			return -EIO;
 		cpu_relax();
 	}
@@ -258,7 +258,7 @@ int cxl_tlb_slb_invalidate(struct cxl *adapter)
 			dev_warn(&adapter->dev, "WARNING: CXL adapter wide SLBIA timed out!\n");
 			return -EBUSY;
 		}
-		if (!cxl_adapter_link_ok(adapter))
+		if (!cxl_ops->link_ok(adapter))
 			return -EIO;
 		cpu_relax();
 	}
@@ -299,7 +299,7 @@ static void slb_invalid(struct cxl_context *ctx)
 	cxl_p1_write(adapter, CXL_PSL_SLBIA, CXL_TLB_SLB_IQ_LPIDPID);
 
 	while (1) {
-		if (!cxl_adapter_link_ok(adapter))
+		if (!cxl_ops->link_ok(adapter))
 			break;
 		slbia = cxl_p1_read(adapter, CXL_PSL_SLBIA);
 		if (!(slbia & CXL_TLB_SLB_P))
@@ -330,7 +330,7 @@ static int do_process_element_cmd(struct cxl_context *ctx,
 			rc = -EBUSY;
 			goto out;
 		}
-		if (!cxl_adapter_link_ok(ctx->afu->adapter)) {
+		if (!cxl_ops->link_ok(ctx->afu->adapter)) {
 			dev_warn(&ctx->afu->dev, "WARNING: Device link down, aborting Process Element Command!\n");
 			rc = -EIO;
 			goto out;
@@ -386,7 +386,7 @@ static int terminate_process_element(struct cxl_context *ctx)
 	 * should always succeed: it's not running if the hw has gone
 	 * away and is being reset.
 	 */
-	if (cxl_adapter_link_ok(ctx->afu->adapter))
+	if (cxl_ops->link_ok(ctx->afu->adapter))
 		rc = do_process_element_cmd(ctx, CXL_SPA_SW_CMD_TERMINATE,
 					    CXL_PE_SOFTWARE_STATE_V | CXL_PE_SOFTWARE_STATE_T);
 	ctx->elem->software_state = 0;	/* Remove Valid bit */
@@ -405,7 +405,7 @@ static int remove_process_element(struct cxl_context *ctx)
 	/* We could be asked to remove when the hw is down. Again, if
 	 * the hw is down, the PE is gone, so we succeed.
 	 */
-	if (cxl_adapter_link_ok(ctx->afu->adapter))
+	if (cxl_ops->link_ok(ctx->afu->adapter))
 		rc = do_process_element_cmd(ctx, CXL_SPA_SW_CMD_REMOVE, 0);
 
 	if (!rc)
@@ -531,7 +531,7 @@ static int attach_afu_directed(struct cxl_context *ctx, u64 wed, u64 amr)
 	ctx->elem->common.wed = cpu_to_be64(wed);
 
 	/* first guy needs to enable */
-	if ((result = cxl_afu_check_and_enable(ctx->afu)))
+	if ((result = cxl_ops->afu_check_and_enable(ctx->afu)))
 		return result;
 
 	return add_process_element(ctx);
@@ -547,7 +547,7 @@ static int deactivate_afu_directed(struct cxl_afu *afu)
 	cxl_sysfs_afu_m_remove(afu);
 	cxl_chardev_afu_remove(afu);
 
-	__cxl_afu_reset(afu);
+	cxl_ops->afu_reset(afu);
 	cxl_afu_disable(afu);
 	cxl_psl_purge(afu);
 
@@ -611,7 +611,7 @@ static int attach_dedicated(struct cxl_context *ctx, u64 wed, u64 amr)
 	/* master only context for dedicated */
 	cxl_assign_psn_space(ctx);
 
-	if ((rc = __cxl_afu_reset(afu)))
+	if ((rc = cxl_ops->afu_reset(afu)))
 		return rc;
 
 	cxl_p2n_write(afu, CXL_PSL_WED_An, wed);
@@ -631,7 +631,7 @@ static int deactivate_dedicated_process(struct cxl_afu *afu)
 	return 0;
 }
 
-int _cxl_afu_deactivate_mode(struct cxl_afu *afu, int mode)
+static int cxl_afu_deactivate_mode(struct cxl_afu *afu, int mode)
 {
 	if (mode == CXL_MODE_DIRECTED)
 		return deactivate_afu_directed(afu);
@@ -640,19 +640,14 @@ int _cxl_afu_deactivate_mode(struct cxl_afu *afu, int mode)
 	return 0;
 }
 
-int cxl_afu_deactivate_mode(struct cxl_afu *afu)
-{
-	return _cxl_afu_deactivate_mode(afu, afu->current_mode);
-}
-
-int cxl_afu_activate_mode(struct cxl_afu *afu, int mode)
+static int cxl_afu_activate_mode(struct cxl_afu *afu, int mode)
 {
 	if (!mode)
 		return 0;
 	if (!(mode & afu->modes_supported))
 		return -EINVAL;
 
-	if (!cxl_adapter_link_ok(afu->adapter)) {
+	if (!cxl_ops->link_ok(afu->adapter)) {
 		WARN(1, "Device link is down, refusing to activate!\n");
 		return -EIO;
 	}
@@ -665,9 +660,9 @@ int cxl_afu_activate_mode(struct cxl_afu *afu, int mode)
 	return -EINVAL;
 }
 
-int cxl_attach_process(struct cxl_context *ctx, bool kernel, u64 wed, u64 amr)
+static int cxl_attach_process(struct cxl_context *ctx, bool kernel, u64 wed, u64 amr)
 {
-	if (!cxl_adapter_link_ok(ctx->afu->adapter)) {
+	if (!cxl_ops->link_ok(ctx->afu->adapter)) {
 		WARN(1, "Device link is down, refusing to attach process!\n");
 		return -EIO;
 	}
@@ -684,7 +679,7 @@ int cxl_attach_process(struct cxl_context *ctx, bool kernel, u64 wed, u64 amr)
 
 static inline int detach_process_native_dedicated(struct cxl_context *ctx)
 {
-	__cxl_afu_reset(ctx->afu);
+	cxl_ops->afu_reset(ctx->afu);
 	cxl_afu_disable(ctx->afu);
 	cxl_psl_purge(ctx->afu);
 	return 0;
@@ -702,7 +697,7 @@ static inline int detach_process_native_afu_directed(struct cxl_context *ctx)
 	return 0;
 }
 
-int cxl_detach_process(struct cxl_context *ctx)
+static int cxl_detach_process(struct cxl_context *ctx)
 {
 	trace_cxl_detach(ctx);
 
@@ -719,7 +714,7 @@ static int cxl_get_irq(struct cxl_afu *afu, struct cxl_irq_info *info)
 	/* If the adapter has gone away, we can't get any meaningful
 	 * information.
 	 */
-	if (!cxl_adapter_link_ok(afu->adapter))
+	if (!cxl_ops->link_ok(afu->adapter))
 		return -EIO;
 
 	info->dsisr = cxl_p2n_read(afu, CXL_PSL_DSISR_An);
@@ -734,7 +729,7 @@ static int cxl_get_irq(struct cxl_afu *afu, struct cxl_irq_info *info)
 	return 0;
 }
 
-irqreturn_t handle_psl_slice_error(struct cxl_context *ctx, u64 dsisr, u64 errstat)
+static irqreturn_t handle_psl_slice_error(struct cxl_context *ctx, u64 dsisr, u64 errstat)
 {
 	u64 fir1, fir2, fir_slice, serr, afu_debug;
 
@@ -754,7 +749,7 @@ irqreturn_t handle_psl_slice_error(struct cxl_context *ctx, u64 dsisr, u64 errst
 	dev_crit(&ctx->afu->dev, "STOPPING CXL TRACE\n");
 	cxl_stop_trace(ctx->afu->adapter);
 
-	return cxl_ack_irq(ctx, 0, errstat);
+	return cxl_ops->ack_irq(ctx, 0, errstat);
 }
 
 static irqreturn_t fail_psl_irq(struct cxl_afu *afu, struct cxl_irq_info *irq_info)
@@ -868,7 +863,7 @@ void cxl_release_psl_err_irq(struct cxl *adapter)
 
 	cxl_p1_write(adapter, CXL_PSL_ErrIVTE, 0x0000000000000000);
 	cxl_unmap_irq(adapter->err_virq, adapter);
-	cxl_release_one_irq(adapter, adapter->err_hwirq);
+	cxl_ops->release_one_irq(adapter, adapter->err_hwirq);
 	kfree(adapter->irq_name);
 }
 
@@ -904,7 +899,7 @@ void cxl_release_serr_irq(struct cxl_afu *afu)
 
 	cxl_p1n_write(afu, CXL_PSL_SERR_An, 0x0000000000000000);
 	cxl_unmap_irq(afu->serr_virq, afu);
-	cxl_release_one_irq(afu->adapter, afu->serr_hwirq);
+	cxl_ops->release_one_irq(afu->adapter, afu->serr_hwirq);
 	kfree(afu->err_irq_name);
 }
 
@@ -932,7 +927,7 @@ void cxl_release_psl_irq(struct cxl_afu *afu)
 		return;
 
 	cxl_unmap_irq(afu->psl_virq, afu);
-	cxl_release_one_irq(afu->adapter, afu->psl_hwirq);
+	cxl_ops->release_one_irq(afu->adapter, afu->psl_hwirq);
 	kfree(afu->psl_irq_name);
 }
 
@@ -950,7 +945,7 @@ static void recover_psl_err(struct cxl_afu *afu, u64 errstat)
 	cxl_p2n_write(afu, CXL_PSL_ErrStat_An, errstat);
 }
 
-int cxl_ack_irq(struct cxl_context *ctx, u64 tfc, u64 psl_reset_mask)
+static int cxl_ack_irq(struct cxl_context *ctx, u64 tfc, u64 psl_reset_mask)
 {
 	trace_cxl_psl_irq_ack(ctx, tfc);
 	if (tfc)
@@ -966,38 +961,74 @@ int cxl_check_error(struct cxl_afu *afu)
 	return (cxl_p1n_read(afu, CXL_PSL_SCNTL_An) == ~0ULL);
 }
 
-u64 cxl_afu_cr_read64(struct cxl_afu *afu, int cr, u64 off)
+static int cxl_afu_cr_read64(struct cxl_afu *afu, int cr, u64 off, u64 *out)
 {
-	if (likely(cxl_adapter_link_ok(afu->adapter)))
-		return in_le64((afu)->afu_desc_mmio + (afu)->crs_offset +
-			       ((cr) * (afu)->crs_len) + (off));
-	else
-		return ~0ULL;
+	if (unlikely(!cxl_ops->link_ok(afu->adapter)))
+		return -EIO;
+	if (unlikely(off >= afu->crs_len))
+		return -ERANGE;
+	*out = in_le64(afu->afu_desc_mmio + afu->crs_offset +
+		(cr * afu->crs_len) + off);
+	return 0;
 }
 
-u32 cxl_afu_cr_read32(struct cxl_afu *afu, int cr, u64 off)
+static int cxl_afu_cr_read32(struct cxl_afu *afu, int cr, u64 off, u32 *out)
 {
-	if (likely(cxl_adapter_link_ok(afu->adapter)))
-		return in_le32((afu)->afu_desc_mmio + (afu)->crs_offset +
-			       ((cr) * (afu)->crs_len) + (off));
-	else
-		return 0xffffffff;
+	if (unlikely(!cxl_ops->link_ok(afu->adapter)))
+		return -EIO;
+	if (unlikely(off >= afu->crs_len))
+		return -ERANGE;
+	*out = in_le32(afu->afu_desc_mmio + afu->crs_offset +
+		(cr * afu->crs_len) + off);
+	return 0;
 }
 
-u16 cxl_afu_cr_read16(struct cxl_afu *afu, int cr, u64 off)
+static int cxl_afu_cr_read16(struct cxl_afu *afu, int cr, u64 off, u16 *out)
 {
 	u64 aligned_off = off & ~0x3L;
 	u32 val;
+	int rc;
 
-	val = cxl_afu_cr_read32(afu, cr, aligned_off);
-	return (val >> ((off & 0x2) * 8)) & 0xffff;
+	rc = cxl_afu_cr_read32(afu, cr, aligned_off, &val);
+	if (!rc)
+		*out = (val >> ((off & 0x3) * 8)) & 0xffff;
+	return rc;
 }
 
-u8 cxl_afu_cr_read8(struct cxl_afu *afu, int cr, u64 off)
+static int cxl_afu_cr_read8(struct cxl_afu *afu, int cr, u64 off, u8 *out)
 {
 	u64 aligned_off = off & ~0x3L;
 	u32 val;
+	int rc;
 
-	val = cxl_afu_cr_read32(afu, cr, aligned_off);
-	return (val >> ((off & 0x3) * 8)) & 0xff;
+	rc = cxl_afu_cr_read32(afu, cr, aligned_off, &val);
+	if (!rc)
+		*out = (val >> ((off & 0x3) * 8)) & 0xff;
+	return rc;
 }
+
+const struct cxl_backend_ops cxl_native_ops = {
+	.module = THIS_MODULE,
+	.adapter_reset = cxl_reset,
+	.alloc_one_irq = cxl_alloc_one_irq,
+	.release_one_irq = cxl_release_one_irq,
+	.alloc_irq_ranges = cxl_alloc_irq_ranges,
+	.release_irq_ranges = cxl_release_irq_ranges,
+	.setup_irq = cxl_setup_irq,
+	.handle_psl_slice_error = handle_psl_slice_error,
+	.psl_interrupt = NULL,
+	.ack_irq = cxl_ack_irq,
+	.attach_process = cxl_attach_process,
+	.detach_process = cxl_detach_process,
+	.link_ok = cxl_adapter_link_ok,
+	.release_afu = cxl_release_afu,
+	.afu_read_err_buffer = cxl_afu_read_err_buffer,
+	.afu_check_and_enable = cxl_afu_check_and_enable,
+	.afu_activate_mode = cxl_afu_activate_mode,
+	.afu_deactivate_mode = cxl_afu_deactivate_mode,
+	.afu_reset = __cxl_afu_reset,
+	.afu_cr_read8 = cxl_afu_cr_read8,
+	.afu_cr_read16 = cxl_afu_cr_read16,
+	.afu_cr_read32 = cxl_afu_cr_read32,
+	.afu_cr_read64 = cxl_afu_cr_read64,
+};
diff --git a/drivers/misc/cxl/pci.c b/drivers/misc/cxl/pci.c
index c6279e5..6e2c274 100644
--- a/drivers/misc/cxl/pci.c
+++ b/drivers/misc/cxl/pci.c
@@ -646,7 +646,8 @@ static int cxl_read_afu_descriptor(struct cxl_afu *afu)
 
 static int cxl_afu_descriptor_looks_ok(struct cxl_afu *afu)
 {
-	int i;
+	int i, rc;
+	u32 val;
 
 	if (afu->psa && afu->adapter->ps_size <
 			(afu->pp_offset + afu->pp_size*afu->max_procs_virtualised)) {
@@ -658,7 +659,8 @@ static int cxl_afu_descriptor_looks_ok(struct cxl_afu *afu)
 		dev_warn(&afu->dev, "AFU uses < PAGE_SIZE per-process PSA!");
 
 	for (i = 0; i < afu->crs_num; i++) {
-		if ((cxl_afu_cr_read32(afu, i, 0) == 0)) {
+		rc = cxl_ops->afu_cr_read32(afu, i, 0, &val);
+		if (rc || val == 0) {
 			dev_err(&afu->dev, "ABORTING: AFU configuration record %i is invalid\n", i);
 			return -EINVAL;
 		}
@@ -679,7 +681,7 @@ static int sanitise_afu_regs(struct cxl_afu *afu)
 	reg = cxl_p2n_read(afu, CXL_AFU_Cntl_An);
 	if ((reg & CXL_AFU_Cntl_An_ES_MASK) != CXL_AFU_Cntl_An_ES_Disabled) {
 		dev_warn(&afu->dev, "WARNING: AFU was not disabled: %#016llx\n", reg);
-		if (__cxl_afu_reset(afu))
+		if (cxl_ops->afu_reset(afu))
 			return -EIO;
 		if (cxl_afu_disable(afu))
 			return -EIO;
@@ -775,7 +777,7 @@ static int cxl_configure_afu(struct cxl_afu *afu, struct cxl *adapter, struct pc
 		goto err1;
 
 	/* We need to reset the AFU before we can read the AFU descriptor */
-	if ((rc = __cxl_afu_reset(afu)))
+	if ((rc = cxl_ops->afu_reset(afu)))
 		goto err1;
 
 	if (cxl_verbose)
@@ -876,7 +878,7 @@ static void cxl_remove_afu(struct cxl_afu *afu)
 	spin_unlock(&afu->adapter->afu_list_lock);
 
 	cxl_context_detach_all(afu);
-	cxl_afu_deactivate_mode(afu);
+	cxl_ops->afu_deactivate_mode(afu, afu->current_mode);
 
 	cxl_deconfigure_afu(afu);
 	device_unregister(&afu->dev);
@@ -1398,7 +1400,7 @@ static pci_ers_result_t cxl_pci_error_detected(struct pci_dev *pdev,
 			return result;
 
 		cxl_context_detach_all(afu);
-		cxl_afu_deactivate_mode(afu);
+		cxl_ops->afu_deactivate_mode(afu, afu->current_mode);
 		cxl_deconfigure_afu(afu);
 	}
 	cxl_deconfigure_adapter(adapter);
@@ -1445,7 +1447,7 @@ static pci_ers_result_t cxl_pci_slot_reset(struct pci_dev *pdev)
 
 			afu_dev->dev.archdata.cxl_ctx = ctx;
 
-			if (cxl_afu_check_and_enable(afu))
+			if (cxl_ops->afu_check_and_enable(afu))
 				goto err;
 
 			afu_dev->error_state = pci_channel_io_normal;
diff --git a/drivers/misc/cxl/sysfs.c b/drivers/misc/cxl/sysfs.c
index 02006f71..300eafe 100644
--- a/drivers/misc/cxl/sysfs.c
+++ b/drivers/misc/cxl/sysfs.c
@@ -69,7 +69,7 @@ static ssize_t reset_adapter_store(struct device *device,
 	if ((rc != 1) || (val != 1))
 		return -EINVAL;
 
-	if ((rc = cxl_reset(adapter)))
+	if ((rc = cxl_ops->adapter_reset(adapter)))
 		return rc;
 	return count;
 }
@@ -211,7 +211,7 @@ static ssize_t reset_store_afu(struct device *device,
 		goto err;
 	}
 
-	if ((rc = __cxl_afu_reset(afu)))
+	if ((rc = cxl_ops->afu_reset(afu)))
 		goto err;
 
 	rc = count;
@@ -348,7 +348,7 @@ static ssize_t mode_store(struct device *device, struct device_attribute *attr,
 	}
 
 	/*
-	 * cxl_afu_deactivate_mode needs to be done outside the lock, prevent
+	 * afu_deactivate_mode needs to be done outside the lock, prevent
 	 * other contexts coming in before we are ready:
 	 */
 	old_mode = afu->current_mode;
@@ -357,9 +357,9 @@ static ssize_t mode_store(struct device *device, struct device_attribute *attr,
 
 	mutex_unlock(&afu->contexts_lock);
 
-	if ((rc = _cxl_afu_deactivate_mode(afu, old_mode)))
+	if ((rc = cxl_ops->afu_deactivate_mode(afu, old_mode)))
 		return rc;
-	if ((rc = cxl_afu_activate_mode(afu, mode)))
+	if ((rc = cxl_ops->afu_activate_mode(afu, mode)))
 		return rc;
 
 	return count;
@@ -389,7 +389,7 @@ static ssize_t afu_eb_read(struct file *filp, struct kobject *kobj,
 	struct cxl_afu *afu = to_cxl_afu(container_of(kobj,
 						      struct device, kobj));
 
-	return cxl_afu_read_err_buffer(afu, buf, off, count);
+	return cxl_ops->afu_read_err_buffer(afu, buf, off, count);
 }
 
 static struct device_attribute afu_attrs[] = {
@@ -469,10 +469,12 @@ static ssize_t afu_read_config(struct file *filp, struct kobject *kobj,
 	struct afu_config_record *cr = to_cr(kobj);
 	struct cxl_afu *afu = to_cxl_afu(container_of(kobj->parent, struct device, kobj));
 
-	u64 i, j, val;
+	u64 i, j, val, rc;
 
 	for (i = 0; i < count;) {
-		val = cxl_afu_cr_read64(afu, cr->cr, off & ~0x7);
+		rc = cxl_ops->afu_cr_read64(afu, cr->cr, off & ~0x7, &val);
+		if (rc)
+			val = ~0ULL;
 		for (j = off & 0x7; j < 8 && i < count; i++, j++, off++)
 			buf[i] = (val >> (j * 8)) & 0xff;
 	}
@@ -517,9 +519,17 @@ static struct afu_config_record *cxl_sysfs_afu_new_cr(struct cxl_afu *afu, int c
 		return ERR_PTR(-ENOMEM);
 
 	cr->cr = cr_idx;
-	cr->device = cxl_afu_cr_read16(afu, cr_idx, PCI_DEVICE_ID);
-	cr->vendor = cxl_afu_cr_read16(afu, cr_idx, PCI_VENDOR_ID);
-	cr->class = cxl_afu_cr_read32(afu, cr_idx, PCI_CLASS_REVISION) >> 8;
+
+	rc = cxl_ops->afu_cr_read16(afu, cr_idx, PCI_DEVICE_ID, &cr->device);
+	if (rc)
+		goto err;
+	rc = cxl_ops->afu_cr_read16(afu, cr_idx, PCI_VENDOR_ID, &cr->vendor);
+	if (rc)
+		goto err;
+	rc = cxl_ops->afu_cr_read32(afu, cr_idx, PCI_CLASS_REVISION, &cr->class);
+	if (rc)
+		goto err;
+	cr->class >>= 8;
 
 	/*
 	 * Export raw AFU PCIe like config record. For now this is read only by
diff --git a/drivers/misc/cxl/vphb.c b/drivers/misc/cxl/vphb.c
index cbd4331..e8a8eed 100644
--- a/drivers/misc/cxl/vphb.c
+++ b/drivers/misc/cxl/vphb.c
@@ -49,7 +49,7 @@ static bool cxl_pci_enable_device_hook(struct pci_dev *dev)
 	phb = pci_bus_to_host(dev->bus);
 	afu = (struct cxl_afu *)phb->private_data;
 
-	if (!cxl_adapter_link_ok(afu->adapter)) {
+	if (!cxl_ops->link_ok(afu->adapter)) {
 		dev_warn(&dev->dev, "%s: Device link is down, refusing to enable AFU\n", __func__);
 		return false;
 	}
@@ -66,7 +66,7 @@ static bool cxl_pci_enable_device_hook(struct pci_dev *dev)
 		return false;
 	dev->dev.archdata.cxl_ctx = ctx;
 
-	return (cxl_afu_check_and_enable(afu) == 0);
+	return (cxl_ops->afu_check_and_enable(afu) == 0);
 }
 
 static void cxl_pci_disable_device(struct pci_dev *dev)
@@ -161,7 +161,7 @@ static inline bool cxl_config_link_ok(struct pci_bus *bus)
 	if (phb == NULL)
 		return false;
 	afu = (struct cxl_afu *)phb->private_data;
-	return cxl_adapter_link_ok(afu->adapter);
+	return cxl_ops->link_ok(afu->adapter);
 }
 
 static int cxl_pcie_read_config(struct pci_bus *bus, unsigned int devfn,