ocxl: Allow external drivers to use OpenCAPI contexts

Most OpenCAPI operations require a valid context, so
exposing these functions to external drivers is necessary.
Signed-off-by: Alastair D'Silva <alastair@d-silva.org>
Reviewed-by: Greg Kurz <groug@kaod.org>
Acked-by: Frederic Barrat <fbarrat@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

drivers/misc/ocxl/context.c

@@ -4,15 +4,17 @@
 #include "trace.h"
 #include "ocxl_internal.h"
 
-struct ocxl_context *ocxl_context_alloc(void)
-{
-	return kzalloc(sizeof(struct ocxl_context), GFP_KERNEL);
-}
-
-int ocxl_context_init(struct ocxl_context *ctx, struct ocxl_afu *afu,
+int ocxl_context_alloc(struct ocxl_context **context, struct ocxl_afu *afu,
 		struct address_space *mapping)
 {
 	int pasid;
+	struct ocxl_context *ctx;
+
+	*context = kzalloc(sizeof(struct ocxl_context), GFP_KERNEL);
+	if (!*context)
+		return -ENOMEM;
+
+	ctx = *context;
 
 	ctx->afu = afu;
 	mutex_lock(&afu->contexts_lock);
@@ -43,6 +45,7 @@ int ocxl_context_init(struct ocxl_context *ctx, struct ocxl_afu *afu,
 	ocxl_afu_get(afu);
 	return 0;
 }
+EXPORT_SYMBOL_GPL(ocxl_context_alloc);
 
 /*
  * Callback for when a translation fault triggers an error
@@ -63,7 +66,7 @@ static void xsl_fault_error(void *data, u64 addr, u64 dsisr)
 	wake_up_all(&ctx->events_wq);
 }
 
-int ocxl_context_attach(struct ocxl_context *ctx, u64 amr)
+int ocxl_context_attach(struct ocxl_context *ctx, u64 amr, struct mm_struct *mm)
 {
 	int rc;
 
@@ -75,7 +78,7 @@ int ocxl_context_attach(struct ocxl_context *ctx, u64 amr)
 	}
 
 	rc = ocxl_link_add_pe(ctx->afu->fn->link, ctx->pasid,
-			current->mm->context.id, ctx->tidr, amr, current->mm,
+			mm->context.id, ctx->tidr, amr, mm,
 			xsl_fault_error, ctx);
 	if (rc)
 		goto out;
@@ -85,6 +88,7 @@ int ocxl_context_attach(struct ocxl_context *ctx, u64 amr)
 	mutex_unlock(&ctx->status_mutex);
 	return rc;
 }
+EXPORT_SYMBOL_GPL(ocxl_context_attach);
 
 static vm_fault_t map_afu_irq(struct vm_area_struct *vma, unsigned long address,
 		u64 offset, struct ocxl_context *ctx)
@@ -243,6 +247,7 @@ int ocxl_context_detach(struct ocxl_context *ctx)
 	}
 	return 0;
 }
+EXPORT_SYMBOL_GPL(ocxl_context_detach);
 
 void ocxl_context_detach_all(struct ocxl_afu *afu)
 {
@@ -280,3 +285,4 @@ void ocxl_context_free(struct ocxl_context *ctx)
 	ocxl_afu_put(ctx->afu);
 	kfree(ctx);
 }
+EXPORT_SYMBOL_GPL(ocxl_context_free);

drivers/misc/ocxl/file.c

@@ -61,11 +61,7 @@ static int afu_open(struct inode *inode, struct file *file)
 	if (!info)
 		return -ENODEV;
 
-	ctx = ocxl_context_alloc();
-	if (!ctx)
-		return -ENOMEM;
-
-	rc = ocxl_context_init(ctx, info->afu, inode->i_mapping);
+	rc = ocxl_context_alloc(&ctx, info->afu, inode->i_mapping);
 	if (rc)
 		return rc;
 
@@ -90,7 +86,7 @@ static long afu_ioctl_attach(struct ocxl_context *ctx,
 		return -EINVAL;
 
 	amr = arg.amr & mfspr(SPRN_UAMOR);
-	rc = ocxl_context_attach(ctx, amr);
+	rc = ocxl_context_attach(ctx, amr, current->mm);
 	return rc;
 }
 

drivers/misc/ocxl/ocxl_internal.h

@@ -130,15 +130,9 @@ int ocxl_config_check_afu_index(struct pci_dev *dev,
  */
 int ocxl_link_update_pe(void *link_handle, int pasid, __u16 tid);
 
-struct ocxl_context *ocxl_context_alloc(void);
-int ocxl_context_init(struct ocxl_context *ctx, struct ocxl_afu *afu,
-			struct address_space *mapping);
-int ocxl_context_attach(struct ocxl_context *ctx, u64 amr);
 int ocxl_context_mmap(struct ocxl_context *ctx,
 			struct vm_area_struct *vma);
-int ocxl_context_detach(struct ocxl_context *ctx);
 void ocxl_context_detach_all(struct ocxl_afu *afu);
-void ocxl_context_free(struct ocxl_context *ctx);
 
 int ocxl_sysfs_register_afu(struct ocxl_file_info *info);
 void ocxl_sysfs_unregister_afu(struct ocxl_file_info *info);

include/misc/ocxl.h

@@ -48,6 +48,7 @@ struct ocxl_fn_config {
 // These are opaque outside the ocxl driver
 struct ocxl_afu;
 struct ocxl_fn;
+struct ocxl_context;
 
 // Device detection & initialisation
 
@@ -116,6 +117,44 @@ const struct ocxl_fn_config *ocxl_function_config(struct ocxl_fn *fn);
  */
 void ocxl_function_close(struct ocxl_fn *fn);
 
+// Context allocation
+
+/**
+ * Allocate an OpenCAPI context
+ *
+ * @context: The OpenCAPI context to allocate, must be freed with ocxl_context_free
+ * @afu: The AFU the context belongs to
+ * @mapping: The mapping to unmap when the context is closed (may be NULL)
+ */
+int ocxl_context_alloc(struct ocxl_context **context, struct ocxl_afu *afu,
+			struct address_space *mapping);
+
+/**
+ * Free an OpenCAPI context
+ *
+ * @ctx: The OpenCAPI context to free
+ */
+void ocxl_context_free(struct ocxl_context *ctx);
+
+/**
+ * Grant access to an MM to an OpenCAPI context
+ * @ctx: The OpenCAPI context to attach
+ * @amr: The value of the AMR register to restrict access
+ * @mm: The mm to attach to the context
+ *
+ * Returns 0 on success, negative on failure
+ */
+int ocxl_context_attach(struct ocxl_context *ctx, u64 amr,
+				struct mm_struct *mm);
+
+/**
+ * Detach an MM from an OpenCAPI context
+ * @ctx: The OpenCAPI context to attach
+ *
+ * Returns 0 on success, negative on failure
+ */
+int ocxl_context_detach(struct ocxl_context *ctx);
+
 // AFU Metadata
 
 /**