s390/hypfs: add interface for diagnose 0x304

To provide access to the set-partition-resource-parameter interface
to user space add a new attribute to hypfs/debugfs:
 * s390_hypsfs/diag_304
The data for the query-partition-resource-parameters command can
be access by a read on the attribute. All other diagnose 0x304
requests need to be submitted via ioctl with CAP_SYS_ADMIN rights.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

Documentation/ioctl/ioctl-number.txt

@@ -73,6 +73,7 @@ Code  Seq#(hex)	Include File		Comments
 0x09	all	linux/raid/md_u.h
 0x10	00-0F	drivers/char/s390/vmcp.h
 0x10	10-1F	arch/s390/include/uapi/sclp_ctl.h
+0x10	20-2F	arch/s390/include/uapi/asm/hypfs.h
 0x12	all	linux/fs.h
 		linux/blkpg.h
 0x1b	all	InfiniBand Subsystem	<http://infiniband.sourceforge.net/>

arch/s390/hypfs/Makefile

@@ -4,4 +4,4 @@
 
 obj-$(CONFIG_S390_HYPFS_FS) += s390_hypfs.o
 
-s390_hypfs-objs := inode.o hypfs_diag.o hypfs_vm.o hypfs_dbfs.o
+s390_hypfs-objs := inode.o hypfs_diag.o hypfs_vm.o hypfs_dbfs.o hypfs_sprp.o

arch/s390/hypfs/hypfs.h

@@ -13,6 +13,7 @@
 #include <linux/debugfs.h>
 #include <linux/workqueue.h>
 #include <linux/kref.h>
+#include <asm/hypfs.h>
 
 #define REG_FILE_MODE    0440
 #define UPDATE_FILE_MODE 0220
@@ -36,6 +37,10 @@ extern int hypfs_vm_init(void);
 extern void hypfs_vm_exit(void);
 extern int hypfs_vm_create_files(struct dentry *root);
 
+/* Set Partition-Resource Parameter */
+int hypfs_sprp_init(void);
+void hypfs_sprp_exit(void);
+
 /* debugfs interface */
 struct hypfs_dbfs_file;
 
@@ -52,6 +57,8 @@ struct hypfs_dbfs_file {
 	int		(*data_create)(void **data, void **data_free_ptr,
 				       size_t *size);
 	void		(*data_free)(const void *buf_free_ptr);
+	long		(*unlocked_ioctl) (struct file *, unsigned int,
+					   unsigned long);
 
 	/* Private data for hypfs_dbfs.c */
 	struct hypfs_dbfs_data	*data;

arch/s390/hypfs/hypfs_dbfs.c

@@ -81,9 +81,25 @@ static ssize_t dbfs_read(struct file *file, char __user *buf,
 	return rc;
 }
 
+static long dbfs_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	struct hypfs_dbfs_file *df;
+	long rc;
+
+	df = file->f_path.dentry->d_inode->i_private;
+	mutex_lock(&df->lock);
+	if (df->unlocked_ioctl)
+		rc = df->unlocked_ioctl(file, cmd, arg);
+	else
+		rc = -ENOTTY;
+	mutex_unlock(&df->lock);
+	return rc;
+}
+
 static const struct file_operations dbfs_ops = {
 	.read		= dbfs_read,
 	.llseek		= no_llseek,
+	.unlocked_ioctl = dbfs_ioctl,
 };
 
 int hypfs_dbfs_create_file(struct hypfs_dbfs_file *df)

arch/s390/hypfs/hypfs_sprp.c

+/*
+ *    Hypervisor filesystem for Linux on s390.
+ *    Set Partition-Resource Parameter interface.
+ *
+ *    Copyright IBM Corp. 2013
+ *    Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>
+ */
+
+#include <linux/compat.h>
+#include <linux/errno.h>
+#include <linux/gfp.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/uaccess.h>
+#include <asm/compat.h>
+#include <asm/sclp.h>
+#include "hypfs.h"
+
+#define DIAG304_SET_WEIGHTS	0
+#define DIAG304_QUERY_PRP	1
+#define DIAG304_SET_CAPPING	2
+
+#define DIAG304_CMD_MAX		2
+
+static unsigned long hypfs_sprp_diag304(void *data, unsigned long cmd)
+{
+	register unsigned long _data asm("2") = (unsigned long) data;
+	register unsigned long _rc asm("3");
+	register unsigned long _cmd asm("4") = cmd;
+
+	asm volatile("diag %1,%2,0x304\n"
+		     : "=d" (_rc) : "d" (_data), "d" (_cmd) : "memory");
+
+	return _rc;
+}
+
+static void hypfs_sprp_free(const void *data)
+{
+	free_page((unsigned long) data);
+}
+
+static int hypfs_sprp_create(void **data_ptr, void **free_ptr, size_t *size)
+{
+	unsigned long rc;
+	void *data;
+
+	data = (void *) get_zeroed_page(GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+	rc = hypfs_sprp_diag304(data, DIAG304_QUERY_PRP);
+	if (rc != 1) {
+		*data_ptr = *free_ptr = NULL;
+		*size = 0;
+		free_page((unsigned long) data);
+		return -EIO;
+	}
+	*data_ptr = *free_ptr = data;
+	*size = PAGE_SIZE;
+	return 0;
+}
+
+static int __hypfs_sprp_ioctl(void __user *user_area)
+{
+	struct hypfs_diag304 diag304;
+	unsigned long cmd;
+	void __user *udata;
+	void *data;
+	int rc;
+
+	if (copy_from_user(&diag304, user_area, sizeof(diag304)))
+		return -EFAULT;
+	if ((diag304.args[0] >> 8) != 0 || diag304.args[1] > DIAG304_CMD_MAX)
+		return -EINVAL;
+
+	data = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
+	if (!data)
+		return -ENOMEM;
+
+	udata = (void __user *)(unsigned long) diag304.data;
+	if (diag304.args[1] == DIAG304_SET_WEIGHTS ||
+	    diag304.args[1] == DIAG304_SET_CAPPING)
+		if (copy_from_user(data, udata, PAGE_SIZE)) {
+			rc = -EFAULT;
+			goto out;
+		}
+
+	cmd = *(unsigned long *) &diag304.args[0];
+	diag304.rc = hypfs_sprp_diag304(data, cmd);
+
+	if (diag304.args[1] == DIAG304_QUERY_PRP)
+		if (copy_to_user(udata, data, PAGE_SIZE)) {
+			rc = -EFAULT;
+			goto out;
+		}
+
+	rc = copy_to_user(user_area, &diag304, sizeof(diag304)) ? -EFAULT : 0;
+out:
+	free_page((unsigned long) data);
+	return rc;
+}
+
+static long hypfs_sprp_ioctl(struct file *file, unsigned int cmd,
+			       unsigned long arg)
+{
+	void __user *argp;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EACCES;
+	if (is_compat_task())
+		argp = compat_ptr(arg);
+	else
+		argp = (void __user *) arg;
+	switch (cmd) {
+	case HYPFS_DIAG304:
+		return __hypfs_sprp_ioctl(argp);
+	default: /* unknown ioctl number */
+		return -ENOTTY;
+	}
+	return 0;
+}
+
+static struct hypfs_dbfs_file hypfs_sprp_file = {
+	.name		= "diag_304",
+	.data_create	= hypfs_sprp_create,
+	.data_free	= hypfs_sprp_free,
+	.unlocked_ioctl = hypfs_sprp_ioctl,
+};
+
+int hypfs_sprp_init(void)
+{
+	if (!sclp_has_sprp())
+		return 0;
+	return hypfs_dbfs_create_file(&hypfs_sprp_file);
+}
+
+void hypfs_sprp_exit(void)
+{
+	if (!sclp_has_sprp())
+		return;
+	hypfs_dbfs_remove_file(&hypfs_sprp_file);
+}

arch/s390/hypfs/inode.c

@@ -478,10 +478,14 @@ static int __init hypfs_init(void)
 		rc = -ENODATA;
 		goto fail_hypfs_diag_exit;
 	}
+	if (hypfs_sprp_init()) {
+		rc = -ENODATA;
+		goto fail_hypfs_vm_exit;
+	}
 	s390_kobj = kobject_create_and_add("s390", hypervisor_kobj);
 	if (!s390_kobj) {
 		rc = -ENOMEM;
-		goto fail_hypfs_vm_exit;
+		goto fail_hypfs_sprp_exit;
 	}
 	rc = register_filesystem(&hypfs_type);
 	if (rc)
@@ -490,6 +494,8 @@ static int __init hypfs_init(void)
 
 fail_filesystem:
 	kobject_put(s390_kobj);
+fail_hypfs_sprp_exit:
+	hypfs_sprp_exit();
 fail_hypfs_vm_exit:
 	hypfs_vm_exit();
 fail_hypfs_diag_exit:
@@ -502,11 +508,12 @@ static int __init hypfs_init(void)
 
 static void __exit hypfs_exit(void)
 {
-	hypfs_diag_exit();
-	hypfs_vm_exit();
-	hypfs_dbfs_exit();
 	unregister_filesystem(&hypfs_type);
 	kobject_put(s390_kobj);
+	hypfs_sprp_exit();
+	hypfs_vm_exit();
+	hypfs_diag_exit();
+	hypfs_dbfs_exit();
 }
 
 module_init(hypfs_init)

arch/s390/include/asm/sclp.h

@@ -54,6 +54,7 @@ int sclp_chp_read_info(struct sclp_chp_info *info);
 void sclp_get_ipl_info(struct sclp_ipl_info *info);
 bool __init sclp_has_linemode(void);
 bool __init sclp_has_vt220(void);
+bool sclp_has_sprp(void);
 int sclp_pci_configure(u32 fid);
 int sclp_pci_deconfigure(u32 fid);
 int memcpy_hsa(void *dest, unsigned long src, size_t count, int mode);

arch/s390/include/uapi/asm/hypfs.h

+/*
+ * IOCTL interface for hypfs
+ *
+ * Copyright IBM Corp. 2013
+ *
+ * Author: Martin Schwidefsky <schwidefsky@de.ibm.com>
+ */
+
+#ifndef _ASM_HYPFS_CTL_H
+#define _ASM_HYPFS_CTL_H
+
+#include <linux/types.h>
+
+struct hypfs_diag304 {
+	__u32	args[2];
+	__u64	data;
+	__u64	rc;
+} __attribute__((packed));
+
+#define HYPFS_IOCTL_MAGIC 0x10
+
+#define HYPFS_DIAG304 \
+	_IOWR(HYPFS_IOCTL_MAGIC, 0x20, struct hypfs_diag304)
+
+#endif

drivers/s390/char/sclp_cmd.c

@@ -700,3 +700,8 @@ int sclp_chp_read_info(struct sclp_chp_info *info)
 	free_page((unsigned long) sccb);
 	return rc;
 }
+
+bool sclp_has_sprp(void)
+{
+	return !!(sclp_fac84 & 0x2);
+}