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>

1 files changed, 141 insertions, 0 deletions

diff --git a/arch/s390/hypfs/hypfs_sprp.c b/arch/s390/hypfs/hypfs_sprp.c
new file mode 100644
index 000000000000..f043c3c7e73c
--- /dev/null
+++ b/arch/s390/hypfs/hypfs_sprp.c
@@ -0,0 +1,141 @@
+/*
+ *    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);
+}