1 files changed, 80 insertions, 7 deletions

diff --git a/arch/s390/hypfs/hypfs_vm.c b/arch/s390/hypfs/hypfs_vm.c
index f0b0d31f0b48..ee5ab1a578e7 100644
--- a/arch/s390/hypfs/hypfs_vm.c
+++ b/arch/s390/hypfs/hypfs_vm.c
@@ -10,14 +10,18 @@
 #include <linux/string.h>
 #include <linux/vmalloc.h>
 #include <asm/ebcdic.h>
+#include <asm/timex.h>
 #include "hypfs.h"
 
 #define NAME_LEN 8
+#define DBFS_D2FC_HDR_VERSION 0
 
 static char local_guest[] = "        ";
 static char all_guests[] = "*       ";
 static char *guest_query;
 
+static struct dentry *dbfs_d2fc_file;
+
 struct diag2fc_data {
         __u32 version;
         __u32 flags;
@@ -76,23 +80,26 @@ static int diag2fc(int size, char* query, void *addr)
                 return -residual_cnt;
 }
 
-static struct diag2fc_data *diag2fc_store(char *query, int *count)
+/*
+ * Allocate buffer for "query" and store diag 2fc at "offset"
+ */
+static void *diag2fc_store(char *query, unsigned int *count, int offset)
 {
+        void *data;
         int size;
-        struct diag2fc_data *data;
 
         do {
                 size = diag2fc(0, query, NULL);
                 if (size < 0)
                         return ERR_PTR(-EACCES);
-                data = vmalloc(size);
+                data = vmalloc(size + offset);
                 if (!data)
                         return ERR_PTR(-ENOMEM);
-                if (diag2fc(size, query, data) == 0)
+                if (diag2fc(size, query, data + offset) == 0)
                         break;
                 vfree(data);
         } while (1);
-        *count = (size / sizeof(*data));
+        *count = (size / sizeof(struct diag2fc_data));
 
         return data;
 }
@@ -168,9 +175,10 @@ int hypfs_vm_create_files(struct super_block *sb, struct dentry *root)
 {
         struct dentry *dir, *file;
         struct diag2fc_data *data;
-        int rc, i, count = 0;
+        unsigned int count = 0;
+        int rc, i;
 
-        data = diag2fc_store(guest_query, &count);
+        data = diag2fc_store(guest_query, &count, 0);
         if (IS_ERR(data))
                 return PTR_ERR(data);
 
@@ -218,8 +226,61 @@ failed:
         return rc;
 }
 
+struct dbfs_d2fc_hdr {
+        u64     len;            /* Length of d2fc buffer without header */
+        u16     version;        /* Version of header */
+        char    tod_ext[16];    /* TOD clock for d2fc */
+        u64     count;          /* Number of VM guests in d2fc buffer */
+        char    reserved[30];
+} __attribute__ ((packed));
+
+struct dbfs_d2fc {
+        struct dbfs_d2fc_hdr    hdr;    /* 64 byte header */
+        char                    buf[];  /* d2fc buffer */
+} __attribute__ ((packed));
+
+static int dbfs_d2fc_open(struct inode *inode, struct file *file)
+{
+        struct dbfs_d2fc *data;
+        unsigned int count;
+
+        data = diag2fc_store(guest_query, &count, sizeof(data->hdr));
+        if (IS_ERR(data))
+                return PTR_ERR(data);
+        get_clock_ext(data->hdr.tod_ext);
+        data->hdr.len = count * sizeof(struct diag2fc_data);
+        data->hdr.version = DBFS_D2FC_HDR_VERSION;
+        data->hdr.count = count;
+        memset(&data->hdr.reserved, 0, sizeof(data->hdr.reserved));
+        file->private_data = data;
+        return nonseekable_open(inode, file);
+}
+
+static int dbfs_d2fc_release(struct inode *inode, struct file *file)
+{
+        diag2fc_free(file->private_data);
+        return 0;
+}
+
+static ssize_t dbfs_d2fc_read(struct file *file, char __user *buf,
+                                    size_t size, loff_t *ppos)
+{
+        struct dbfs_d2fc *data = file->private_data;
+
+        return simple_read_from_buffer(buf, size, ppos, data, data->hdr.len +
+                                       sizeof(struct dbfs_d2fc_hdr));
+}
+
+static const struct file_operations dbfs_d2fc_ops = {
+        .open           = dbfs_d2fc_open,
+        .read           = dbfs_d2fc_read,
+        .release        = dbfs_d2fc_release,
+};
+
 int hypfs_vm_init(void)
 {
+        if (!MACHINE_IS_VM)
+                return 0;
         if (diag2fc(0, all_guests, NULL) > 0)
                 guest_query = all_guests;
         else if (diag2fc(0, local_guest, NULL) > 0)
@@ -227,5 +288,17 @@ int hypfs_vm_init(void)
         else
                 return -EACCES;
 
+        dbfs_d2fc_file = debugfs_create_file("diag_2fc", 0400, hypfs_dbfs_dir,
+                                             NULL, &dbfs_d2fc_ops);
+        if (IS_ERR(dbfs_d2fc_file))
+                return PTR_ERR(dbfs_d2fc_file);
+
         return 0;
 }
+
+void hypfs_vm_exit(void)
+{
+        if (!MACHINE_IS_VM)
+                return;
+        debugfs_remove(dbfs_d2fc_file);
+}