s390/hypfs: factor out filesystem code

The s390_hypfs filesystem is deprecated and shouldn't be used due to its
rather odd semantics. It creates a whole directory structure with static
file contents so a user can read a consistent state while within that
directory.
Writing to its update attribute will remove and rebuild nearly the whole
filesystem, so that again a user can read a consistent state, even if
multiple files need to be read.

Given that this wastes a lot of CPU cycles, and involves a lot of code,
binary interfaces have been added quite a couple of years ago, which simply
pass the binary data to user space, and let user space decode the data.
This is the preferred and only way how the data should be retrieved.

The assumption is that there are no users of the s390_hypfs filesystem.
However instead of just removing the code, and having to revert in case
there are actually users, factor the filesystem code out and make it only
available via a new config option.

This config option is supposed to be disabled. If it turns out there are no
complaints the filesystem code can be removed probably in a couple of
years.

Acked-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

1 files changed, 139 insertions, 0 deletions

diff --git a/arch/s390/hypfs/hypfs_vm_fs.c b/arch/s390/hypfs/hypfs_vm_fs.c
new file mode 100644
index 000000000000..6011289afa8c
--- /dev/null
+++ b/arch/s390/hypfs/hypfs_vm_fs.c
@@ -0,0 +1,139 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *    Hypervisor filesystem for Linux on s390. z/VM implementation.
+ *
+ *    Copyright IBM Corp. 2006
+ *    Author(s): Michael Holzheu <holzheu@de.ibm.com>
+ */
+
+#include <linux/types.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/vmalloc.h>
+#include <asm/extable.h>
+#include <asm/diag.h>
+#include <asm/ebcdic.h>
+#include <asm/timex.h>
+#include "hypfs_vm.h"
+#include "hypfs.h"
+
+#define ATTRIBUTE(dir, name, member) \
+do { \
+	void *rc; \
+	rc = hypfs_create_u64(dir, name, member); \
+	if (IS_ERR(rc)) \
+		return PTR_ERR(rc); \
+} while (0)
+
+static int hypfs_vm_create_guest(struct dentry *systems_dir,
+				 struct diag2fc_data *data)
+{
+	char guest_name[DIAG2FC_NAME_LEN + 1] = {};
+	struct dentry *guest_dir, *cpus_dir, *samples_dir, *mem_dir;
+	int dedicated_flag, capped_value;
+
+	capped_value = (data->flags & 0x00000006) >> 1;
+	dedicated_flag = (data->flags & 0x00000008) >> 3;
+
+	/* guest dir */
+	memcpy(guest_name, data->guest_name, DIAG2FC_NAME_LEN);
+	EBCASC(guest_name, DIAG2FC_NAME_LEN);
+	strim(guest_name);
+	guest_dir = hypfs_mkdir(systems_dir, guest_name);
+	if (IS_ERR(guest_dir))
+		return PTR_ERR(guest_dir);
+	ATTRIBUTE(guest_dir, "onlinetime_us", data->el_time);
+
+	/* logical cpu information */
+	cpus_dir = hypfs_mkdir(guest_dir, "cpus");
+	if (IS_ERR(cpus_dir))
+		return PTR_ERR(cpus_dir);
+	ATTRIBUTE(cpus_dir, "cputime_us", data->used_cpu);
+	ATTRIBUTE(cpus_dir, "capped", capped_value);
+	ATTRIBUTE(cpus_dir, "dedicated", dedicated_flag);
+	ATTRIBUTE(cpus_dir, "count", data->vcpus);
+	/*
+	 * Note: The "weight_min" attribute got the wrong name.
+	 * The value represents the number of non-stopped (operating)
+	 * CPUS.
+	 */
+	ATTRIBUTE(cpus_dir, "weight_min", data->ocpus);
+	ATTRIBUTE(cpus_dir, "weight_max", data->cpu_max);
+	ATTRIBUTE(cpus_dir, "weight_cur", data->cpu_shares);
+
+	/* memory information */
+	mem_dir = hypfs_mkdir(guest_dir, "mem");
+	if (IS_ERR(mem_dir))
+		return PTR_ERR(mem_dir);
+	ATTRIBUTE(mem_dir, "min_KiB", data->mem_min_kb);
+	ATTRIBUTE(mem_dir, "max_KiB", data->mem_max_kb);
+	ATTRIBUTE(mem_dir, "used_KiB", data->mem_used_kb);
+	ATTRIBUTE(mem_dir, "share_KiB", data->mem_share_kb);
+
+	/* samples */
+	samples_dir = hypfs_mkdir(guest_dir, "samples");
+	if (IS_ERR(samples_dir))
+		return PTR_ERR(samples_dir);
+	ATTRIBUTE(samples_dir, "cpu_using", data->cpu_use_samp);
+	ATTRIBUTE(samples_dir, "cpu_delay", data->cpu_delay_samp);
+	ATTRIBUTE(samples_dir, "mem_delay", data->page_wait_samp);
+	ATTRIBUTE(samples_dir, "idle", data->idle_samp);
+	ATTRIBUTE(samples_dir, "other", data->other_samp);
+	ATTRIBUTE(samples_dir, "total", data->total_samp);
+	return 0;
+}
+
+int hypfs_vm_create_files(struct dentry *root)
+{
+	struct dentry *dir, *file;
+	struct diag2fc_data *data;
+	unsigned int count = 0;
+	int rc, i;
+
+	data = diag2fc_store(diag2fc_guest_query, &count, 0);
+	if (IS_ERR(data))
+		return PTR_ERR(data);
+
+	/* Hypervisor Info */
+	dir = hypfs_mkdir(root, "hyp");
+	if (IS_ERR(dir)) {
+		rc = PTR_ERR(dir);
+		goto failed;
+	}
+	file = hypfs_create_str(dir, "type", "z/VM Hypervisor");
+	if (IS_ERR(file)) {
+		rc = PTR_ERR(file);
+		goto failed;
+	}
+
+	/* physical cpus */
+	dir = hypfs_mkdir(root, "cpus");
+	if (IS_ERR(dir)) {
+		rc = PTR_ERR(dir);
+		goto failed;
+	}
+	file = hypfs_create_u64(dir, "count", data->lcpus);
+	if (IS_ERR(file)) {
+		rc = PTR_ERR(file);
+		goto failed;
+	}
+
+	/* guests */
+	dir = hypfs_mkdir(root, "systems");
+	if (IS_ERR(dir)) {
+		rc = PTR_ERR(dir);
+		goto failed;
+	}
+
+	for (i = 0; i < count; i++) {
+		rc = hypfs_vm_create_guest(dir, &data[i]);
+		if (rc)
+			goto failed;
+	}
+	diag2fc_free(data);
+	return 0;
+
+failed:
+	diag2fc_free(data);
+	return rc;
+}