// SPDX-License-Identifier: GPL-2.0
/*
 * Hypervisor filesystem for Linux on s390
 *
 * Diag 0C implementation
 *
 * Copyright IBM Corp. 2014
 */

#include <linux/slab.h>
#include <linux/cpu.h>
#include <asm/machine.h>
#include <asm/diag.h>
#include <asm/hypfs.h>
#include "hypfs.h"

#define DBFS_D0C_HDR_VERSION 0

/*
 * Get hypfs_diag0c_entry from CPU vector and store diag0c data
 */
static void diag0c_fn(void *data)
{
        diag0c(((void **)data)[smp_processor_id()]);
}

/*
 * Allocate buffer and store diag 0c data
 */
static void *diag0c_store(unsigned int *count)
{
        struct hypfs_diag0c_data *diag0c_data;
        unsigned int cpu_count, cpu, i;
        void **cpu_vec;

        cpus_read_lock();
        cpu_count = num_online_cpus();
        cpu_vec = kmalloc_objs(*cpu_vec, num_possible_cpus());
        if (!cpu_vec)
                goto fail_unlock_cpus;
        /* Note: Diag 0c needs 8 byte alignment and real storage */
        diag0c_data = kzalloc_flex(*diag0c_data, entry, cpu_count,
                                   GFP_KERNEL | GFP_DMA);
        if (!diag0c_data)
                goto fail_kfree_cpu_vec;
        i = 0;
        /* Fill CPU vector for each online CPU */
        for_each_online_cpu(cpu) {
                diag0c_data->entry[i].cpu = cpu;
                cpu_vec[cpu] = &diag0c_data->entry[i++];
        }
        /* Collect data all CPUs */
        on_each_cpu(diag0c_fn, cpu_vec, 1);
        *count = cpu_count;
        kfree(cpu_vec);
        cpus_read_unlock();
        return diag0c_data;

fail_kfree_cpu_vec:
        kfree(cpu_vec);
fail_unlock_cpus:
        cpus_read_unlock();
        return ERR_PTR(-ENOMEM);
}

/*
 * Hypfs DBFS callback: Free diag 0c data
 */
static void dbfs_diag0c_free(const void *data)
{
        kfree(data);
}

/*
 * Hypfs DBFS callback: Create diag 0c data
 */
static int dbfs_diag0c_create(void **data, void **data_free_ptr, size_t *size)
{
        struct hypfs_diag0c_data *diag0c_data;
        unsigned int count;

        diag0c_data = diag0c_store(&count);
        if (IS_ERR(diag0c_data))
                return PTR_ERR(diag0c_data);
        memset(&diag0c_data->hdr, 0, sizeof(diag0c_data->hdr));
        store_tod_clock_ext((union tod_clock *)diag0c_data->hdr.tod_ext);
        diag0c_data->hdr.len = count * sizeof(struct hypfs_diag0c_entry);
        diag0c_data->hdr.version = DBFS_D0C_HDR_VERSION;
        diag0c_data->hdr.count = count;
        *data = diag0c_data;
        *data_free_ptr = diag0c_data;
        *size = diag0c_data->hdr.len + sizeof(struct hypfs_diag0c_hdr);
        return 0;
}

/*
 * Hypfs DBFS file structure
 */
static struct hypfs_dbfs_file dbfs_file_0c = {
        .name           = "diag_0c",
        .data_create    = dbfs_diag0c_create,
        .data_free      = dbfs_diag0c_free,
};

/*
 * Initialize diag 0c interface for z/VM
 */
int __init hypfs_diag0c_init(void)
{
        if (!machine_is_vm())
                return 0;
        hypfs_dbfs_create_file(&dbfs_file_0c);
        return 0;
}

/*
 * Shutdown diag 0c interface for z/VM
 */
void hypfs_diag0c_exit(void)
{
        if (!machine_is_vm())
                return;
        hypfs_dbfs_remove_file(&dbfs_file_0c);
}