// SPDX-License-Identifier: GPL-2.0-only
/*
* VDPA simulator for block device.
*
* Copyright (c) 2020, NVIDIA CORPORATION. All rights reserved.
* Copyright (c) 2021, Red Hat Inc. All rights reserved.
*
*/
#include <linux/init.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/blkdev.h>
#include <linux/vringh.h>
#include <linux/vdpa.h>
#include <uapi/linux/virtio_blk.h>
#include "vdpa_sim.h"
#define DRV_VERSION "0.1"
#define DRV_AUTHOR "Max Gurtovoy <[email protected]>"
#define DRV_DESC "vDPA Device Simulator for block device"
#define DRV_LICENSE "GPL v2"
#define VDPASIM_BLK_FEATURES (VDPASIM_FEATURES | \
(1ULL << VIRTIO_BLK_F_FLUSH) | \
(1ULL << VIRTIO_BLK_F_SIZE_MAX) | \
(1ULL << VIRTIO_BLK_F_SEG_MAX) | \
(1ULL << VIRTIO_BLK_F_BLK_SIZE) | \
(1ULL << VIRTIO_BLK_F_TOPOLOGY) | \
(1ULL << VIRTIO_BLK_F_MQ) | \
(1ULL << VIRTIO_BLK_F_DISCARD) | \
(1ULL << VIRTIO_BLK_F_WRITE_ZEROES))
#define VDPASIM_BLK_CAPACITY 0x40000
#define VDPASIM_BLK_SIZE_MAX 0x1000
#define VDPASIM_BLK_SEG_MAX 32
#define VDPASIM_BLK_DWZ_MAX_SECTORS UINT_MAX
/* 1 virtqueue, 1 address space, 1 virtqueue group */
#define VDPASIM_BLK_VQ_NUM 1
#define VDPASIM_BLK_AS_NUM 1
#define VDPASIM_BLK_GROUP_NUM 1
struct vdpasim_blk {
struct vdpasim vdpasim;
void *buffer;
bool shared_backend;
};
static struct vdpasim_blk *sim_to_blk(struct vdpasim *vdpasim)
{
return container_of(vdpasim, struct vdpasim_blk, vdpasim);
}
static char vdpasim_blk_id[VIRTIO_BLK_ID_BYTES] = "vdpa_blk_sim";
static bool shared_backend;
module_param(shared_backend, bool, 0444);
MODULE_PARM_DESC(shared_backend, "Enable the shared backend between virtio-blk devices");
static void *shared_buffer;
/* mutex to synchronize shared_buffer access */
static DEFINE_MUTEX(shared_buffer_mutex);
static void vdpasim_blk_buffer_lock(struct vdpasim_blk *blk)
{
if (blk->shared_backend)
mutex_lock(&shared_buffer_mutex);
}
static void vdpasim_blk_buffer_unlock(struct vdpasim_blk *blk)
{
if (blk->shared_backend)
mutex_unlock(&shared_buffer_mutex);
}
static bool vdpasim_blk_check_range(struct vdpasim *vdpasim, u64 start_sector,
u64 num_sectors, u64 max_sectors)
{
if (start_sector > VDPASIM_BLK_CAPACITY) {
dev_dbg(&vdpasim->vdpa.dev,
"starting sector exceeds the capacity - start: 0x%llx capacity: 0x%x\n",
start_sector, VDPASIM_BLK_CAPACITY);
}
if (num_sectors > max_sectors) {
dev_dbg(&vdpasim->vdpa.dev,
"number of sectors exceeds the max allowed in a request - num: 0x%llx max: 0x%llx\n",
num_sectors, max_sectors);
return false;
}
if (num_sectors > VDPASIM_BLK_CAPACITY - start_sector) {
dev_dbg(&vdpasim->vdpa.dev,
"request exceeds the capacity - start: 0x%llx num: 0x%llx capacity: 0x%x\n",
start_sector, num_sectors, VDPASIM_BLK_CAPACITY);
return false;
}
return true;
}
/* Returns 'true' if the request is handled (with or without an I/O error)
* and the status is correctly written in the last byte of the 'in iov',
* 'false' otherwise.
*/
static bool vdpasim_blk_handle_req(struct vdpasim *vdpasim,
struct vdpasim_virtqueue *vq)
{
struct vdpasim_blk *blk = sim_to_blk(vdpasim);
size_t pushed = 0, to_pull, to_push;
struct virtio_blk_outhdr hdr;
bool handled = false;
ssize_t bytes;
loff_t offset;
u64 sector;
u8 status;
u32 type;
int ret;
ret = vringh_getdesc_iotlb(&vq->vring, &vq->out_iov, &vq->in_iov,
&vq->head, GFP_ATOMIC);
if (ret != 1)
return false;
if (vq->out_iov.used < 1 || vq->in_iov.used < 1) {
dev_dbg(&vdpasim->vdpa.dev, "missing headers - out_iov: %u in_iov %u\n",
vq->out_iov.used, vq->in_iov.used);
goto err;
}
if (vq->in_iov.iov[vq->in_iov.used - 1].iov_len < 1) {
dev_dbg(&vdpasim->vdpa.dev, "request in header too short\n");
goto err;
}
/* The last byte is the status and we checked if the last iov has
* enough room for it.
*/
to_push = vringh_kiov_length(&vq->in_iov) - 1;
to_pull = vringh_kiov_length(&vq->out_iov);
bytes = vringh_iov_pull_iotlb(&vq->vring, &vq->out_iov, &hdr,
sizeof(hdr));
if (bytes != sizeof(hdr)) {
dev_dbg(&vdpasim->vdpa.dev, "request out header too short\n");
goto err;
}
to_pull -= bytes;
type = vdpasim32_to_cpu(vdpasim, hdr.type);
sector = vdpasim64_to_cpu(vdpasim, hdr.sector);
offset = sector << SECTOR_SHIFT;
status = VIRTIO_BLK_S_OK;
if (type != VIRTIO_BLK_T_IN && type != VIRTIO_BLK_T_OUT &&
sector != 0) {
dev_dbg(&vdpasim->vdpa.dev,
"sector must be 0 for %u request - sector: 0x%llx\n",
type, sector);
status = VIRTIO_BLK_S_IOERR;
goto err_status;
}
switch (type) {
case VIRTIO_BLK_T_IN:
if (!vdpasim_blk_check_range(vdpasim, sector,
to_push >> SECTOR_SHIFT,
VDPASIM_BLK_SIZE_MAX * VDPASIM_BLK_SEG_MAX)) {
status = VIRTIO_BLK_S_IOERR;
break;
}
vdpasim_blk_buffer_lock(blk);
bytes = vringh_iov_push_iotlb(&vq->vring, &vq->in_iov,
blk->buffer + offset, to_push);
vdpasim_blk_buffer_unlock(blk);
if (bytes < 0) {
dev_dbg(&vdpasim->vdpa.dev,
"vringh_iov_push_iotlb() error: %zd offset: 0x%llx len: 0x%zx\n",
bytes, offset, to_push);
status = VIRTIO_BLK_S_IOERR;
break;
}
pushed += bytes;
break;
case VIRTIO_BLK_T_OUT:
if (!vdpasim_blk_check_range(vdpasim, sector,
to_pull >> SECTOR_SHIFT,
VDPASIM_BLK_SIZE_MAX * VDPASIM_BLK_SEG_MAX)) {
status = VIRTIO_BLK_S_IOERR;
break;
}
vdpasim_blk_buffer_lock(blk);
bytes = vringh_iov_pull_iotlb(&vq->vring, &vq->out_iov,
blk->buffer + offset, to_pull);
vdpasim_blk_buffer_unlock(blk);
if (bytes < 0) {
dev_dbg(&vdpasim->vdpa.dev,
"vringh_iov_pull_iotlb() error: %zd offset: 0x%llx len: 0x%zx\n",
bytes, offset, to_pull);
status = VIRTIO_BLK_S_IOERR;
break;
}
break;
case VIRTIO_BLK_T_GET_ID:
bytes = vringh_iov_push_iotlb(&vq->vring, &vq->in_iov,
vdpasim_blk_id,
VIRTIO_BLK_ID_BYTES);
if (bytes < 0) {
dev_dbg(&vdpasim->vdpa.dev,
"vringh_iov_push_iotlb() error: %zd\n", bytes);
status = VIRTIO_BLK_S_IOERR;
break;
}
pushed += bytes;
break;
case VIRTIO_BLK_T_FLUSH:
/* nothing to do */
break;
case VIRTIO_BLK_T_DISCARD:
case VIRTIO_BLK_T_WRITE_ZEROES: {
struct virtio_blk_discard_write_zeroes range;
u32 num_sectors, flags;
if (to_pull != sizeof(range)) {
dev_dbg(&vdpasim->vdpa.dev,
"discard/write_zeroes header len: 0x%zx [expected: 0x%zx]\n",
to_pull, sizeof(range));
status = VIRTIO_BLK_S_IOERR;
break;
}
bytes = vringh_iov_pull_iotlb(&vq->vring, &vq->out_iov, &range,
to_pull);
if (bytes < 0) {
dev_dbg(&vdpasim->vdpa.dev,
"vringh_iov_pull_iotlb() error: %zd offset: 0x%llx len: 0x%zx\n",
bytes, offset, to_pull);
status = VIRTIO_BLK_S_IOERR;
break;
}
sector = le64_to_cpu(range.sector);
offset = sector << SECTOR_SHIFT;
num_sectors = le32_to_cpu(range.num_sectors);
flags = le32_to_cpu(range.flags);
if (type == VIRTIO_BLK_T_DISCARD && flags != 0) {
dev_dbg(&vdpasim->vdpa.dev,
"discard unexpected flags set - flags: 0x%x\n",
flags);
status = VIRTIO_BLK_S_UNSUPP;
break;
}
if (type == VIRTIO_BLK_T_WRITE_ZEROES &&
flags & ~VIRTIO_BLK_WRITE_ZEROES_FLAG_UNMAP) {
dev_dbg(&vdpasim->vdpa.dev,
"write_zeroes unexpected flags set - flags: 0x%x\n",
flags);
status = VIRTIO_BLK_S_UNSUPP;
break;
}
if (!vdpasim_blk_check_range(vdpasim, sector, num_sectors,
VDPASIM_BLK_DWZ_MAX_SECTORS)) {
status = VIRTIO_BLK_S_IOERR;
break;
}
if (type == VIRTIO_BLK_T_WRITE_ZEROES) {
vdpasim_blk_buffer_lock(blk);
memset(blk->buffer + offset, 0,
num_sectors << SECTOR_SHIFT);
vdpasim_blk_buffer_unlock(blk);
}
break;
}
default:
dev_dbg(&vdpasim->vdpa.dev,
"Unsupported request type %d\n", type);
status = VIRTIO_BLK_S_IOERR;
break;
}
err_status:
/* If some operations fail, we need to skip the remaining bytes
* to put the status in the last byte
*/
if (to_push - pushed > 0)
vringh_kiov_advance(&vq->in_iov, to_push - pushed);
/* Last byte is the status */
bytes = vringh_iov_push_iotlb(&vq->vring, &vq->in_iov, &status, 1);
if (bytes != 1)
goto err;
pushed += bytes;
/* Make sure data is wrote before advancing index */
smp_wmb();
handled = true;
err:
vringh_complete_iotlb(&vq->vring, vq->head, pushed);
return handled;
}
static void vdpasim_blk_work(struct vdpasim *vdpasim)
{
bool reschedule = false;
int i;
mutex_lock(&vdpasim->mutex);
if (!(vdpasim->status & VIRTIO_CONFIG_S_DRIVER_OK))
goto out;
if (!vdpasim->running)
goto out;
for (i = 0; i < VDPASIM_BLK_VQ_NUM; i++) {
struct vdpasim_virtqueue *vq = &vdpasim->vqs[i];
int reqs = 0;
if (!vq->ready)
continue;
while (vdpasim_blk_handle_req(vdpasim, vq)) {
/* Make sure used is visible before rasing the interrupt. */
smp_wmb();
local_bh_disable();
if (vringh_need_notify_iotlb(&vq->vring) > 0)
vringh_notify(&vq->vring);
local_bh_enable();
if (++reqs > 4) {
reschedule = true;
break;
}
}
}
out:
mutex_unlock(&vdpasim->mutex);
if (reschedule)
vdpasim_schedule_work(vdpasim);
}
static void vdpasim_blk_get_config(struct vdpasim *vdpasim, void *config)
{
struct virtio_blk_config *blk_config = config;
memset(config, 0, sizeof(struct virtio_blk_config));
blk_config->capacity = cpu_to_vdpasim64(vdpasim, VDPASIM_BLK_CAPACITY);
blk_config->size_max = cpu_to_vdpasim32(vdpasim, VDPASIM_BLK_SIZE_MAX);
blk_config->seg_max = cpu_to_vdpasim32(vdpasim, VDPASIM_BLK_SEG_MAX);
blk_config->num_queues = cpu_to_vdpasim16(vdpasim, VDPASIM_BLK_VQ_NUM);
blk_config->min_io_size = cpu_to_vdpasim16(vdpasim, 1);
blk_config->opt_io_size = cpu_to_vdpasim32(vdpasim, 1);
blk_config->blk_size = cpu_to_vdpasim32(vdpasim, SECTOR_SIZE);
/* VIRTIO_BLK_F_DISCARD */
blk_config->discard_sector_alignment =
cpu_to_vdpasim32(vdpasim, SECTOR_SIZE);
blk_config->max_discard_sectors =
cpu_to_vdpasim32(vdpasim, VDPASIM_BLK_DWZ_MAX_SECTORS);
blk_config->max_discard_seg = cpu_to_vdpasim32(vdpasim, 1);
/* VIRTIO_BLK_F_WRITE_ZEROES */
blk_config->max_write_zeroes_sectors =
cpu_to_vdpasim32(vdpasim, VDPASIM_BLK_DWZ_MAX_SECTORS);
blk_config->max_write_zeroes_seg = cpu_to_vdpasim32(vdpasim, 1);
}
static void vdpasim_blk_free(struct vdpasim *vdpasim)
{
struct vdpasim_blk *blk = sim_to_blk(vdpasim);
if (!blk->shared_backend)
kvfree(blk->buffer);
}
static void vdpasim_blk_mgmtdev_release(struct device *dev)
{
}
static struct device vdpasim_blk_mgmtdev = {
.init_name = "vdpasim_blk",
.release = vdpasim_blk_mgmtdev_release,
};
static int vdpasim_blk_dev_add(struct vdpa_mgmt_dev *mdev, const char *name,
const struct vdpa_dev_set_config *config)
{
struct vdpasim_dev_attr dev_attr = {};
struct vdpasim_blk *blk;
struct vdpasim *simdev;
int ret;
dev_attr.mgmt_dev = mdev;
dev_attr.name = name;
dev_attr.id = VIRTIO_ID_BLOCK;
dev_attr.supported_features = VDPASIM_BLK_FEATURES;
dev_attr.nvqs = VDPASIM_BLK_VQ_NUM;
dev_attr.ngroups = VDPASIM_BLK_GROUP_NUM;
dev_attr.nas = VDPASIM_BLK_AS_NUM;
dev_attr.alloc_size = sizeof(struct vdpasim_blk);
dev_attr.config_size = sizeof(struct virtio_blk_config);
dev_attr.get_config = vdpasim_blk_get_config;
dev_attr.work_fn = vdpasim_blk_work;
dev_attr.free = vdpasim_blk_free;
simdev = vdpasim_create(&dev_attr, config);
if (IS_ERR(simdev))
return PTR_ERR(simdev);
blk = sim_to_blk(simdev);
blk->shared_backend = shared_backend;
if (blk->shared_backend) {
blk->buffer = shared_buffer;
} else {
blk->buffer = kvzalloc(VDPASIM_BLK_CAPACITY << SECTOR_SHIFT,
GFP_KERNEL);
if (!blk->buffer) {
ret = -ENOMEM;
goto put_dev;
}
}
ret = _vdpa_register_device(&simdev->vdpa, VDPASIM_BLK_VQ_NUM);
if (ret)
goto put_dev;
return 0;
put_dev:
put_device(&simdev->vdpa.dev);
return ret;
}
static void vdpasim_blk_dev_del(struct vdpa_mgmt_dev *mdev,
struct vdpa_device *dev)
{
struct vdpasim *simdev = container_of(dev, struct vdpasim, vdpa);
_vdpa_unregister_device(&simdev->vdpa);
}
static const struct vdpa_mgmtdev_ops vdpasim_blk_mgmtdev_ops = {
.dev_add = vdpasim_blk_dev_add,
.dev_del = vdpasim_blk_dev_del
};
static struct virtio_device_id id_table[] = {
{ VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID },
{ 0 },
};
static struct vdpa_mgmt_dev mgmt_dev = {
.device = &vdpasim_blk_mgmtdev,
.id_table = id_table,
.ops = &vdpasim_blk_mgmtdev_ops,
};
static int __init vdpasim_blk_init(void)
{
int ret;
ret = device_register(&vdpasim_blk_mgmtdev);
if (ret) {
put_device(&vdpasim_blk_mgmtdev);
return ret;
}
ret = vdpa_mgmtdev_register(&mgmt_dev);
if (ret)
goto parent_err;
if (shared_backend) {
shared_buffer = kvzalloc(VDPASIM_BLK_CAPACITY << SECTOR_SHIFT,
GFP_KERNEL);
if (!shared_buffer) {
ret = -ENOMEM;
goto mgmt_dev_err;
}
}
return 0;
mgmt_dev_err:
vdpa_mgmtdev_unregister(&mgmt_dev);
parent_err:
device_unregister(&vdpasim_blk_mgmtdev);
return ret;
}
static void __exit vdpasim_blk_exit(void)
{
kvfree(shared_buffer);
vdpa_mgmtdev_unregister(&mgmt_dev);
device_unregister(&vdpasim_blk_mgmtdev);
}
module_init(vdpasim_blk_init)
module_exit(vdpasim_blk_exit)
MODULE_VERSION(DRV_VERSION);
MODULE_LICENSE(DRV_LICENSE);
MODULE_AUTHOR(DRV_AUTHOR);
MODULE_DESCRIPTION(DRV_DESC);
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