1 files changed, 527 insertions, 0 deletions

diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim_blk.c b/drivers/vdpa/vdpa_sim/vdpa_sim_blk.c
new file mode 100644
index 000000000..b137f3679
--- /dev/null
+++ b/drivers/vdpa/vdpa_sim/vdpa_sim_blk.c
@@ -0,0 +1,527 @@
+// 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 <mgurtovoy@nvidia.com>"
+#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);