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// SPDX-License-Identifier: GPL-2.0-only
/* Copyright(c) 2024 Intel Corporation */

#include <linux/anon_inodes.h>
#include <linux/container_of.h>
#include <linux/device.h>
#include <linux/file.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/pci.h>
#include <linux/sizes.h>
#include <linux/types.h>
#include <linux/uaccess.h>
#include <linux/vfio_pci_core.h>
#include <linux/qat/qat_mig_dev.h>

/*
 * The migration data of each Intel QAT VF device is encapsulated into a
 * 4096 bytes block. The data consists of two parts.
 * The first is a pre-configured set of attributes of the VF being migrated,
 * which are only set when it is created. This can be migrated during pre-copy
 * stage and used for a device compatibility check.
 * The second is the VF state. This includes the required MMIO regions and
 * the shadow states maintained by the QAT PF driver. This part can only be
 * saved when the VF is fully quiesced and be migrated during stop-copy stage.
 * Both these 2 parts of data are saved in hierarchical structures including
 * a preamble section and several raw state sections.
 * When the pre-configured part of the migration data is fully retrieved from
 * user space, the preamble section are used to validate the correctness of
 * the data blocks and check the version compatibility. The raw state sections
 * are then used to do a device compatibility check.
 * When the device transits from RESUMING state, the VF states are extracted
 * from the raw state sections of the VF state part of the migration data and
 * then loaded into the device.
 */

struct qat_vf_migration_file {
	struct file *filp;
	/* protects migration region context */
	struct mutex lock;
	bool disabled;
	struct qat_vf_core_device *qat_vdev;
	ssize_t filled_size;
};

struct qat_vf_core_device {
	struct vfio_pci_core_device core_device;
	struct qat_mig_dev *mdev;
	/* protects migration state */
	struct mutex state_mutex;
	enum vfio_device_mig_state mig_state;
	struct qat_vf_migration_file *resuming_migf;
	struct qat_vf_migration_file *saving_migf;
};

static int qat_vf_pci_open_device(struct vfio_device *core_vdev)
{
	struct qat_vf_core_device *qat_vdev =
		container_of(core_vdev, struct qat_vf_core_device,
			     core_device.vdev);
	struct vfio_pci_core_device *vdev = &qat_vdev->core_device;
	int ret;

	ret = vfio_pci_core_enable(vdev);
	if (ret)
		return ret;

	ret = qat_vfmig_open(qat_vdev->mdev);
	if (ret) {
		vfio_pci_core_disable(vdev);
		return ret;
	}
	qat_vdev->mig_state = VFIO_DEVICE_STATE_RUNNING;

	vfio_pci_core_finish_enable(vdev);

	return 0;
}

static void qat_vf_disable_fd(struct qat_vf_migration_file *migf)
{
	mutex_lock(&migf->lock);
	migf->disabled = true;
	migf->filp->f_pos = 0;
	migf->filled_size = 0;
	mutex_unlock(&migf->lock);
}

static void qat_vf_disable_fds(struct qat_vf_core_device *qat_vdev)
{
	if (qat_vdev->resuming_migf) {
		qat_vf_disable_fd(qat_vdev->resuming_migf);
		fput(qat_vdev->resuming_migf->filp);
		qat_vdev->resuming_migf = NULL;
	}

	if (qat_vdev->saving_migf) {
		qat_vf_disable_fd(qat_vdev->saving_migf);
		fput(qat_vdev->saving_migf->filp);
		qat_vdev->saving_migf = NULL;
	}
}

static void qat_vf_pci_close_device(struct vfio_device *core_vdev)
{
	struct qat_vf_core_device *qat_vdev = container_of(core_vdev,
			struct qat_vf_core_device, core_device.vdev);

	qat_vfmig_close(qat_vdev->mdev);
	qat_vf_disable_fds(qat_vdev);
	vfio_pci_core_close_device(core_vdev);
}

static long qat_vf_precopy_ioctl(struct file *filp, unsigned int cmd,
				 unsigned long arg)
{
	struct qat_vf_migration_file *migf = filp->private_data;
	struct qat_vf_core_device *qat_vdev = migf->qat_vdev;
	struct qat_mig_dev *mig_dev = qat_vdev->mdev;
	struct vfio_precopy_info info;
	loff_t *pos = &filp->f_pos;
	unsigned long minsz;
	int ret = 0;

	if (cmd != VFIO_MIG_GET_PRECOPY_INFO)
		return -ENOTTY;

	minsz = offsetofend(struct vfio_precopy_info, dirty_bytes);

	if (copy_from_user(&info, (void __user *)arg, minsz))
		return -EFAULT;
	if (info.argsz < minsz)
		return -EINVAL;

	mutex_lock(&qat_vdev->state_mutex);
	if (qat_vdev->mig_state != VFIO_DEVICE_STATE_PRE_COPY &&
	    qat_vdev->mig_state != VFIO_DEVICE_STATE_PRE_COPY_P2P) {
		mutex_unlock(&qat_vdev->state_mutex);
		return -EINVAL;
	}

	mutex_lock(&migf->lock);
	if (migf->disabled) {
		ret = -ENODEV;
		goto out;
	}

	if (*pos > mig_dev->setup_size) {
		ret = -EINVAL;
		goto out;
	}

	info.dirty_bytes = 0;
	info.initial_bytes = mig_dev->setup_size - *pos;

out:
	mutex_unlock(&migf->lock);
	mutex_unlock(&qat_vdev->state_mutex);
	if (ret)
		return ret;
	return copy_to_user((void __user *)arg, &info, minsz) ? -EFAULT : 0;
}

static ssize_t qat_vf_save_read(struct file *filp, char __user *buf,
				size_t len, loff_t *pos)
{
	struct qat_vf_migration_file *migf = filp->private_data;
	struct qat_mig_dev *mig_dev = migf->qat_vdev->mdev;
	ssize_t done = 0;
	loff_t *offs;
	int ret;

	if (pos)
		return -ESPIPE;
	offs = &filp->f_pos;

	mutex_lock(&migf->lock);
	if (*offs > migf->filled_size || *offs < 0) {
		done = -EINVAL;
		goto out_unlock;
	}

	if (migf->disabled) {
		done = -ENODEV;
		goto out_unlock;
	}

	len = min_t(size_t, migf->filled_size - *offs, len);
	if (len) {
		ret = copy_to_user(buf, mig_dev->state + *offs, len);
		if (ret) {
			done = -EFAULT;
			goto out_unlock;
		}
		*offs += len;
		done = len;
	}

out_unlock:
	mutex_unlock(&migf->lock);
	return done;
}

static int qat_vf_release_file(struct inode *inode, struct file *filp)
{
	struct qat_vf_migration_file *migf = filp->private_data;

	qat_vf_disable_fd(migf);
	mutex_destroy(&migf->lock);
	kfree(migf);

	return 0;
}

static const struct file_operations qat_vf_save_fops = {
	.owner = THIS_MODULE,
	.read = qat_vf_save_read,
	.unlocked_ioctl = qat_vf_precopy_ioctl,
	.compat_ioctl = compat_ptr_ioctl,
	.release = qat_vf_release_file,
	.llseek = no_llseek,
};

static int qat_vf_save_state(struct qat_vf_core_device *qat_vdev,
			     struct qat_vf_migration_file *migf)
{
	int ret;

	ret = qat_vfmig_save_state(qat_vdev->mdev);
	if (ret)
		return ret;
	migf->filled_size = qat_vdev->mdev->state_size;

	return 0;
}

static int qat_vf_save_setup(struct qat_vf_core_device *qat_vdev,
			     struct qat_vf_migration_file *migf)
{
	int ret;

	ret = qat_vfmig_save_setup(qat_vdev->mdev);
	if (ret)
		return ret;
	migf->filled_size = qat_vdev->mdev->setup_size;

	return 0;
}

/*
 * Allocate a file handler for user space and then save the migration data for
 * the device being migrated. If this is called in the pre-copy stage, save the
 * pre-configured device data. Otherwise, if this is called in the stop-copy
 * stage, save the device state. In both cases, update the data size which can
 * then be read from user space.
 */
static struct qat_vf_migration_file *
qat_vf_save_device_data(struct qat_vf_core_device *qat_vdev, bool pre_copy)
{
	struct qat_vf_migration_file *migf;
	int ret;

	migf = kzalloc(sizeof(*migf), GFP_KERNEL);
	if (!migf)
		return ERR_PTR(-ENOMEM);

	migf->filp = anon_inode_getfile("qat_vf_mig", &qat_vf_save_fops,
					migf, O_RDONLY);
	ret = PTR_ERR_OR_ZERO(migf->filp);
	if (ret) {
		kfree(migf);
		return ERR_PTR(ret);
	}

	stream_open(migf->filp->f_inode, migf->filp);
	mutex_init(&migf->lock);

	if (pre_copy)
		ret = qat_vf_save_setup(qat_vdev, migf);
	else
		ret = qat_vf_save_state(qat_vdev, migf);
	if (ret) {
		fput(migf->filp);
		return ERR_PTR(ret);
	}

	migf->qat_vdev = qat_vdev;

	return migf;
}

static ssize_t qat_vf_resume_write(struct file *filp, const char __user *buf,
				   size_t len, loff_t *pos)
{
	struct qat_vf_migration_file *migf = filp->private_data;
	struct qat_mig_dev *mig_dev = migf->qat_vdev->mdev;
	loff_t end, *offs;
	ssize_t done = 0;
	int ret;

	if (pos)
		return -ESPIPE;
	offs = &filp->f_pos;

	if (*offs < 0 ||
	    check_add_overflow((loff_t)len, *offs, &end))
		return -EOVERFLOW;

	if (end > mig_dev->state_size)
		return -ENOMEM;

	mutex_lock(&migf->lock);
	if (migf->disabled) {
		done = -ENODEV;
		goto out_unlock;
	}

	ret = copy_from_user(mig_dev->state + *offs, buf, len);
	if (ret) {
		done = -EFAULT;
		goto out_unlock;
	}
	*offs += len;
	migf->filled_size += len;

	/*
	 * Load the pre-configured device data first to check if the target
	 * device is compatible with the source device.
	 */
	ret = qat_vfmig_load_setup(mig_dev, migf->filled_size);
	if (ret && ret != -EAGAIN) {
		done = ret;
		goto out_unlock;
	}
	done = len;

out_unlock:
	mutex_unlock(&migf->lock);
	return done;
}

static const struct file_operations qat_vf_resume_fops = {
	.owner = THIS_MODULE,
	.write = qat_vf_resume_write,
	.release = qat_vf_release_file,
	.llseek = no_llseek,
};

static struct qat_vf_migration_file *
qat_vf_resume_device_data(struct qat_vf_core_device *qat_vdev)
{
	struct qat_vf_migration_file *migf;
	int ret;

	migf = kzalloc(sizeof(*migf), GFP_KERNEL);
	if (!migf)
		return ERR_PTR(-ENOMEM);

	migf->filp = anon_inode_getfile("qat_vf_mig", &qat_vf_resume_fops, migf, O_WRONLY);
	ret = PTR_ERR_OR_ZERO(migf->filp);
	if (ret) {
		kfree(migf);
		return ERR_PTR(ret);
	}

	migf->qat_vdev = qat_vdev;
	migf->filled_size = 0;
	stream_open(migf->filp->f_inode, migf->filp);
	mutex_init(&migf->lock);

	return migf;
}

static int qat_vf_load_device_data(struct qat_vf_core_device *qat_vdev)
{
	return qat_vfmig_load_state(qat_vdev->mdev);
}

static struct file *qat_vf_pci_step_device_state(struct qat_vf_core_device *qat_vdev, u32 new)
{
	u32 cur = qat_vdev->mig_state;
	int ret;

	/*
	 * As the device is not capable of just stopping P2P DMAs, suspend the
	 * device completely once any of the P2P states are reached.
	 * When it is suspended, all its MMIO registers can still be operated
	 * correctly, jobs submitted through ring are queued while no jobs are
	 * processed by the device. The MMIO states can be safely migrated to
	 * the target VF during stop-copy stage and restored correctly in the
	 * target VF. All queued jobs can be resumed then.
	 */
	if ((cur == VFIO_DEVICE_STATE_RUNNING && new == VFIO_DEVICE_STATE_RUNNING_P2P) ||
	    (cur == VFIO_DEVICE_STATE_PRE_COPY && new == VFIO_DEVICE_STATE_PRE_COPY_P2P)) {
		ret = qat_vfmig_suspend(qat_vdev->mdev);
		if (ret)
			return ERR_PTR(ret);
		return NULL;
	}

	if ((cur == VFIO_DEVICE_STATE_RUNNING_P2P && new == VFIO_DEVICE_STATE_RUNNING) ||
	    (cur == VFIO_DEVICE_STATE_PRE_COPY_P2P && new == VFIO_DEVICE_STATE_PRE_COPY)) {
		qat_vfmig_resume(qat_vdev->mdev);
		return NULL;
	}

	if ((cur == VFIO_DEVICE_STATE_RUNNING_P2P && new == VFIO_DEVICE_STATE_STOP) ||
	    (cur == VFIO_DEVICE_STATE_STOP && new == VFIO_DEVICE_STATE_RUNNING_P2P))
		return NULL;

	if (cur == VFIO_DEVICE_STATE_STOP && new == VFIO_DEVICE_STATE_STOP_COPY) {
		struct qat_vf_migration_file *migf;

		migf = qat_vf_save_device_data(qat_vdev, false);
		if (IS_ERR(migf))
			return ERR_CAST(migf);
		get_file(migf->filp);
		qat_vdev->saving_migf = migf;
		return migf->filp;
	}

	if (cur == VFIO_DEVICE_STATE_STOP && new == VFIO_DEVICE_STATE_RESUMING) {
		struct qat_vf_migration_file *migf;

		migf = qat_vf_resume_device_data(qat_vdev);
		if (IS_ERR(migf))
			return ERR_CAST(migf);
		get_file(migf->filp);
		qat_vdev->resuming_migf = migf;
		return migf->filp;
	}

	if ((cur == VFIO_DEVICE_STATE_STOP_COPY && new == VFIO_DEVICE_STATE_STOP) ||
	    (cur == VFIO_DEVICE_STATE_PRE_COPY && new == VFIO_DEVICE_STATE_RUNNING) ||
	    (cur == VFIO_DEVICE_STATE_PRE_COPY_P2P && new == VFIO_DEVICE_STATE_RUNNING_P2P)) {
		qat_vf_disable_fds(qat_vdev);
		return NULL;
	}

	if ((cur == VFIO_DEVICE_STATE_RUNNING && new == VFIO_DEVICE_STATE_PRE_COPY) ||
	    (cur == VFIO_DEVICE_STATE_RUNNING_P2P && new == VFIO_DEVICE_STATE_PRE_COPY_P2P)) {
		struct qat_vf_migration_file *migf;

		migf = qat_vf_save_device_data(qat_vdev, true);
		if (IS_ERR(migf))
			return ERR_CAST(migf);
		get_file(migf->filp);
		qat_vdev->saving_migf = migf;
		return migf->filp;
	}

	if (cur == VFIO_DEVICE_STATE_PRE_COPY_P2P && new == VFIO_DEVICE_STATE_STOP_COPY) {
		struct qat_vf_migration_file *migf = qat_vdev->saving_migf;

		if (!migf)
			return ERR_PTR(-EINVAL);
		ret = qat_vf_save_state(qat_vdev, migf);
		if (ret)
			return ERR_PTR(ret);
		return NULL;
	}

	if (cur == VFIO_DEVICE_STATE_RESUMING && new == VFIO_DEVICE_STATE_STOP) {
		ret = qat_vf_load_device_data(qat_vdev);
		if (ret)
			return ERR_PTR(ret);

		qat_vf_disable_fds(qat_vdev);
		return NULL;
	}

	/* vfio_mig_get_next_state() does not use arcs other than the above */
	WARN_ON(true);
	return ERR_PTR(-EINVAL);
}

static void qat_vf_reset_done(struct qat_vf_core_device *qat_vdev)
{
	qat_vdev->mig_state = VFIO_DEVICE_STATE_RUNNING;
	qat_vfmig_reset(qat_vdev->mdev);
	qat_vf_disable_fds(qat_vdev);
}

static struct file *qat_vf_pci_set_device_state(struct vfio_device *vdev,
						enum vfio_device_mig_state new_state)
{
	struct qat_vf_core_device *qat_vdev = container_of(vdev,
			struct qat_vf_core_device, core_device.vdev);
	enum vfio_device_mig_state next_state;
	struct file *res = NULL;
	int ret;

	mutex_lock(&qat_vdev->state_mutex);
	while (new_state != qat_vdev->mig_state) {
		ret = vfio_mig_get_next_state(vdev, qat_vdev->mig_state,
					      new_state, &next_state);
		if (ret) {
			res = ERR_PTR(ret);
			break;
		}
		res = qat_vf_pci_step_device_state(qat_vdev, next_state);
		if (IS_ERR(res))
			break;
		qat_vdev->mig_state = next_state;
		if (WARN_ON(res && new_state != qat_vdev->mig_state)) {
			fput(res);
			res = ERR_PTR(-EINVAL);
			break;
		}
	}
	mutex_unlock(&qat_vdev->state_mutex);

	return res;
}

static int qat_vf_pci_get_device_state(struct vfio_device *vdev,
				       enum vfio_device_mig_state *curr_state)
{
	struct qat_vf_core_device *qat_vdev = container_of(vdev,
			struct qat_vf_core_device, core_device.vdev);

	mutex_lock(&qat_vdev->state_mutex);
	*curr_state = qat_vdev->mig_state;
	mutex_unlock(&qat_vdev->state_mutex);

	return 0;
}

static int qat_vf_pci_get_data_size(struct vfio_device *vdev,
				    unsigned long *stop_copy_length)
{
	struct qat_vf_core_device *qat_vdev = container_of(vdev,
			struct qat_vf_core_device, core_device.vdev);

	mutex_lock(&qat_vdev->state_mutex);
	*stop_copy_length = qat_vdev->mdev->state_size;
	mutex_unlock(&qat_vdev->state_mutex);

	return 0;
}

static const struct vfio_migration_ops qat_vf_pci_mig_ops = {
	.migration_set_state = qat_vf_pci_set_device_state,
	.migration_get_state = qat_vf_pci_get_device_state,
	.migration_get_data_size = qat_vf_pci_get_data_size,
};

static void qat_vf_pci_release_dev(struct vfio_device *core_vdev)
{
	struct qat_vf_core_device *qat_vdev = container_of(core_vdev,
			struct qat_vf_core_device, core_device.vdev);

	qat_vfmig_cleanup(qat_vdev->mdev);
	qat_vfmig_destroy(qat_vdev->mdev);
	mutex_destroy(&qat_vdev->state_mutex);
	vfio_pci_core_release_dev(core_vdev);
}

static int qat_vf_pci_init_dev(struct vfio_device *core_vdev)
{
	struct qat_vf_core_device *qat_vdev = container_of(core_vdev,
			struct qat_vf_core_device, core_device.vdev);
	struct qat_mig_dev *mdev;
	struct pci_dev *parent;
	int ret, vf_id;

	core_vdev->migration_flags = VFIO_MIGRATION_STOP_COPY | VFIO_MIGRATION_P2P |
				     VFIO_MIGRATION_PRE_COPY;
	core_vdev->mig_ops = &qat_vf_pci_mig_ops;

	ret = vfio_pci_core_init_dev(core_vdev);
	if (ret)
		return ret;

	mutex_init(&qat_vdev->state_mutex);

	parent = pci_physfn(qat_vdev->core_device.pdev);
	vf_id = pci_iov_vf_id(qat_vdev->core_device.pdev);
	if (vf_id < 0) {
		ret = -ENODEV;
		goto err_rel;
	}

	mdev = qat_vfmig_create(parent, vf_id);
	if (IS_ERR(mdev)) {
		ret = PTR_ERR(mdev);
		goto err_rel;
	}

	ret = qat_vfmig_init(mdev);
	if (ret)
		goto err_destroy;

	qat_vdev->mdev = mdev;

	return 0;

err_destroy:
	qat_vfmig_destroy(mdev);
err_rel:
	vfio_pci_core_release_dev(core_vdev);
	return ret;
}

static const struct vfio_device_ops qat_vf_pci_ops = {
	.name = "qat-vf-vfio-pci",
	.init = qat_vf_pci_init_dev,
	.release = qat_vf_pci_release_dev,
	.open_device = qat_vf_pci_open_device,
	.close_device = qat_vf_pci_close_device,
	.ioctl = vfio_pci_core_ioctl,
	.read = vfio_pci_core_read,
	.write = vfio_pci_core_write,
	.mmap = vfio_pci_core_mmap,
	.request = vfio_pci_core_request,
	.match = vfio_pci_core_match,
	.bind_iommufd = vfio_iommufd_physical_bind,
	.unbind_iommufd = vfio_iommufd_physical_unbind,
	.attach_ioas = vfio_iommufd_physical_attach_ioas,
	.detach_ioas = vfio_iommufd_physical_detach_ioas,
};

static struct qat_vf_core_device *qat_vf_drvdata(struct pci_dev *pdev)
{
	struct vfio_pci_core_device *core_device = pci_get_drvdata(pdev);

	return container_of(core_device, struct qat_vf_core_device, core_device);
}

static void qat_vf_pci_aer_reset_done(struct pci_dev *pdev)
{
	struct qat_vf_core_device *qat_vdev = qat_vf_drvdata(pdev);

	if (!qat_vdev->mdev)
		return;

	mutex_lock(&qat_vdev->state_mutex);
	qat_vf_reset_done(qat_vdev);
	mutex_unlock(&qat_vdev->state_mutex);
}

static int
qat_vf_vfio_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
{
	struct device *dev = &pdev->dev;
	struct qat_vf_core_device *qat_vdev;
	int ret;

	qat_vdev = vfio_alloc_device(qat_vf_core_device, core_device.vdev, dev, &qat_vf_pci_ops);
	if (IS_ERR(qat_vdev))
		return PTR_ERR(qat_vdev);

	pci_set_drvdata(pdev, &qat_vdev->core_device);
	ret = vfio_pci_core_register_device(&qat_vdev->core_device);
	if (ret)
		goto out_put_device;

	return 0;

out_put_device:
	vfio_put_device(&qat_vdev->core_device.vdev);
	return ret;
}

static void qat_vf_vfio_pci_remove(struct pci_dev *pdev)
{
	struct qat_vf_core_device *qat_vdev = qat_vf_drvdata(pdev);

	vfio_pci_core_unregister_device(&qat_vdev->core_device);
	vfio_put_device(&qat_vdev->core_device.vdev);
}

static const struct pci_device_id qat_vf_vfio_pci_table[] = {
	/* Intel QAT GEN4 4xxx VF device */
	{ PCI_DRIVER_OVERRIDE_DEVICE_VFIO(PCI_VENDOR_ID_INTEL, 0x4941) },
	{ PCI_DRIVER_OVERRIDE_DEVICE_VFIO(PCI_VENDOR_ID_INTEL, 0x4943) },
	{ PCI_DRIVER_OVERRIDE_DEVICE_VFIO(PCI_VENDOR_ID_INTEL, 0x4945) },
	{}
};
MODULE_DEVICE_TABLE(pci, qat_vf_vfio_pci_table);

static const struct pci_error_handlers qat_vf_err_handlers = {
	.reset_done = qat_vf_pci_aer_reset_done,
	.error_detected = vfio_pci_core_aer_err_detected,
};

static struct pci_driver qat_vf_vfio_pci_driver = {
	.name = "qat_vfio_pci",
	.id_table = qat_vf_vfio_pci_table,
	.probe = qat_vf_vfio_pci_probe,
	.remove = qat_vf_vfio_pci_remove,
	.err_handler = &qat_vf_err_handlers,
	.driver_managed_dma = true,
};
module_pci_driver(qat_vf_vfio_pci_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Xin Zeng <xin.zeng@intel.com>");
MODULE_DESCRIPTION("QAT VFIO PCI - VFIO PCI driver with live migration support for Intel(R) QAT GEN4 device family");
MODULE_IMPORT_NS(CRYPTO_QAT);