// SPDX-License-Identifier: GPL-2.0
/*
 * vfio-ISM driver for s390
 *
 * Copyright IBM Corp.
 */

#include <linux/slab.h>
#include "../vfio_pci_priv.h"

#define ISM_VFIO_PCI_OFFSET_SHIFT   48
#define ISM_VFIO_PCI_OFFSET_TO_INDEX(off) ((off) >> ISM_VFIO_PCI_OFFSET_SHIFT)
#define ISM_VFIO_PCI_INDEX_TO_OFFSET(index) ((u64)(index) << ISM_VFIO_PCI_OFFSET_SHIFT)
#define ISM_VFIO_PCI_OFFSET_MASK (((u64)(1) << ISM_VFIO_PCI_OFFSET_SHIFT) - 1)

/*
 * Use __zpci_load() to bypass automatic use of
 * PCI MIO instructions which are not supported on ISM devices
 */
#define ISM_READ(size)                                                        \
	static int ism_read##size(struct zpci_dev *zdev, int bar,             \
				  size_t *filled, char __user *buf,           \
				  loff_t off)                                 \
	{                                                                     \
		u64 req, tmp;                                                 \
		u##size val;                                                  \
		int ret;                                                      \
									      \
		req = ZPCI_CREATE_REQ(READ_ONCE(zdev->fh), bar, sizeof(val)); \
		ret = __zpci_load(&tmp, req, off);                            \
		if (ret)                                                      \
			return ret;                                           \
		val = (u##size)tmp;                                           \
		if (copy_to_user(buf, &val, sizeof(val)))                     \
			return -EFAULT;                                       \
		*filled = sizeof(val);                                        \
		return 0;						      \
	}

ISM_READ(64);
ISM_READ(32);
ISM_READ(16);
ISM_READ(8);

struct ism_vfio_pci_core_device {
	struct vfio_pci_core_device core_device;
	struct kmem_cache *store_block_cache;
};

static int ism_vfio_pci_open_device(struct vfio_device *core_vdev)
{
	struct ism_vfio_pci_core_device *ivpcd;
	struct vfio_pci_core_device *vdev;
	int ret;

	ivpcd = container_of(core_vdev, struct ism_vfio_pci_core_device,
			     core_device.vdev);
	vdev = &ivpcd->core_device;

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

	vfio_pci_core_finish_enable(vdev);
	return 0;
}

/*
 * ism_vfio_pci_do_io_r()
 *
 * On s390, kernel primitives such as ioread() and iowrite() are switched over
 * from function-handle-based PCI load/stores instructions to PCI memory-I/O (MIO)
 * loads/stores when these are available and not explicitly disabled. Since these
 * instructions cannot be used with ISM devices, ensure that classic
 * function-handle-based PCI instructions are used instead.
 */
static ssize_t ism_vfio_pci_do_io_r(struct vfio_pci_core_device *vdev,
				    char __user *buf, loff_t off, size_t count,
				    int bar)
{
	struct zpci_dev *zdev = to_zpci(vdev->pdev);
	ssize_t done = 0;
	int ret;

	while (count) {
		size_t filled;

		if (count >= 8 && IS_ALIGNED(off, 8)) {
			ret = ism_read64(zdev, bar, &filled, buf, off);
			if (ret)
				return ret;
		} else if (count >= 4 && IS_ALIGNED(off, 4)) {
			ret = ism_read32(zdev, bar, &filled, buf, off);
			if (ret)
				return ret;
		} else if (count >= 2 && IS_ALIGNED(off, 2)) {
			ret = ism_read16(zdev, bar, &filled, buf, off);
			if (ret)
				return ret;
		} else {
			ret = ism_read8(zdev, bar, &filled, buf, off);
			if (ret)
				return ret;
		}

		count -= filled;
		done += filled;
		off += filled;
		buf += filled;
	}

	return done;
}

/*
 * ism_vfio_pci_do_io_w()
 *
 * Ensure that the PCI store block (PCISTB) instruction is used as required by the
 * ISM device. The ISM device also uses a 256 TiB BAR 0 for write operations,
 * which requires a 48bit region address space (ISM_VFIO_PCI_OFFSET_SHIFT).
 */
static ssize_t ism_vfio_pci_do_io_w(struct vfio_pci_core_device *vdev,
				    char __user *buf, loff_t off, size_t count,
				    int bar)
{
	struct zpci_dev *zdev = to_zpci(vdev->pdev);
	struct ism_vfio_pci_core_device *ivpcd;
	ssize_t ret;
	void *data;
	u64 req;

	if (count > zdev->maxstbl)
		return -EINVAL;
	if (((off % PAGE_SIZE) + count) > PAGE_SIZE)
		return -EINVAL;

	ivpcd = container_of(vdev, struct ism_vfio_pci_core_device,
			     core_device);
	data = kmem_cache_alloc(ivpcd->store_block_cache, GFP_KERNEL);
	if (!data)
		return -ENOMEM;

	if (copy_from_user(data, buf, count)) {
		ret = -EFAULT;
		goto out_free;
	}

	req = ZPCI_CREATE_REQ(READ_ONCE(zdev->fh), bar, count);
	ret = __zpci_store_block(data, req, off);
	if (ret)
		goto out_free;

	ret = count;

out_free:
	kmem_cache_free(ivpcd->store_block_cache, data);
	return ret;
}

static ssize_t ism_vfio_pci_bar_rw(struct vfio_pci_core_device *vdev,
				   char __user *buf, size_t count, loff_t *ppos,
				   bool iswrite)
{
	int bar = ISM_VFIO_PCI_OFFSET_TO_INDEX(*ppos);
	loff_t pos = *ppos & ISM_VFIO_PCI_OFFSET_MASK;
	resource_size_t end;
	ssize_t done = 0;

	if (pci_resource_start(vdev->pdev, bar))
		end = pci_resource_len(vdev->pdev, bar);
	else
		return -EINVAL;

	if (pos >= end)
		return -EINVAL;

	count = min(count, (size_t)(end - pos));

	if (iswrite)
		done = ism_vfio_pci_do_io_w(vdev, buf, pos, count, bar);
	else
		done = ism_vfio_pci_do_io_r(vdev, buf, pos, count, bar);

	if (done >= 0)
		*ppos += done;

	return done;
}

static ssize_t ism_vfio_pci_config_rw(struct vfio_pci_core_device *vdev,
				      char __user *buf, size_t count,
				      loff_t *ppos, bool iswrite)
{
	loff_t pos = *ppos;
	size_t done = 0;
	int ret = 0;

	pos &= ISM_VFIO_PCI_OFFSET_MASK;

	while (count) {
		/*
		 * zPCI must not use MIO instructions for config space access,
		 * so we can use common code path here.
		 */
		ret = vfio_pci_config_rw_single(vdev, buf, count, &pos, iswrite);
		if (ret < 0)
			return ret;

		count -= ret;
		done += ret;
		buf += ret;
		pos += ret;
	}

	*ppos += done;

	return done;
}

static ssize_t ism_vfio_pci_rw(struct vfio_device *core_vdev, char __user *buf,
			       size_t count, loff_t *ppos, bool iswrite)
{
	unsigned int index = ISM_VFIO_PCI_OFFSET_TO_INDEX(*ppos);
	struct vfio_pci_core_device *vdev;
	int ret;

	vdev = container_of(core_vdev, struct vfio_pci_core_device, vdev);

	if (!count)
		return 0;

	switch (index) {
	case VFIO_PCI_CONFIG_REGION_INDEX:
		ret = ism_vfio_pci_config_rw(vdev, buf, count, ppos, iswrite);
		break;

	case VFIO_PCI_BAR0_REGION_INDEX ... VFIO_PCI_BAR5_REGION_INDEX:
		ret = ism_vfio_pci_bar_rw(vdev, buf, count, ppos, iswrite);
		break;

	default:
		return -EINVAL;
	}

	return ret;
}

static ssize_t ism_vfio_pci_read(struct vfio_device *core_vdev,
				 char __user *buf, size_t count, loff_t *ppos)
{
	return ism_vfio_pci_rw(core_vdev, buf, count, ppos, false);
}

static ssize_t ism_vfio_pci_write(struct vfio_device *core_vdev,
				  const char __user *buf, size_t count,
				  loff_t *ppos)
{
	return ism_vfio_pci_rw(core_vdev, (char __user *)buf, count, ppos,
			       true);
}

static int ism_vfio_pci_ioctl_get_region_info(struct vfio_device *core_vdev,
					      struct vfio_region_info *info,
					      struct vfio_info_cap *caps)
{
	struct vfio_pci_core_device *vdev =
		container_of(core_vdev, struct vfio_pci_core_device, vdev);
	struct pci_dev *pdev = vdev->pdev;

	switch (info->index) {
	case VFIO_PCI_CONFIG_REGION_INDEX:
		info->offset = ISM_VFIO_PCI_INDEX_TO_OFFSET(info->index);
		info->size = pdev->cfg_size;
		info->flags = VFIO_REGION_INFO_FLAG_READ |
			      VFIO_REGION_INFO_FLAG_WRITE;
		break;
	case VFIO_PCI_BAR0_REGION_INDEX ... VFIO_PCI_BAR5_REGION_INDEX:
		info->offset = ISM_VFIO_PCI_INDEX_TO_OFFSET(info->index);
		info->size = pci_resource_len(pdev, info->index);
		if (!info->size) {
			info->flags = 0;
			break;
		}
		info->flags = VFIO_REGION_INFO_FLAG_READ |
			      VFIO_REGION_INFO_FLAG_WRITE;
		break;
	default:
		info->offset = 0;
		info->size = 0;
		info->flags = 0;
		return -EINVAL;
	}
	return 0;
}

static int ism_vfio_pci_init_dev(struct vfio_device *core_vdev)
{
	struct zpci_dev *zdev = to_zpci(to_pci_dev(core_vdev->dev));
	struct ism_vfio_pci_core_device *ivpcd;
	char cache_name[20];
	int ret;

	ivpcd = container_of(core_vdev, struct ism_vfio_pci_core_device,
			     core_device.vdev);

	snprintf(cache_name, sizeof(cache_name), "ism_sb_fid_%08x", zdev->fid);

	ivpcd->store_block_cache =
		kmem_cache_create(cache_name, zdev->maxstbl,
				  (&(struct kmem_cache_args){
					  .align = PAGE_SIZE,
					  .useroffset = 0,
					  .usersize = zdev->maxstbl,
				  }),
				  (SLAB_RECLAIM_ACCOUNT | SLAB_ACCOUNT));
	if (!ivpcd->store_block_cache)
		return -ENOMEM;

	ret = vfio_pci_core_init_dev(core_vdev);
	if (ret)
		kmem_cache_destroy(ivpcd->store_block_cache);

	return ret;
}

static void ism_vfio_pci_release_dev(struct vfio_device *core_vdev)
{
	struct ism_vfio_pci_core_device *ivpcd = container_of(
		core_vdev, struct ism_vfio_pci_core_device, core_device.vdev);

	kmem_cache_destroy(ivpcd->store_block_cache);
	vfio_pci_core_release_dev(core_vdev);
}

static const struct vfio_device_ops ism_pci_ops = {
	.name = "ism-vfio-pci",
	.init = ism_vfio_pci_init_dev,
	.release = ism_vfio_pci_release_dev,
	.open_device = ism_vfio_pci_open_device,
	.close_device = vfio_pci_core_close_device,
	.ioctl = vfio_pci_core_ioctl,
	.get_region_info_caps = ism_vfio_pci_ioctl_get_region_info,
	.device_feature = vfio_pci_core_ioctl_feature,
	.read = ism_vfio_pci_read,
	.write = ism_vfio_pci_write,
	.request = vfio_pci_core_request,
	.match = vfio_pci_core_match,
	.match_token_uuid = vfio_pci_core_match_token_uuid,
	.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 int ism_vfio_pci_probe(struct pci_dev *pdev,
			      const struct pci_device_id *id)
{
	struct ism_vfio_pci_core_device *ivpcd;
	int ret;

	ivpcd = vfio_alloc_device(ism_vfio_pci_core_device, core_device.vdev,
				  &pdev->dev, &ism_pci_ops);
	if (IS_ERR(ivpcd))
		return PTR_ERR(ivpcd);

	dev_set_drvdata(&pdev->dev, &ivpcd->core_device);

	ret = vfio_pci_core_register_device(&ivpcd->core_device);
	if (ret)
		vfio_put_device(&ivpcd->core_device.vdev);

	return ret;
}

static void ism_vfio_pci_remove(struct pci_dev *pdev)
{
	struct vfio_pci_core_device *core_device;
	struct ism_vfio_pci_core_device *ivpcd;

	core_device = dev_get_drvdata(&pdev->dev);
	ivpcd = container_of(core_device, struct ism_vfio_pci_core_device,
			     core_device);

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

static const struct pci_device_id ism_device_table[] = {
	{ PCI_DRIVER_OVERRIDE_DEVICE_VFIO(PCI_VENDOR_ID_IBM,
					  PCI_DEVICE_ID_IBM_ISM) },
	{}
};
MODULE_DEVICE_TABLE(pci, ism_device_table);

static struct pci_driver ism_vfio_pci_driver = {
	.name = KBUILD_MODNAME,
	.id_table = ism_device_table,
	.probe = ism_vfio_pci_probe,
	.remove = ism_vfio_pci_remove,
	.err_handler = &vfio_pci_core_err_handlers,
	.driver_managed_dma = true,
};

module_pci_driver(ism_vfio_pci_driver);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("vfio-pci variant driver for the IBM Internal Shared Memory (ISM) device");
MODULE_AUTHOR("IBM Corporation");