xref: /linux/drivers/vfio/pci/virtio/legacy_io.c (revision 4f9786035f9e519db41375818e1d0b5f20da2f10)

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2023, NVIDIA CORPORATION & AFFILIATES. All rights reserved
 */

#include <linux/device.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/pci.h>
#include <linux/pm_runtime.h>
#include <linux/types.h>
#include <linux/uaccess.h>
#include <linux/vfio.h>
#include <linux/vfio_pci_core.h>
#include <linux/virtio_pci.h>
#include <linux/virtio_net.h>
#include <linux/virtio_pci_admin.h>

#include "common.h"

static int
virtiovf_issue_legacy_rw_cmd(struct virtiovf_pci_core_device *virtvdev,
			     loff_t pos, char __user *buf,
			     size_t count, bool read)
{
	bool msix_enabled =
		(virtvdev->core_device.irq_type == VFIO_PCI_MSIX_IRQ_INDEX);
	struct pci_dev *pdev = virtvdev->core_device.pdev;
	u8 *bar0_buf = virtvdev->bar0_virtual_buf;
	bool common;
	u8 offset;
	int ret;

	common = pos < VIRTIO_PCI_CONFIG_OFF(msix_enabled);
	/* offset within the relevant configuration area */
	offset = common ? pos : pos - VIRTIO_PCI_CONFIG_OFF(msix_enabled);
	mutex_lock(&virtvdev->bar_mutex);
	if (read) {
		if (common)
			ret = virtio_pci_admin_legacy_common_io_read(pdev, offset,
					count, bar0_buf + pos);
		else
			ret = virtio_pci_admin_legacy_device_io_read(pdev, offset,
					count, bar0_buf + pos);
		if (ret)
			goto out;
		if (copy_to_user(buf, bar0_buf + pos, count))
			ret = -EFAULT;
	} else {
		if (copy_from_user(bar0_buf + pos, buf, count)) {
			ret = -EFAULT;
			goto out;
		}

		if (common)
			ret = virtio_pci_admin_legacy_common_io_write(pdev, offset,
					count, bar0_buf + pos);
		else
			ret = virtio_pci_admin_legacy_device_io_write(pdev, offset,
					count, bar0_buf + pos);
	}
out:
	mutex_unlock(&virtvdev->bar_mutex);
	return ret;
}

static int
virtiovf_pci_bar0_rw(struct virtiovf_pci_core_device *virtvdev,
		     loff_t pos, char __user *buf,
		     size_t count, bool read)
{
	struct vfio_pci_core_device *core_device = &virtvdev->core_device;
	struct pci_dev *pdev = core_device->pdev;
	u16 queue_notify;
	int ret;

	if (!(le16_to_cpu(virtvdev->pci_cmd) & PCI_COMMAND_IO))
		return -EIO;

	if (pos + count > virtvdev->bar0_virtual_buf_size)
		return -EINVAL;

	ret = pm_runtime_resume_and_get(&pdev->dev);
	if (ret) {
		pci_info_ratelimited(pdev, "runtime resume failed %d\n", ret);
		return -EIO;
	}

	switch (pos) {
	case VIRTIO_PCI_QUEUE_NOTIFY:
		if (count != sizeof(queue_notify)) {
			ret = -EINVAL;
			goto end;
		}
		if (read) {
			ret = vfio_pci_core_ioread16(core_device, true, &queue_notify,
						     virtvdev->notify_addr);
			if (ret)
				goto end;
			if (copy_to_user(buf, &queue_notify,
					 sizeof(queue_notify))) {
				ret = -EFAULT;
				goto end;
			}
		} else {
			if (copy_from_user(&queue_notify, buf, count)) {
				ret = -EFAULT;
				goto end;
			}
			ret = vfio_pci_core_iowrite16(core_device, true, queue_notify,
						      virtvdev->notify_addr);
		}
		break;
	default:
		ret = virtiovf_issue_legacy_rw_cmd(virtvdev, pos, buf, count,
						   read);
	}

end:
	pm_runtime_put(&pdev->dev);
	return ret ? ret : count;
}

static ssize_t virtiovf_pci_read_config(struct vfio_device *core_vdev,
					char __user *buf, size_t count,
					loff_t *ppos)
{
	struct virtiovf_pci_core_device *virtvdev = container_of(
		core_vdev, struct virtiovf_pci_core_device, core_device.vdev);
	loff_t pos = *ppos & VFIO_PCI_OFFSET_MASK;
	size_t register_offset;
	loff_t copy_offset;
	size_t copy_count;
	__le32 val32;
	__le16 val16;
	u8 val8;
	int ret;

	ret = vfio_pci_core_read(core_vdev, buf, count, ppos);
	if (ret < 0)
		return ret;

	if (vfio_pci_core_range_intersect_range(pos, count, PCI_DEVICE_ID,
						sizeof(val16), &copy_offset,
						&copy_count, &register_offset)) {
		val16 = cpu_to_le16(VIRTIO_TRANS_ID_NET);
		if (copy_to_user(buf + copy_offset, (void *)&val16 + register_offset, copy_count))
			return -EFAULT;
	}

	if ((le16_to_cpu(virtvdev->pci_cmd) & PCI_COMMAND_IO) &&
	    vfio_pci_core_range_intersect_range(pos, count, PCI_COMMAND,
						sizeof(val16), &copy_offset,
						&copy_count, &register_offset)) {
		if (copy_from_user((void *)&val16 + register_offset, buf + copy_offset,
				   copy_count))
			return -EFAULT;
		val16 |= cpu_to_le16(PCI_COMMAND_IO);
		if (copy_to_user(buf + copy_offset, (void *)&val16 + register_offset,
				 copy_count))
			return -EFAULT;
	}

	if (vfio_pci_core_range_intersect_range(pos, count, PCI_REVISION_ID,
						sizeof(val8), &copy_offset,
						&copy_count, &register_offset)) {
		/* Transional needs to have revision 0 */
		val8 = 0;
		if (copy_to_user(buf + copy_offset, &val8, copy_count))
			return -EFAULT;
	}

	if (vfio_pci_core_range_intersect_range(pos, count, PCI_BASE_ADDRESS_0,
						sizeof(val32), &copy_offset,
						&copy_count, &register_offset)) {
		u32 bar_mask = ~(virtvdev->bar0_virtual_buf_size - 1);
		u32 pci_base_addr_0 = le32_to_cpu(virtvdev->pci_base_addr_0);

		val32 = cpu_to_le32((pci_base_addr_0 & bar_mask) | PCI_BASE_ADDRESS_SPACE_IO);
		if (copy_to_user(buf + copy_offset, (void *)&val32 + register_offset, copy_count))
			return -EFAULT;
	}

	if (vfio_pci_core_range_intersect_range(pos, count, PCI_SUBSYSTEM_ID,
						sizeof(val16), &copy_offset,
						&copy_count, &register_offset)) {
		/*
		 * Transitional devices use the PCI subsystem device id as
		 * virtio device id, same as legacy driver always did.
		 */
		val16 = cpu_to_le16(VIRTIO_ID_NET);
		if (copy_to_user(buf + copy_offset, (void *)&val16 + register_offset,
				 copy_count))
			return -EFAULT;
	}

	if (vfio_pci_core_range_intersect_range(pos, count, PCI_SUBSYSTEM_VENDOR_ID,
						sizeof(val16), &copy_offset,
						&copy_count, &register_offset)) {
		val16 = cpu_to_le16(PCI_VENDOR_ID_REDHAT_QUMRANET);
		if (copy_to_user(buf + copy_offset, (void *)&val16 + register_offset,
				 copy_count))
			return -EFAULT;
	}

	return count;
}

ssize_t virtiovf_pci_core_read(struct vfio_device *core_vdev, char __user *buf,
			       size_t count, loff_t *ppos)
{
	struct virtiovf_pci_core_device *virtvdev = container_of(
		core_vdev, struct virtiovf_pci_core_device, core_device.vdev);
	unsigned int index = VFIO_PCI_OFFSET_TO_INDEX(*ppos);
	loff_t pos = *ppos & VFIO_PCI_OFFSET_MASK;

	if (!count)
		return 0;

	if (index == VFIO_PCI_CONFIG_REGION_INDEX)
		return virtiovf_pci_read_config(core_vdev, buf, count, ppos);

	if (index == VFIO_PCI_BAR0_REGION_INDEX)
		return virtiovf_pci_bar0_rw(virtvdev, pos, buf, count, true);

	return vfio_pci_core_read(core_vdev, buf, count, ppos);
}

static ssize_t virtiovf_pci_write_config(struct vfio_device *core_vdev,
					 const char __user *buf, size_t count,
					 loff_t *ppos)
{
	struct virtiovf_pci_core_device *virtvdev = container_of(
		core_vdev, struct virtiovf_pci_core_device, core_device.vdev);
	loff_t pos = *ppos & VFIO_PCI_OFFSET_MASK;
	size_t register_offset;
	loff_t copy_offset;
	size_t copy_count;

	if (vfio_pci_core_range_intersect_range(pos, count, PCI_COMMAND,
						sizeof(virtvdev->pci_cmd),
						&copy_offset, &copy_count,
						&register_offset)) {
		if (copy_from_user((void *)&virtvdev->pci_cmd + register_offset,
				   buf + copy_offset,
				   copy_count))
			return -EFAULT;
	}

	if (vfio_pci_core_range_intersect_range(pos, count, PCI_BASE_ADDRESS_0,
						sizeof(virtvdev->pci_base_addr_0),
						&copy_offset, &copy_count,
						&register_offset)) {
		if (copy_from_user((void *)&virtvdev->pci_base_addr_0 + register_offset,
				   buf + copy_offset,
				   copy_count))
			return -EFAULT;
	}

	return vfio_pci_core_write(core_vdev, buf, count, ppos);
}

ssize_t virtiovf_pci_core_write(struct vfio_device *core_vdev, const char __user *buf,
				size_t count, loff_t *ppos)
{
	struct virtiovf_pci_core_device *virtvdev = container_of(
		core_vdev, struct virtiovf_pci_core_device, core_device.vdev);
	unsigned int index = VFIO_PCI_OFFSET_TO_INDEX(*ppos);
	loff_t pos = *ppos & VFIO_PCI_OFFSET_MASK;

	if (!count)
		return 0;

	if (index == VFIO_PCI_CONFIG_REGION_INDEX)
		return virtiovf_pci_write_config(core_vdev, buf, count, ppos);

	if (index == VFIO_PCI_BAR0_REGION_INDEX)
		return virtiovf_pci_bar0_rw(virtvdev, pos, (char __user *)buf, count, false);

	return vfio_pci_core_write(core_vdev, buf, count, ppos);
}

int virtiovf_pci_ioctl_get_region_info(struct vfio_device *core_vdev,
				       unsigned int cmd, unsigned long arg)
{
	struct virtiovf_pci_core_device *virtvdev = container_of(
		core_vdev, struct virtiovf_pci_core_device, core_device.vdev);
	unsigned long minsz = offsetofend(struct vfio_region_info, offset);
	void __user *uarg = (void __user *)arg;
	struct vfio_region_info info = {};

	if (copy_from_user(&info, uarg, minsz))
		return -EFAULT;

	if (info.argsz < minsz)
		return -EINVAL;

	switch (info.index) {
	case VFIO_PCI_BAR0_REGION_INDEX:
		info.offset = VFIO_PCI_INDEX_TO_OFFSET(info.index);
		info.size = virtvdev->bar0_virtual_buf_size;
		info.flags = VFIO_REGION_INFO_FLAG_READ |
			     VFIO_REGION_INFO_FLAG_WRITE;
		return copy_to_user(uarg, &info, minsz) ? -EFAULT : 0;
	default:
		return vfio_pci_core_ioctl(core_vdev, cmd, arg);
	}
}

long virtiovf_vfio_pci_core_ioctl(struct vfio_device *core_vdev, unsigned int cmd,
				  unsigned long arg)
{
	switch (cmd) {
	case VFIO_DEVICE_GET_REGION_INFO:
		return virtiovf_pci_ioctl_get_region_info(core_vdev, cmd, arg);
	default:
		return vfio_pci_core_ioctl(core_vdev, cmd, arg);
	}
}

static int virtiovf_set_notify_addr(struct virtiovf_pci_core_device *virtvdev)
{
	struct vfio_pci_core_device *core_device = &virtvdev->core_device;
	int ret;

	/*
	 * Setup the BAR where the 'notify' exists to be used by vfio as well
	 * This will let us mmap it only once and use it when needed.
	 */
	ret = vfio_pci_core_setup_barmap(core_device,
					 virtvdev->notify_bar);
	if (ret)
		return ret;

	virtvdev->notify_addr = core_device->barmap[virtvdev->notify_bar] +
			virtvdev->notify_offset;
	return 0;
}

int virtiovf_open_legacy_io(struct virtiovf_pci_core_device *virtvdev)
{
	if (!virtvdev->bar0_virtual_buf)
		return 0;

	/*
	 * Upon close_device() the vfio_pci_core_disable() is called
	 * and will close all the previous mmaps, so it seems that the
	 * valid life cycle for the 'notify' addr is per open/close.
	 */
	return virtiovf_set_notify_addr(virtvdev);
}

static int virtiovf_get_device_config_size(unsigned short device)
{
	/* Network card */
	return offsetofend(struct virtio_net_config, status);
}

static int virtiovf_read_notify_info(struct virtiovf_pci_core_device *virtvdev)
{
	u64 offset;
	int ret;
	u8 bar;

	ret = virtio_pci_admin_legacy_io_notify_info(virtvdev->core_device.pdev,
				VIRTIO_ADMIN_CMD_NOTIFY_INFO_FLAGS_OWNER_MEM,
				&bar, &offset);
	if (ret)
		return ret;

	virtvdev->notify_bar = bar;
	virtvdev->notify_offset = offset;
	return 0;
}

static bool virtiovf_bar0_exists(struct pci_dev *pdev)
{
	struct resource *res = pdev->resource;

	return res->flags;
}

bool virtiovf_support_legacy_io(struct pci_dev *pdev)
{
	/* For now, the legacy IO functionality is supported only for virtio-net */
	return pdev->device == 0x1041 && virtio_pci_admin_has_legacy_io(pdev) &&
	       !virtiovf_bar0_exists(pdev);
}

int virtiovf_init_legacy_io(struct virtiovf_pci_core_device *virtvdev)
{
	struct pci_dev *pdev = virtvdev->core_device.pdev;
	int ret;

	ret = virtiovf_read_notify_info(virtvdev);
	if (ret)
		return ret;

	virtvdev->bar0_virtual_buf_size = VIRTIO_PCI_CONFIG_OFF(true) +
				virtiovf_get_device_config_size(pdev->device);
	BUILD_BUG_ON(!is_power_of_2(virtvdev->bar0_virtual_buf_size));
	virtvdev->bar0_virtual_buf = kzalloc(virtvdev->bar0_virtual_buf_size,
					     GFP_KERNEL);
	if (!virtvdev->bar0_virtual_buf)
		return -ENOMEM;
	mutex_init(&virtvdev->bar_mutex);
	return 0;
}

void virtiovf_release_legacy_io(struct virtiovf_pci_core_device *virtvdev)
{
	kfree(virtvdev->bar0_virtual_buf);
}

void virtiovf_legacy_io_reset_done(struct pci_dev *pdev)
{
	struct virtiovf_pci_core_device *virtvdev = dev_get_drvdata(&pdev->dev);

	virtvdev->pci_cmd = 0;
}