static ssize_t vfio_pci_igd_rw()

in pci/vfio_pci_igd.c [64:149]

• 63 lines of code
• 23 McCabe index (conditional complexity)

static ssize_t vfio_pci_igd_rw(struct vfio_pci_core_device *vdev,
			       char __user *buf, size_t count, loff_t *ppos,
			       bool iswrite)
{
	unsigned int i = VFIO_PCI_OFFSET_TO_INDEX(*ppos) - VFIO_PCI_NUM_REGIONS;
	struct igd_opregion_vbt *opregionvbt = vdev->region[i].data;
	loff_t pos = *ppos & VFIO_PCI_OFFSET_MASK, off = 0;
	size_t remaining;

	if (pos >= vdev->region[i].size || iswrite)
		return -EINVAL;

	count = min_t(size_t, count, vdev->region[i].size - pos);
	remaining = count;

	/* Copy until OpRegion version */
	if (remaining && pos < OPREGION_VERSION) {
		size_t bytes = min_t(size_t, remaining, OPREGION_VERSION - pos);

		if (igd_opregion_shift_copy(buf, &off,
					    opregionvbt->opregion + pos, &pos,
					    &remaining, bytes))
			return -EFAULT;
	}

	/* Copy patched (if necessary) OpRegion version */
	if (remaining && pos < OPREGION_VERSION + sizeof(__le16)) {
		size_t bytes = min_t(size_t, remaining,
				     OPREGION_VERSION + sizeof(__le16) - pos);
		__le16 version = *(__le16 *)(opregionvbt->opregion +
					     OPREGION_VERSION);

		/* Patch to 2.1 if OpRegion 2.0 has extended VBT */
		if (le16_to_cpu(version) == 0x0200 && opregionvbt->vbt_ex)
			version = cpu_to_le16(0x0201);

		if (igd_opregion_shift_copy(buf, &off,
					    (u8 *)&version +
					    (pos - OPREGION_VERSION),
					    &pos, &remaining, bytes))
			return -EFAULT;
	}

	/* Copy until RVDA */
	if (remaining && pos < OPREGION_RVDA) {
		size_t bytes = min_t(size_t, remaining, OPREGION_RVDA - pos);

		if (igd_opregion_shift_copy(buf, &off,
					    opregionvbt->opregion + pos, &pos,
					    &remaining, bytes))
			return -EFAULT;
	}

	/* Copy modified (if necessary) RVDA */
	if (remaining && pos < OPREGION_RVDA + sizeof(__le64)) {
		size_t bytes = min_t(size_t, remaining,
				     OPREGION_RVDA + sizeof(__le64) - pos);
		__le64 rvda = cpu_to_le64(opregionvbt->vbt_ex ?
					  OPREGION_SIZE : 0);

		if (igd_opregion_shift_copy(buf, &off,
					    (u8 *)&rvda + (pos - OPREGION_RVDA),
					    &pos, &remaining, bytes))
			return -EFAULT;
	}

	/* Copy the rest of OpRegion */
	if (remaining && pos < OPREGION_SIZE) {
		size_t bytes = min_t(size_t, remaining, OPREGION_SIZE - pos);

		if (igd_opregion_shift_copy(buf, &off,
					    opregionvbt->opregion + pos, &pos,
					    &remaining, bytes))
			return -EFAULT;
	}

	/* Copy extended VBT if exists */
	if (remaining &&
	    copy_to_user(buf + off, opregionvbt->vbt_ex + (pos - OPREGION_SIZE),
			 remaining))
		return -EFAULT;

	*ppos += count;

	return count;
}