static int vfio_pci_igd_opregion_init()

in pci/vfio_pci_igd.c [168:279]

• 69 lines of code
• 15 McCabe index (conditional complexity)

static int vfio_pci_igd_opregion_init(struct vfio_pci_core_device *vdev)
{
	__le32 *dwordp = (__le32 *)(vdev->vconfig + OPREGION_PCI_ADDR);
	u32 addr, size;
	struct igd_opregion_vbt *opregionvbt;
	int ret;
	u16 version;

	ret = pci_read_config_dword(vdev->pdev, OPREGION_PCI_ADDR, &addr);
	if (ret)
		return ret;

	if (!addr || !(~addr))
		return -ENODEV;

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

	opregionvbt->opregion = memremap(addr, OPREGION_SIZE, MEMREMAP_WB);
	if (!opregionvbt->opregion) {
		kfree(opregionvbt);
		return -ENOMEM;
	}

	if (memcmp(opregionvbt->opregion, OPREGION_SIGNATURE, 16)) {
		memunmap(opregionvbt->opregion);
		kfree(opregionvbt);
		return -EINVAL;
	}

	size = le32_to_cpu(*(__le32 *)(opregionvbt->opregion + 16));
	if (!size) {
		memunmap(opregionvbt->opregion);
		kfree(opregionvbt);
		return -EINVAL;
	}

	size *= 1024; /* In KB */

	/*
	 * OpRegion and VBT:
	 * When VBT data doesn't exceed 6KB, it's stored in Mailbox #4.
	 * When VBT data exceeds 6KB size, Mailbox #4 is no longer large enough
	 * to hold the VBT data, the Extended VBT region is introduced since
	 * OpRegion 2.0 to hold the VBT data. Since OpRegion 2.0, RVDA/RVDS are
	 * introduced to define the extended VBT data location and size.
	 * OpRegion 2.0: RVDA defines the absolute physical address of the
	 *   extended VBT data, RVDS defines the VBT data size.
	 * OpRegion 2.1 and above: RVDA defines the relative address of the
	 *   extended VBT data to OpRegion base, RVDS defines the VBT data size.
	 *
	 * Due to the RVDA definition diff in OpRegion VBT (also the only diff
	 * between 2.0 and 2.1), exposing OpRegion and VBT as a contiguous range
	 * for OpRegion 2.0 and above makes it possible to support the
	 * non-contiguous VBT through a single vfio region. From r/w ops view,
	 * only contiguous VBT after OpRegion with version 2.1+ is exposed,
	 * regardless the host OpRegion is 2.0 or non-contiguous 2.1+. The r/w
	 * ops will on-the-fly shift the actural offset into VBT so that data at
	 * correct position can be returned to the requester.
	 */
	version = le16_to_cpu(*(__le16 *)(opregionvbt->opregion +
					  OPREGION_VERSION));
	if (version >= 0x0200) {
		u64 rvda = le64_to_cpu(*(__le64 *)(opregionvbt->opregion +
						   OPREGION_RVDA));
		u32 rvds = le32_to_cpu(*(__le32 *)(opregionvbt->opregion +
						   OPREGION_RVDS));

		/* The extended VBT is valid only when RVDA/RVDS are non-zero */
		if (rvda && rvds) {
			size += rvds;

			/*
			 * Extended VBT location by RVDA:
			 * Absolute physical addr for 2.0.
			 * Relative addr to OpRegion header for 2.1+.
			 */
			if (version == 0x0200)
				addr = rvda;
			else
				addr += rvda;

			opregionvbt->vbt_ex = memremap(addr, rvds, MEMREMAP_WB);
			if (!opregionvbt->vbt_ex) {
				memunmap(opregionvbt->opregion);
				kfree(opregionvbt);
				return -ENOMEM;
			}
		}
	}

	ret = vfio_pci_register_dev_region(vdev,
		PCI_VENDOR_ID_INTEL | VFIO_REGION_TYPE_PCI_VENDOR_TYPE,
		VFIO_REGION_SUBTYPE_INTEL_IGD_OPREGION, &vfio_pci_igd_regops,
		size, VFIO_REGION_INFO_FLAG_READ, opregionvbt);
	if (ret) {
		if (opregionvbt->vbt_ex)
			memunmap(opregionvbt->vbt_ex);

		memunmap(opregionvbt->opregion);
		kfree(opregionvbt);
		return ret;
	}

	/* Fill vconfig with the hw value and virtualize register */
	*dwordp = cpu_to_le32(addr);
	memset(vdev->pci_config_map + OPREGION_PCI_ADDR,
	       PCI_CAP_ID_INVALID_VIRT, 4);

	return ret;
}