[PATCH v2] vfio/pci: Add support for opregion v2.0+

[Fred Gao <fred.gao@intel.com>]

Before opregion version 2.0 VBT data is stored in opregion mailbox #4,
However, When VBT data exceeds 6KB size and cannot be within mailbox #4
starting from opregion v2.0+, Extended VBT region, next to opregion, is
used to hold the VBT data, so the total size will be opregion size plus
extended VBT region size.

Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: Swee Yee Fonn <swee.yee.fonn@intel.com>
Signed-off-by: Fred Gao <fred.gao@intel.com>
---
 drivers/vfio/pci/vfio_pci_igd.c | 59 +++++++++++++++++++++++++++++++++
 1 file changed, 59 insertions(+)

diff --git a/drivers/vfio/pci/vfio_pci_igd.c b/drivers/vfio/pci/vfio_pci_igd.c
index 53d97f459252..fc470278a492 100644
--- a/drivers/vfio/pci/vfio_pci_igd.c
+++ b/drivers/vfio/pci/vfio_pci_igd.c
@@ -21,6 +21,10 @@
 #define OPREGION_SIZE		(8 * 1024)
 #define OPREGION_PCI_ADDR	0xfc
 
+#define OPREGION_RVDA		0x3ba
+#define OPREGION_RVDS		0x3c2
+#define OPREGION_VERSION	0x16
+
 static size_t vfio_pci_igd_rw(struct vfio_pci_device *vdev, char __user *buf,
 			      size_t count, loff_t *ppos, bool iswrite)
 {
@@ -58,6 +62,7 @@ static int vfio_pci_igd_opregion_init(struct vfio_pci_device *vdev)
 	u32 addr, size;
 	void *base;
 	int ret;
+	u16 version;
 
 	ret = pci_read_config_dword(vdev->pdev, OPREGION_PCI_ADDR, &addr);
 	if (ret)
@@ -83,6 +88,60 @@ static int vfio_pci_igd_opregion_init(struct vfio_pci_device *vdev)
 
 	size *= 1024; /* In KB */
 
+	/*
+	 * Support opregion v2.0+
+	 * When VBT data exceeds 6KB size and cannot be within mailbox #4
+	 * Extended VBT region, next to opregion, is used to hold the VBT data.
+	 * RVDA (Relative Address of VBT Data from Opregion Base) and RVDS
+	 * (VBT Data Size) from opregion structure member are used to hold the
+	 * address from region base and size of VBT data while RVDA/RVDS
+	 * are not defined before opregion 2.0.
+	 *
+	 * opregion 2.0: rvda is the physical VBT address.
+	 *
+	 * opregion 2.1+: rvda is unsigned, relative offset from
+	 * opregion base, and should never point within opregion.
+	 */
+	version = le16_to_cpu(*(__le16 *)(base + OPREGION_VERSION));
+	if (version >= 0x0200) {
+		u64 rvda;
+		u32 rvds;
+
+		rvda = le64_to_cpu(*(__le64 *)(base + OPREGION_RVDA));
+		rvds = le32_to_cpu(*(__le32 *)(base + OPREGION_RVDS));
+		if (rvda && rvds) {
+			u32 offset;
+
+			if (version == 0x0200)
+				offset = rvda - (u64)addr;
+			else
+				offset = rvda;
+
+			if (offset != size) {
+				pci_err(vdev->pdev,
+				"Extended VBT does not follow opregion !\n"
+				"opregion version 0x%x:offset 0x%x\n", version, offset);
+				return -EINVAL;
+			}
+
+			/*
+			 * the only difference between opregion 2.0 and 2.1 is
+			 * rvda addressing mode. since rvda is physical host
+			 * VBT address and cannot be directly used in guest,
+			 * faked into opregion 2.1's relative offset.
+			 */
+			if (version == 0x0200) {
+				*(__le16 *)(base + OPREGION_VERSION) =
+					cpu_to_le16(0x0201);
+				(*(__le64 *)(base + OPREGION_RVDA)) =
+					cpu_to_le64((rvda - (u64)addr));
+			}
+
+			/* region size for opregion v2.0+: opregion and VBT size */
+			size = offset + rvds;
+		}
+	}
+
 	if (size != OPREGION_SIZE) {
 		memunmap(base);
 		base = memremap(addr, size, MEMREMAP_WB);
-- 
2.24.1.1.gb6d4d82bd5