drm/amdgpu: handle vfct with multiple vbios images

The vfct table can contain multiple vbios images if the
platform contains multiple GPUs. Noticed by netkas on
phoronix forums.  This patch fixes those platforms.

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_bios.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_bios.c
index 2602ea1..d9def01 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_bios.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_bios.c
@@ -358,8 +358,7 @@
 	struct acpi_table_header *hdr;
 	acpi_size tbl_size;
 	UEFI_ACPI_VFCT *vfct;
-	GOP_VBIOS_CONTENT *vbios;
-	VFCT_IMAGE_HEADER *vhdr;
+	unsigned offset;
 
 	if (!ACPI_SUCCESS(acpi_get_table("VFCT", 1, &hdr)))
 		return false;
@@ -370,42 +369,45 @@
 	}
 
 	vfct = (UEFI_ACPI_VFCT *)hdr;
-	if (vfct->VBIOSImageOffset + sizeof(VFCT_IMAGE_HEADER) > tbl_size) {
-		DRM_ERROR("ACPI VFCT table present but broken (too short #2)\n");
-		return false;
+	offset = vfct->VBIOSImageOffset;
+
+	while (offset < tbl_size) {
+		GOP_VBIOS_CONTENT *vbios = (GOP_VBIOS_CONTENT *)((char *)hdr + offset);
+		VFCT_IMAGE_HEADER *vhdr = &vbios->VbiosHeader;
+
+		offset += sizeof(VFCT_IMAGE_HEADER);
+		if (offset > tbl_size) {
+			DRM_ERROR("ACPI VFCT image header truncated\n");
+			return false;
+		}
+
+		offset += vhdr->ImageLength;
+		if (offset > tbl_size) {
+			DRM_ERROR("ACPI VFCT image truncated\n");
+			return false;
+		}
+
+		if (vhdr->ImageLength &&
+		    vhdr->PCIBus == adev->pdev->bus->number &&
+		    vhdr->PCIDevice == PCI_SLOT(adev->pdev->devfn) &&
+		    vhdr->PCIFunction == PCI_FUNC(adev->pdev->devfn) &&
+		    vhdr->VendorID == adev->pdev->vendor &&
+		    vhdr->DeviceID == adev->pdev->device) {
+			adev->bios = kmemdup(&vbios->VbiosContent,
+					     vhdr->ImageLength,
+					     GFP_KERNEL);
+
+			if (!check_atom_bios(adev->bios, vhdr->ImageLength)) {
+				kfree(adev->bios);
+				return false;
+			}
+			adev->bios_size = vhdr->ImageLength;
+			return true;
+		}
 	}
 
-	vbios = (GOP_VBIOS_CONTENT *)((char *)hdr + vfct->VBIOSImageOffset);
-	vhdr = &vbios->VbiosHeader;
-	DRM_INFO("ACPI VFCT contains a BIOS for %02x:%02x.%d %04x:%04x, size %d\n",
-			vhdr->PCIBus, vhdr->PCIDevice, vhdr->PCIFunction,
-			vhdr->VendorID, vhdr->DeviceID, vhdr->ImageLength);
-
-	if (vhdr->PCIBus != adev->pdev->bus->number ||
-	    vhdr->PCIDevice != PCI_SLOT(adev->pdev->devfn) ||
-	    vhdr->PCIFunction != PCI_FUNC(adev->pdev->devfn) ||
-	    vhdr->VendorID != adev->pdev->vendor ||
-	    vhdr->DeviceID != adev->pdev->device) {
-		DRM_INFO("ACPI VFCT table is not for this card\n");
-		return false;
-	}
-
-	if (vfct->VBIOSImageOffset + sizeof(VFCT_IMAGE_HEADER) + vhdr->ImageLength > tbl_size) {
-		DRM_ERROR("ACPI VFCT image truncated\n");
-		return false;
-	}
-
-	adev->bios = kmemdup(&vbios->VbiosContent,
-				vhdr->ImageLength,
-				GFP_KERNEL);
-
-	if (!check_atom_bios(adev->bios, vhdr->ImageLength)) {
-		kfree(adev->bios);
-		return false;
-	}
-	adev->bios_size = vhdr->ImageLength;
-
-	return true;
+	DRM_ERROR("ACPI VFCT table present but broken (too short #2)\n");
+	return false;
 }
 #else
 static inline bool amdgpu_acpi_vfct_bios(struct amdgpu_device *adev)