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

drivers/gpu/drm/amd/amdgpu/amdgpu_bios.c

@@ -358,8 +358,7 @@ static bool amdgpu_acpi_vfct_bios(struct amdgpu_device *adev)
 	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;
@@ -370,31 +369,30 @@ static bool amdgpu_acpi_vfct_bios(struct amdgpu_device *adev)
 	}
 
 	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;
 
-	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);
+	while (offset < tbl_size) {
+		GOP_VBIOS_CONTENT *vbios = (GOP_VBIOS_CONTENT *)((char *)hdr + offset);
+		VFCT_IMAGE_HEADER *vhdr = &vbios->VbiosHeader;
 
-	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");
+		offset += sizeof(VFCT_IMAGE_HEADER);
+		if (offset > tbl_size) {
+			DRM_ERROR("ACPI VFCT image header truncated\n");
 			return false;
 		}
 
-	if (vfct->VBIOSImageOffset + sizeof(VFCT_IMAGE_HEADER) + vhdr->ImageLength > tbl_size) {
+		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);
@@ -404,8 +402,12 @@ static bool amdgpu_acpi_vfct_bios(struct amdgpu_device *adev)
 				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)