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diff --git a/Documentation/gpu/nova/core/vbios.rst b/Documentation/gpu/nova/core/vbios.rst new file mode 100644 index 000000000000..9d3379ccfb30 --- /dev/null +++ b/Documentation/gpu/nova/core/vbios.rst @@ -0,0 +1,240 @@ +.. SPDX-License-Identifier: (GPL-2.0+ OR MIT) + +========== +VBIOS +========== +This document describes the layout of the VBIOS image which is a series of concatenated +images in the ROM of the GPU. The VBIOS is mirrored onto the BAR 0 space and is read +by both Boot ROM firmware (also known as IFR or init-from-rom firmware) on the GPU to +bootstrap various microcontrollers (PMU, SEC, GSP) with critical initialization before +the driver loads, as well as by the nova-core driver in the kernel to boot the GSP. + +The format of the images in the ROM follow the "BIOS Specification" part of the +PCI specification, with Nvidia-specific extensions. The ROM images of type FwSec +are the ones that contain Falcon ucode and what we are mainly looking for. + +As an example, the following are the different image types that can be found in the +VBIOS of an Ampere GA102 GPU which is supported by the nova-core driver. + +- PciAt Image (Type 0x00) - This is the standard PCI BIOS image, whose name + likely comes from the "IBM PC/AT" architecture. + +- EFI Image (Type 0x03) - This is the EFI BIOS image. It contains the UEFI GOP + driver that is used to display UEFI graphics output. + +- First FwSec Image (Type 0xE0) - The first FwSec image (Secure Firmware) + +- Second FwSec Image (Type 0xE0) - The second FwSec image (Secure Firmware) + contains various microcodes (also known as an applications) that do a range + of different functions. The FWSEC ucode is run in heavy-secure mode and + typically runs directly on the GSP (it could be running on a different + designated processor in future generations but as of Ampere, it is the GSP). + This firmware then loads other firmware ucodes onto the PMU and SEC2 + microcontrollers for gfw initialization after GPU reset and before the driver + loads (see devinit.rst). The DEVINIT ucode is itself another ucode that is + stored in this ROM partition. + +Once located, the Falcon ucodes have "Application Interfaces" in their data +memory (DMEM). For FWSEC, the application interface we use for FWSEC is the +"DMEM mapper" interface which is configured to run the "FRTS" command. This +command carves out the WPR2 (Write-Protected Region) in VRAM. It then places +important power-management data, called 'FRTS', into this region. The WPR2 +region is only accessible to heavy-secure ucode. + +.. note:: + It is not clear why FwSec has 2 different partitions in the ROM, but they both + are of type 0xE0 and can be identified as such. This could be subject to change + in future generations. + +IFR Header +---------- +On Kepler and later GPUs, the ROM begins with an Init-from-ROM (IFR) header +rather than a standard PCI ROM signature (0xAA55). The driver must parse the +IFR header to find where the PCI ROM images actually start. + +Init-from-ROM (IFR) is a special GPU feature used for power management +on some Nvidia GPUs. It references data in the VBIOS for its operation, +but for drivers the important piece is a header that precedes the +VBIOS PCI Expansion ROM. + +Most such GPUs do not need to parse the IFR header in order to find the +VBIOS, but the Nvidia GA100 is the exception. GA100 lacks a display engine, +so the PRAMIN method (which reads the VBIOS from VRAM via display hardware) +is unavailable, forcing the driver to read the ROM directly via PROM. +On other similar GPUs, either PRAMIN succeeds before PROM is tried, or the +IFR hardware has already applied the ROM offset so that PROM reads +transparently skip the IFR header. + +The driver should first check for the standard 0xAA55 signature at offset 0. +If found, there is no IFR header and the PCI ROM images start at +offset 0. If not found, check for the IFR signature and parse the header to +determine the PCI ROM image offset. + +Fixed Header Format +~~~~~~~~~~~~~~~~~~~ + +The IFR header begins with four 32-bit words at fixed offsets:: + + Offset Name Fields + ------ ------- ------ + 0x00 FIXED0 bits 31:0 - Signature (must be 0x4947564E, ASCII "NVGI") + 0x04 FIXED1 bit 31 - Reserved + bits 30:16 - FIXED_DATA_SIZE Fixed data size (offset to extended section) + bits 15:8 - VERSIONSW Software version + bits 7:0 - Reserved + 0x08 FIXED2 bit 31 - Reserved + bits 30:20 - Reserved (zero) + bits 19:0 - TOTAL_DATA_SIZE Total data size + +Finding the PCI ROM Image Offset +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + +The method to find this offset depends on `VERSIONSW`. + +- **Version 1 and 2**: Read `FIXED_DATA_SIZE` from `FIXED1` to get the extended + section offset. The PCI ROM image is the 32-bit value at `FIXED_DATA_SIZE + 4`. + +- **Version 3**: Read `TOTAL_DATA_SIZE` from `FIXED2`. The 32-bit value at that + offset is a flash status offset. Add 4096 to get the ROM directory offset, + `ROM_DIRECTORY_OFFSET`. The ROM directory must have signature 0x44524652 + (ASCII "RFRD"). The PCI ROM image offset is the 32-bit value at + `ROM_DIRECTORY_OFFSET + 8`. + +The PCI ROM image offset must be 4-byte aligned. All offsets are relative to the +start of ROM (BAR0 + 0x300000). + +VBIOS ROM Layout +---------------- +The VBIOS (PCI Expansion ROM) is a series of concatenated images laid out as +follows. On GPUs with an IFR header, this layout begins at the image offset +determined by parsing the IFR header. On older GPUs, it begins at offset 0:: + + +----------------------------------------------------------------------------+ + | VBIOS (Starting at ROM_OFFSET: 0x300000 + IFR image offset) | + +----------------------------------------------------------------------------+ + | +-----------------------------------------------+ | + | | PciAt Image (Type 0x00) | | + | +-----------------------------------------------+ | + | | +-------------------+ | | + | | | ROM Header | | | + | | | (Signature 0xAA55)| | | + | | +-------------------+ | | + | | | rom header's pci_data_struct_offset | | + | | | points to the PCIR structure | | + | | V | | + | | +-------------------+ | | + | | | PCIR Structure | | | + | | | (Signature "PCIR")| | | + | | | last_image: 0x80 | | | + | | | image_len: size | | | + | | | in 512-byte units | | | + | | +-------------------+ | | + | | | | | + | | | NPDE immediately follows PCIR | | + | | V | | + | | +-------------------+ | | + | | | NPDE Structure | | | + | | | (Signature "NPDE")| | | + | | | last_image: 0x00 | | | + | | +-------------------+ | | + | | | | + | | +-------------------+ | | + | | | BIT Header | (Signature scanning | | + | | | (Signature "BIT") | provides the location | | + | | +-------------------+ of the BIT table) | | + | | | header is | | + | | | followed by a table of tokens | | + | | V one of which is for falcon data. | | + | | +-------------------+ | | + | | | BIT Tokens | | | + | | | ______________ | | | + | | | | Falcon Data | | | | + | | | | Token (0x70)|---+------------>------------+--+ | + | | | +-------------+ | falcon_data_ptr() | | | + | | +-------------------+ | V | + | +-----------------------------------------------+ | | + | (no gap between images) | | + | +-----------------------------------------------+ | | + | | EFI Image (Type 0x03) | | | + | +-----------------------------------------------+ | | + | | Contains the UEFI GOP driver (Graphics Output)| | | + | | +-------------------+ | | | + | | | ROM Header | | | | + | | +-------------------+ | | | + | | | PCIR Structure | | | | + | | +-------------------+ | | | + | | | NPDE Structure | | | | + | | +-------------------+ | | | + | | | Image data | | | | + | | +-------------------+ | | | + | +-----------------------------------------------+ | | + | (no gap between images) | | + | +-----------------------------------------------+ | | + | | First FwSec Image (Type 0xE0) | | | + | +-----------------------------------------------+ | | + | | +-------------------+ | | | + | | | ROM Header | | | | + | | +-------------------+ | | | + | | | PCIR Structure | | | | + | | +-------------------+ | | | + | | | NPDE Structure | | | | + | | +-------------------+ | | | + | | | Image data | | | | + | | +-------------------+ | | | + | +-----------------------------------------------+ | | + | (no gap between images) | | + | +-----------------------------------------------+ | | + | | Second FwSec Image (Type 0xE0) | | | + | +-----------------------------------------------+ | | + | | +-------------------+ | | | + | | | ROM Header | | | | + | | +-------------------+ | | | + | | | PCIR Structure | | | | + | | +-------------------+ | | | + | | | NPDE Structure | | | | + | | +-------------------+ | | | + | | | | | + | | +-------------------+ | | | + | | | PMU Lookup Table | <- falcon_data_offset <----+ | + | | | +-------------+ | pmu_lookup_table | | + | | | | Entry 0x85 | | | | + | | | | FWSEC_PROD | | | | + | | | +-------------+ | | | + | | +-------------------+ | | + | | | | | + | | | points to | | + | | V | | + | | +-------------------+ | | + | | | FalconUCodeDescV3 | <- falcon_ucode_offset | | + | | | (FWSEC Firmware) | fwsec_header() | | + | | +-------------------+ | | + | | | immediately followed by... | | + | | V | | + | | +----------------------------+ | | + | | | Signatures + FWSEC Ucode | | | + | | | fwsec_sigs(), fwsec_ucode()| | | + | | +----------------------------+ | | + | +-----------------------------------------------+ | + | | + +----------------------------------------------------------------------------+ + +.. note:: + This diagram is created based on an GA-102 Ampere GPU as an example and could + vary for future or other GPUs. + +.. note:: + For more explanations of acronyms, see the detailed descriptions in `vbios.rs`. + +Falcon data Lookup +------------------ +A key part of the VBIOS extraction code (vbios.rs) is to find the location of the +Falcon data in the VBIOS which contains the PMU lookup table. This lookup table is +used to find the required Falcon ucode based on an application ID. + +The location of the PMU lookup table is found by scanning the BIT (`BIOS Information Table`_) +tokens for a token with the Falcon data token id (0x70) which indicates the +offset of the same from the start of the VBIOS image. Unfortunately, the offset +does not account for the EFI image located between the PciAt and FwSec images. +The `vbios.rs` code compensates for this with appropriate arithmetic. + +.. _`BIOS Information Table`: https://download.nvidia.com/open-gpu-doc/BIOS-Information-Table/1/BIOS-Information-Table.html |