Add an encoder for NVKV, which is the wire format for GMCAPI. The encoded stream is a sequence of 64-bit values. The first 64-bit value encodes an op word which describes the function of the next N values.
Essentially, the format encodes a sequence of calls to some function f(key, index, value), where value is a [u8], u32, u64, [u32], or a [u64]. The key is a u16 and the index is a 12 bit integer. The interpretation of these function calls is per GMCAPI. Add tests for the wire encoding for each primitive. Signed-off-by: Eliot Courtney <[email protected]> --- drivers/gpu/nova-core/gsp.rs | 1 + drivers/gpu/nova-core/gsp/nvkv.rs | 142 +++++++++++++++++++++ drivers/gpu/nova-core/gsp/nvkv/encode.rs | 210 +++++++++++++++++++++++++++++++ 3 files changed, 353 insertions(+) diff --git a/drivers/gpu/nova-core/gsp.rs b/drivers/gpu/nova-core/gsp.rs index 13f361406a6c..84dfe07ae6ba 100644 --- a/drivers/gpu/nova-core/gsp.rs +++ b/drivers/gpu/nova-core/gsp.rs @@ -24,6 +24,7 @@ pub(crate) mod cmdq; pub(crate) mod commands; mod fw; +mod nvkv; mod regs; mod sequencer; diff --git a/drivers/gpu/nova-core/gsp/nvkv.rs b/drivers/gpu/nova-core/gsp/nvkv.rs new file mode 100644 index 000000000000..a8e16687a134 --- /dev/null +++ b/drivers/gpu/nova-core/gsp/nvkv.rs @@ -0,0 +1,142 @@ +// SPDX-License-Identifier: GPL-2.0 +// SPDX-FileCopyrightText: Copyright (c) 2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved. + +//! Codec for NVKV, the binary key-value format of GMCAPI. +//! +//! Essentially, the format encodes a sequence of calls to some function f(key, index, value), +//! where value is a [u8], u32, u64, [u32], or a [u64]. The key is a u16 and the index is a 12 bit +//! integer. The interpretation of these function calls is per GMCAPI. Generally speaking, the +//! function calls will map to some struct - for example, f(GPU_NAME_STRING_KEY, 0, b"some gpu") +//! naturally maps to storing a &str with the GPU name. + +#![expect(unused_imports)] + +use core::ops::Deref; + +use kernel::{ + alloc::{ + allocator::KVmalloc, + Allocator, // + }, + bitfield, + num::Bounded, + prelude::*, // +}; +use zerocopy::Immutable; + +mod encode; +pub(crate) use encode::*; + +/// The allocator backing [`EncodedStream`]. +type StreamAllocator = KVmalloc; + +/// An encoded NVKV byte stream. +/// +/// # Invariants +/// +/// The byte length is always a multiple of `size_of::<u64>()`. +pub(crate) struct EncodedStream(Vec<u8, StreamAllocator>); + +impl EncodedStream { + /// Creates an empty stream. + fn new() -> Self { + // INVARIANT: An empty stream's byte length is 0, a multiple of `size_of::<u64>()`. + Self(Vec::new()) + } + + /// Appends a single `u64` to the stream. + fn push_u64(&mut self, value: u64) -> Result { + // INVARIANT: Appending `size_of::<u64>()` bytes keeps the byte length a multiple of + // `size_of::<u64>()`. + Ok(self.0.extend_from_slice(&value.to_ne_bytes(), GFP_KERNEL)?) + } + + /// Appends `data` as bytes to the stream, zero-padded to a `u64` boundary. + fn extend_with_padding<T: IntoBytes + Immutable + ?Sized>(&mut self, data: &T) -> Result { + let bytes = data.as_bytes(); + let padded = bytes.len().next_multiple_of(size_of::<u64>()); + // Reserve so that a failed allocation can't leave the invariant violated. + self.0.reserve(padded, GFP_KERNEL)?; + self.0.extend_from_slice(bytes, GFP_KERNEL)?; + // INVARIANT: The padding ensures the total length remains a multiple of + // `size_of::<u64>()`. + Ok(self.0.extend_with(padded - bytes.len(), 0u8, GFP_KERNEL)?) + } +} + +// The Deref to &[u64] relies on this alignment guarantee. +static_assert!(align_of::<u64>() <= StreamAllocator::MIN_ALIGN); + +impl Deref for EncodedStream { + type Target = [u64]; + + fn deref(&self) -> &Self::Target { + // An empty `Vec`'s pointer isn't necessarily aligned by `StreamAllocator::MIN_ALIGN`. + if self.0.is_empty() { + return &[]; + } + + // PANIC: By the type invariants the byte length is a multiple of `size_of::<u64>()`, and + // the backing buffer of a non-empty vector has at least `u64` alignment per + // `StreamAllocator`'s minimum alignment. + <[u64]>::ref_from_bytes(&self.0).expect("EncodedStream invariant violated") + } +} + +/// The identifier of an NVKV key. +pub(crate) type KeyId = u16; + +/// The index of an NVKV value. +pub(crate) type Index = Bounded<u64, 12>; + +bitfield! { + /// The op word that starts each NVKV operation. + struct Op(u64) { + 15:0 key; + 27:16 index => Index; + 31:28 opcode ?=> Opcode; + 63:32 value; + } +} + +/// Describes the format of the following NVKV operation. +#[derive(Debug, Copy, Clone, PartialEq, Eq)] +#[repr(u8)] +enum Opcode { + /// A 32-bit value in the op word. + Imm32 = 0, + /// 32-bit values for consecutive keys, starting at the op word's key. + Seq32 = 1, + /// 64-bit values for consecutive keys, starting at the op word's key. + Seq64 = 2, + /// An array of bytes. + Array8 = 3, + /// An array of 32-bit elements. + Array32 = 4, + /// An array of 64-bit elements. + Array64 = 5, +} + +// TODO[FPRI]: This is a temporary solution to be replaced with the corresponding derive macros once +// they land. +impl TryFrom<Bounded<u64, 4>> for Opcode { + type Error = Error; + + fn try_from(value: Bounded<u64, 4>) -> Result<Self> { + match value.get() { + 0 => Ok(Self::Imm32), + 1 => Ok(Self::Seq32), + 2 => Ok(Self::Seq64), + 3 => Ok(Self::Array8), + 4 => Ok(Self::Array32), + 5 => Ok(Self::Array64), + _ => Err(EINVAL), + } + } +} + +impl From<Opcode> for Bounded<u64, 4> { + fn from(value: Opcode) -> Self { + Bounded::from_expr(value as u64) + } +} diff --git a/drivers/gpu/nova-core/gsp/nvkv/encode.rs b/drivers/gpu/nova-core/gsp/nvkv/encode.rs new file mode 100644 index 000000000000..6c1a9cbd90e8 --- /dev/null +++ b/drivers/gpu/nova-core/gsp/nvkv/encode.rs @@ -0,0 +1,210 @@ +// SPDX-License-Identifier: GPL-2.0 +// SPDX-FileCopyrightText: Copyright (c) 2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved. + +#![cfg_attr(not(CONFIG_KUNIT), expect(dead_code))] + +use kernel::prelude::*; + +use super::{ + EncodedStream, + Index, + KeyId, + Op, + Opcode, // +}; + +/// An encoder for an NVKV stream. +pub(crate) struct Encoder { + stream: EncodedStream, +} + +impl Encoder { + /// Creates an empty encoder. + pub(crate) fn new() -> Self { + Self { + stream: EncodedStream::new(), + } + } + + /// Returns the encoded data. + #[must_use = "encoded stream must be consumed"] + pub(crate) fn finish(self) -> EncodedStream { + self.stream + } + + #[inline(always)] + fn encode_op(&mut self, op: Op) -> Result { + self.stream.push_u64(op.into_raw()) + } + + /// Encodes a 32-bit value as an IMM32 pair, with the value in the op word. + #[inline(always)] + pub(crate) fn encode_u32(&mut self, key: KeyId, index: Index, value: u32) -> Result { + // TODO: Consider automatically merging sequential keys. + self.encode_op( + Op::zeroed() + .with_key(key) + .with_index(index) + .with_opcode(Opcode::Imm32) + .with_value(value), + ) + } + + /// Encodes a 64-bit value as a single-element SEQ64 pair. + #[inline(always)] + pub(crate) fn encode_u64(&mut self, key: KeyId, index: Index, value: u64) -> Result { + // TODO: Consider automatically merging sequential keys. + const KEY_COUNT: u32 = 1; + self.encode_op( + Op::zeroed() + .with_key(key) + .with_index(index) + .with_opcode(Opcode::Seq64) + .with_value(KEY_COUNT), + )?; + self.stream.push_u64(value) + } + + /// Encodes a byte array as an ARRAY8 pair, zero-padded to a multiple of 8 bytes. + #[inline(always)] + pub(crate) fn encode_array8(&mut self, key: KeyId, index: Index, array: &[u8]) -> Result { + let value_count = u32::try_from(array.len()).map_err(|_| EMSGSIZE)?; + self.encode_op( + Op::zeroed() + .with_key(key) + .with_index(index) + .with_opcode(Opcode::Array8) + .with_value(value_count), + )?; + self.stream.extend_with_padding(array) + } + + /// Encodes a 32-bit array as an ARRAY32 pair, zero-padded to a multiple of 8 bytes. + #[inline(always)] + pub(crate) fn encode_array32(&mut self, key: KeyId, index: Index, array: &[u32]) -> Result { + let value_count = u32::try_from(array.len()).map_err(|_| EMSGSIZE)?; + self.encode_op( + Op::zeroed() + .with_key(key) + .with_index(index) + .with_opcode(Opcode::Array32) + .with_value(value_count), + )?; + self.stream.extend_with_padding(array) + } + + /// Encodes a 64-bit array as an ARRAY64 pair. + #[inline(always)] + pub(crate) fn encode_array64(&mut self, key: KeyId, index: Index, array: &[u64]) -> Result { + let value_count = u32::try_from(array.len()).map_err(|_| EMSGSIZE)?; + self.encode_op( + Op::zeroed() + .with_key(key) + .with_index(index) + .with_opcode(Opcode::Array64) + .with_value(value_count), + )?; + self.stream.extend_with_padding(array) + } +} + +#[kunit_tests(nova_core_nvkv_encode)] +mod tests { + use super::*; + + // Tests that each kind of value is encoded to NVKV wire format properly. + #[test] + fn encode_all_value_kinds() -> Result { + // All keys, indexes, and values are distinct but arbitrary values to make it easier for the + // test to catch bugs in the encoded output. + const U32_KEY: KeyId = 0x1001; + const U64_KEY: KeyId = 0x1002; + const ARRAY8_KEY: KeyId = 0x1003; + const ARRAY32_KEY: KeyId = 0x1004; + const ARRAY64_KEY: KeyId = 0x1005; + + const U32_VALUE: u32 = 0x1111_2222; + const U64_VALUE: u64 = 0x3333_4444_5555_6666; + const ARRAY8_VALUE: &[u8] = &[0xaa, 0xbb, 0xcc]; + const ARRAY32_VALUE: &[u32] = &[0xbbbb_cccc, 0xdddd_eeee]; + const ARRAY64_VALUE: &[u64] = &[0x0123_4567_89ab_cdef, 0xfedc_ba98_7654_3210]; + + let mut encoder = Encoder::new(); + encoder.encode_u32(U32_KEY, Index::new::<0>(), U32_VALUE)?; + encoder.encode_u64(U64_KEY, Index::new::<1>(), U64_VALUE)?; + encoder.encode_array8(ARRAY8_KEY, Index::new::<2>(), ARRAY8_VALUE)?; + encoder.encode_array32(ARRAY32_KEY, Index::new::<3>(), ARRAY32_VALUE)?; + encoder.encode_array64(ARRAY64_KEY, Index::new::<4>(), ARRAY64_VALUE)?; + + let encoded = encoder.finish(); + assert_eq!(encoded.len(), 10); + + // IMM32 has its value in the op word. + assert_eq!( + encoded[0], + Op::zeroed() + .with_key(U32_KEY) + .with_index(Index::new::<0>()) + .with_opcode(Opcode::Imm32) + .with_value(U32_VALUE) + .into_raw() + ); + + // The SEQ64 op word followed by the value. + assert_eq!( + encoded[1], + Op::zeroed() + .with_key(U64_KEY) + .with_index(Index::new::<1>()) + .with_opcode(Opcode::Seq64) + .with_value(1u32) + .into_raw() + ); + assert_eq!(encoded[2], U64_VALUE); + + // The ARRAY8 op word has the byte count. The bytes follow, padded out to a whole word. + assert_eq!( + encoded[3], + Op::zeroed() + .with_key(ARRAY8_KEY) + .with_index(Index::new::<2>()) + .with_opcode(Opcode::Array8) + .with_value(3u32) + .into_raw() + ); + assert_eq!( + encoded[4], + u64::from_le_bytes([0xaa, 0xbb, 0xcc, 0, 0, 0, 0, 0]) + ); + + // The ARRAY32 op word has the element count. The two elements follow in little endian. + assert_eq!( + encoded[5], + Op::zeroed() + .with_key(ARRAY32_KEY) + .with_index(Index::new::<3>()) + .with_opcode(Opcode::Array32) + .with_value(2u32) + .into_raw() + ); + assert_eq!( + encoded[6], + u64::from(ARRAY32_VALUE[1]) << 32 | u64::from(ARRAY32_VALUE[0]) + ); + + // The ARRAY64 op word has the element count with the two elements after. + assert_eq!( + encoded[7], + Op::zeroed() + .with_key(ARRAY64_KEY) + .with_index(Index::new::<4>()) + .with_opcode(Opcode::Array64) + .with_value(2u32) + .into_raw() + ); + assert_eq!(encoded[8], ARRAY64_VALUE[0]); + assert_eq!(encoded[9], ARRAY64_VALUE[1]); + + Ok(()) + } +} -- 2.55.0
