If built on architectures with CONFIG_ARCH_DMA_ADDR_T_64BIT=y nova-core
produces that following build failures:
error[E0308]: mismatched types
--> drivers/gpu/nova-core/fb.rs:49:59
|
49 | hal::fb_hal(chipset).write_sysmem_flush_page(bar, page.dma_handle())?;
| ----------------------- ^^^^^^^^^^^^^^^^^ expected `u64`, found `u32`
| |
| arguments to this method are incorrect
|
note: method defined here
--> drivers/gpu/nova-core/fb/hal.rs:19:8
|
19 | fn write_sysmem_flush_page(&self, bar: &Bar0, addr: u64) -> Result;
| ^^^^^^^^^^^^^^^^^^^^^^^
help: you can convert a `u32` to a `u64`
|
49 | hal::fb_hal(chipset).write_sysmem_flush_page(bar, page.dma_handle().into())?;
| +++++++
error[E0308]: mismatched types
--> drivers/gpu/nova-core/fb.rs:65:47
|
65 | if hal.read_sysmem_flush_page(bar) == self.page.dma_handle() {
| ------------------------------- ^^^^^^^^^^^^^^^^^^^^^^ expected `u64`, found `u32`
| |
| expected because this is `u64`
|
help: you can convert a `u32` to a `u64`
|
65 | if hal.read_sysmem_flush_page(bar) == self.page.dma_handle().into() {
| +++++++
error: this arithmetic operation will overflow
--> drivers/gpu/nova-core/falcon.rs:469:23
|
469 | .set_base((dma_start >> 40) as u16)
| ^^^^^^^^^^^^^^^^^ attempt to shift right by `40_i32`, which would overflow
|
= note: `#[deny(arithmetic_overflow)]` on by default
This is due to the code making assumptions on the width of dma_addr_t to
be 64 bit.
While this could technically be handled, it is rather painful to deal
with, as the following example illustrates:
pub(super) fn read_sysmem_flush_page_ga100(bar: &Bar0) -> DmaAddress {
let addr = u64::from(regs::NV_PFB_NISO_FLUSH_SYSMEM_ADDR::read(bar).adr_39_08())
<< FLUSH_SYSMEM_ADDR_SHIFT
| u64::from(regs::NV_PFB_NISO_FLUSH_SYSMEM_ADDR_HI::read(bar).adr_63_40())
<< FLUSH_SYSMEM_ADDR_SHIFT_HI;
addr.try_into().unwrap_or_else(|_| {
kernel::warn_on!(true);
0
})
}
At the same time there's not much value for nova-core to support 32-bit,
given that the supported GPU architectures are Turing and later, hence
depend on CONFIG_64BIT.
Cc: John Hubbard <jhubbard@nvidia.com>
Reported-by: Miguel Ojeda <ojeda@kernel.org>
Closes: https://lore.kernel.org/lkml/20250828160247.37492-1-ojeda@kernel.org/
Fixes: 6554ad65b5 ("gpu: nova-core: register sysmem flush page")
Fixes: 69f5cd67ce ("gpu: nova-core: add falcon register definitions and base code")
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Link: https://lore.kernel.org/r/20250828223954.351348-1-dakr@kernel.org
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
Add the initial nova-core driver stub.
nova-core is intended to serve as a common base for nova-drm (the
corresponding DRM driver) and the vGPU manager VFIO driver, serving as a
hard- and firmware abstraction layer for GSP-based NVIDIA GPUs.
The Nova project, including nova-core and nova-drm, in the long term,
is intended to serve as the successor of Nouveau for all GSP-based GPUs.
The motivation for both, starting a successor project for Nouveau and
doing so using the Rust programming language, is documented in detail
through a previous post on the mailing list [1], an LWN article [2] and a
talk from LPC '24.
In order to avoid the chicken and egg problem to require a user to
upstream Rust abstractions, but at the same time require the Rust
abstractions to implement the driver, nova-core kicks off as a driver
stub and is subsequently developed upstream.
Link: https://lore.kernel.org/dri-devel/Zfsj0_tb-0-tNrJy@cassiopeiae/T/#u [1]
Link: https://lwn.net/Articles/990736/ [2]
Link: https://youtu.be/3Igmx28B3BQ?si=sBdSEer4tAPKGpOs [3]
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Link: https://lore.kernel.org/r/20250306222336.23482-5-dakr@kernel.org
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
