Message-ID: <20250930131648.411720-3-apopple@nvidia.com>
Date: Tue, 30 Sep 2025 23:16:35 +1000
From: Alistair Popple <apopple@...dia.com>
To: rust-for-linux@...r.kernel.org,
	dri-devel@...ts.freedesktop.org,
	dakr@...nel.org,
	acourbot@...dia.com
Cc: Alistair Popple <apopple@...dia.com>,
	Miguel Ojeda <ojeda@...nel.org>,
	Alex Gaynor <alex.gaynor@...il.com>,
	Boqun Feng <boqun.feng@...il.com>,
	Gary Guo <gary@...yguo.net>,
	Björn Roy Baron <bjorn3_gh@...tonmail.com>,
	Benno Lossin <lossin@...nel.org>,
	Andreas Hindborg <a.hindborg@...nel.org>,
	Alice Ryhl <aliceryhl@...gle.com>,
	Trevor Gross <tmgross@...ch.edu>,
	David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	John Hubbard <jhubbard@...dia.com>,
	Joel Fernandes <joelagnelf@...dia.com>,
	Timur Tabi <ttabi@...dia.com>,
	linux-kernel@...r.kernel.org,
	nouveau@...ts.freedesktop.org
Subject: [PATCH v3 02/13] gpu: nova-core: Create initial Gsp

The GSP requires several areas of memory to operate. Each of these have
their own simple embedded page tables. Set these up and map them for DMA
to/from GSP using CoherentAllocation's. Return the DMA handle describing
where each of these regions are for future use when booting GSP.

Signed-off-by: Alistair Popple <apopple@...dia.com>

---

Change for v3:
 - Clean up the PTE array creation, with much thanks to Alex for doing
   most it (please let me know if I should put you as co-developer!)

Changes for v2:
 - Renamed GspMemOjbects to Gsp as that is what they are
 - Rebased on Alex's latest series
---
 drivers/gpu/nova-core/gpu.rs                  |  2 +-
 drivers/gpu/nova-core/gsp.rs                  | 83 +++++++++++++++++--
 drivers/gpu/nova-core/gsp/fw.rs               | 39 +++++++++
 .../gpu/nova-core/gsp/fw/r570_144/bindings.rs | 19 +++++
 4 files changed, 134 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/nova-core/gpu.rs b/drivers/gpu/nova-core/gpu.rs
index 5da9ad726483..c939b3868271 100644
--- a/drivers/gpu/nova-core/gpu.rs
+++ b/drivers/gpu/nova-core/gpu.rs
@@ -221,7 +221,7 @@ pub(crate) fn new<'a>(
 
             sec2_falcon: Falcon::new(pdev.as_ref(), spec.chipset, bar, true)?,
 
-            gsp <- Gsp::new(),
+            gsp <- Gsp::new(pdev)?,
 
             _: { gsp.boot(pdev, bar, spec.chipset, gsp_falcon, sec2_falcon)? },
 
diff --git a/drivers/gpu/nova-core/gsp.rs b/drivers/gpu/nova-core/gsp.rs
index 503ce8ee0420..91aa9ce17c57 100644
--- a/drivers/gpu/nova-core/gsp.rs
+++ b/drivers/gpu/nova-core/gsp.rs
@@ -1,27 +1,94 @@
 // SPDX-License-Identifier: GPL-2.0
 
 mod boot;
-
-use kernel::prelude::*;
-
 mod fw;
 
 pub(crate) use fw::{GspFwWprMeta, LibosParams};
 
+use kernel::device;
+use kernel::dma::CoherentAllocation;
+use kernel::dma::DmaAddress;
+use kernel::dma_write;
+use kernel::pci;
+use kernel::prelude::*;
 use kernel::ptr::Alignment;
+use kernel::transmute::AsBytes;
+
+use fw::LibosMemoryRegionInitArgument;
 
 pub(crate) const GSP_PAGE_SHIFT: usize = 12;
 pub(crate) const GSP_PAGE_SIZE: usize = 1 << GSP_PAGE_SHIFT;
 pub(crate) const GSP_HEAP_ALIGNMENT: Alignment = Alignment::new::<{ 1 << 20 }>();
 
+/// Number of GSP pages to use in a RM log buffer.
+const RM_LOG_BUFFER_NUM_PAGES: usize = 0x10;
+
 /// GSP runtime data.
-///
-/// This is an empty pinned placeholder for now.
 #[pin_data]
-pub(crate) struct Gsp {}
+pub(crate) struct Gsp {
+    libos: CoherentAllocation<LibosMemoryRegionInitArgument>,
+    pub loginit: CoherentAllocation<u8>,
+    pub logintr: CoherentAllocation<u8>,
+    pub logrm: CoherentAllocation<u8>,
+}
+
+#[repr(C)]
+struct PteArray<const NUM_ENTRIES: usize>([u64; NUM_ENTRIES]);
+/// SAFETY: arrays of `u64` implement `AsBytes` and we are but a wrapper around it.
+unsafe impl<const NUM_ENTRIES: usize> AsBytes for PteArray<NUM_ENTRIES> {}
+impl<const NUM_PAGES: usize> PteArray<NUM_PAGES> {
+    fn new(handle: DmaAddress) -> Self {
+        let mut ptes = [0u64; NUM_PAGES];
+        for (i, pte) in ptes.iter_mut().enumerate() {
+            *pte = handle + ((i as u64) << GSP_PAGE_SHIFT);
+        }
+
+        Self(ptes)
+    }
+}
+
+/// Creates a new `CoherentAllocation<A>` with `name` of `size` elements, and
+/// register it into the `libos` object at argument position `libos_arg_nr`.
+fn create_logbuffer_dma_object(
+    dev: &device::Device<device::Bound>,
+) -> Result<CoherentAllocation<u8>> {
+    let mut obj = CoherentAllocation::<u8>::alloc_coherent(
+        dev,
+        RM_LOG_BUFFER_NUM_PAGES * GSP_PAGE_SIZE,
+        GFP_KERNEL | __GFP_ZERO,
+    )?;
+    let ptes = PteArray::<RM_LOG_BUFFER_NUM_PAGES>::new(obj.dma_handle());
+
+    // SAFETY: `obj` has just been created and we are its sole user.
+    unsafe {
+        // Copy the self-mapping PTE at the expected location.
+        obj.as_slice_mut(size_of::<u64>(), size_of_val(&ptes))?
+            .copy_from_slice(ptes.as_bytes())
+    };
+
+    Ok(obj)
+}
 
 impl Gsp {
-    pub(crate) fn new() -> impl PinInit<Self> {
-        pin_init!(Self {})
+    pub(crate) fn new(pdev: &pci::Device<device::Bound>) -> Result<impl PinInit<Self, Error>> {
+        let dev = pdev.as_ref();
+        let libos = CoherentAllocation::<LibosMemoryRegionInitArgument>::alloc_coherent(
+            dev,
+            GSP_PAGE_SIZE / size_of::<LibosMemoryRegionInitArgument>(),
+            GFP_KERNEL | __GFP_ZERO,
+        )?;
+        let loginit = create_logbuffer_dma_object(dev)?;
+        dma_write!(libos[0] = LibosMemoryRegionInitArgument::new("LOGINIT", &loginit))?;
+        let logintr = create_logbuffer_dma_object(dev)?;
+        dma_write!(libos[1] = LibosMemoryRegionInitArgument::new("LOGINTR", &logintr))?;
+        let logrm = create_logbuffer_dma_object(dev)?;
+        dma_write!(libos[2] = LibosMemoryRegionInitArgument::new("LOGRM", &logrm))?;
+
+        Ok(try_pin_init!(Self {
+            libos,
+            loginit,
+            logintr,
+            logrm,
+        }))
     }
 }
diff --git a/drivers/gpu/nova-core/gsp/fw.rs b/drivers/gpu/nova-core/gsp/fw.rs
index 181baa401770..dd1e7fc85d85 100644
--- a/drivers/gpu/nova-core/gsp/fw.rs
+++ b/drivers/gpu/nova-core/gsp/fw.rs
@@ -7,8 +7,10 @@
 
 use core::ops::Range;
 
+use kernel::dma::CoherentAllocation;
 use kernel::ptr::Alignable;
 use kernel::sizes::SZ_1M;
+use kernel::transmute::{AsBytes, FromBytes};
 
 use crate::gpu::Chipset;
 use crate::gsp;
@@ -99,3 +101,40 @@ pub(crate) fn wpr_heap_size(&self, chipset: Chipset, fb_size: u64) -> u64 {
 /// addresses of the GSP bootloader and firmware.
 #[repr(transparent)]
 pub(crate) struct GspFwWprMeta(bindings::GspFwWprMeta);
+
+#[repr(transparent)]
+pub(crate) struct LibosMemoryRegionInitArgument(bindings::LibosMemoryRegionInitArgument);
+
+// SAFETY: Padding is explicit and will not contain uninitialized data.
+unsafe impl AsBytes for LibosMemoryRegionInitArgument {}
+
+// SAFETY: This struct only contains integer types for which all bit patterns
+// are valid.
+unsafe impl FromBytes for LibosMemoryRegionInitArgument {}
+
+impl LibosMemoryRegionInitArgument {
+    pub(crate) fn new<A: AsBytes + FromBytes>(
+        name: &'static str,
+        obj: &CoherentAllocation<A>,
+    ) -> Self {
+        /// Generates the `ID8` identifier required for some GSP objects.
+        fn id8(name: &str) -> u64 {
+            let mut bytes = [0u8; core::mem::size_of::<u64>()];
+
+            for (c, b) in name.bytes().rev().zip(&mut bytes) {
+                *b = c;
+            }
+
+            u64::from_ne_bytes(bytes)
+        }
+
+        Self(bindings::LibosMemoryRegionInitArgument {
+            id8: id8(name),
+            pa: obj.dma_handle(),
+            size: obj.size() as u64,
+            kind: bindings::LibosMemoryRegionKind_LIBOS_MEMORY_REGION_CONTIGUOUS as u8,
+            loc: bindings::LibosMemoryRegionLoc_LIBOS_MEMORY_REGION_LOC_SYSMEM as u8,
+            ..Default::default()
+        })
+    }
+}
diff --git a/drivers/gpu/nova-core/gsp/fw/r570_144/bindings.rs b/drivers/gpu/nova-core/gsp/fw/r570_144/bindings.rs
index 0407000cca22..6a14cc324391 100644
--- a/drivers/gpu/nova-core/gsp/fw/r570_144/bindings.rs
+++ b/drivers/gpu/nova-core/gsp/fw/r570_144/bindings.rs
@@ -124,3 +124,22 @@ fn default() -> Self {
         }
     }
 }
+pub type LibosAddress = u64_;
+pub const LibosMemoryRegionKind_LIBOS_MEMORY_REGION_NONE: LibosMemoryRegionKind = 0;
+pub const LibosMemoryRegionKind_LIBOS_MEMORY_REGION_CONTIGUOUS: LibosMemoryRegionKind = 1;
+pub const LibosMemoryRegionKind_LIBOS_MEMORY_REGION_RADIX3: LibosMemoryRegionKind = 2;
+pub type LibosMemoryRegionKind = ffi::c_uint;
+pub const LibosMemoryRegionLoc_LIBOS_MEMORY_REGION_LOC_NONE: LibosMemoryRegionLoc = 0;
+pub const LibosMemoryRegionLoc_LIBOS_MEMORY_REGION_LOC_SYSMEM: LibosMemoryRegionLoc = 1;
+pub const LibosMemoryRegionLoc_LIBOS_MEMORY_REGION_LOC_FB: LibosMemoryRegionLoc = 2;
+pub type LibosMemoryRegionLoc = ffi::c_uint;
+#[repr(C)]
+#[derive(Debug, Default, Copy, Clone)]
+pub struct LibosMemoryRegionInitArgument {
+    pub id8: LibosAddress,
+    pub pa: LibosAddress,
+    pub size: LibosAddress,
+    pub kind: u8_,
+    pub loc: u8_,
+    pub __bindgen_padding_0: [u8; 6usize],
+}
-- 
2.50.1

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