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@nvidia.com>
Co-developed-by: Alexandre Courbot <acourbot@nvidia.com>
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Message-ID: <20251110-gsp_boot-v9-4-8ae4058e3c0e@nvidia.com>

4 files changed, 197 insertions, 7 deletions

diff --git a/drivers/gpu/nova-core/gpu.rs b/drivers/gpu/nova-core/gpu.rs
index 802e71e4f97d..03dae437bc37 100644
--- a/drivers/gpu/nova-core/gpu.rs
+++ b/drivers/gpu/nova-core/gpu.rs
@@ -231,7 +231,7 @@ impl Gpu {
 
             sec2_falcon: Falcon::new(pdev.as_ref(), spec.chipset)?,
 
-            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 55a1ad90a373..ec053395694b 100644
--- a/drivers/gpu/nova-core/gsp.rs
+++ b/drivers/gpu/nova-core/gsp.rs
@@ -2,7 +2,17 @@
 
 mod boot;
 
-use kernel::prelude::*;
+use kernel::{
+    device,
+    dma::{
+        CoherentAllocation,
+        DmaAddress, //
+    },
+    dma_write,
+    pci,
+    prelude::*,
+    transmute::AsBytes, //
+};
 
 mod fw;
 
@@ -11,17 +21,118 @@ pub(crate) use fw::{
     LibosParams, //
 };
 
+use crate::{
+    gsp::fw::LibosMemoryRegionInitArgument,
+    num, //
+};
+
 pub(crate) const GSP_PAGE_SHIFT: usize = 12;
 pub(crate) const GSP_PAGE_SIZE: usize = 1 << GSP_PAGE_SHIFT;
 
-/// GSP runtime data.
+/// Number of GSP pages to use in a RM log buffer.
+const RM_LOG_BUFFER_NUM_PAGES: usize = 0x10;
+
+/// Array of page table entries, as understood by the GSP bootloader.
+#[repr(C)]
+struct PteArray<const NUM_ENTRIES: usize>([u64; NUM_ENTRIES]);
+
+/// SAFETY: arrays of `u64` implement `AsBytes` and we are but a wrapper around one.
+unsafe impl<const NUM_ENTRIES: usize> AsBytes for PteArray<NUM_ENTRIES> {}
+
+impl<const NUM_PAGES: usize> PteArray<NUM_PAGES> {
+    /// Creates a new page table array mapping `NUM_PAGES` GSP pages starting at address `start`.
+    fn new(start: DmaAddress) -> Result<Self> {
+        let mut ptes = [0u64; NUM_PAGES];
+        for (i, pte) in ptes.iter_mut().enumerate() {
+            *pte = start
+                .checked_add(num::usize_as_u64(i) << GSP_PAGE_SHIFT)
+                .ok_or(EOVERFLOW)?;
+        }
+
+        Ok(Self(ptes))
+    }
+}
+
+/// The logging buffers are byte queues that contain encoded printf-like
+/// messages from GSP-RM.  They need to be decoded by a special application
+/// that can parse the buffers.
+///
+/// The 'loginit' buffer contains logs from early GSP-RM init and
+/// exception dumps.  The 'logrm' buffer contains the subsequent logs. Both are
+/// written to directly by GSP-RM and can be any multiple of GSP_PAGE_SIZE.
 ///
-/// This is an empty pinned placeholder for now.
+/// The physical address map for the log buffer is stored in the buffer
+/// itself, starting with offset 1. Offset 0 contains the "put" pointer (pp).
+/// Initially, pp is equal to 0. If the buffer has valid logging data in it,
+/// then pp points to index into the buffer where the next logging entry will
+/// be written. Therefore, the logging data is valid if:
+///   1 <= pp < sizeof(buffer)/sizeof(u64)
+struct LogBuffer(CoherentAllocation<u8>);
+
+impl LogBuffer {
+    /// Creates a new `LogBuffer` mapped on `dev`.
+    fn new(dev: &device::Device<device::Bound>) -> Result<Self> {
+        const NUM_PAGES: usize = RM_LOG_BUFFER_NUM_PAGES;
+
+        let mut obj = Self(CoherentAllocation::<u8>::alloc_coherent(
+            dev,
+            NUM_PAGES * GSP_PAGE_SIZE,
+            GFP_KERNEL | __GFP_ZERO,
+        )?);
+        let ptes = PteArray::<NUM_PAGES>::new(obj.0.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.0
+                .as_slice_mut(size_of::<u64>(), size_of_val(&ptes))?
+                .copy_from_slice(ptes.as_bytes())
+        };
+
+        Ok(obj)
+    }
+}
+
+/// GSP runtime data.
 #[pin_data]
-pub(crate) struct Gsp {}
+pub(crate) struct Gsp {
+    /// Libos arguments.
+    pub(crate) libos: CoherentAllocation<LibosMemoryRegionInitArgument>,
+    /// Init log buffer.
+    loginit: LogBuffer,
+    /// Interrupts log buffer.
+    logintr: LogBuffer,
+    /// RM log buffer.
+    logrm: LogBuffer,
+}
 
 impl Gsp {
-    pub(crate) fn new() -> impl PinInit<Self> {
-        pin_init!(Self {})
+    // Creates an in-place initializer for a `Gsp` manager for `pdev`.
+    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,
+        )?;
+
+        // Initialise the logging structures. The OpenRM equivalents are in:
+        // _kgspInitLibosLoggingStructures (allocates memory for buffers)
+        // kgspSetupLibosInitArgs_IMPL (creates pLibosInitArgs[] array)
+        let loginit = LogBuffer::new(dev)?;
+        dma_write!(libos[0] = LibosMemoryRegionInitArgument::new("LOGINIT", &loginit.0))?;
+
+        let logintr = LogBuffer::new(dev)?;
+        dma_write!(libos[1] = LibosMemoryRegionInitArgument::new("LOGINTR", &logintr.0))?;
+
+        let logrm = LogBuffer::new(dev)?;
+        dma_write!(libos[2] = LibosMemoryRegionInitArgument::new("LOGRM", &logrm.0))?;
+
+        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 436c00d07b16..458b5610061f 100644
--- a/drivers/gpu/nova-core/gsp/fw.rs
+++ b/drivers/gpu/nova-core/gsp/fw.rs
@@ -8,11 +8,16 @@ use r570_144 as bindings;
 use core::ops::Range;
 
 use kernel::{
+    dma::CoherentAllocation,
     ptr::{
         Alignable,
         Alignment, //
     },
     sizes::SZ_1M,
+    transmute::{
+        AsBytes,
+        FromBytes, //
+    },
 };
 
 use crate::{
@@ -116,3 +121,58 @@ impl LibosParams {
 /// addresses of the GSP bootloader and firmware.
 #[repr(transparent)]
 pub(crate) struct GspFwWprMeta(bindings::GspFwWprMeta);
+
+/// Struct containing the arguments required to pass a memory buffer to the GSP
+/// for use during initialisation.
+///
+/// The GSP only understands 4K pages (GSP_PAGE_SIZE), so even if the kernel is
+/// configured for a larger page size (e.g. 64K pages), we need to give
+/// the GSP an array of 4K pages. Since we only create physically contiguous
+/// buffers the math to calculate the addresses is simple.
+///
+/// The buffers must be a multiple of GSP_PAGE_SIZE.  GSP-RM also currently
+/// ignores the @kind field for LOGINIT, LOGINTR, and LOGRM, but expects the
+/// buffers to be physically contiguous anyway.
+///
+/// The memory allocated for the arguments must remain until the GSP sends the
+/// init_done RPC.
+#[repr(transparent)]
+pub(crate) struct LibosMemoryRegionInitArgument(bindings::LibosMemoryRegionInitArgument);
+
+// SAFETY: Padding is explicit and does 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: num::usize_as_u64(obj.size()),
+            kind: num::u32_into_u8::<
+                { bindings::LibosMemoryRegionKind_LIBOS_MEMORY_REGION_CONTIGUOUS },
+            >(),
+            loc: num::u32_into_u8::<
+                { bindings::LibosMemoryRegionLoc_LIBOS_MEMORY_REGION_LOC_SYSMEM },
+            >(),
+            ..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 @@ impl Default for GspFwWprMeta {
         }
     }
 }
+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],
+}