gpu: nova-core: Set correct DMA mask

Set the correct DMA mask. Without this DMA will fail on some setups.

Signed-off-by: Alistair Popple <apopple@nvidia.com>
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Message-ID: <20251110-gsp_boot-v9-2-8ae4058e3c0e@nvidia.com>

diff --git a/drivers/gpu/nova-core/driver.rs b/drivers/gpu/nova-core/driver.rs
index 2509f75eccb996980f9dc2096606fac6d5c9440f..d91bbc50cde7e9da9d3050327c430493e3f1d40c 100644 (file)
--- a/drivers/gpu/nova-core/driver.rs
+++ b/drivers/gpu/nova-core/driver.rs
@@ -4,6 +4,8 @@ use kernel::{
     auxiliary,
     c_str,
     device::Core,
+    dma::Device,
+    dma::DmaMask,
     pci,
     pci::{
         Class,
@@ -25,6 +27,15 @@ pub(crate) struct NovaCore {
 }
 
 const BAR0_SIZE: usize = SZ_16M;
+
+// For now we only support Ampere which can use up to 47-bit DMA addresses.
+//
+// TODO: Add an abstraction for this to support newer GPUs which may support
+// larger DMA addresses. Limiting these GPUs to smaller address widths won't
+// have any adverse affects, unless installed on systems which require larger
+// DMA addresses. These systems should be quite rare.
+const GPU_DMA_BITS: u32 = 47;
+
 pub(crate) type Bar0 = pci::Bar<BAR0_SIZE>;
 
 kernel::pci_device_table!(
@@ -62,6 +73,11 @@ impl pci::Driver for NovaCore {
         pdev.enable_device_mem()?;
         pdev.set_master();
 
+        // SAFETY: No concurrent DMA allocations or mappings can be made because
+        // the device is still being probed and therefore isn't being used by
+        // other threads of execution.
+        unsafe { pdev.dma_set_mask_and_coherent(DmaMask::new::<GPU_DMA_BITS>())? };
+
         let devres_bar = Arc::pin_init(
             pdev.iomap_region_sized::<BAR0_SIZE>(0, c_str!("nova-core/bar0")),
             GFP_KERNEL,