gpu: nova-core: align LibosMemoryRegionInitArgument size to page size

On Turing and GA100 (i.e. the versions that use Libos v2), GSP-RM insists
that the 'size' parameter of the LibosMemoryRegionInitArgument struct be
aligned to 4KB.  The logging buffers are already aligned to that size, so
only the GSP_ARGUMENTS_CACHED struct needs to be adjusted.  Make that
adjustment by adding padding to the end of the struct.

Signed-off-by: Timur Tabi <ttabi@nvidia.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Acked-by: Danilo Krummrich <dakr@kernel.org>
Link: https://patch.msgid.link/20260122222848.2555890-12-ttabi@nvidia.com
[acourbot@nvidia.com: GspArgumentsAligned -> GspArgumentsPadded]
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>

Author: Gnurou

drivers/gpu/nova-core/gsp.rs

@@ -27,7 +27,7 @@ pub(crate) use fw::{
 use crate::{
     gsp::cmdq::Cmdq,
     gsp::fw::{
-        GspArgumentsCached,
+        GspArgumentsPadded,
         LibosMemoryRegionInitArgument, //
     },
     num,
@@ -114,7 +114,7 @@ pub(crate) struct Gsp {
     /// Command queue.
     pub(crate) cmdq: Cmdq,
     /// RM arguments.
-    rmargs: CoherentAllocation<GspArgumentsCached>,
+    rmargs: CoherentAllocation<GspArgumentsPadded>,
 }
 
 impl Gsp {
@@ -133,7 +133,7 @@ impl Gsp {
                 logintr: LogBuffer::new(dev)?,
                 logrm: LogBuffer::new(dev)?,
                 cmdq: Cmdq::new(dev)?,
-                rmargs: CoherentAllocation::<GspArgumentsCached>::alloc_coherent(
+                rmargs: CoherentAllocation::<GspArgumentsPadded>::alloc_coherent(
                     dev,
                     1,
                     GFP_KERNEL | __GFP_ZERO,
@@ -149,7 +149,7 @@ impl Gsp {
                         libos[1] = LibosMemoryRegionInitArgument::new("LOGINTR", &logintr.0)
                     )?;
                     dma_write!(libos[2] = LibosMemoryRegionInitArgument::new("LOGRM", &logrm.0))?;
-                    dma_write!(rmargs[0] = fw::GspArgumentsCached::new(cmdq))?;
+                    dma_write!(rmargs[0].inner = fw::GspArgumentsCached::new(cmdq))?;
                     dma_write!(libos[3] = LibosMemoryRegionInitArgument::new("RMARGS", rmargs))?;
                 },
             }))

drivers/gpu/nova-core/gsp/fw.rs

@@ -904,9 +904,21 @@ impl GspArgumentsCached {
 // SAFETY: Padding is explicit and will not contain uninitialized data.
 unsafe impl AsBytes for GspArgumentsCached {}
 
+/// On Turing and GA100, the entries in the `LibosMemoryRegionInitArgument`
+/// must all be a multiple of GSP_PAGE_SIZE in size, so add padding to force it
+/// to that size.
+#[repr(C)]
+pub(crate) struct GspArgumentsPadded {
+    pub(crate) inner: GspArgumentsCached,
+    _padding: [u8; GSP_PAGE_SIZE - core::mem::size_of::<bindings::GSP_ARGUMENTS_CACHED>()],
+}
+
+// SAFETY: Padding is explicit and will not contain uninitialized data.
+unsafe impl AsBytes for GspArgumentsPadded {}
+
 // SAFETY: This struct only contains integer types for which all bit patterns
 // are valid.
-unsafe impl FromBytes for GspArgumentsCached {}
+unsafe impl FromBytes for GspArgumentsPadded {}
 
 /// Init arguments for the message queue.
 #[repr(transparent)]