gpu: nova-core: check for overflow to DMATRFBASE1

The NV_PFALCON_FALCON_DMATRFBASE/1 register pair supports DMA addresses
up to 49 bits only, but the write to DMATRFBASE1 could exceed that.
To mitigate, check first that the DMA address will fit.

Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Joel Fernandes <joelagnelf@nvidia.com>
Fixes: 69f5cd67ce ("gpu: nova-core: add falcon register definitions and base code")
Signed-off-by: Timur Tabi <ttabi@nvidia.com>
Link: https://patch.msgid.link/20260107201647.2490140-1-ttabi@nvidia.com
[ Import ::kernel::dma::DmaMask. - Danilo ]
Signed-off-by: Danilo Krummrich <dakr@kernel.org>

drivers/gpu/nova-core/falcon.rs

@@ -8,7 +8,10 @@
 
 use kernel::{
     device,
-    dma::DmaAddress,
+    dma::{
+        DmaAddress,
+        DmaMask, //
+    },
     io::poll::read_poll_timeout,
     prelude::*,
     sync::aref::ARef,
@@ -472,6 +475,12 @@ fn dma_wr<F: FalconFirmware<Target = E>>(
             return Err(EINVAL);
         }
 
+        // The DMATRFBASE/1 register pair only supports a 49-bit address.
+        if dma_start > DmaMask::new::<49>().value() {
+            dev_err!(self.dev, "DMA address {:#x} exceeds 49 bits\n", dma_start);
+            return Err(ERANGE);
+        }
+
         // DMA transfers can only be done in units of 256 bytes. Compute how many such transfers we
         // need to perform.
         let num_transfers = load_offsets.len.div_ceil(DMA_LEN);