[PATCH v2 1/2] gpu: nova-core: check for overflow to DMATRFBASE1

[Timur Tabi <ttabi@nvidia.com>]

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: 69f5cd67ce41 ("gpu: nova-core: add falcon register definitions and base code")
Signed-off-by: Timur Tabi <ttabi@nvidia.com>
---

v2: Improved comment and moved check earlier in function

 drivers/gpu/nova-core/falcon.rs | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/gpu/nova-core/falcon.rs b/drivers/gpu/nova-core/falcon.rs
index 82c661aef594..6ae0490caffa 100644
--- a/drivers/gpu/nova-core/falcon.rs
+++ b/drivers/gpu/nova-core/falcon.rs
@@ -472,6 +472,12 @@ fn dma_wr<F: FalconFirmware<Target = E>>(
             return Err(EINVAL);
         }
 
+        // The DMATRFBASE/1 register pair only supports a 49-bit address.
+        if dma_start > kernel::dma::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);

base-commit: 2d7b4a44fb768e1887e7e4cdd8b86817ccd9c3bf
-- 
2.52.0