gpu: nova-core: replace use of `as` with functions from `num`

Use the newly-introduced `num` module to replace the use of `as`
wherever it is safe to do. This ensures that a given conversion cannot
lose data if its source or destination type ever changes.

Acked-by: Danilo Krummrich <dakr@kernel.org>
[acourbot@nvidia.com: fix merge conflicts after rebase.]
Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>
Message-ID: <20251029-nova-as-v3-5-6a30c7333ad9@nvidia.com>

1 files changed, 5 insertions, 4 deletions

diff --git a/drivers/gpu/nova-core/vbios.rs b/drivers/gpu/nova-core/vbios.rs
index 9c5b93adeb96..abf423560ff4 100644
--- a/drivers/gpu/nova-core/vbios.rs
+++ b/drivers/gpu/nova-core/vbios.rs
@@ -21,6 +21,7 @@ use crate::{
         fwsec::Bcrt30Rsa3kSignature,
         FalconUCodeDescV3, //
     },
+    num::FromSafeCast,
 };
 
 /// The offset of the VBIOS ROM in the BAR0 space.
@@ -795,7 +796,7 @@ impl PciAtBiosImage {
 
         let data_ptr = u32::from_le_bytes(bytes);
 
-        if (data_ptr as usize) < self.base.data.len() {
+        if (usize::from_safe_cast(data_ptr)) < self.base.data.len() {
             dev_err!(self.base.dev, "Falcon data pointer out of bounds\n");
             return Err(EINVAL);
         }
@@ -922,7 +923,7 @@ impl FwSecBiosBuilder {
         pci_at_image: &PciAtBiosImage,
         first_fwsec: &FwSecBiosBuilder,
     ) -> Result {
-        let mut offset = pci_at_image.falcon_data_ptr()? as usize;
+        let mut offset = usize::from_safe_cast(pci_at_image.falcon_data_ptr()?);
         let mut pmu_in_first_fwsec = false;
 
         // The falcon data pointer assumes that the PciAt and FWSEC images
@@ -963,7 +964,7 @@ impl FwSecBiosBuilder {
             .find_entry_by_type(FALCON_UCODE_ENTRY_APPID_FWSEC_PROD)
         {
             Ok(entry) => {
-                let mut ucode_offset = entry.data as usize;
+                let mut ucode_offset = usize::from_safe_cast(entry.data);
                 ucode_offset -= pci_at_image.base.data.len();
                 if ucode_offset < first_fwsec.base.data.len() {
                     dev_err!(self.base.dev, "Falcon Ucode offset not in second Fwsec.\n");
@@ -1049,7 +1050,7 @@ impl FwSecBiosImage {
 
         // The ucode data follows the descriptor.
         let ucode_data_offset = falcon_ucode_offset + desc.size();
-        let size = (desc.imem_load_size + desc.dmem_load_size) as usize;
+        let size = usize::from_safe_cast(desc.imem_load_size + desc.dmem_load_size);
 
         // Get the data slice, checking bounds in a single operation.
         self.base