Re: [PATCH v3 3/7] gpu: nova-core: transition booter_load to TLV images

[Timur Tabi <ttabi@nvidia.com>]

On Mon, 2026-07-06 at 15:31 +0900, Alexandre Courbot wrote:
> 
> > +        let os_data_offset = tlv.get_u32(b"DAOF")?;
> > +        let os_data_size = tlv.get_u32(b"DASZ")?;
> > +        let os_code_offset = tlv.get_u32(b"CDOF")?;
> > +        let os_code_size = tlv.get_u32(b"CDSZ")?;
> > +        let patch_loc = tlv.get_u32(b"PLOC")?;
> > +        let fuse_version = tlv.get_u32(b"FUSE")?;
> > +        let engine_id = tlv.get_u32(b"ENID")?;
> > +        let ucode_id = tlv.get_u32(b"UCID")?;
> > +        let app0_code_offset = tlv.get_u32(b"A0CO")?;
> > +        let app0_code_size = tlv.get_u32(b"A0CS")?;
> > +        let num_sigs = tlv.get_u32(b"NSIG")?;
> > +        let sig_bytes = tlv.get_bytes(b"SIGN")?;
> > +
> > +        // Booter is always signed
> 
> The `.rst` file mentions the non-signed case though - we should
> reconcile the spec and the code one way or the other.

The .rst does not mention that Booter is signed, only that if the firmware is unsigned, then NSIG is
0 and SIGN does not exist.  And since get_bytes() now returns Error if SIGN doesn't exist, we
enforce that here.

But you're right in that it does feel a little off.  That's one of the reasons I had get_nth() in v1
-- to streamline getting the nth signature.  

What do you think about adding a get_signature(index) method that combines parsing NSIG and SIGN,
automatically calculating sig_size and returning Option<&[u8]> ?

> 
> >  
> > +        // The size of one signature
> > +        let sig_size = sig_bytes
> > +            .len()
> > +            .checked_div(num_sigs.into_safe_cast())
> > +            .ok_or(EINVAL)?;
> > +
> > +        // Extract the nth signature
> > +        let sig_chunk = sig_bytes
> > +            .chunks_exact(sig_size)
> 
> As Sashiko pointed out, this will panic if `sig_size == 0`, so we need
> to check that - and whether an unsigned Booter is valid at all.

sig_size cannot be 0 because of this:

        if !(1..=15).contains(&num_sigs) || sig_bytes.len() % num_sigs != 0 {

Neither sig_bytes.len() nor num_sigs can be 0.

But IMHO, this just reinforces the idea that I should add get_signature().