Re: [PATCH v5 08/44] x86/boot: convert setup.c mod refs to early_mod

["Daniel P. Smith" <dpsmith@xxxxxxxxxxxxxxxxxxxx>]

On 10/7/24 15:34, Jason Andryuk wrote:
> On 2024-10-06 17:49, Daniel P. Smith wrote:
> > To allow a slow conversion of x86 over to struct boot_module, start with
> > replacing all references to struct mod to the early_mod element of struct
> > boot_module. These serves twofold, first to allow the incremental 
> > transition
> > from struct mod fields to struct boot_module fields. The second is to 
> > allow
> > the conversion of function definitions from taking struct mod 
> > parameters to
> > accepting struct boot_module as needed when a transitioned field will be
> > accessed.
> >
> > Signed-off-by: Daniel P. Smith <dpsmith@xxxxxxxxxxxxxxxxxxxx>
> > ---
> >   xen/arch/x86/setup.c | 61 ++++++++++++++++++++++++--------------------
> >   1 file changed, 34 insertions(+), 27 deletions(-)
> >
> > diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c
> > index dd82ca3d43e2..ba4bee6b93af 100644
> > --- a/xen/arch/x86/setup.c
> > +++ b/xen/arch/x86/setup.c
> > @@ -1341,15 +1341,15 @@ void asmlinkage __init noreturn 
> > __start_xen(unsigned long mbi_p)
> >       set_kexec_crash_area_size((u64)nr_pages << PAGE_SHIFT);
> >       kexec_reserve_area();
> > -    initial_images = mod;
> > +    initial_images = bi->mods[0].mod;
> Isn't this wrong?
> mod is the array of module_t * of *all* modules, but bi->mods[0].mod is 
> a single module_t *?
No it is not wrong:
  bi->mods[0].mod == __va(mbi->mods_addr)[0]

While the modules themselves get relocated, the location of the array of 
module_t never change.
The question does give me pause to double check the patch ordering, just 
to be sure that mod_start and mod_end are correct up until we transition
to using the boot_module fields.

> >       for ( i = 0; !efi_enabled(EFI_LOADER) && i < bi->nr_modules; i++ )
> >       {
> > -        if ( mod[i].mod_start & (PAGE_SIZE - 1) )
> > +        if ( bi->mods[i].mod->mod_start & (PAGE_SIZE - 1) )
> >               panic("Bootloader didn't honor module alignment 
> > request\n");
> > -        mod[i].mod_end -= mod[i].mod_start;
> > -        mod[i].mod_start >>= PAGE_SHIFT;
> > -        mod[i].reserved = 0;
> > +        bi->mods[i].mod->mod_end -= bi->mods[i].mod->mod_start;
> > +        bi->mods[i].mod->mod_start >>= PAGE_SHIFT;
> > +        bi->mods[i].mod->reserved = 0;
> >       }
> >       /*
> > @@ -1509,13 +1510,15 @@ void asmlinkage __init noreturn 
> > __start_xen(unsigned long mbi_p)
> >   #endif
> >       }
> > -    if ( bi->mods[0].headroom && !mod->reserved )
> > +    if ( bi->mods[0].headroom && !bi->mods[0].mod->reserved )
> >           panic("Not enough memory to relocate the dom0 kernel image\n");
> >       for ( i = 0; i < bi->nr_modules; ++i )
> >       {
> > -        uint64_t s = (uint64_t)mod[i].mod_start << PAGE_SHIFT;
> > +        uint64_t s = (uint64_t)bi->mods[i].mod->mod_start
> > +                        << PAGE_SHIFT;
> pfn_to_paddr() ?
Yep, missed one ( ._.)

> > -        reserve_e820_ram(&boot_e820, s, s + PAGE_ALIGN(mod[i].mod_end));
> > +        reserve_e820_ram(&boot_e820, s,
> > +                         s + PAGE_ALIGN(bi->mods[i].mod->mod_end));
> >       }
> >       if ( !xen_phys_start )
> > @@ -1593,8 +1596,9 @@ void asmlinkage __init noreturn 
> > __start_xen(unsigned long mbi_p)
> >                   map_e = boot_e820.map[j].addr + boot_e820.map[j].size;
> >                   for ( j = 0; j < bi->nr_modules; ++j )
> >                   {
> > -                    uint64_t end = pfn_to_paddr(mod[j].mod_start) +
> > -                                   mod[j].mod_end;
> > +                    uint64_t end = pfn_to_paddr(
> > +                                   bi->mods[j].mod->mod_start) +
> > +                                   bi->mods[j].mod->mod_end;
> I think you want a different indent.  I think
>      uint64_t end = pfn_to_paddr(bi->mods[j].mod->mod_start)
>
> will all fit on one line (indented all the way).  (Thunderbird makes it 
> difficult me to send indented.)
Yes, it will fit on one line without the '+', but I believe one of the 
many unwritten coding style rules is that the '+' stays with the LHS, so 
I wrapped the LHS with the '+'.
> >                       if ( map_e < end )
> >                           map_e = end;
> > @@ -1668,11 +1672,13 @@ void asmlinkage __init noreturn 
> > __start_xen(unsigned long mbi_p)
> >       for ( i = 0; i < bi->nr_modules; ++i )
> >       {
> > -        set_pdx_range(mod[i].mod_start,
> > -                      mod[i].mod_start + PFN_UP(mod[i].mod_end));
> > -        map_pages_to_xen((unsigned long)mfn_to_virt(mod[i].mod_start),
> > -                         _mfn(mod[i].mod_start),
> > -                         PFN_UP(mod[i].mod_end), PAGE_HYPERVISOR);
> > +        set_pdx_range(bi->mods[i].mod->mod_start,
> > +                      bi->mods[i].mod->mod_start +
> > +                      PFN_UP(bi->mods[i].mod->mod_end));
> > +        map_pages_to_xen(
> > +            (unsigned long)mfn_to_virt(bi->mods[i].mod->mod_start),
> map_pages_to_xen((unsigned long)maddr_to_virt(bi->mods[i].start),
>
> All fits on one line.
If it does, I will bring it back up.

v/r,
dps