mm/validate: fully migrate and clear bitmap & other cleanups

[00xc]

• Remove useless pub on ValidBitmap methods.
• Fix: if the number of pages in the bitmap was not a multiple of 64, the remainder would not be copied over to the new bitmap during migration, which could lead to tracking validated pages as invalid.
• Use an usize to index into the bitmap, as offsets are always positive.
• Fully clear the bitmap after initialization.

[00xc]

@joergroedel I think this is ready to be merged

[joergroedel]

@00xc This breaks make test-in-svsm. Can you please have a look?

[joergroedel]

Bisection points at

commit 9e5d903b2d940bf2e81cfbf305582af7e35591fd (HEAD)
Author: Carlos López <carlos.lopez@suse.com>
Date:   Tue Oct 17 14:35:44 2023 +0200

    mm/validate: use usize instead of isize to index into the bitmap
    
    The offsets are always positive from the start of the bitmap, so use
    an unsigned type.
    
    Signed-off-by: Carlos López <carlos.lopez@suse.com>

[00xc]

Bisection points at

commit 9e5d903b2d940bf2e81cfbf305582af7e35591fd (HEAD)
Author: Carlos López <carlos.lopez@suse.com>
Date:   Tue Oct 17 14:35:44 2023 +0200

    mm/validate: use usize instead of isize to index into the bitmap
    
    The offsets are always positive from the start of the bitmap, so use
    an unsigned type.
    
    Signed-off-by: Carlos López <carlos.lopez@suse.com>

Only happens in debug builds, so I suspect some debug assertion is being triggered.

[00xc]

I'm working on a bigger rework of the bitmap to increase safety.

[00xc]

Turns out my assumption on 498b599 was wrong, things should work now. I'll push my rework of the bitmap to a separate PR.