Re: Re: [PATCH v2 0/3] hw/pflash: implement update buffer for block writes

[Gerd Hoffmann]

On Sat, Jan 20, 2024 at 01:18:14PM +0300, Michael Tokarev wrote:
> 08.01.2024 19:08, Gerd Hoffmann:
> > When running qemu with edk2 efi firmware on aarch64 the efi
> > variable store in pflash can get corrupted.  qemu not doing
> > proper block writes -- flush all or nothing to storage -- is
> > a hot candidate for being the root cause.
> > 
> > This little series tries to fix that with an update buffer
> > where block writes are staged, so we can commit or discard
> > the changes when the block write is completed or canceled.
> 
> It looks like we can pick this up for stable too.  It's not
> usual to pick up new features for stable, but this one fixes
> actual bug and if not applied, can easily lead to data corruption.
> 
> I'd pick it up for 8.2.x and 8.1.x at least.

Well, it turned out there was a edk2 bug causing flash corruption.
While debugging edk2 I was using a qemu build with fixed pflash.

So on one hand I don't know for sure whenever the incorrect block
flash emulation /alone/ can cause pflash corruption too.

On the other hand the edk2 debugging session also was a stress
test for the pflash fix, so I'm pretty confident it works
correctly.

I think it makes sense to include it.

take care,
  Gerd