Re: [PATCH] x86/tsx: fix KVM guest live migration for tsx=on

[Pawan Gupta]

On Tue, Apr 12, 2022 at 04:08:32PM +0000, Jon Kohler wrote:
> > On Apr 12, 2022, at 11:54 AM, Dave Hansen <dave.hansen@xxxxxxxxx> wrote:
> >
> > On 4/12/22 06:36, Jon Kohler wrote:
> > > So my theory here is to extend the logical effort of the microcode driven
> > > automatic disablement as well as the tsx=auto automatic disablement and
> > > have tsx=on force abort all transactions on X86_BUG_TAA SKUs, but leave
> > > the CPU features enumerated to maintain live migration.
> > >
> > > This would still leave TSX totally good on Ice Lake / non-buggy systems.
> > >
> > > If it would help, I'm working up an RFC patch, and we could discuss there?
> >
> > Sure.  But, it sounds like you really want a new tdx=something rather
> > than to muck with tsx=on behavior.  Surely someone else will come along
> > and complain that we broke their TDX setup if we change its behavior.
>
> Good point, there will always be a squeaky wheel. I’ll work that into the RFC,
> I’ll do something like tsx=compat and see how it shapes up.

FYI, the original series had tsx=fake, that would have taken care of
this breakage.

  https://lore.kernel.org/lkml/de6b97a567e273adff1f5268998692bad548aa10.1623272033.git-series.pawan.kumar.gupta@xxxxxxxxxxxxxxx/

For the lack of real world use-cases at that time, this patch was dropped.

Thanks,
Pawan