Re: [PATCH 00/18] CXL RAM and the 'Soft Reserved' => 'System RAM' default

[Gregory Price]

On Wed, Feb 15, 2023 at 10:03:27AM +0000, Jonathan Cameron wrote:
> On Tue, 14 Feb 2023 16:54:02 -0500
> Gregory Price <gregory.price@memverge.com> wrote:
> 
> > Just clarifying one thing:  Even with the patch, KVM blows up.
> > Disabling KVM fixes this entirely.  I haven't tested without KVM but
> > with the patch, i will do that now.
> 
> yup.  The patch only fixes TCG so that's expected behavior.
> 
> Fingers crossed on this 'working'.
> 
> I'm open to suggestions on how to work around the problem with KVM
> or indeed allow TCG to cache the instructions (right not it has
> to fetch and emulate each instruction on it's own).
> 
> I can envision how we might do it for KVM with userspace page fault handling
> used to get a fault up to QEMU which can then stitch in a cache
> of the underlying memory as a stage 2 translation to the page (a little
> bit like how post migration copy works) though I've not prototyped
> anything...
> 

Just following up.  With the patch applied and KVM turned off, no crash.
I've been working with this for a while.

We should move the instruction alignment issue into a separate
discussion thread.