Re: [Xen-devel] [RFC 15/16] xen/arm: Implement Set/Way operations

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Tue, 6 Nov 2018, Julien Grall wrote:
> Hi Stefano,
> 
> On 06/11/2018 17:31, Stefano Stabellini wrote:
> > On Mon, 5 Nov 2018, Julien Grall wrote:
> > > > This will affect all the registers trapped with TVM. Shouldn't we only
> > > > call p2m_toggle_cache when relevant? i.e. when changing SCTLR?
> > > > I think it would be better to only modify the SCTLR emulation handler.
> > > 
> > > This is made on purpose, you increase the chance to disable TVM as soon as
> > > possible. If you only rely on SCTLR, you may end up to trap a lot of
> > > registers
> > > for a long time.
> > > 
> > > FWIW, as I already wrote in the commit message, this is based on what KVM
> > > does.
> > 
> > I missed that. As you explain it, it makes sense. Maybe worth adding an
> > explicit statement about it: "On ARM64, we call p2m_toggle_cache from on
> > the TVM-trapped register handlers to increase the chances of disabling
> > TVM as soon as possible."
> 
> I am assuming you meant arm32 here? 

Yes, I did


> Looking at the code, it looks like I
> implemented the arm64 differently. But we probably want apply to call
> p2m_toggle_cache in all TVM trapped registers.
> 
> This would keep the logic everywhere the same.

Right, good idea

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel