Re: [Xen-devel] [PATCH v2 4/7] xen/arm: page: Clarify the Xen TLBs helpers name

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Mon, 20 May 2019, Julien Grall wrote:
> On 20/05/2019 22:01, Stefano Stabellini wrote:
> > On Fri, 10 May 2019, Julien Grall wrote:
> >> Feel free to suggest an in-code comment so we can discuss on the 
> >> worthiness.
> > 
> > I suggest something like the following:
> > 
> >   /*
> >    * Flush all hypervisor mappings from the TLB of the local processor. Note
> >    * that instruction cache maintenance might also be required when self
> >    * modifying Xen code, see D5-2522 in ARM DDI 0487D.a and B3.11.2 in ARM
> >    * DDI 0406C.c.
> >    */
> 
> This looks quite out-of-context, what is the relation between 
> self-modifying code and TLB flush?

"Flush all hypervisor mappings from the TLB of the local processor" is
the description of the function below (it cannot be seen here but it's
the function on top of which this comment is supposed to be on,
flush_xen_data_tlb_local). The rest of the comment is informative
regarding difficult cases such as self-modifying code, which was present
in the previous version of the code and I would like to retain. The
relation is that there is a good chance you need to do both.

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