Re: [Qemu-ppc] [PATCH RFC 0/4] Enable MTTCG on PowerPC

[Benjamin Herrenschmidt]

On Fri, 2016-09-02 at 13:09 +0530, Nikunj A Dadhania wrote:
> Benjamin Herrenschmidt <address@hidden> writes:
> 
> > 
> > On Fri, 2016-09-02 at 12:02 +0530, Nikunj A Dadhania wrote:
> > > 
> > > The series is a first attempt at enabling Multi-Threaded TCG on
> > > PowerPC.
> > > Changes that were needed to enable PowerPC are pretty simple;
> > > 
> > > Patch 01: Take a iothread lock during hcall, as hcall can
> > > generate io requests
> > >       02: For TCG, we were harcoding smt as 1, this gets rid of
> > > the limitation
> > 
> > If we do this, we need to implement the shared SPRs properly
> 
> Sure, will have a look at it.

My idea was to have a bitmap of SPRs that are shared. When hitting a
shared one, after a write, we call a helper that "sync" the update to
all the other threads using run_on_cpu.

> > 
> > and the inter-thread doorbells...
> 
> You mean the below ?
> 
> > 
> > > 
> > > TODO
> > > ====
> > > Implement msgsndp instructions(door-bell), newer kernels enable
> > > it 
> > > depending on the PVR. I have been using following workaround to
> > > boot.
> > > https://github.com/nikunjad/qemu/commit/2c10052c5f93418a6b920e6ba
> > > 3ce1813fcf50bc4
> 
> Regards,
> Nikunj