On Tue, Dec 24, 2019 at 01:10:34PM -0300, Fabiano Rosas wrote: > David Gibson <da...@gibson.dropbear.id.au> writes: > > >> It looks like the hflags MSR_LE is being updated correctly with TCG. But > >> with KVM we only touch it on system_reset > > > > Ah.. right. I think to fix that we'd want an hreg_compute_hflags() at > > the end of sucking the state out of KVM. > > > > Hm.. The hflags is a TCG thing that does not get used with KVM at all, > except for that one bit in the monitor disas function. I'd rather keep > it completely out of kvm_enabled code.
That's a fair point.
It doesn't look like there's any reason ppc_tr_init_disas_context()
couldn't initialize ctx->le_mode directly from the MSR rather than
hflags anyway. If we do that, we should again be able to remove the
LE bit from hflags entirely. I think that's the way to go.
>
> Couldn't we perhaps make it conditional on the acceleration type?
> Using kvm_enabled() or some ifdef.
>
> Thanks
>
> >> (and possibly h_cede? I don't
> >> know if it is QEMU who handles it).
> >
> > It's KVM. If we used the qemu one it would add an awful lot of
> > latency to cedes.
> >>
> >> So I would let hflags be.
> >>
> >>
> >> ... Actually, I don't really know the purpose of hflags. It comes from:
> >>
> >> commit 3f3373166227b13e762e20d2fb51eadfa6a2d653
> >> Author: Fabrice Bellard <fabr...@bellard.org>
> >> Date: Wed Aug 20 23:02:09 2003 +0000
> >>
> >> pop ss, mov ss, x and sti disable irqs for the next instruction -
> >> began dispatch optimization by adding new x86 cpu 'hidden' flags
> >>
> >>
> >> git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@372
> >> c046a42c-6fe2-441c-8c8c-71466251a162
> >>
> >> Could any one clarify that?
> >
> > Not really. It's really, really old, in the cruft bits of TCG I don't
> > much understand.
>
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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