On Thu, 22 Sep 2016 07:30:52 +0200 Thomas Huth <th...@redhat.com> wrote:
> On Thu, 22 Sep 2016 11:57:15 +1000 > David Gibson <da...@gibson.dropbear.id.au> wrote: > > > On Wed, Sep 21, 2016 at 10:22:11AM +0200, Thomas Huth wrote: > > > On 20.09.2016 16:39, Cédric Le Goater wrote: > > > > On 09/20/2016 04:24 PM, Thomas Huth wrote: > > > >> On 20.09.2016 16:04, Cédric Le Goater wrote: > > > [...] > > > >>> There are other issues after in the guest (kernel crashing). But I > > > >>> think > > > >>> these are related to TM which is not supported in KVM-PR. I am not > > > >>> sure > > > >>> where we are on that point. > > > >> > > > >> There was a patch some months ago: > > > >> > > > >> https://lists.gnu.org/archive/html/qemu-ppc/2016-04/msg00046.html > > > >> > > > >> ... but I think it has never been included, as far as I can see. > > > > > > > > and with that patch, the guest fully boots. But David had some concerns > > > > on the way it is done. It would be nice to put some cycle on this. > > > > > > Looking at the mail thread, I think TM should be currently disabled for > > > both, KVM-PR and TCG, i.e. only enabled for KVM-HV. The TM support in > > > TCG is just fake, since TBEGIN always fails. > > > > Right. So there's two questions here > > > > 1) Is qemu correctly advertising availability of TM in the device > > tree? > > If I've got that right, it's currently always advertising TM, even if > it's not really available (in TCG mode and PR mode). > > > If not we need to fix that, which might involve adding a kernel > > capability for the PR case. > > > > 2) Is the kvm unit test properly checking for availability of TM > > before executing? > > Not yet. That's why it would be good to get a proper way for testing > for the availability of TM --> i.e. something like Anton's patch. > > > > Once we've got proper TM support in TCG, this can be easily changed > > > within QEMU. And once we've got TM support in KVM-PR, I think we should > > > also introduce a capability flag to KVM which can be used to inform QEMU > > > about this. > > > > > > So I think Anton's patch currently just lacks the check for TCG. > > > Anton, if you've got some spare minutes, could you maybe send an updated > > > version of that patch? > > > > Sorry, which patch of Anton's? > > This one: > https://lists.gnu.org/archive/html/qemu-ppc/2016-04/msg00415.html Actually, looking at that whole pa-feature code in QEMU, I think there's some more work to do here: Everything that is not using mmu_model==POWERPC_MMU_2_06 is automatically getting pa_features_207. This is sometimes completely wrong, for example when running with KVM-PR, the mmu_model for POWER7 is POWERPC_MMU_2_06a instead. Or when running with TCG, I think it's also perfectly legal to run the pseries machine with a POWER5+ or PPC970 CPU - and we certainly do not want to use pa_features_207 there. So if you like, I can try to come up with a small patch series that cleans up this mess - and I could also include an updated versions of Anton's patch there unless he wants to redo the changes on his own...? Thomas
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