> -----Original Message----- > From: Alexander Graf [mailto:agraf@xxxxxxx] > Sent: Sunday, May 04, 2014 1:14 AM > To: Caraman Mihai Claudiu-B02008 > Cc: kvm-ppc@xxxxxxxxxxxxxxx; kvm@xxxxxxxxxxxxxxx; linuxppc- > dev@xxxxxxxxxxxxxxxx > Subject: Re: [PATCH v2 1/4] KVM: PPC: e500mc: Revert "add load inst > fixup" > > > > Am 03.05.2014 um 01:14 schrieb "mihai.caraman@xxxxxxxxxxxxx" > <mihai.caraman@xxxxxxxxxxxxx>: > > >> From: Alexander Graf <agraf@xxxxxxx> > >> Sent: Friday, May 2, 2014 12:24 PM > > This was the first idea that sprang to my mind inspired from how DO_KVM > > is hooked on PR. I actually did a simple POC for e500mc/e5500, but this > will > > not work on e6500 which has shared IVORs between HW threads. > > What if we combine the ideas? On read we flip the IVOR to a separate > handler that checks for a field in the PACA. Only if that field is set, > we treat the fault as kvm fault, otherwise we jump into the normal > handler. > > I suppose we'd have to also take a lock to make sure we don't race with > the other thread when it wants to also read a guest instruction, but you > get the idea. This might be a solution for TLB eviction but not for execute-but-not-read entries which requires access from host context. > > I have no idea whether this would be any faster, it's more of a > brainstorming thing really. But regardless this patch set would be a move > into the right direction. > > Btw, do we have any guarantees that we don't get scheduled away before we > run kvmppc_get_last_inst()? If we run on a different core we can't read > the inst anymore. Hrm. It was your suggestion to move the logic from kvmppc_handle_exit() irq disabled area to kvmppc_get_last_inst(): http://git.freescale.com/git/cgit.cgi/ppc/sdk/linux.git/tree/arch/powerpc/kvm/booke.c Still, what is wrong if we get scheduled on another core? We will emulate again and the guest will populate the TLB on the new core. -Mike -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
