> -----Original Message----- > From: Christian Ehrhardt [mailto:ehrhardt@xxxxxxxxxxxxxxxxxx] > Sent: Monday, August 11, 2008 4:33 PM > To: Liu Yu > Cc: Hollis Blanchard; kvm-ppc@xxxxxxxxxxxxxxx > Subject: Re: [PATCH 4 of 5] kvm: ppc: Write only modified > shadow entries into theTLB on exit > > Liu Yu wrote: > > > > > >> -----Original Message----- > >> From: kvm-ppc-owner@xxxxxxxxxxxxxxx > >> [mailto:kvm-ppc-owner@xxxxxxxxxxxxxxx] On Behalf Of Hollis > Blanchard > >> Sent: Saturday, July 26, 2008 2:55 AM > >> To: avi@xxxxxxxxxxxx > >> Cc: kvm-ppc@xxxxxxxxxxxxxxx; kvm@xxxxxxxxxxxxxxx > >> Subject: [PATCH 4 of 5] kvm: ppc: Write only modified > shadow entries > >> into theTLB on exit > >> > >> @@ -229,6 +235,7 @@ void kvmppc_mmu_priv_switch(struct kvm_v > >> > >> kvmppc_44x_shadow_release(vcpu, i); > >> stlbe->word0 = 0; > >> + kvmppc_tlbe_set_modified(vcpu, i); > >> KVMTRACE_5D(STLB_INVAL, vcpu, i, > >> stlbe->tid, stlbe->word0, stlbe->word1, > >> stlbe->word2, handler); > >> > > > > Can this place use "_tlbia()" instead? > > > Hi Liu, > when we exit&reenter a guest on the lightweight path this > patch saves us from rebuilding too much of the tlb. > It's just the point of the patch to not invalidate all tlb > entries on every exit, but keeping as much as possible. > Additionally I'm not even sure if tlbia is available on all > cores used. > > Am I overlooking something ? - what do you think would be the > benefit of using _tlbia() here? > Do you mean the loop to clear up to the hwater mark where > this patch makes changes and not this patch itself? > Yes. When you set nearly all tlb entries modified in this loop, you have to write all of them back before entering the guest in booke_interrupts.S. So, why not "_tlbia()" here outside this loop, and don't set them modified. Then, you needn't write them back. In fact, the shadow tlb entries are still consistent with the hardware, as all of them are invalidated. Am I overlooking something ? -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
