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[34.82.80.254]) by smtp.gmail.com with ESMTPSA id d9sm2965107pgd.40.2021.11.11.10.55.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 11 Nov 2021 10:55:37 -0800 (PST) Date: Thu, 11 Nov 2021 18:55:34 +0000 From: David Matlack To: Ben Gardon Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Paolo Bonzini , Peter Xu , Sean Christopherson , Peter Shier , Mingwei Zhang , Yulei Zhang , Wanpeng Li , Xiao Guangrong , Kai Huang , Keqian Zhu , David Hildenbrand Subject: Re: [RFC 05/19] KVM: x86/mmu: Remove redundant flushes when disabling dirty logging Message-ID: References: <20211110223010.1392399-1-bgardon@google.com> <20211110223010.1392399-6-bgardon@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211110223010.1392399-6-bgardon@google.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 10, 2021 at 02:29:56PM -0800, Ben Gardon wrote: > tdp_mmu_zap_spte_atomic flushes on every zap already, so no need to > flush again after it's done. > > > Signed-off-by: Ben Gardon Reviewed-by: David Matlack > --- > arch/x86/kvm/mmu/mmu.c | 4 +--- > arch/x86/kvm/mmu/tdp_mmu.c | 21 ++++++--------------- > arch/x86/kvm/mmu/tdp_mmu.h | 5 ++--- > 3 files changed, 9 insertions(+), 21 deletions(-) > > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c > index 354d2ca92df4..baa94acab516 100644 > --- a/arch/x86/kvm/mmu/mmu.c > +++ b/arch/x86/kvm/mmu/mmu.c > @@ -5870,9 +5870,7 @@ void kvm_mmu_zap_collapsible_sptes(struct kvm *kvm, > > if (is_tdp_mmu_enabled(kvm)) { > read_lock(&kvm->mmu_lock); > - flush = kvm_tdp_mmu_zap_collapsible_sptes(kvm, slot, flush); > - if (flush) > - kvm_arch_flush_remote_tlbs_memslot(kvm, slot); > + kvm_tdp_mmu_zap_collapsible_sptes(kvm, slot); > read_unlock(&kvm->mmu_lock); > } > } > diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c > index c2a9f7acf8ef..1ece645e737f 100644 > --- a/arch/x86/kvm/mmu/tdp_mmu.c > +++ b/arch/x86/kvm/mmu/tdp_mmu.c > @@ -1438,10 +1438,9 @@ void kvm_tdp_mmu_clear_dirty_pt_masked(struct kvm *kvm, > * Clear leaf entries which could be replaced by large mappings, for > * GFNs within the slot. > */ > -static bool zap_collapsible_spte_range(struct kvm *kvm, > +static void zap_collapsible_spte_range(struct kvm *kvm, > struct kvm_mmu_page *root, > - const struct kvm_memory_slot *slot, > - bool flush) > + const struct kvm_memory_slot *slot) > { > gfn_t start = slot->base_gfn; > gfn_t end = start + slot->npages; > @@ -1452,10 +1451,8 @@ static bool zap_collapsible_spte_range(struct kvm *kvm, > > tdp_root_for_each_pte(iter, root, start, end) { > retry: > - if (tdp_mmu_iter_cond_resched(kvm, &iter, flush, true)) { > - flush = false; > + if (tdp_mmu_iter_cond_resched(kvm, &iter, false, true)) > continue; > - } > > if (!is_shadow_present_pte(iter.old_spte) || > !is_last_spte(iter.old_spte, iter.level)) > @@ -1475,30 +1472,24 @@ static bool zap_collapsible_spte_range(struct kvm *kvm, > iter.old_spte = READ_ONCE(*rcu_dereference(iter.sptep)); > goto retry; > } > - flush = true; > } > > rcu_read_unlock(); > - > - return flush; > } > > /* > * Clear non-leaf entries (and free associated page tables) which could > * be replaced by large mappings, for GFNs within the slot. > */ > -bool kvm_tdp_mmu_zap_collapsible_sptes(struct kvm *kvm, > - const struct kvm_memory_slot *slot, > - bool flush) > +void kvm_tdp_mmu_zap_collapsible_sptes(struct kvm *kvm, > + const struct kvm_memory_slot *slot) > { > struct kvm_mmu_page *root; > > lockdep_assert_held_read(&kvm->mmu_lock); > > for_each_tdp_mmu_root_yield_safe(kvm, root, slot->as_id, true) > - flush = zap_collapsible_spte_range(kvm, root, slot, flush); > - > - return flush; > + zap_collapsible_spte_range(kvm, root, slot); > } > > /* > diff --git a/arch/x86/kvm/mmu/tdp_mmu.h b/arch/x86/kvm/mmu/tdp_mmu.h > index 476b133544dd..3899004a5d91 100644 > --- a/arch/x86/kvm/mmu/tdp_mmu.h > +++ b/arch/x86/kvm/mmu/tdp_mmu.h > @@ -64,9 +64,8 @@ void kvm_tdp_mmu_clear_dirty_pt_masked(struct kvm *kvm, > struct kvm_memory_slot *slot, > gfn_t gfn, unsigned long mask, > bool wrprot); > -bool kvm_tdp_mmu_zap_collapsible_sptes(struct kvm *kvm, > - const struct kvm_memory_slot *slot, > - bool flush); > +void kvm_tdp_mmu_zap_collapsible_sptes(struct kvm *kvm, > + const struct kvm_memory_slot *slot); > > bool kvm_tdp_mmu_write_protect_gfn(struct kvm *kvm, > struct kvm_memory_slot *slot, gfn_t gfn, > -- > 2.34.0.rc0.344.g81b53c2807-goog >