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([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.gmail.com with ESMTPSA id g14sm12643662edm.31.2021.01.26.06.14.17 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 26 Jan 2021 06:14:18 -0800 (PST) Subject: Re: [PATCH 10/24] kvm: x86/mmu: Factor out handle disconnected pt To: Ben Gardon , linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: Peter Xu , Sean Christopherson , Peter Shier , Peter Feiner , Junaid Shahid , Jim Mattson , Yulei Zhang , Wanpeng Li , Vitaly Kuznetsov , Xiao Guangrong References: <20210112181041.356734-1-bgardon@google.com> <20210112181041.356734-11-bgardon@google.com> From: Paolo Bonzini Message-ID: <47e0b040-f9de-376d-80a3-75b5680a7b85@redhat.com> Date: Tue, 26 Jan 2021 15:14:16 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.6.0 MIME-Version: 1.0 In-Reply-To: <20210112181041.356734-11-bgardon@google.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/01/21 19:10, Ben Gardon wrote: > Factor out the code to handle a disconnected subtree of the TDP paging > structure from the code to handle the change to an individual SPTE. > Future commits will build on this to allow asynchronous page freeing. > > No functional change intended. > > Reviewed-by: Peter Feiner > > Signed-off-by: Ben Gardon > --- > arch/x86/kvm/mmu/tdp_mmu.c | 75 +++++++++++++++++++++++--------------- > 1 file changed, 46 insertions(+), 29 deletions(-) > > diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c > index 55df596696c7..e8f35cd46b4c 100644 > --- a/arch/x86/kvm/mmu/tdp_mmu.c > +++ b/arch/x86/kvm/mmu/tdp_mmu.c > @@ -234,6 +234,49 @@ static void handle_changed_spte_dirty_log(struct kvm *kvm, int as_id, gfn_t gfn, > } > } > > +/** > + * handle_disconnected_tdp_mmu_page - handle a pt removed from the TDP structure > + * > + * @kvm: kvm instance > + * @pt: the page removed from the paging structure > + * > + * Given a page table that has been removed from the TDP paging structure, > + * iterates through the page table to clear SPTEs and free child page tables. > + */ > +static void handle_disconnected_tdp_mmu_page(struct kvm *kvm, u64 *pt) > +{ > + struct kvm_mmu_page *sp; > + gfn_t gfn; > + int level; > + u64 old_child_spte; > + int i; > + > + sp = sptep_to_sp(pt); > + gfn = sp->gfn; > + level = sp->role.level; > + > + trace_kvm_mmu_prepare_zap_page(sp); > + > + list_del(&sp->link); > + > + if (sp->lpage_disallowed) > + unaccount_huge_nx_page(kvm, sp); > + > + for (i = 0; i < PT64_ENT_PER_PAGE; i++) { > + old_child_spte = READ_ONCE(*(pt + i)); > + WRITE_ONCE(*(pt + i), 0); > + handle_changed_spte(kvm, kvm_mmu_page_as_id(sp), > + gfn + (i * KVM_PAGES_PER_HPAGE(level - 1)), > + old_child_spte, 0, level - 1); > + } > + > + kvm_flush_remote_tlbs_with_address(kvm, gfn, > + KVM_PAGES_PER_HPAGE(level)); > + > + free_page((unsigned long)pt); > + kmem_cache_free(mmu_page_header_cache, sp); > +} > + > /** > * handle_changed_spte - handle bookkeeping associated with an SPTE change > * @kvm: kvm instance > @@ -254,10 +297,6 @@ static void __handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn, > bool was_leaf = was_present && is_last_spte(old_spte, level); > bool is_leaf = is_present && is_last_spte(new_spte, level); > bool pfn_changed = spte_to_pfn(old_spte) != spte_to_pfn(new_spte); > - u64 *pt; > - struct kvm_mmu_page *sp; > - u64 old_child_spte; > - int i; > > WARN_ON(level > PT64_ROOT_MAX_LEVEL); > WARN_ON(level < PG_LEVEL_4K); > @@ -321,31 +360,9 @@ static void __handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn, > * Recursively handle child PTs if the change removed a subtree from > * the paging structure. > */ > - if (was_present && !was_leaf && (pfn_changed || !is_present)) { > - pt = spte_to_child_pt(old_spte, level); > - sp = sptep_to_sp(pt); > - > - trace_kvm_mmu_prepare_zap_page(sp); > - > - list_del(&sp->link); > - > - if (sp->lpage_disallowed) > - unaccount_huge_nx_page(kvm, sp); > - > - for (i = 0; i < PT64_ENT_PER_PAGE; i++) { > - old_child_spte = READ_ONCE(*(pt + i)); > - WRITE_ONCE(*(pt + i), 0); > - handle_changed_spte(kvm, as_id, > - gfn + (i * KVM_PAGES_PER_HPAGE(level - 1)), > - old_child_spte, 0, level - 1); > - } > - > - kvm_flush_remote_tlbs_with_address(kvm, gfn, > - KVM_PAGES_PER_HPAGE(level)); > - > - free_page((unsigned long)pt); > - kmem_cache_free(mmu_page_header_cache, sp); > - } > + if (was_present && !was_leaf && (pfn_changed || !is_present)) > + handle_disconnected_tdp_mmu_page(kvm, > + spte_to_child_pt(old_spte, level)); > } > > static void handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn, > Queued, thanks. Paolo