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([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.gmail.com with ESMTPSA id hy13sm2526147ejc.32.2021.04.01.03.12.52 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 01 Apr 2021 03:12:53 -0700 (PDT) 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: <20210331210841.3996155-1-bgardon@google.com> <20210331210841.3996155-11-bgardon@google.com> From: Paolo Bonzini Subject: Re: [PATCH 10/13] KVM: x86/mmu: Allow zapping collapsible SPTEs to use MMU read lock Message-ID: <51034a41-2d03-103e-6c11-1ed27a952de2@redhat.com> Date: Thu, 1 Apr 2021 12:12:52 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.0 MIME-Version: 1.0 In-Reply-To: <20210331210841.3996155-11-bgardon@google.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 31/03/21 23:08, Ben Gardon wrote: > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c > index dcbfc784cf2f..81967b4e7d76 100644 > --- a/arch/x86/kvm/mmu/mmu.c > +++ b/arch/x86/kvm/mmu/mmu.c > @@ -5610,10 +5610,13 @@ void kvm_mmu_zap_collapsible_sptes(struct kvm *kvm, > > write_lock(&kvm->mmu_lock); > slot_handle_leaf(kvm, slot, kvm_mmu_zap_collapsible_spte, true); > - > - if (is_tdp_mmu_enabled(kvm)) > - kvm_tdp_mmu_zap_collapsible_sptes(kvm, slot); > write_unlock(&kvm->mmu_lock); > + > + if (is_tdp_mmu_enabled(kvm)) { > + read_lock(&kvm->mmu_lock); > + kvm_tdp_mmu_zap_collapsible_sptes(kvm, memslot); > + read_unlock(&kvm->mmu_lock); > + } > } Same here, this will conflict with KVM: x86/mmu: Coalesce TLB flushes when zapping collapsible SPTEs Again, you will have to add back some "if (flush)" before the write_unlock. Paolo