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([2001:b07:6468:f312:2f4b:62da:3159:e077]) by smtp.googlemail.com with ESMTPSA id g5-20020a170906868500b0073c74bee6eesm2673719ejx.201.2022.09.28.10.29.22 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 28 Sep 2022 10:29:23 -0700 (PDT) Message-ID: <2f80a561-a338-cdb3-e641-d8803b859ce0@redhat.com> Date: Wed, 28 Sep 2022 19:29:22 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.2.1 Content-Language: en-US To: Emanuele Giuseppe Esposito , kvm@vger.kernel.org Cc: Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , David Hildenbrand , Maxim Levitsky , x86@kernel.org, "H. Peter Anvin" , linux-kernel@vger.kernel.org References: <20220909104506.738478-1-eesposit@redhat.com> <20220909104506.738478-10-eesposit@redhat.com> From: Paolo Bonzini Subject: Re: [RFC PATCH 9/9] kvm_main.c: handle atomic memslot update In-Reply-To: <20220909104506.738478-10-eesposit@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 9/9/22 12:45, Emanuele Giuseppe Esposito wrote: > @@ -1782,7 +1782,8 @@ static void kvm_update_flags_memslot(struct kvm *kvm, > > /* > * Takes kvm->slots_arch_lock, and releases it only if > - * invalid_slot allocation or kvm_prepare_memory_region failed. > + * invalid_slot allocation, kvm_prepare_memory_region failed > + * or batch->is_move_delete is true. > */ This _is_ getting out of hand, though. :) It is not clear to me why you need to do multiple swaps. If you did a single swap, you could do all the allocations of invalid slots in a separate loop, called with slots_arch_lock taken and not released until the final swap. In other words, something like mutex_lock(&kvm->slots_arch_lock); r = create_invalid_slots(); if (r < 0) return r; replace_old_slots(); // also handles abort on failure prepare_memory_regions(); if (r < 0) return r; swap(); finish_memslots(); where each function is little more than a loop over the corresponding function called by KVM_SET_MEMORY_REGION. Paolo