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([2001:b07:add:ec09:c399:bc87:7b6c:fb2a]) by smtp.googlemail.com with ESMTPSA id x19-20020a05640226d300b004228faf83desm808347edd.12.2022.04.22.04.06.28 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 22 Apr 2022 04:06:34 -0700 (PDT) Sender: Paolo Bonzini Message-ID: Date: Fri, 22 Apr 2022 13:06:25 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.8.0 Subject: Re: [PATCH v5 00/13] KVM: mm: fd-based approach for supporting KVM guest private memory Content-Language: en-US To: Chao Peng , Sean Christopherson Cc: Quentin Perret , Andy Lutomirski , Steven Price , kvm list , Linux Kernel Mailing List , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, Linux API , qemu-devel@nongnu.org, Jonathan Corbet , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , the arch/x86 maintainers , "H. Peter Anvin" , Hugh Dickins , Jeff Layton , "J . Bruce Fields" , Andrew Morton , Mike Rapoport , "Maciej S . Szmigiero" , Vlastimil Babka , Vishal Annapurve , Yu Zhang , "Kirill A. Shutemov" , "Nakajima, Jun" , Dave Hansen , Andi Kleen , David Hildenbrand , Marc Zyngier , Will Deacon References: <80aad2f9-9612-4e87-a27a-755d3fa97c92@www.fastmail.com> <83fd55f8-cd42-4588-9bf6-199cbce70f33@www.fastmail.com> <20220422105612.GB61987@chaop.bj.intel.com> From: Paolo Bonzini In-Reply-To: <20220422105612.GB61987@chaop.bj.intel.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-api@vger.kernel.org On 4/22/22 12:56, Chao Peng wrote: > /* memfile notifier flags */ > #define MFN_F_USER_INACCESSIBLE 0x0001 /* memory allocated in the file is inaccessible from userspace (e.g. read/write/mmap) */ > #define MFN_F_UNMOVABLE 0x0002 /* memory allocated in the file is unmovable */ > #define MFN_F_UNRECLAIMABLE 0x0003 /* memory allocated in the file is unreclaimable (e.g. via kswapd or any other pathes) */ You probably mean BIT(0/1/2) here. Paolo > When memfile_notifier is being registered, memfile_register_notifier will > need check these flags. E.g. for MFN_F_USER_INACCESSIBLE, it fails when > previous mmap-ed mapping exists on the fd (I'm still unclear on how to do > this). When multiple consumers are supported it also need check all > registered consumers to see if any conflict (e.g. all consumers should have > MFN_F_USER_INACCESSIBLE set). Only when the register succeeds, the fd is > converted into a private fd, before that, the fd is just a normal (shared) > one. During this conversion, the previous data is preserved so you can put > some initial data in guest pages (whether the architecture allows this is > architecture-specific and out of the scope of this patch).