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[209.132.183.28]) by mx.google.com with ESMTPS id c11si1914499qvd.92.2019.02.04.02.47.06 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 04 Feb 2019 02:47:07 -0800 (PST) Received-SPF: pass (google.com: domain of pbonzini@redhat.com designates 209.132.183.28 as permitted sender) client-ip=209.132.183.28; Authentication-Results: mx.google.com; spf=pass (google.com: domain of pbonzini@redhat.com designates 209.132.183.28 as permitted sender) smtp.mailfrom=pbonzini@redhat.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id CC7A5750CE; Mon, 4 Feb 2019 10:47:05 +0000 (UTC) Received: from [10.36.112.65] (ovpn-112-65.ams2.redhat.com [10.36.112.65]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 6861160851; Mon, 4 Feb 2019 10:46:56 +0000 (UTC) Subject: Re: [RFC][PATCH v2 14/21] kvm: register in mm_struct To: Peter Xu , Fengguang Wu Cc: Andrew Morton , Linux Memory Management List , Nikita Leshenko , Christian Borntraeger , kvm@vger.kernel.org, LKML , Fan Du , Yao Yuan , Peng Dong , Huang Ying , Liu Jingqi , Dong Eddie , Dave Hansen , Zhang Yi , Dan Williams References: <20181226131446.330864849@intel.com> <20181226133351.894160986@intel.com> <20190202065741.GA1011@xz-x1> From: Paolo Bonzini Openpgp: preference=signencrypt Autocrypt: addr=pbonzini@redhat.com; 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Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.3.1 MIME-Version: 1.0 In-Reply-To: <20190202065741.GA1011@xz-x1> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Mon, 04 Feb 2019 10:47:06 +0000 (UTC) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 02/02/19 07:57, Peter Xu wrote: > > I'm thinking whether it's legal for multiple VMs to run on a single mm > address space. I don't see a limitation so far but it's very possible > I am just missing something there (if there is, IMHO they might be > something nice to put into the commit message?). Thanks, Yes, it certainly is legal, and even useful in fact. For example there are people running WebAssembly in a KVM sandbox. In that case you can have multiple KVM instances in a single process. It seems to me that there is already a perfect way to link an mm to its users, which is the MMU notifier. Why do you need a separate proc_ept_idle_operations? You could change ept_idle_read into an MMU notifier callback, and have core mm/ core combine the output of mm_idle_read and all the MMU notifiers? Basically, ept_idle_ctrl becomes an argument to the new MMU notifier callback, or something like that. Paolo