From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 84FA8C43217 for ; Tue, 25 Jan 2022 20:21:22 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 79E836B0075; Tue, 25 Jan 2022 15:21:21 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 74DFC6B007B; Tue, 25 Jan 2022 15:21:21 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 6156A6B007D; Tue, 25 Jan 2022 15:21:21 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0074.hostedemail.com [216.40.44.74]) by kanga.kvack.org (Postfix) with ESMTP id 510366B0075 for ; Tue, 25 Jan 2022 15:21:21 -0500 (EST) Received: from smtpin23.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 0D5641831C2A1 for ; Tue, 25 Jan 2022 20:21:21 +0000 (UTC) X-FDA: 79069929162.23.9E1BBE3 Received: from vps-vb.mhejs.net (vps-vb.mhejs.net [37.28.154.113]) by imf23.hostedemail.com (Postfix) with ESMTP id E3B7B14000D for ; Tue, 25 Jan 2022 20:21:19 +0000 (UTC) Received: from MUA by vps-vb.mhejs.net with esmtps (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.94.2) (envelope-from ) id 1nCSJ4-0006nf-3P; Tue, 25 Jan 2022 21:20:46 +0100 Message-ID: Date: Tue, 25 Jan 2022 21:20:39 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.4.0 Content-Language: en-US To: Chao Peng , Yu Zhang Cc: Paolo Bonzini , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Jonathan Corbet , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Thomas Gleixner , Ingo Molnar , kvm@vger.kernel.org, Borislav Petkov , x86@kernel.org, "H . Peter Anvin" , Hugh Dickins , Jeff Layton , "J . Bruce Fields" , Andrew Morton , "Kirill A . Shutemov" , luto@kernel.org, jun.nakajima@intel.com, dave.hansen@intel.com, ak@linux.intel.com, david@redhat.com, qemu-devel@nongnu.org References: <20220118132121.31388-1-chao.p.peng@linux.intel.com> <20220118132121.31388-13-chao.p.peng@linux.intel.com> From: "Maciej S. Szmigiero" Subject: Re: [PATCH v4 12/12] KVM: Expose KVM_MEM_PRIVATE In-Reply-To: <20220118132121.31388-13-chao.p.peng@linux.intel.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: E3B7B14000D X-Stat-Signature: 84ctadhmead9yhw1msjtmzattwuoh3z8 Authentication-Results: imf23.hostedemail.com; dkim=none; spf=pass (imf23.hostedemail.com: domain of mail@maciej.szmigiero.name designates 37.28.154.113 as permitted sender) smtp.mailfrom=mail@maciej.szmigiero.name; dmarc=none X-Rspam-User: nil X-HE-Tag: 1643142079-381025 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 18.01.2022 14:21, Chao Peng wrote: > KVM_MEM_PRIVATE is not exposed by default but architecture code can turn > on it by implementing kvm_arch_private_memory_supported(). > > Also private memslot cannot be movable and the same file+offset can not > be mapped into different GFNs. > > Signed-off-by: Yu Zhang > Signed-off-by: Chao Peng > --- (..) > > static bool kvm_check_memslot_overlap(struct kvm_memslots *slots, int id, > - gfn_t start, gfn_t end) > + struct file *file, > + gfn_t start, gfn_t end, > + loff_t start_off, loff_t end_off) > { > struct kvm_memslot_iter iter; > + struct kvm_memory_slot *slot; > + struct inode *inode; > + int bkt; > > kvm_for_each_memslot_in_gfn_range(&iter, slots, start, end) { > if (iter.slot->id != id) > return true; > } > > + /* Disallow mapping the same file+offset into multiple gfns. */ > + if (file) { > + inode = file_inode(file); > + kvm_for_each_memslot(slot, bkt, slots) { > + if (slot->private_file && > + file_inode(slot->private_file) == inode && > + !(end_off <= slot->private_offset || > + start_off >= slot->private_offset > + + (slot->npages >> PAGE_SHIFT))) > + return true; > + } > + } That's a linear scan of all memslots on each CREATE (and MOVE) operation with a fd - we just spent more than a year rewriting similar linear scans into more efficient operations in KVM. Thanks, Maciej