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 AF770C433EF for ; Wed, 20 Jul 2022 23:08:24 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 135486B0072; Wed, 20 Jul 2022 19:08:24 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 0E5AF6B0073; Wed, 20 Jul 2022 19:08:24 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id EEF6C6B0074; Wed, 20 Jul 2022 19:08:23 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id DFF836B0072 for ; Wed, 20 Jul 2022 19:08:23 -0400 (EDT) Received: from smtpin01.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay03.hostedemail.com (Postfix) with ESMTP id B9608A077C for ; Wed, 20 Jul 2022 23:08:23 +0000 (UTC) X-FDA: 79709018886.01.9723FA0 Received: from mail-pf1-f173.google.com (mail-pf1-f173.google.com [209.85.210.173]) by imf22.hostedemail.com (Postfix) with ESMTP id 2055BC0018 for ; Wed, 20 Jul 2022 23:08:22 +0000 (UTC) Received: by mail-pf1-f173.google.com with SMTP id g12so128262pfb.3 for ; Wed, 20 Jul 2022 16:08:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=Nszl3bsf2mnME2IbrRKNWdpEyNRDpL7edLFc4oh5rQk=; b=FwlOpTY1Xy5ZtTxSMQshR8kwWNBaEnIm9ywPyxdMxe3T/XxFEM/rXOZ8shtzx6jRRS 91M8w+897Sjn6+U9yhdoQBbOHvUIZbnudqyVKqIbiFL3KIAItk6n7+SblQBLvdTN309V 3g30TPedV8pjIQUF/c55Q9haSHOBERI23VMmBXMMfrJh6ECBxww0/hu+TOsLKCzYQ+gw GdGAnrtzEzMI3WfqML65BzsZafuMe/PQ0gjEW6sraCLwWPSVKqu83KinR/xUkg5DZP6e 1lFSj7wj5ru0N/Lu8b5OfGt3wIdl4NxJaMaNB7fu16Hj/vtrqiGttQ3ijzZC5VLTZ10Y P4jA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=Nszl3bsf2mnME2IbrRKNWdpEyNRDpL7edLFc4oh5rQk=; b=duRxAmswWTvvNo6b5ELe+qgMb0eq2ChVD6ELf2VaXPHJgLrLtZFY0XljLpeg/SGJzS 7eaEc+Kkfkx9Vz1+ZW3+CVW534d3oFI3tCmoJF35rWk+iENoqxi9Ceq2dT7vcAYT+pRR 5wNGSmGOch/EBM4X7pCd71uP+fAmYo4Q2FyL0F5tnDJTrclwrMGZVQRB2H9Z2o58+ZUD U0rTGUjnV94XH9iMSBTpYsTuIUDPr54lsjqZGK2G93vMKJjFULghfRfTtZ1YLalt3P9q +WpOkh7RjxUqXklwXCeehKsxdL+lkBohghkOeex7nk/TylifI4MkSSca2KaaycxDtn10 i7mQ== X-Gm-Message-State: AJIora8asaws1K3GS7EgFOu1rKwy6nLZ8VzgCQ/duh8RV9B6EF/ZaNj/ guEnm44fLJsrcaLcqUam/F1j+8Ffrds0xfB55iLTfQ== X-Google-Smtp-Source: AGRyM1sVSu2sWaA6KhwjXATdLIcan8zoTwRzYetVEkO/NR0+movB4Kj6gdLqTbANspAPpdn1ss3XaAW1x7VvJRw8slU= X-Received: by 2002:a62:1a8b:0:b0:528:d505:1a06 with SMTP id a133-20020a621a8b000000b00528d5051a06mr41267868pfa.78.1658358501699; Wed, 20 Jul 2022 16:08:21 -0700 (PDT) MIME-Version: 1.0 References: <20220519153713.819591-1-chao.p.peng@linux.intel.com> <20220519153713.819591-7-chao.p.peng@linux.intel.com> <20220624090246.GA2181919@chaop.bj.intel.com> <20220630222140.of4md7bufd5jv5bh@amd.com> <4fe3b47d-e94a-890a-5b87-6dfb7763bc7e@intel.com> <5d0b9341-78b5-0959-2517-0fb1fe83a205@intel.com> In-Reply-To: <5d0b9341-78b5-0959-2517-0fb1fe83a205@intel.com> From: Vishal Annapurve Date: Wed, 20 Jul 2022 16:08:10 -0700 Message-ID: Subject: Re: [PATCH v6 6/8] KVM: Handle page fault for private memory To: Xiaoyao Li Cc: Sean Christopherson , Michael Roth , Chao Peng , "Nikunj A. Dadhania" , kvm list , LKML , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, linux-doc@vger.kernel.org, qemu-devel@nongnu.org, Paolo Bonzini , Jonathan Corbet , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86 , "H . Peter Anvin" , Hugh Dickins , Jeff Layton , "J . Bruce Fields" , Andrew Morton , Mike Rapoport , Steven Price , "Maciej S . Szmigiero" , Vlastimil Babka , Yu Zhang , "Kirill A . Shutemov" , Andy Lutomirski , Jun Nakajima , Dave Hansen , Andi Kleen , David Hildenbrand , aarcange@redhat.com, ddutile@redhat.com, dhildenb@redhat.com, Quentin Perret , mhocko@suse.com Content-Type: text/plain; charset="UTF-8" ARC-Authentication-Results: i=1; imf22.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=FwlOpTY1; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf22.hostedemail.com: domain of vannapurve@google.com designates 209.85.210.173 as permitted sender) smtp.mailfrom=vannapurve@google.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1658358503; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=Nszl3bsf2mnME2IbrRKNWdpEyNRDpL7edLFc4oh5rQk=; b=65jKINMxDuREzmH7BI/X9+Ri1tIYX+ifbEmjVSvdRIofIa2FARhcqYJdewqnfRtjmzeXeB idRNTFM+W/YYSGSz+mYjh3qC2AjoJaybPeIyop17hMdEbiYgozbEZ/FiWEBoqMrFKaFlgZ WyswHLDXioSWewQQFixMeLLCI/z3S0U= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1658358503; a=rsa-sha256; cv=none; b=u9IkQRC0PVNGtCRr+714KgiYnVg4e31HoKhdkduMF4ALBFYaiEpLuk9th3pj2boH/lsgPr wSMABEKe6g1KXpzyWgry4+Xx0uKeaed8Xc+hZhJVbe1iSjpNQstwuW/zUu1oHUpfCa9P/5 Qgo/hWOqz3JaicKTDQuzxeknHFL5xzc= X-Stat-Signature: 1jzfmbmekptzsrg6qskpusqkpg54wksh X-Rspamd-Queue-Id: 2055BC0018 X-Rspamd-Server: rspam08 Authentication-Results: imf22.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=FwlOpTY1; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf22.hostedemail.com: domain of vannapurve@google.com designates 209.85.210.173 as permitted sender) smtp.mailfrom=vannapurve@google.com X-Rspam-User: X-HE-Tag: 1658358502-372028 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: > > Hmm, so a new slot->arch.page_attr array shouldn't be necessary, KVM can instead > > update slot->arch.lpage_info on shared<->private conversions. Detecting whether > > a given range is partially mapped could get nasty if KVM defers tracking to the > > backing store, but if KVM itself does the tracking as was previously suggested[*], > > then updating lpage_info should be relatively straightfoward, e.g. use > > xa_for_each_range() to see if a given 2mb/1gb range is completely covered (fully > > shared) or not covered at all (fully private). > > > > [*] https://lore.kernel.org/all/YofeZps9YXgtP3f1@google.com > > Yes, slot->arch.page_attr was introduced to help identify whether a page > is completely shared/private at given level. It seems XARRAY can serve > the same purpose, though I know nothing about it. Looking forward to > seeing the patch of using XARRAY. > > yes, update slot->arch.lpage_info is good to utilize the existing logic > and Isaku has applied it to slot->arch.lpage_info for 2MB support patches. Chao, are you planning to implement these changes to ensure proper handling of hugepages partially mapped as private/shared in subsequent versions of this series? Or is this something left to be handled by the architecture specific code? Regards, Vishal