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 E1AF1C433EF for ; Mon, 28 Mar 2022 21:56:39 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 309A18D0002; Mon, 28 Mar 2022 17:56:39 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 2B8648D0001; Mon, 28 Mar 2022 17:56:39 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 15A328D0002; Mon, 28 Mar 2022 17:56:39 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.a.hostedemail.com [64.99.140.24]) by kanga.kvack.org (Postfix) with ESMTP id 06DCF8D0001 for ; Mon, 28 Mar 2022 17:56:39 -0400 (EDT) Received: from smtpin10.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id C974B23369 for ; Mon, 28 Mar 2022 21:56:38 +0000 (UTC) X-FDA: 79295154876.10.7017888 Received: from mail-pj1-f48.google.com (mail-pj1-f48.google.com [209.85.216.48]) by imf25.hostedemail.com (Postfix) with ESMTP id 6AEF9A003B for ; Mon, 28 Mar 2022 21:56:38 +0000 (UTC) Received: by mail-pj1-f48.google.com with SMTP id mp11-20020a17090b190b00b001c79aa8fac4so594162pjb.0 for ; Mon, 28 Mar 2022 14:56:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=6f0ymM3PuwfqwB+Ks8BX5URDH2m1K5HGD6I5Zz3ti5Q=; b=NH33JvMBIiaBL7bqX1PZbItw0IUfTlXD/v9oqWvIintdpR2SKhlN4igL4tSF3ZcIDp sV7t/z5vUZKMAtkNNIq3fFQIP8pHmS/iH5/d3fDdTtMOUOLAAD1+ikzXU14mMAKEblor 4qnKBqDpRZ8YwY9xRDH8/eoduqsp55EmqJBNPUueA0rhCUGOiGOlII+LABdG9Wk0Hc3R 2awwTxAZNazlQDZKuyoiqCopjHbUAqm/HeKkYLztMk8p5n3ui448LMrVKA1TASyWX6yl sdiO5htV6zcmiQKdeSxAr5/4UbEU2TU1WB53fCfupefYoUkwxYsso2NclryjmPsTGZ3j ZU4w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=6f0ymM3PuwfqwB+Ks8BX5URDH2m1K5HGD6I5Zz3ti5Q=; b=7my9cpWgN6oVbgMXkjFtQ5m3PBuX0K/Yd2a9fmqW0VQZNPs2E7Q80be6x+1+CfL8Z3 UbgksnAi4wboj3rcf1XTb/nxVsggfI+vRIyN1n76yrdT1Z+ivbRMd+Hl7EAHADXS4E2Z LhuPAECKVBDWmgX1/AVpy47BR54ZqbCMcpAt+MFKqm66PSkT/VBJUOLDxv9rhGmK8MQa 6fs+Ebnxomg+di7lHgG9JB8FP2LvbjLeBMuRRxhmAaGjNvECOVyG+g73QgVytZm3u3Cb gkP1tnkOSgCUo5BugzKJQaQqePi3B+tn53oDyrDSqWiARot4sUzuM/0CEZYXPH5VfXBH XVZA== X-Gm-Message-State: AOAM531ffTDsbJaYb+br10usMYxXmD75fbgH/uTcvAhjiMCg7n3Yh0X6 /Gu5pCn5QPAAhFBQDfSIIacamA== X-Google-Smtp-Source: ABdhPJxzsrphJ5SAHT6xGnE9Zsu1eetVvZtTotZHLXscXA64kqeWZA3FguQ77T0PrIoYl9MNauVa6A== X-Received: by 2002:a17:90a:d3d1:b0:1bb:fdc5:182 with SMTP id d17-20020a17090ad3d100b001bbfdc50182mr1207841pjw.206.1648504597150; Mon, 28 Mar 2022 14:56:37 -0700 (PDT) Received: from google.com (157.214.185.35.bc.googleusercontent.com. [35.185.214.157]) by smtp.gmail.com with ESMTPSA id 3-20020a630003000000b003828fc1455esm13974792pga.60.2022.03.28.14.56.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 28 Mar 2022 14:56:36 -0700 (PDT) Date: Mon, 28 Mar 2022 21:56:33 +0000 From: Sean Christopherson To: Chao Peng Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-api@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@kernel.org, "H . Peter Anvin" , Hugh Dickins , Jeff Layton , "J . Bruce Fields" , Andrew Morton , Mike Rapoport , Steven Price , "Maciej S . Szmigiero" , Vlastimil Babka , Vishal Annapurve , Yu Zhang , "Kirill A . Shutemov" , luto@kernel.org, jun.nakajima@intel.com, dave.hansen@intel.com, ak@linux.intel.com, david@redhat.com Subject: Re: [PATCH v5 05/13] KVM: Extend the memslot to support fd-based private memory Message-ID: References: <20220310140911.50924-1-chao.p.peng@linux.intel.com> <20220310140911.50924-6-chao.p.peng@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220310140911.50924-6-chao.p.peng@linux.intel.com> X-Stat-Signature: yky545bddieu1xd6j8res5ztachfdno3 Authentication-Results: imf25.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=NH33JvMB; spf=pass (imf25.hostedemail.com: domain of seanjc@google.com designates 209.85.216.48 as permitted sender) smtp.mailfrom=seanjc@google.com; dmarc=pass (policy=reject) header.from=google.com X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 6AEF9A003B X-HE-Tag: 1648504598-451468 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 Thu, Mar 10, 2022, Chao Peng wrote: > Extend the memslot definition to provide fd-based private memory support > by adding two new fields (private_fd/private_offset). The memslot then > can maintain memory for both shared pages and private pages in a single > memslot. Shared pages are provided by existing userspace_addr(hva) field > and private pages are provided through the new private_fd/private_offset > fields. > > Since there is no 'hva' concept anymore for private memory so we cannot > rely on get_user_pages() to get a pfn, instead we use the newly added > memfile_notifier to complete the same job. > > This new extension is indicated by a new flag KVM_MEM_PRIVATE. > > Signed-off-by: Yu Zhang > Signed-off-by: Chao Peng > --- > Documentation/virt/kvm/api.rst | 37 +++++++++++++++++++++++++++------- > include/linux/kvm_host.h | 7 +++++++ > include/uapi/linux/kvm.h | 8 ++++++++ > 3 files changed, 45 insertions(+), 7 deletions(-) > > diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst > index 3acbf4d263a5..f76ac598606c 100644 > --- a/Documentation/virt/kvm/api.rst > +++ b/Documentation/virt/kvm/api.rst > @@ -1307,7 +1307,7 @@ yet and must be cleared on entry. > :Capability: KVM_CAP_USER_MEMORY > :Architectures: all > :Type: vm ioctl > -:Parameters: struct kvm_userspace_memory_region (in) > +:Parameters: struct kvm_userspace_memory_region(_ext) (in) > :Returns: 0 on success, -1 on error > > :: > @@ -1320,9 +1320,17 @@ yet and must be cleared on entry. > __u64 userspace_addr; /* start of the userspace allocated memory */ > }; > > + struct kvm_userspace_memory_region_ext { > + struct kvm_userspace_memory_region region; Peeking ahead, the partial switch to the _ext variant is rather gross. I would prefer that KVM use an entirely different, but binary compatible, struct internally. And once the kernel supports C11[*], I'm pretty sure we can make the "region" in _ext an anonymous struct, and make KVM's internal struct a #define of _ext. That should minimize the churn (no need to get the embedded "region" field), reduce line lengths, and avoid confusion due to some flows taking the _ext but others dealing with only the "base" struct. Maybe kvm_user_memory_region or kvm_user_mem_region? Though it's tempting to be evil and usurp the old kvm_memory_region :-) E.g. pre-C11 do struct kvm_userspace_memory_region_ext { struct kvm_userspace_memory_region region; __u64 private_offset; __u32 private_fd; __u32 padding[5]; }; #ifdef __KERNEL__ struct kvm_user_mem_region { __u32 slot; __u32 flags; __u64 guest_phys_addr; __u64 memory_size; /* bytes */ __u64 userspace_addr; /* start of the userspace allocated memory */ __u64 private_offset; __u32 private_fd; __u32 padding[5]; }; #endif and then post-C11 do struct kvm_userspace_memory_region_ext { #ifdef __KERNEL__ struct kvm_userspace_memory_region region; #else struct kvm_userspace_memory_region; #endif __u64 private_offset; __u32 private_fd; __u32 padding[5]; }; #ifdef __KERNEL__ #define kvm_user_mem_region kvm_userspace_memory_region_ext #endif [*] https://lore.kernel.org/all/20220301145233.3689119-1-arnd@kernel.org > + __u64 private_offset; > + __u32 private_fd; > + __u32 padding[5]; > +};