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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id EF235EB64DA for ; Thu, 20 Jul 2023 15:15:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232470AbjGTPPI (ORCPT ); Thu, 20 Jul 2023 11:15:08 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52026 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232512AbjGTPPB (ORCPT ); Thu, 20 Jul 2023 11:15:01 -0400 Received: from mail-yb1-xb49.google.com (mail-yb1-xb49.google.com [IPv6:2607:f8b0:4864:20::b49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6B9DD273C for ; Thu, 20 Jul 2023 08:14:50 -0700 (PDT) Received: by mail-yb1-xb49.google.com with SMTP id 3f1490d57ef6-cf4cb742715so776289276.2 for ; Thu, 20 Jul 2023 08:14:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1689866089; x=1690470889; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=jyO/GZcznauRS+IxFjefkQ411ageTxV8Pq4vykaVGvo=; b=zTnr2gXYIfqrhSL0WP50qLuqh3ZSH0gfVOnKmqwBvWYCge11/urc6Mcz48DQC5VeI6 s/bgjrFlzBMXd0PxaHBdxoR2ZqKrVqjnkCnhcQbbSnTvJYQ3aBe8wGkYdi1iCIBydfGh kDBro1Ztm9Xs7cfFTvZ7Ey8Gxe05PCCIDn4nx9L+2nwHbFPbro9d3jap/zFGaLY9lF26 GO0Vu5OUt+nUmBQOwJoSD8n40MC7ZQXlXpaj59Y1nIZxZy5/TzmEdTKZZXkcpmTSKYdO Y0fmzsgj8zCYsvUdMgpPWIv3Ur8RBp8NDUrrxEURomdLy8NcckIjCEtpSXTS4KS2mzFS 29+g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1689866089; x=1690470889; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=jyO/GZcznauRS+IxFjefkQ411ageTxV8Pq4vykaVGvo=; b=TG4jc3F6dGExDgLIY0Ek2KTugAMWv/zJroWzIdHnitSZ8XGBSs1KgsTgeTYln0/Zkj MEkHOBBT4U+et1KDxh+R1qS479EFZ/cQKjT7jtR02qe01QQekeLwfn9gxSIYRBTKhy/Q 6Yteo7NDNgt7VzXA9eyQ+0PTahZtWYryC/R8Bxe4/Ms17p4/1uYNDZ1T3jvErpAdtDF8 rNbSq/+5zdX8ZgHgaggTuw3AX4s9Jt2mHueCwFTBkvqar7aIbgNysgGG/dw23kFYFkL8 9qlRvCnc0P5qZwDT5aSN3LsfShErPeTEznIWxi6fxMOozEsYwMwrSQtFmTJ5WjATE5lC sUng== X-Gm-Message-State: ABy/qLaT6OA49Wl7idxLZ0UogpSlTE2r0+RpY4pUKewMry6BBNLo0zPN wMO8IDTbaM0blA0lZu7mRRdaLYzxjkw= X-Google-Smtp-Source: APBJJlHgB47FmXfk0Rt+Hyu6ZgRaD/aSiXUWbAQerG5WzFKE3pY5cKaePpzhb9OPvUF/5F0XHeWF4GbW2oc= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a25:a105:0:b0:c65:8983:ac2 with SMTP id z5-20020a25a105000000b00c6589830ac2mr17912ybh.5.1689866089303; Thu, 20 Jul 2023 08:14:49 -0700 (PDT) Date: Thu, 20 Jul 2023 08:14:47 -0700 In-Reply-To: <83eb5c50-7287-7845-ffc3-a7c58e638ea5@intel.com> Mime-Version: 1.0 References: <20230718234512.1690985-1-seanjc@google.com> <20230718234512.1690985-13-seanjc@google.com> <83eb5c50-7287-7845-ffc3-a7c58e638ea5@intel.com> Message-ID: Subject: Re: [RFC PATCH v11 12/29] KVM: Add KVM_CREATE_GUEST_MEMFD ioctl() for guest-specific backing memory From: Sean Christopherson To: Xiaoyao Li Cc: Paolo Bonzini , Marc Zyngier , Oliver Upton , Huacai Chen , Michael Ellerman , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , "Matthew Wilcox (Oracle)" , Andrew Morton , Paul Moore , James Morris , "Serge E. Hallyn" , kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, Chao Peng , Fuad Tabba , Jarkko Sakkinen , Yu Zhang , Vishal Annapurve , Ackerley Tng , Maciej Szmigiero , Vlastimil Babka , David Hildenbrand , Quentin Perret , Michael Roth , Wang , Liam Merwick , Isaku Yamahata , "Kirill A . Shutemov" Content-Type: text/plain; charset="us-ascii" Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Thu, Jul 20, 2023, Xiaoyao Li wrote: > On 7/19/2023 7:44 AM, Sean Christopherson wrote: > > @@ -5134,6 +5167,16 @@ static long kvm_vm_ioctl(struct file *filp, > > case KVM_GET_STATS_FD: > > r = kvm_vm_ioctl_get_stats_fd(kvm); > > break; > > + case KVM_CREATE_GUEST_MEMFD: { > > + struct kvm_create_guest_memfd guest_memfd; > > + > > + r = -EFAULT; > > + if (copy_from_user(&guest_memfd, argp, sizeof(guest_memfd))) > > + goto out; > > + > > + r = kvm_gmem_create(kvm, &guest_memfd); > > + break; > > + } > > Does it need a new CAP to indicate the support of guest_memfd? Yeah, I meant to add that to the TODO list and forgot (obviously). > This is patch series introduces 3 new CAPs and it seems any one of them can > serve as the indicator of guest_memfd. > > +#define KVM_CAP_USER_MEMORY2 230 > +#define KVM_CAP_MEMORY_ATTRIBUTES 231 > +#define KVM_CAP_VM_TYPES 232 The number of new caps being added is the main why I didn't just add another one. On the other hand, we have room for a few billion caps, so one more isn't a big deal. So yeah, KVM_CAP_GUEST_MEMFD is probably the way to go.