From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-yb1-f202.google.com (mail-yb1-f202.google.com [209.85.219.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6EC8718B07 for ; Thu, 20 Jul 2023 15:14:50 +0000 (UTC) Received: by mail-yb1-f202.google.com with SMTP id 3f1490d57ef6-cf4cb742715so776290276.2 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=Vj4CBtsZ/EVBbDNkrO2WOwgVjTWxwJ/lmeZWg3FrCVC2JRBmKie/UtHeKN1Nz6XGw/ BuLDWrUKBCmHIxXfdLk6qt9Dqzg2dvKOy+70lRsbUino1D1ovg9nHXR7jUHW8DceFy6+ i/dEkRfCHnPIVZsAZAMHkGioYi6kgTXkv7mcS6gVScaaV6wp12DsaGk+Av1W/FERSwji Mq2xyT95mp+fLM3hCvKuCcpEpynCj+qLK+yiW9qMm8HbDb9kRnnReAUZhDnRh6AMnWnc Pen+bicGwCmUp7u5eZa4GRUyVQu9LDMZMRqdxHmgkgt+6lRZaXhc2PITWyCMWcM5spEp 3MHw== X-Gm-Message-State: ABy/qLbXOAjcQw4m+4F9XpTzDuZyYgoKeFFq3XJHcYQucOGOmYIIVxLp 5DpwDp8oJSmZx0SMNj5t8pBZC4tWUXw= 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> Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: 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" 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.