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 0B78EC43334 for ; Thu, 21 Jul 2022 09:34:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232478AbiGUJe0 (ORCPT ); Thu, 21 Jul 2022 05:34:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36290 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229663AbiGUJeZ (ORCPT ); Thu, 21 Jul 2022 05:34:25 -0400 Received: from mga07.intel.com (mga07.intel.com [134.134.136.100]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 897D48053F; Thu, 21 Jul 2022 02:34:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1658396064; x=1689932064; h=date:from:to:cc:subject:message-id:reply-to:references: mime-version:in-reply-to; bh=wCb9PX4Sp0/BeSAl8rvIo3FQtV/S7LHLo0bGkTMYvrA=; b=TztBwVMhKq369DA2k08ewtfAXu9LZpAjXKVivbEJIVR6GjjdyXJ4DKx2 L/bM0MgvQmYONtr8u3N504B/v+KOZDhtOx5aQJSH6xKe5f+e9d+yvIP4f cwF84aN6RNa7V0Fq+KMd9H+4yFmFH8eWEg4oYnr6MWsctfEWUrWw8OSJB +DBGymO1Im9DlG9PUUMSWmTWLPHppbN7T86A1DwLB7/kAhRgcvvM1AAzQ KY5eeys0UEejnRrnlebBNbUB4PcefCXj0Nmqo+QQzUK/Uhs6XJLSss/0T 4psZu8l/Rts/oKACBA/aElGcQOCzQ1EyZ55yeHRnP/TQDJbsLExiTTadI w==; X-IronPort-AV: E=McAfee;i="6400,9594,10414"; a="350988486" X-IronPort-AV: E=Sophos;i="5.92,289,1650956400"; d="scan'208";a="350988486" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Jul 2022 02:34:06 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.92,289,1650956400"; d="scan'208";a="656666919" Received: from chaop.bj.intel.com (HELO localhost) ([10.240.193.75]) by fmsmga008.fm.intel.com with ESMTP; 21 Jul 2022 02:33:56 -0700 Date: Thu, 21 Jul 2022 17:29:06 +0800 From: Chao Peng To: Wei Wang Cc: Sean Christopherson , "Gupta, Pankaj" , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, linux-doc@vger.kernel.org, qemu-devel@nongnu.org, linux-kselftest@vger.kernel.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 , Shuah Khan , 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, aarcange@redhat.com, ddutile@redhat.com, dhildenb@redhat.com, Quentin Perret , Michael Roth , mhocko@suse.com, Muchun Song Subject: Re: [PATCH v7 11/14] KVM: Register/unregister the guest private memory regions Message-ID: <20220721092906.GA153288@chaop.bj.intel.com> Reply-To: Chao Peng References: <20220706082016.2603916-1-chao.p.peng@linux.intel.com> <20220706082016.2603916-12-chao.p.peng@linux.intel.com> <20220719140843.GA84779@chaop.bj.intel.com> <36e671d2-6b95-8e4f-c2ac-fee4b2670c6e@amd.com> <20220720150706.GB124133@chaop.bj.intel.com> <45ae9f57-d595-f202-abb5-26a03a2ca131@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <45ae9f57-d595-f202-abb5-26a03a2ca131@linux.intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-api@vger.kernel.org On Thu, Jul 21, 2022 at 03:34:59PM +0800, Wei Wang wrote: > > > On 7/21/22 00:21, Sean Christopherson wrote: > > On Wed, Jul 20, 2022, Gupta, Pankaj wrote: > > > > > > > > +bool __weak kvm_arch_private_mem_supported(struct kvm *kvm) > > Use kvm_arch_has_private_mem(), both because "has" makes it obvious this is checking > > a flag of sorts, and to align with other helpers of this nature (and with > > CONFIG_HAVE_KVM_PRIVATE_MEM). > > > > $ git grep kvm_arch | grep supported | wc -l > > 0 > > $ git grep kvm_arch | grep has | wc -l > > 26 Make sense. kvm_arch_has_private_mem it actually better. > > > > > > > > > > +#ifdef CONFIG_HAVE_KVM_PRIVATE_MEM > > > > > > > > + case KVM_MEMORY_ENCRYPT_REG_REGION: > > > > > > > > + case KVM_MEMORY_ENCRYPT_UNREG_REGION: { > > > > > > > > + struct kvm_enc_region region; > > > > > > > > + > > > > > > > > + if (!kvm_arch_private_mem_supported(kvm)) > > > > > > > > + goto arch_vm_ioctl; > > > > > > > > + > > > > > > > > + r = -EFAULT; > > > > > > > > + if (copy_from_user(®ion, argp, sizeof(region))) > > > > > > > > + goto out; > > > > > > > > + > > > > > > > > + r = kvm_vm_ioctl_set_encrypted_region(kvm, ioctl, ®ion); > > > > > > > this is to store private region metadata not only the encrypted region? > > > > > > Correct. > > > > > Sorry for not being clear, was suggesting name change of this function from: > > > > > "kvm_vm_ioctl_set_encrypted_region" to "kvm_vm_ioctl_set_private_region" > > > > Though I don't have strong reason to change it, I'm fine with this and > > > Yes, no strong reason, just thought "kvm_vm_ioctl_set_private_region" would > > > depict the actual functionality :) > > > > > > > this name matches the above kvm_arch_private_mem_supported perfectly. > > > BTW could not understand this, how "kvm_vm_ioctl_set_encrypted_region" > > > matches "kvm_arch_private_mem_supported"? > > Chao is saying that kvm_vm_ioctl_set_private_region() pairs nicely with > > kvm_arch_private_mem_supported(), not that the "encrypted" variant pairs nicely. > > > > I also like using "private" instead of "encrypted", though we should probably > > find a different verb than "set", because calling "set_private" when making the > > region shared is confusing. I'm struggling to come up with a good alternative > > though. > > > > kvm_vm_ioctl_set_memory_region() is already taken by KVM_SET_USER_MEMORY_REGION, > > and that also means that anything with "memory_region" in the name is bound to be > > confusing. > > > > Hmm, and if we move away from "encrypted", it probably makes sense to pass in > > addr+size instead of a kvm_enc_region. This makes sense. > > > > Maybe this? > > > > static int kvm_vm_ioctl_set_or_clear_mem_private(struct kvm *kvm, gpa_t gpa, > > gpa_t size, bool set_private) Currently this should work. > > > > and then: > > > > #ifdef CONFIG_HAVE_KVM_PRIVATE_MEM > > case KVM_MEMORY_ENCRYPT_REG_REGION: > > case KVM_MEMORY_ENCRYPT_UNREG_REGION: { > > bool set = ioctl == KVM_MEMORY_ENCRYPT_REG_REGION; > > struct kvm_enc_region region; > > > > if (!kvm_arch_private_mem_supported(kvm)) > > goto arch_vm_ioctl; > > > > r = -EFAULT; > > if (copy_from_user(®ion, argp, sizeof(region))) > > goto out; > > > > r = kvm_vm_ioctl_set_or_clear_mem_private(kvm, region.addr, > > region.size, set); > > break; > > } > > #endif > > > > I don't love it, so if someone has a better idea... > > > Maybe you could tag it with cgs for all the confidential guest support > related stuff: > e.g. kvm_vm_ioctl_set_cgs_mem() > > bool is_private = ioctl == KVM_MEMORY_ENCRYPT_REG_REGION; > ... > kvm_vm_ioctl_set_cgs_mem(, is_private) If we plan to widely use such abbr. through KVM (e.g. it's well known), I'm fine. I actually use mem_attr in patch: https://lkml.org/lkml/2022/7/20/610 But I also don't quite like it, it's so generic and sounds say nothing. But I do want a name can cover future usages other than just private/shared (pKVM for example may have a third state). Thanks, Chao