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 B6CFAC4167B for ; Tue, 20 Dec 2022 07:47:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229924AbiLTHrv (ORCPT ); Tue, 20 Dec 2022 02:47:51 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60078 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229556AbiLTHrt (ORCPT ); Tue, 20 Dec 2022 02:47:49 -0500 Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BAD2A106; Mon, 19 Dec 2022 23:47:48 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1671522468; x=1703058468; h=date:from:to:cc:subject:message-id:reply-to:references: mime-version:in-reply-to; bh=18JY1Rv+JmD8fqHB1Zwfy2CyVc6av0CO+XzWDU5pLU8=; b=cvT3hrCnlih0FOk9rqv+UWjL3sEjGz0Y7aaLsz37QwUFtTyPcNKqcYFE p4HFw9mVsrCDLGtvZFb65MKGgey0+vZ5rHKCU6Khc15qVY3oZp3HnvqTI RcPpA+cy9HNUSBNNWdo63xMW1LG3Iu5YtiuinDx0oJbXVeR/qn/k5+GHp Fx2Bt8MCL/zjLBAlv+6Y19rX0NPzDFLz+qpvt/9uj5rJ0CDvzOfxs827I s7bvoHeI1wcA5LJb5xYGllAOWxAFKIO958eWZEXm0unBG29D4aM2V3/Oe 8kPqSp3/Yy7YbJfbHC3t1ie9PykQtP6HYnngfkP7IsuILxbCmk0BJpzMz Q==; X-IronPort-AV: E=McAfee;i="6500,9779,10566"; a="317187844" X-IronPort-AV: E=Sophos;i="5.96,258,1665471600"; d="scan'208";a="317187844" Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Dec 2022 23:47:47 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6500,9779,10566"; a="896319288" X-IronPort-AV: E=Sophos;i="5.96,258,1665471600"; d="scan'208";a="896319288" Received: from chaop.bj.intel.com (HELO localhost) ([10.240.193.75]) by fmsmga006.fm.intel.com with ESMTP; 19 Dec 2022 23:47:34 -0800 Date: Tue, 20 Dec 2022 15:43:18 +0800 From: Chao Peng To: Borislav Petkov Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, linux-doc@vger.kernel.org, qemu-devel@nongnu.org, Paolo Bonzini , Jonathan Corbet , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Thomas Gleixner , Ingo Molnar , Arnd Bergmann , Naoya Horiguchi , Miaohe Lin , 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 , tabba@google.com, Michael Roth , mhocko@suse.com, wei.w.wang@intel.com Subject: Re: [PATCH v10 3/9] KVM: Extend the memslot to support fd-based private memory Message-ID: <20221220074318.GC1724933@chaop.bj.intel.com> Reply-To: Chao Peng References: <20221202061347.1070246-1-chao.p.peng@linux.intel.com> <20221202061347.1070246-4-chao.p.peng@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-api@vger.kernel.org On Mon, Dec 19, 2022 at 03:36:28PM +0100, Borislav Petkov wrote: > On Fri, Dec 02, 2022 at 02:13:41PM +0800, Chao Peng wrote: > > In memory encryption usage, guest memory may be encrypted with special > > key and can be accessed only by the guest itself. We call such memory > > private memory. It's valueless and sometimes can cause problem to allow > > valueless? > > I can't parse that. It's unnecessary and ... > > > userspace to access guest private memory. This new KVM memslot extension > > allows guest private memory being provided through a restrictedmem > > backed file descriptor(fd) and userspace is restricted to access the > > bookmarked memory in the fd. > > bookmarked? userspace is restricted to access the memory content in the fd. > > > This new extension, indicated by the new flag KVM_MEM_PRIVATE, adds two > > additional KVM memslot fields restricted_fd/restricted_offset to allow > > userspace to instruct KVM to provide guest memory through restricted_fd. > > 'guest_phys_addr' is mapped at the restricted_offset of restricted_fd > > and the size is 'memory_size'. > > > > The extended memslot can still have the userspace_addr(hva). When use, a > > "When un use, ..." When both userspace_addr and restricted_fd/offset were used, ... > > ... > > > diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig > > index a8e379a3afee..690cb21010e7 100644 > > --- a/arch/x86/kvm/Kconfig > > +++ b/arch/x86/kvm/Kconfig > > @@ -50,6 +50,8 @@ config KVM > > select INTERVAL_TREE > > select HAVE_KVM_PM_NOTIFIER if PM > > select HAVE_KVM_MEMORY_ATTRIBUTES > > + select HAVE_KVM_RESTRICTED_MEM if X86_64 > > + select RESTRICTEDMEM if HAVE_KVM_RESTRICTED_MEM > > Those deps here look weird. > > RESTRICTEDMEM should be selected by TDX_GUEST as it can't live without > it. RESTRICTEDMEM is needed by TDX_HOST, not TDX_GUEST. > > Then you don't have to select HAVE_KVM_RESTRICTED_MEM simply because of > X86_64 - you need that functionality when the respective guest support > is enabled in KVM. Letting the actual feature(e.g. TDX or pKVM) select it or add dependency sounds a viable and clearer solution. Sean, let me know your opinion. > > Then, looking forward into your patchset, I'm not sure you even > need HAVE_KVM_RESTRICTED_MEM - you could make it all depend on > CONFIG_RESTRICTEDMEM. But that's KVM folks call - I'd always aim for > less Kconfig items because we have waay too many. The only reason to add another HAVE_KVM_RESTRICTED_MEM is some code only works for 64bit[*] and CONFIG_RESTRICTEDMEM is not sufficient to enforce that. [*] https://lore.kernel.org/all/YkJLFu98hZOvTSrL@google.com/ Thanks, Chao > > Thx. > > -- > Regards/Gruss, > Boris. > > https://people.kernel.org/tglx/notes-about-netiquette