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 41507C3F6B0 for ; Tue, 26 Jul 2022 14:37:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239073AbiGZOhy (ORCPT ); Tue, 26 Jul 2022 10:37:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47172 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229530AbiGZOhv (ORCPT ); Tue, 26 Jul 2022 10:37:51 -0400 Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 975A21166; Tue, 26 Jul 2022 07:37:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1658846270; x=1690382270; h=date:from:to:cc:subject:message-id:reply-to:references: mime-version:in-reply-to; bh=R3oRo4zkn7MbH8aoe6XdFaSA5NI0RZoxoAoMOkLwIII=; b=FYZNBJ9CLI1zOgxwxAuG0P99TGus0+Uh7H+41+TN9KTX+tEk8KOkbE9f 4IYXt2lrRXSQzPNY87y16pIMqo1FKmQb0fRcBSPhXF6YdgDEWWe1Qb8CS w4oLc/PVT4cEWUWLOCHQIm2+B+hJkZyHsntADPY0Mqpl7Af60FK2pep/D lZ2p/yQraYpOjpQa7e6n5wkzzM96ZFZq+2LTT0itvl90xFez60kpKolX/ fwkahmSncKa1r4v324rSozS+fdEskvBBFXHSBiddgVWJWqYtaWPCG3tB6 5gdRPcQ3rs1aWNn0RN/bCDGJZtpICoiDtyfog4AKSOPPeQT2duIkY1f5q Q==; X-IronPort-AV: E=McAfee;i="6400,9594,10420"; a="313735726" X-IronPort-AV: E=Sophos;i="5.93,193,1654585200"; d="scan'208";a="313735726" Received: from orsmga007.jf.intel.com ([10.7.209.58]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Jul 2022 07:37:50 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.93,193,1654585200"; d="scan'208";a="597044850" Received: from chaop.bj.intel.com (HELO localhost) ([10.240.193.75]) by orsmga007.jf.intel.com with ESMTP; 26 Jul 2022 07:37:47 -0700 Date: Tue, 26 Jul 2022 22:32:59 +0800 From: Chao Peng To: "Nikunj A. Dadhania" Cc: Sean Christopherson , isaku.yamahata@intel.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, isaku.yamahata@gmail.com, Paolo Bonzini Subject: Re: [PATCH v7 000/102] KVM TDX basic feature support Message-ID: <20220726143259.GA323308@chaop.bj.intel.com> Reply-To: Chao Peng References: <20220720145927.GA124133@chaop.bj.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-kernel@vger.kernel.org On Mon, Jul 25, 2022 at 07:16:24PM +0530, Nikunj A. Dadhania wrote: > On 7/20/2022 8:29 PM, Chao Peng wrote: > > On Thu, Jul 14, 2022 at 01:03:46AM +0000, Sean Christopherson wrote: > > ... > >> > >> Option D). track shared regions in an Xarray, update kvm_arch_memory_slot.lpage_info > >> on insertion/removal to (dis)allow hugepages as needed. > >> > >> + efficient on KVM page fault (no new lookups) > >> + zero memory overhead (assuming KVM has to eat the cost of the Xarray anyways) > >> + straightforward to implement > >> + can (and should) be merged as part of the UPM series > >> > >> I believe xa_for_each_range() can be used to see if a given 2mb/1gb range is > >> completely covered (fully shared) or not covered at all (fully private), but I'm > >> not 100% certain that xa_for_each_range() works the way I think it does. > > > > Hi Sean, > > > > Below is the implementation to support 2M as you mentioned as option D. > > It's based on UPM v7 xarray code: https://lkml.org/lkml/2022/7/6/259 > > > > Everything sounds good, the only trick bit is inc/dec disallow_lpage. If > > we still treat it as a count, it will be a challenge to make the inc/dec > > balanced. So in this patch I stole a bit for the purpose, looks ugly. > > > > Any feedback is welcome. > > > > Thanks, > > Chao > > > > ----------------------------------------------------------------------- > > From: Chao Peng > > Date: Wed, 20 Jul 2022 11:37:18 +0800 > > Subject: [PATCH] KVM: Add large page support for private memory > > > > Update lpage_info when handling KVM_MEMORY_ENCRYPT_{UN,}REG_REGION. > > > > Reserve a bit in disallow_lpage to indicate a large page has > > private/share pages mixed. > > > > Signed-off-by: Chao Peng > > --- > > > > +static void update_mem_lpage_info(struct kvm *kvm, > > + struct kvm_memory_slot *slot, > > + unsigned int attr, > > + gfn_t start, gfn_t end) > > +{ > > + unsigned long lpage_start, lpage_end; > > + unsigned long gfn, pages, mask; > > + int level; > > + > > + for (level = PG_LEVEL_2M; level <= KVM_MAX_HUGEPAGE_LEVEL; level++) { > > + pages = KVM_PAGES_PER_HPAGE(level); > > + mask = ~(pages - 1); > > + lpage_start = start & mask; > > + lpage_end = end & mask; > > + > > + /* > > + * We only need to scan the head and tail page, for middle pages > > + * we know they are not mixed. > > + */ > > + update_mixed(lpage_info_slot(lpage_start, slot, level), > > + mem_attr_is_mixed(kvm, attr, lpage_start, > > + lpage_start + pages)); > > + > > + if (lpage_start == lpage_end) > > + return; > > + > > + for (gfn = lpage_start + pages; gfn < lpage_end; gfn += pages) { > > + update_mixed(lpage_info_slot(gfn, slot, level), false); > > + } > > Boundary check missing here for the case when gfn reaches lpage_end. > > if (gfn == lpage_end) > return; In this case, it's actually the tail page that I want to scan for with below code. It's also possible I misunderstand something here. Chao > > > + > > + update_mixed(lpage_info_slot(lpage_end, slot, level), > > + mem_attr_is_mixed(kvm, attr, lpage_end, > > + lpage_end + pages)); > > + } > > +} > > Regards > Nikunj