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 X-Spam-Level: X-Spam-Status: No, score=-17.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 34A59C433E0 for ; Mon, 22 Mar 2021 11:28:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id ED3FF61998 for ; Mon, 22 Mar 2021 11:28:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230055AbhCVL1y (ORCPT ); Mon, 22 Mar 2021 07:27:54 -0400 Received: from mail.kernel.org ([198.145.29.99]:37954 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230062AbhCVL1r (ORCPT ); Mon, 22 Mar 2021 07:27:47 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 7C85F6191F; Mon, 22 Mar 2021 11:27:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1616412467; bh=2rQCKuAt/izeJLTYF4MTljlVoBabkTjdYFUOiQ846kg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=hCdtEo/cGqar4OAPPbwzZ28D6YUm9xkGkk1tyTKkmhP5BD0PvzRwzSgkiCBHJAHi3 0Oi+rd9f0hcStg2vT2O9d7ZbUfYzXiJdeqZcXb9Ep/TxIScPofF1zjqC16ZAlJeIxt QsT72YQmboZA/spmbvmXpElGMuaRW9TfpgpoP5EL2NSZNf8MFAJYAM98BddOjwfg2f C1oL7A2WJbicW71oOLiWXHvVnxBpNesdUlv2Gek+l4o+2ydE6+/ijgQs+EiILfSYm+ lPzMM8JFbFyGUpV+oX40F9xnPg1R8+0vIof9WNSw2uQxt47WjJFWBpJdWbMGLtz9xw 1NDgNzSETgyYg== Date: Mon, 22 Mar 2021 11:27:41 +0000 From: Will Deacon To: Quentin Perret Cc: catalin.marinas@arm.com, maz@kernel.org, james.morse@arm.com, julien.thierry.kdev@gmail.com, suzuki.poulose@arm.com, android-kvm@google.com, seanjc@google.com, mate.toth-pal@arm.com, linux-kernel@vger.kernel.org, robh+dt@kernel.org, linux-arm-kernel@lists.infradead.org, kernel-team@android.com, kvmarm@lists.cs.columbia.edu, tabba@google.com, ardb@kernel.org, mark.rutland@arm.com, dbrazdil@google.com Subject: Re: [PATCH v6 29/38] KVM: arm64: Use page-table to track page ownership Message-ID: <20210322112741.GC10318@willie-the-truck> References: <20210319100146.1149909-1-qperret@google.com> <20210319100146.1149909-30-qperret@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210319100146.1149909-30-qperret@google.com> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Mar 19, 2021 at 10:01:37AM +0000, Quentin Perret wrote: > As the host stage 2 will be identity mapped, all the .hyp memory regions > and/or memory pages donated to protected guestis will have to marked > invalid in the host stage 2 page-table. At the same time, the hypervisor > will need a way to track the ownership of each physical page to ensure > memory sharing or donation between entities (host, guests, hypervisor) is > legal. > > In order to enable this tracking at EL2, let's use the host stage 2 > page-table itself. The idea is to use the top bits of invalid mappings > to store the unique identifier of the page owner. The page-table owner > (the host) gets identifier 0 such that, at boot time, it owns the entire > IPA space as the pgd starts zeroed. > > Provide kvm_pgtable_stage2_set_owner() which allows to modify the > ownership of pages in the host stage 2. It re-uses most of the map() > logic, but ends up creating invalid mappings instead. This impacts > how we do refcount as we now need to count invalid mappings when they > are used for ownership tracking. > > Signed-off-by: Quentin Perret > --- > arch/arm64/include/asm/kvm_pgtable.h | 20 +++++ > arch/arm64/kvm/hyp/pgtable.c | 126 ++++++++++++++++++++++----- > 2 files changed, 122 insertions(+), 24 deletions(-) Acked-by: Will Deacon Will