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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CA656C433EF for ; Thu, 18 Nov 2021 18:04:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A19F46138D for ; Thu, 18 Nov 2021 18:04:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234251AbhKRSHs (ORCPT ); Thu, 18 Nov 2021 13:07:48 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:28624 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229660AbhKRSHr (ORCPT ); Thu, 18 Nov 2021 13:07:47 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1637258686; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=o1StevES6LFcxzq9JDjfXql1NL6xb4MMT2aPM+84e4g=; b=ONmuSn7Zu/jEiwSqNXJ8vLn5yF2+dLLDaN9XHayKNQx01NjJUR9LcwZtaSJkOMkkkDNzDK pC2mRDL8dlWDeNdwv4yU4THXJzz67CKetWp+A5MqzJPmPQ95Q+a4i+9TGZwgH38bfXoZpu G40SD8FmYm0J9JPvHb6kXSQ+TaNOwjc= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-207-UDZOTr8sOcmcdfUFsHXRwA-1; Thu, 18 Nov 2021 13:04:43 -0500 X-MC-Unique: UDZOTr8sOcmcdfUFsHXRwA-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 00533804143; Thu, 18 Nov 2021 18:04:41 +0000 (UTC) Received: from [10.39.192.245] (unknown [10.39.192.245]) by smtp.corp.redhat.com (Postfix) with ESMTP id D92384ABA3; Thu, 18 Nov 2021 18:04:37 +0000 (UTC) Message-ID: Date: Thu, 18 Nov 2021 19:04:36 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.2.0 Subject: Re: [RFC 07/19] KVM: x86/mmu: Factor wrprot for nested PML out of make_spte Content-Language: en-US To: Ben Gardon , Sean Christopherson Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Peter Xu , Peter Shier , David Matlack , Mingwei Zhang , Yulei Zhang , Wanpeng Li , Xiao Guangrong , Kai Huang , Keqian Zhu , David Hildenbrand References: <20211110223010.1392399-1-bgardon@google.com> <20211110223010.1392399-8-bgardon@google.com> From: Paolo Bonzini In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/18/21 18:43, Ben Gardon wrote: >> Aha! The dependency on @vcpu can be avoided without having to take a flag from >> the caller. The shadow page has everything we need. The check is really "is this >> a page for L2 EPT". The kvm_x86_ops.cpu_dirty_log_size gets us the EPT part, and >> kvm_mmu_page.guest_mode gets us the L2 part. > > Haha that's way cleaner than what I was doing! Seems like an obvious > solution in retrospect. I'll include this in the next version of the > series I send out unless Paolo beats me and just merges it directly. > Happy to give this my reviewed-by. Yeah, I am including the early cleanup parts because it makes no sense to hold off on them; and Sean's patch qualifies as well. I can't blame you for not remembering role.guest_mode. Jim added it for a decidedly niche reason: commit 1313cc2bd8f6568dd8801feef446afbe43e6d313 Author: Jim Mattson Date: Wed May 9 17:02:04 2018 -0400 kvm: mmu: Add guest_mode to kvm_mmu_page_role L1 and L2 need to have disjoint mappings, so that L1's APIC access page (under VMX) can be omitted from L2's mappings. Signed-off-by: Jim Mattson Signed-off-by: Krish Sadhukhan Signed-off-by: Paolo Bonzini though it's actually gotten a lot more important than just that: commit 992edeaefed682511bd173dabd2f54b1ce5387df Author: Liran Alon Date: Wed Nov 20 14:24:52 2019 +0200 KVM: nVMX: Assume TLB entries of L1 and L2 are tagged differently if L0 use EPT Since commit 1313cc2bd8f6 ("kvm: mmu: Add guest_mode to kvm_mmu_page_role"), guest_mode was added to mmu-role and therefore if L0 use EPT, it will always run L1 and L2 with different EPTP. i.e. EPTP01!=EPTP02. Because TLB entries are tagged with EP4TA, KVM can assume TLB entries populated while running L2 are tagged differently than TLB entries populated while running L1. Paolo