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 D22DBC433F5 for ; Wed, 23 Feb 2022 15:02:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241873AbiBWPDT (ORCPT ); Wed, 23 Feb 2022 10:03:19 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33690 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233778AbiBWPDS (ORCPT ); Wed, 23 Feb 2022 10:03:18 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id AA83F60CEF for ; Wed, 23 Feb 2022 07:02:50 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1645628569; 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=exzpM2LSG9f05DEW2rVqdo8gegc7G06w4mF6UEiw0ho=; b=D7QpVSEiqPF2kT1cs0isZZa3Qa2WaapHrTcA5dYhE5xxIIq43ftcbNWHhLUfNCYT/TnNa4 ollvIej5MJ3J1iokRP2X0j4Dhb5f0MudOkJMRegMacfAOUwigvxdd+H8nKFvnVa3Z7lyw3 NyLcqrp9/wQjJ+dA0u0xUmGOLKuL3bc= 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-270-tTCdhBjuNFOB5XnGGGSZkQ-1; Wed, 23 Feb 2022 10:02:47 -0500 X-MC-Unique: tTCdhBjuNFOB5XnGGGSZkQ-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 3C886800425; Wed, 23 Feb 2022 15:02:45 +0000 (UTC) Received: from starship (unknown [10.40.195.190]) by smtp.corp.redhat.com (Postfix) with ESMTP id 6C7F210631FB; Wed, 23 Feb 2022 15:02:43 +0000 (UTC) Message-ID: <9af820b8deecf3b6ea31db0993e83f746221634d.camel@redhat.com> Subject: Re: [PATCH v2 07/18] KVM: x86/mmu: Do not use guest root level in audit From: Maxim Levitsky To: Paolo Bonzini , Sean Christopherson Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Lai Jiangshan Date: Wed, 23 Feb 2022 17:02:42 +0200 In-Reply-To: <219937f8-6b49-47db-4ecf-f354b110da1c@redhat.com> References: <20220217210340.312449-1-pbonzini@redhat.com> <20220217210340.312449-8-pbonzini@redhat.com> <219937f8-6b49-47db-4ecf-f354b110da1c@redhat.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.36.5 (3.36.5-2.fc32) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2022-02-18 at 19:46 +0100, Paolo Bonzini wrote: > On 2/18/22 19:37, Sean Christopherson wrote: > > Since I keep bringing it up... > > > > From: Sean Christopherson > > Date: Fri, 18 Feb 2022 09:43:05 -0800 > > Subject: [PATCH] KVM: x86/mmu: Remove MMU auditing > > > > Remove mmu_audit.c and all its collateral, the auditing code has suffered > > severe bitrot, ironically partly due to shadow paging being more stable > > and thus not benefiting as much from auditing, but mostly due to TDP > > supplanting shadow paging for non-nested guests and shadowing of nested > > TDP not heavily stressing the logic that is being audited. > > > > Signed-off-by: Sean Christopherson > > Queued, thanks. O:-) I once kind of played with it. Note that shadow mmu does have bugs - I can easily crash L1/L2 when doing repeated migrations when I disable NPT either in L0 or L1, and when I force the mmu to be always sync (see my strict_mmu patch), the crashes go away. mmu audit maybe could have helped with that. But I won't argue too much about this. Best regards, Maxim Levitsky > > Paolo >