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 lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 33A12C433EF for ; Thu, 5 May 2022 08:06:45 +0000 (UTC) Received: from localhost ([::1]:48106 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1nmWVX-0000Z6-VE for qemu-devel@archiver.kernel.org; Thu, 05 May 2022 04:06:44 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:49762) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nmWPX-00077v-HC for qemu-devel@nongnu.org; Thu, 05 May 2022 04:00:31 -0400 Received: from us-smtp-delivery-74.mimecast.com ([170.10.133.74]:43954) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nmWPQ-0004Yf-0K for qemu-devel@nongnu.org; Thu, 05 May 2022 04:00:29 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1651737623; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:in-reply-to:in-reply-to: references:references; bh=Ez9jLrCnZoNkfXtCu5OMIxT/HF6e0MOJ6DV3q6H3hZ4=; b=FBCLUY7m0D7O+EmPkdAGERJOQOhc+iPXkkLqlFkVlDAh3BiPmcDmRejrdBmeOqCkMEH+M6 m0DF3FjbBha1asl8M+QadZppL8LYeuLPJvreUjOhNzCIM8WQiJvArzxrLWjKL6fLsxVtEq CEuwFQR6it7m/nE5hi5GOdtckod/Sag= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-604-jDgxbMKvN7m0u3OyR8x67w-1; Thu, 05 May 2022 04:00:22 -0400 X-MC-Unique: jDgxbMKvN7m0u3OyR8x67w-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.rdu2.redhat.com [10.11.54.7]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 0C83F802819; Thu, 5 May 2022 08:00:22 +0000 (UTC) Received: from redhat.com (unknown [10.33.36.128]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 1BEF814A5077; Thu, 5 May 2022 08:00:20 +0000 (UTC) Date: Thu, 5 May 2022 09:00:18 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Paolo Bonzini Cc: Markus Armbruster , qemu-devel@nongnu.org, mark.kanda@oracle.com, dgilbert@redhat.com Subject: Re: [PATCH 1/8] qmp: Support for querying stats Message-ID: References: <20220426141619.304611-1-pbonzini@redhat.com> <20220426141619.304611-2-pbonzini@redhat.com> <87sfpp3018.fsf@pond.sub.org> <41B27AED-A9E0-4666-AEBB-0F3C9F436DF1@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <41B27AED-A9E0-4666-AEBB-0F3C9F436DF1@redhat.com> User-Agent: Mutt/2.1.5 (2021-12-30) X-Scanned-By: MIMEDefang 2.85 on 10.11.54.7 Received-SPF: pass client-ip=170.10.133.74; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-74.mimecast.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.082, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Thu, May 05, 2022 at 09:10:17AM +0200, Paolo Bonzini wrote: > > > Il 4 maggio 2022 15:22:27 CEST, Markus Armbruster ha scritto: > >Can you point to existing uses of KVM binary stats introspection data? > > There's none, but Google is using it in house. The same data was > available before in debugfs and available via the kvm_stat script, > so you could also refer to Christian Borntraeger's KVM Forum 2019 > talk. The problems with debugfs are basically that it's only > available to root and is disabled by secure boot (both issues > are not fixable on general because they are Linux policy). Libvirt currently uses debugfs to get /sys/kernel/debug/kvm/-/halt_poll_success_ns when we report on CPU usage for VMs. WHen kernel lockdown is enforced under secure boot we're unable to access this file and even worse every attempt to access it spams dmesg[1]. We need this query stats QMP support for that single statistic alone today. With regards, Daniel [1] https://gitlab.com/libvirt/libvirt/-/issues/213 -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|