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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7E345C433F5 for ; Mon, 15 Nov 2021 10:11:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 63F1661C4F for ; Mon, 15 Nov 2021 10:11:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237055AbhKOKN7 (ORCPT ); Mon, 15 Nov 2021 05:13:59 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:32452 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237566AbhKOKM4 (ORCPT ); Mon, 15 Nov 2021 05:12:56 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1636971000; 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: in-reply-to:in-reply-to:references:references; bh=spkFhHBfLWoUmEEFu9X0mCN465cERkwIsbNUF4+/SDk=; b=LWPrEfDFIf4R/CW7f23//a9eIPjpx9AVLWquDgMM6gwOrTlvJXpdGG8Olf87CQ05iJbwTp phPul1X+E3t/QxDNkpSLcDWrtZV+C/QXM7YYBGsS489+Big+Hu3L0ekEK0HrpD9GtoImiX yWnz1L4bW7TM7L98DudrJlcYTm+1E6U= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-595-4P8OZEEMO_C9S0E69bbHIQ-1; Mon, 15 Nov 2021 05:09:57 -0500 X-MC-Unique: 4P8OZEEMO_C9S0E69bbHIQ-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 59E1B87D545; Mon, 15 Nov 2021 10:09:56 +0000 (UTC) Received: from sirius.home.kraxel.org (unknown [10.39.193.245]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 1653517C58; Mon, 15 Nov 2021 10:09:45 +0000 (UTC) Received: by sirius.home.kraxel.org (Postfix, from userid 1000) id 5BF2918000A9; Mon, 15 Nov 2021 11:09:43 +0100 (CET) Date: Mon, 15 Nov 2021 11:09:43 +0100 From: Gerd Hoffmann To: Lukas Wunner Cc: linux-pci@vger.kernel.org, mst@redhat.com, Bjorn Helgaas , open list Subject: Re: [PATCH] pciehp: fast unplug for virtual machines Message-ID: <20211115100943.ezvirlrxc2qzms3i@sirius.home.kraxel.org> References: <20211111090225.946381-1-kraxel@redhat.com> <20211114163958.GA7211@wunner.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211114163958.GA7211@wunner.de> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, > Same for the 1 second delay in remove_board(). That's mandated by > PCIe r5.0, sec. 6.7.1.8, but it's only observed if a Power Controller > is present. So just clear the Power Controller Present bit in the > Slot Capabilities register and the delay is gone. Well, the power control bit is a useful data channel. qemu can use that to figure whenever the guest uses the device (power is on) or not (power is off). And in case power is off anyway we can simply remove the device without the attention button dance. take care, Gerd