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 8210EC4332F for ; Wed, 1 Nov 2023 22:20:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234974AbjKAWUa (ORCPT ); Wed, 1 Nov 2023 18:20:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43312 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232848AbjKAWUa (ORCPT ); Wed, 1 Nov 2023 18:20:30 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DD15C126 for ; Wed, 1 Nov 2023 15:20:27 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4EE77C433C7; Wed, 1 Nov 2023 22:20:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1698877227; bh=AZmA7dROASpovfPrfzw/u4RFujdY0pYB86EMcQ8XBDA=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=EkmAv8spIRwRwE7FtCqYD+s6oLnzFMg0Bh5CDwhvp+LXspH7UZ6ijTLG/0EkzKpLV nlHIvP9IUPotDXy/CSJyaX1gdTxgaR4NFOmrymcnPQ4Dz5sTUlb5zOdAgmAKZylvrT j1hK0bCW1ck9JcxcHA0bmJ2uekeBNwg/+/96cjuCxzTxm8uOZ28tj6IAPt5NCE8oyW xy9VkApCCGAVO2WKEk4KrREG9BubZ/ERIgkteVNFfbZp/FiNmuNNnGrP74hhkZRVGC w8NJthX6UkPn4X2vjjUhvDXmvIeYLKhL0vLQhBKT3LJZ4mQber2X2NMHLlNGdlo1hU c/hMyKswNZ1DA== Date: Wed, 1 Nov 2023 17:20:25 -0500 From: Bjorn Helgaas To: Nirmal Patel Cc: linux-pci@vger.kernel.org Subject: Re: [PATCH] PCI: vmd: Enable Hotplug based on BIOS setting on VMD rootports Message-ID: <20231101222025.GA101237@bhelgaas> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Tue, Oct 31, 2023 at 12:59:34PM -0700, Nirmal Patel wrote: > On Tue, 2023-10-31 at 10:31 -0500, Bjorn Helgaas wrote: > > On Mon, Oct 30, 2023 at 04:16:54PM -0400, Nirmal Patel wrote: > > > VMD Hotplug should be enabled or disabled based on VMD rootports' > > > Hotplug configuration in BIOS. is_hotplug_bridge is set on each > > > VMD rootport based on Hotplug capable bit in SltCap in probe.c. > > > Check is_hotplug_bridge and enable or disable native_pcie_hotplug > > > based on that value. > > > > > > Currently VMD driver copies ACPI settings or platform > > > configurations > > > for Hotplug, AER, DPC, PM, etc and enables or disables these > > > features > > > on VMD bridge which is not correct in case of Hotplug. > > > > This needs some background about why it's correct to copy the ACPI > > settings in the case of AER, DPC, PM, etc, but incorrect for hotplug. > > > > > Also during the Guest boot up, ACPI settings along with VMD UEFI > > > driver are not present in Guest BIOS which results in assigning > > > default values to Hotplug, AER, DPC, etc. As a result Hotplug is > > > disabled on VMD in the Guest OS. > > > > > > This patch will make sure that Hotplug is enabled properly in Host > > > as well as in VM. > > > > Did we come to some consensus about how or whether _OSC for the host > > bridge above the VMD device should apply to devices in the separate > > domain below the VMD? > > We are not able to come to any consensus. Someone suggested to copy > either all _OSC flags or none. But logic behind that assumption is > that the VMD is a bridge device which is not completely true. VMD is an > endpoint device and it owns its domain. Do you want to facilitate a discussion in the PCI firmware SIG about this? It seems like we may want a little text in the spec about how to handle this situation so platforms and OSes have the same expectations. Bjorn