From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.12]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0D9A65F56B for ; Tue, 13 Feb 2024 17:40:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.12 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707846014; cv=none; b=ea4m4qPrUtBJ8mEW8jTGlA4YExFSGpR/QcBnJWrIjdG9nNlsv/PfmtJBuwBlX1/JBVqrquGapThV90kmb+gmtxdpcuDwpw5gDKtX9ParAOYGiMowrGnvCqaIQA0HKq/QXtR72E4BELPRQxgPV6utZZTuQiVAirEx65wgNAK6SAw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707846014; c=relaxed/simple; bh=FDOPvEPKGiMsMpgbyFwDNn0uxWKm/spMxX/rgwFf6Jw=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=LDtgY27oB5XIq/4nVBlbP8/YUu4g4tcJtheIiMkY6cKwh5q/5gPoWVWEMYKbQXQ2bMOFc7buXWip/bGqS7nOM02Z+9h37Y6cFFki9KMsOPgtqyJwRUuC4QXg1a5TtRzhZAotKTBz98+5x4mFUUv/ellBZCn09xI/M/Xi2MDwD0g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=none smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=Xo176lsj; arc=none smtp.client-ip=198.175.65.12 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="Xo176lsj" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1707846013; x=1739382013; h=message-id:subject:from:to:cc:date:in-reply-to: references:mime-version:content-transfer-encoding; bh=FDOPvEPKGiMsMpgbyFwDNn0uxWKm/spMxX/rgwFf6Jw=; b=Xo176lsjTgOm/JG+JNFV+jv80dMbEAbAKBBPOg5OYIqrm35eufQV6Elw 0GtFf9la3svsM7J7hKTYJPWC96BwsbogLoTuLSH9xdjemXvrxaSeoE90W h6CEFXz8EJsxIvZGOtEXitfc6nEm4Jq7RBApKCtC5fStBpKGm6pLm51rN VHubHa6g2E/sT3qaKG7HhCac2cxIQEV4W4oT01imHhvXfzuxxlDBGQ3hv 1yMCvZjWxQkhZoRIaTQquHJM/QsE3QhtztVFxpmWi4fR2mecDa/TWWMMI LaTyfVH3n1jHP+E6AihhHLuMF8hfF5G69/vl93MxKHUfotqyEH8Y87XeZ w==; X-IronPort-AV: E=McAfee;i="6600,9927,10982"; a="13261572" X-IronPort-AV: E=Sophos;i="6.06,157,1705392000"; d="scan'208";a="13261572" Received: from fmviesa003.fm.intel.com ([10.60.135.143]) by orvoesa104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Feb 2024 09:39:59 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.06,157,1705392000"; d="scan'208";a="7524694" Received: from patelni-ubuntu-dev.ch.intel.com ([10.2.132.59]) by fmviesa003-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Feb 2024 09:39:59 -0800 Message-ID: Subject: Re: [PATCH v2] PCI: vmd: Enable Hotplug based on BIOS setting on VMD rootports From: Nirmal Patel To: Bjorn Helgaas Cc: Lorenzo Pieralisi , linux-pci@vger.kernel.org, "Rafael J. Wysocki" , Kai-Heng Feng Date: Tue, 13 Feb 2024 10:47:27 -0700 In-Reply-To: <20240207185549.GA910460@bhelgaas> References: <20240207185549.GA910460@bhelgaas> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.36.5-0ubuntu1 Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 7bit On Wed, 2024-02-07 at 12:55 -0600, Bjorn Helgaas wrote: > On Tue, Feb 06, 2024 at 05:27:29PM -0700, Nirmal Patel wrote: > > ... > > Did you have a chance to look at my response on January 16th to > > your > > questions? I tried to summarize all of the potential problems and > > issues with different fixes. Please let me know if it is easier if > > I > > resend the explanation. Thanks. > > I did see your Jan 16 response, thanks. > > I had more questions after reading it, but they're more about > understanding the topology seen by the host and the guest: > Jan 16: https://lore.kernel.org/r/20240117004933.GA108810@bhelgaas > Feb 1: https://lore.kernel.org/r/20240201211620.GA650432@bhelgaas > > As I mentioned in my second Feb 1 response > (https://lore.kernel.org/r/20240201222245.GA650725@bhelgaas), the > usual plan envisioned by the PCI Firmware spec is that an OS can use > a > PCIe feature if the platform has granted the OS ownership via _OSC > and > a device advertises the feature via a Capability in config space. > > My main concern with the v2 patch > ( > https://lore.kernel.org/r/20231127211729.42668-1-nirmal.patel@linux.intel.com > ) > is that it overrides _OSC for native_pcie_hotplug, but not for any of > the other features (AER, PME, LTR, DPC, etc.) > > I think it's hard to read the specs and conclude that PCIe hotplug is > a special case, and I think we're likely to have similar issues with > other features in the future. > > But if you think this is the best solution, I'm OK with merging it. I sincerely apologize for late responses. I just found out that my evolution mail client is automatically sending linux-pci emails to junk since January 2024. At the moment Hotplug is an exception for us, but I do share your concern about other flags. We have done lot of testing and so far patch v2 is the best solution we have. Thanks nirmal > > Bjorn