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From: Joerg Roedel <joro@8bytes.org>
To: Bjorn Helgaas <helgaas@kernel.org>
Cc: Todd Broch <tbroch@google.com>,
	linux-pci <linux-pci@vger.kernel.org>,
	"Krishnakumar,
	Lalithambika" <lalithambika.krishnakumar@intel.com>,
	Heikki Krogerus <heikki.krogerus@linux.intel.com>,
	Diego Rivas <diegorivas@google.com>,
	Rajat Jain <rajatja@google.com>,
	Jean-Philippe Brucker <jean-philippe@linaro.org>,
	Furquan Shaikh <furquan@google.com>,
	"Raj, Ashok" <ashok.raj@intel.com>,
	Saravana Kannan <saravanak@google.com>,
	ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
	Christian Kellner <christian@kellner.me>,
	Mattias Nissler <mnissler@google.com>,
	Jesse Barnes <jsbarnes@google.com>, Len Brown <lenb@kernel.org>,
	Rajat Jain <rajatxjain@gmail.com>,
	Prashant Malani <pmalani@google.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Aaron Durbin <adurbin@google.com>,
	Alex Williamson <alex.williamson@redhat.com>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Mika Westerberg <mika.westerberg@linux.intel.com>,
	Bernie Keany <bernie.keany@intel.com>,
	Duncan Laurie <dlaurie@google.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	"open list:AMD IOMMU \(AMD-VI\)"
	<iommu@lists.linux-foundation.org>, Arnd Bergmann <arnd@arndb.de>,
	Oliver O'Halloran <oohall@gmail.com>,
	Benson Leung <bleung@google.com>,
	David Woodhouse <dwmw2@infradead.org>,
	Alex Levin <levinale@google.com>
Subject: Re: [PATCH v4 4/4] PCI/ACS: Enable PCI_ACS_TB for untrusted/external-facing devices
Date: Mon, 13 Jul 2020 10:01:15 +0200	[thread overview]
Message-ID: <20200713080115.GN27672@8bytes.org> (raw)
In-Reply-To: <20200712025838.GA147150@bjorn-Precision-5520>

On Sat, Jul 11, 2020 at 09:58:38PM -0500, Bjorn Helgaas wrote:
> If BIOS handed off with ATS enabled and we somehow relied on it being
> already enabled, something might break if we start disabling ATS.
> Just a theoretical possibility, doesn't seem likely to me.

I don't think this will be a problem. When the BIOS enables ATS for a
device it also needs to enable the IOMMU already, an we are not handling
an already enabled IOMMU (outside of kdump kernels) very well.


Regards,

	Joerg
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  reply	other threads:[~2020-07-13  8:01 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-07 22:46 [PATCH v4 1/4] PCI: Move pci_enable_acs() and its dependencies up in pci.c Rajat Jain via iommu
2020-07-07 22:46 ` [PATCH v4 2/4] PCI: Keep the ACS capability offset in device Rajat Jain via iommu
2020-07-07 22:46 ` [PATCH v4 3/4] PCI: Treat "external-facing" devices as internal Rajat Jain via iommu
2020-07-07 22:46 ` [PATCH v4 4/4] PCI/ACS: Enable PCI_ACS_TB for untrusted/external-facing devices Rajat Jain via iommu
2020-07-10 20:29   ` Bjorn Helgaas
2020-07-10 21:28     ` Raj, Ashok
2020-07-10 22:53       ` Rajat Jain via iommu
2020-07-10 23:32         ` Bjorn Helgaas
2020-07-11 19:53         ` Bjorn Helgaas
2020-07-12  0:08           ` Rajat Jain
2020-07-12  2:58             ` Bjorn Helgaas
2020-07-13  8:01               ` Joerg Roedel [this message]
2020-07-14 20:19           ` Rajat Jain via iommu
2020-09-15 23:01             ` Rajat Jain via iommu
2020-09-16 21:46   ` Bjorn Helgaas
2020-07-10 20:39 ` [PATCH v4 1/4] PCI: Move pci_enable_acs() and its dependencies up in pci.c Bjorn Helgaas

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