Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <20220120000409.2706549-1-rajatja@google.com> <20220121214117.GA1154852@bhelgaas>
 <Ye5GvQbFKo+CFtRb@lahna> <Ye/X7E2dKb+zem34@lahna>
In-Reply-To: <Ye/X7E2dKb+zem34@lahna>
From:   "Rafael J. Wysocki" <rafael@kernel.org>
Date:   Tue, 25 Jan 2022 15:40:01 +0100
Message-ID: <CAJZ5v0gii3z=DfFbGvubyg=f3t+74eNFdtpJDauwzH4roL-dAQ@mail.gmail.com>
Subject: Re: [PATCH] PCI: ACPI: Allow internal devices to be marked as untrusted
To:     Mika Westerberg <mika.westerberg@linux.intel.com>
Cc:     Bjorn Helgaas <helgaas@kernel.org>,
        Rajat Jain <rajatja@google.com>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Len Brown <lenb@kernel.org>,
        Bjorn Helgaas <bhelgaas@google.com>,
        ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
        Linux PCI <linux-pci@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Rajat Jain <rajatxjain@gmail.com>,
        Dmitry Torokhov <dtor@google.com>,
        Jesse Barnes <jsbarnes@google.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Jean-Philippe Brucker <jean-philippe@linaro.org>,
        Pavel Machek <pavel@denx.de>,
        "Oliver O'Halloran" <oohall@gmail.com>,
        Joerg Roedel <joro@8bytes.org>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Tue, Jan 25, 2022 at 11:59 AM Mika Westerberg
<mika.westerberg@linux.intel.com> wrote:
>
> On Mon, Jan 24, 2022 at 08:27:17AM +0200, Mika Westerberg wrote:
> > > > This patch introduces a new "UntrustedDevice" property that can be used
> > > > by the firmware to mark any device as untrusted.
> >
> > I think this new property should be documented somewhere too (also
> > explain when to use it instead of ExternalFacingPort). If not in the
> > next ACPI spec or some supplemental doc then perhaps in the DT bindings
> > under Documentation/devicetree/bindings.
>
> Actually Microsoft has similar already:
>
> https://docs.microsoft.com/en-us/windows-hardware/drivers/pci/dsd-for-pcie-root-ports#identifying-internal-pcie-ports-accessible-to-users-and-requiring-dma-protection
>
> I think we should use that too here.

Agreed.

This is what the platform firmware will need to use anyway for Windows
compatibility and OEMs may not care about running Linux on their
platforms.