linux-kernel - [PATCH v4 4/4] PCI/ACS: Enable PCI_ACS_TB for untrusted/external-facing devices

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Date:   Tue,  7 Jul 2020 15:46:04 -0700
From:   Rajat Jain <rajatja@...gle.com>
To:     David Woodhouse <dwmw2@...radead.org>,
        Lu Baolu <baolu.lu@...ux.intel.com>,
        Joerg Roedel <joro@...tes.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>, iommu@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org,
        linux-acpi@...r.kernel.org, Raj Ashok <ashok.raj@...el.com>,
        lalithambika.krishnakumar@...el.com,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Jean-Philippe Brucker <jean-philippe@...aro.org>,
        Prashant Malani <pmalani@...gle.com>,
        Benson Leung <bleung@...gle.com>,
        Todd Broch <tbroch@...gle.com>,
        Alex Levin <levinale@...gle.com>,
        Mattias Nissler <mnissler@...gle.com>,
        Rajat Jain <rajatxjain@...il.com>,
        Bernie Keany <bernie.keany@...el.com>,
        Aaron Durbin <adurbin@...gle.com>,
        Diego Rivas <diegorivas@...gle.com>,
        Duncan Laurie <dlaurie@...gle.com>,
        Furquan Shaikh <furquan@...gle.com>,
        Jesse Barnes <jsbarnes@...gle.com>,
        Christian Kellner <christian@...lner.me>,
        Alex Williamson <alex.williamson@...hat.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        oohall@...il.com, Saravana Kannan <saravanak@...gle.com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Arnd Bergmann <arnd@...db.de>,
        Heikki Krogerus <heikki.krogerus@...ux.intel.com>
Cc:     Rajat Jain <rajatja@...gle.com>
Subject: [PATCH v4 4/4] PCI/ACS: Enable PCI_ACS_TB for untrusted/external-facing
 devices

When enabling ACS, enable translation blocking for external facing ports
and untrusted devices.

Signed-off-by: Rajat Jain <rajatja@...gle.com>
---
v4: Add braces to avoid warning from kernel robot
    print warning for only external-facing devices.
v3: print warning if ACS_TB not supported on external-facing/untrusted ports.
    Minor code comments fixes.
v2: Commit log change

 drivers/pci/pci.c    |  8 ++++++++
 drivers/pci/quirks.c | 15 +++++++++++++++
 2 files changed, 23 insertions(+)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 73a8627822140..a5a6bea7af7ce 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -876,6 +876,14 @@ static void pci_std_enable_acs(struct pci_dev *dev)
 	/* Upstream Forwarding */
 	ctrl |= (cap & PCI_ACS_UF);
 
+	/* Enable Translation Blocking for external devices */
+	if (dev->external_facing || dev->untrusted) {
+		if (cap & PCI_ACS_TB)
+			ctrl |= PCI_ACS_TB;
+		else if (dev->external_facing)
+			pci_warn(dev, "ACS: No Translation Blocking on external-facing dev\n");
+	}
+
 	pci_write_config_word(dev, pos + PCI_ACS_CTRL, ctrl);
 }
 
diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index b341628e47527..bb22b46c1d719 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -4934,6 +4934,13 @@ static void pci_quirk_enable_intel_rp_mpc_acs(struct pci_dev *dev)
 	}
 }
 
+/*
+ * Currently this quirk does the equivalent of
+ * PCI_ACS_SV | PCI_ACS_RR | PCI_ACS_CR | PCI_ACS_UF
+ *
+ * TODO: This quirk also needs to do equivalent of PCI_ACS_TB,
+ * if dev->external_facing || dev->untrusted
+ */
 static int pci_quirk_enable_intel_pch_acs(struct pci_dev *dev)
 {
 	if (!pci_quirk_intel_pch_acs_match(dev))
@@ -4973,6 +4980,14 @@ static int pci_quirk_enable_intel_spt_pch_acs(struct pci_dev *dev)
 	ctrl |= (cap & PCI_ACS_CR);
 	ctrl |= (cap & PCI_ACS_UF);
 
+	/* Enable Translation Blocking for external devices */
+	if (dev->external_facing || dev->untrusted) {
+		if (cap & PCI_ACS_TB)
+			ctrl |= PCI_ACS_TB;
+		else if (dev->external_facing)
+			pci_warn(dev, "ACS: No Translation Blocking on external-facing dev\n");
+	}
+
 	pci_write_config_dword(dev, pos + INTEL_SPT_ACS_CTRL, ctrl);
 
 	pci_info(dev, "Intel SPT PCH root port ACS workaround enabled\n");
-- 
2.27.0.212.ge8ba1cc988-goog