Linux-PCI Archive on lore.kernel.org
 help / color / Atom feed
From: Alex Williamson <alex.williamson@redhat.com>
To: linux-pci@vger.kernel.org, bhelgaas@google.com
Cc: rajatja@google.com, linux-kernel@vger.kernel.org
Subject: [PATCH] PCI/ACS: Enforce pci=noats with Transaction Blocking
Date: Fri, 18 Jun 2021 14:55:14 -0600
Message-ID: <162404966325.2362347.12176138291577486015.stgit@omen> (raw)

PCIe Address Translation Services (ATS) provides a mechanism for a
device to provide an on-device caching translation agent (device
iotlb).  We already have a means to disable support for this feature
via the pci=noats option.  For untrusted and externally facing
devices, we not only disable ATS support for the device, but we use
Access Control Services (ACS) Transaction Blocking to actively
prevent devices from sending TLPs with non-default AT field values.

Extend pci=noats to also make use of PCI_ACS_TB so that not only is
ATS disabled at the device, but blocked at the downstream ports.
This provides a means to further lock-down ATS for cases such as
device assignment, where it may not be the hardware configuration of
the device that makes it untrusted, but the driver running on the
device.

Cc: Rajat Jain <rajatja@google.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
---
 drivers/pci/pci.c    |    4 ++--
 drivers/pci/quirks.c |    2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 68f57d86b243..5aa1bb2ddd80 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -915,8 +915,8 @@ 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)
+	/* Enable Translation Blocking for external devices and noats */
+	if (pci_ats_disabled() || dev->external_facing || dev->untrusted)
 		ctrl |= (cap & PCI_ACS_TB);
 
 	pci_write_config_word(dev, pos + PCI_ACS_CTRL, ctrl);
diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index 6d74386eadc2..d541076c083a 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -5031,7 +5031,7 @@ static int pci_quirk_enable_intel_spt_pch_acs(struct pci_dev *dev)
 	ctrl |= (cap & PCI_ACS_CR);
 	ctrl |= (cap & PCI_ACS_UF);
 
-	if (dev->external_facing || dev->untrusted)
+	if (pci_ats_disabled() || dev->external_facing || dev->untrusted)
 		ctrl |= (cap & PCI_ACS_TB);
 
 	pci_write_config_dword(dev, pos + INTEL_SPT_ACS_CTRL, ctrl);



             reply index

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-18 20:55 Alex Williamson [this message]
2021-08-03 18:49 ` Alex Williamson
2021-08-03 23:28 ` Bjorn Helgaas

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=162404966325.2362347.12176138291577486015.stgit@omen \
    --to=alex.williamson@redhat.com \
    --cc=bhelgaas@google.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-pci@vger.kernel.org \
    --cc=rajatja@google.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux-PCI Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-pci/0 linux-pci/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-pci linux-pci/ https://lore.kernel.org/linux-pci \
		linux-pci@vger.kernel.org
	public-inbox-index linux-pci

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-pci


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git