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

From: Rajat Jain
Date: Tue Jul 07 2020 - 18:46:18 EST


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

Signed-off-by: Rajat Jain <rajatja@xxxxxxxxxx>
---
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