The Cavium ThunderX (CN8XXX) family of PCIe Root Ports does not advertise
an ACS capability. However, the RTL internally implements similar
protection as if ACS had Request Redirection, Completion Redirection,
Source Validation, and Upstream Forwarding features enabled.
diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index 02b009426670..fcf734231c4d 100644
@@ -4253,12 +4253,14 @@ static int pci_quirk_amd_sb_acs(struct pci_dev *dev, u16 acs_flags)
static int pci_quirk_cavium_acs(struct pci_dev *dev, u16 acs_flags)
- * Cavium devices matching this quirk do not perform peer-to-peer
- * with other functions, allowing masking out these bits as if they
- * were unimplemented in the ACS capability.
+ * Cavium root ports don't advertise an ACS capability. However,
+ * the RTL internally implements similar protection as if ACS had
+ * Request Redirection, Completion Redirection, Source Validation,
+ * and Upstream Forwarding features enabled. Assert that the
+ * hardware implements and enables equivalent ACS functionality for
+ * these flags.
- acs_flags &= ~(PCI_ACS_SV | PCI_ACS_TB | PCI_ACS_RR |
- PCI_ACS_CR | PCI_ACS_UF | PCI_ACS_DT);
+ acs_flags &= ~(PCI_ACS_RR | PCI_ACS_CR | PCI_ACS_SV | PCI_ACS_UF);