diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 447e83472c01558705d0685f7fd6af17a6f8deef..1ccf7d49f5227c91542fdfd2676a448fda95acde 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -2359,6 +2359,75 @@ void pci_enable_acs(struct pci_dev *dev)
 	pci_write_config_word(dev, pos + PCI_ACS_CTRL, ctrl);
 }
 
+/**
+ * pci_acs_enabled - test ACS against required flags for a given device
+ * @pdev: device to test
+ * @acs_flags: required PCI ACS flags
+ *
+ * Return true if the device supports the provided flags.  Automatically
+ * filters out flags that are not implemented on multifunction devices.
+ */
+bool pci_acs_enabled(struct pci_dev *pdev, u16 acs_flags)
+{
+	int pos, ret;
+	u16 ctrl;
+
+	ret = pci_dev_specific_acs_enabled(pdev, acs_flags);
+	if (ret >= 0)
+		return ret > 0;
+
+	if (!pci_is_pcie(pdev))
+		return false;
+
+	/* Filter out flags not applicable to multifunction */
+	if (pdev->multifunction)
+		acs_flags &= (PCI_ACS_RR | PCI_ACS_CR |
+			      PCI_ACS_EC | PCI_ACS_DT);
+
+	if (pdev->pcie_type == PCI_EXP_TYPE_DOWNSTREAM ||
+	    pdev->pcie_type == PCI_EXP_TYPE_ROOT_PORT ||
+	    pdev->multifunction) {
+		pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_ACS);
+		if (!pos)
+			return false;
+
+		pci_read_config_word(pdev, pos + PCI_ACS_CTRL, &ctrl);
+		if ((ctrl & acs_flags) != acs_flags)
+			return false;
+	}
+
+	return true;
+}
+
+/**
+ * pci_acs_path_enable - test ACS flags from start to end in a hierarchy
+ * @start: starting downstream device
+ * @end: ending upstream device or NULL to search to the root bus
+ * @acs_flags: required flags
+ *
+ * Walk up a device tree from start to end testing PCI ACS support.  If
+ * any step along the way does not support the required flags, return false.
+ */
+bool pci_acs_path_enabled(struct pci_dev *start,
+			  struct pci_dev *end, u16 acs_flags)
+{
+	struct pci_dev *pdev, *parent = start;
+
+	do {
+		pdev = parent;
+
+		if (!pci_acs_enabled(pdev, acs_flags))
+			return false;
+
+		if (pci_is_root_bus(pdev->bus))
+			return (end == NULL);
+
+		parent = pdev->bus->self;
+	} while (pdev != end);
+
+	return true;
+}
+
 /**
  * pci_swizzle_interrupt_pin - swizzle INTx for device behind bridge
  * @dev: the PCI device
diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index acd3956b44bddb81f6d576f835d1ea1905abd780..27e2c8f4ec7304de8bfa9aae257555a6cfe70999 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -3230,3 +3230,36 @@ struct pci_dev *pci_get_dma_source(struct pci_dev *dev)
 
 	return pci_dev_get(dev);
 }
+
+static const struct pci_dev_acs_enabled {
+	u16 vendor;
+	u16 device;
+	int (*acs_enabled)(struct pci_dev *dev, u16 acs_flags);
+} pci_dev_acs_enabled[] = {
+	{ 0 }
+};
+
+int pci_dev_specific_acs_enabled(struct pci_dev *dev, u16 acs_flags)
+{
+	const struct pci_dev_acs_enabled *i;
+	int ret;
+
+	/*
+	 * Allow devices that do not expose standard PCIe ACS capabilities
+	 * or control to indicate their support here.  Multi-function express
+	 * devices which do not allow internal peer-to-peer between functions,
+	 * but do not implement PCIe ACS may wish to return true here.
+	 */
+	for (i = pci_dev_acs_enabled; i->acs_enabled; i++) {
+		if ((i->vendor == dev->vendor ||
+		     i->vendor == (u16)PCI_ANY_ID) &&
+		    (i->device == dev->device ||
+		     i->device == (u16)PCI_ANY_ID)) {
+			ret = i->acs_enabled(dev, acs_flags);
+			if (ret >= 0)
+				return ret;
+		}
+	}
+
+	return -ENOTTY;
+}
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 39983be7b25bc7ee9c2f750c82c928c7e3309724..dd7af0f37b3a76a5919e93f9e3d13707752c287a 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1490,6 +1490,7 @@ enum pci_fixup_pass {
 #ifdef CONFIG_PCI_QUIRKS
 void pci_fixup_device(enum pci_fixup_pass pass, struct pci_dev *dev);
 struct pci_dev *pci_get_dma_source(struct pci_dev *dev);
+int pci_dev_specific_acs_enabled(struct pci_dev *dev, u16 acs_flags);
 #else
 static inline void pci_fixup_device(enum pci_fixup_pass pass,
 				    struct pci_dev *dev) {}
@@ -1497,6 +1498,11 @@ static inline struct pci_dev *pci_get_dma_source(struct pci_dev *dev)
 {
 	return pci_dev_get(dev);
 }
+static inline int pci_dev_specific_acs_enabled(struct pci_dev *dev,
+					       u16 acs_flags)
+{
+	return -ENOTTY;
+}
 #endif
 
 void __iomem *pcim_iomap(struct pci_dev *pdev, int bar, unsigned long maxlen);
@@ -1599,7 +1605,9 @@ static inline bool pci_is_pcie(struct pci_dev *dev)
 }
 
 void pci_request_acs(void);
-
+bool pci_acs_enabled(struct pci_dev *pdev, u16 acs_flags);
+bool pci_acs_path_enabled(struct pci_dev *start,
+			  struct pci_dev *end, u16 acs_flags);
 
 #define PCI_VPD_LRDT			0x80	/* Large Resource Data Type */
 #define PCI_VPD_LRDT_ID(x)		(x | PCI_VPD_LRDT)