PCI: Check all ACS features for multifunction downstream ports (0a67119f) · Commits · 戴 / test

drivers/pci/pci.c

+70 −14

Original line number	Diff line number	Diff line
		@@ -2359,6 +2359,19 @@ void pci_enable_acs(struct pci_dev *dev)
		pci_write_config_word(dev, pos + PCI_ACS_CTRL, ctrl);
		}

		static bool pci_acs_flags_enabled(struct pci_dev *pdev, u16 acs_flags)
		{
		int pos;
		u16 ctrl;

		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);
		return (ctrl & acs_flags) == acs_flags;
		}

		/**
		* pci_acs_enabled - test ACS against required flags for a given device
		* @pdev: device to test
		@@ -2366,36 +2379,79 @@ void pci_enable_acs(struct pci_dev *dev)
		*
		* Return true if the device supports the provided flags. Automatically
		* filters out flags that are not implemented on multifunction devices.
		*
		* Note that this interface checks the effective ACS capabilities of the
		* device rather than the actual capabilities. For instance, most single
		* function endpoints are not required to support ACS because they have no
		* opportunity for peer-to-peer access. We therefore return 'true'
		* regardless of whether the device exposes an ACS capability. This makes
		* it much easier for callers of this function to ignore the actual type
		* or topology of the device when testing ACS support.
		*/
		bool pci_acs_enabled(struct pci_dev *pdev, u16 acs_flags)
		{
		int pos, ret;
		u16 ctrl;
		int ret;

		ret = pci_dev_specific_acs_enabled(pdev, acs_flags);
		if (ret >= 0)
		return ret > 0;

		/*
		* Conventional PCI and PCI-X devices never support ACS, either
		* effectively or actually. The shared bus topology implies that
		* any device on the bus can receive or snoop DMA.
		*/
		if (!pci_is_pcie(pdev))
		return false;

		/* Filter out flags not applicable to multifunction */
		if (pdev->multifunction)
		switch (pci_pcie_type(pdev)) {
		/*
		* PCI/X-to-PCIe bridges are not specifically mentioned by the spec,
		* but since their primary inteface is PCI/X, we conservatively
		* handle them as we would a non-PCIe device.
		*/
		case PCI_EXP_TYPE_PCIE_BRIDGE:
		/*
		* PCIe 3.0, 6.12.1 excludes ACS on these devices. "ACS is never
		* applicable... must never implement an ACS Extended Capability...".
		* This seems arbitrary, but we take a conservative interpretation
		* of this statement.
		*/
		case PCI_EXP_TYPE_PCI_BRIDGE:
		case PCI_EXP_TYPE_RC_EC:
		return false;
		/*
		* PCIe 3.0, 6.12.1.1 specifies that downstream and root ports should
		* implement ACS in order to indicate their peer-to-peer capabilities,
		* regardless of whether they are single- or multi-function devices.
		*/
		case PCI_EXP_TYPE_DOWNSTREAM:
		case PCI_EXP_TYPE_ROOT_PORT:
		return pci_acs_flags_enabled(pdev, acs_flags);
		/*
		* PCIe 3.0, 6.12.1.2 specifies ACS capabilities that should be
		* implemented by the remaining PCIe types to indicate peer-to-peer
		* capabilities, but only when they are part of a multifunciton
		* device. The footnote for section 6.12 indicates the specific
		* PCIe types included here.
		*/
		case PCI_EXP_TYPE_ENDPOINT:
		case PCI_EXP_TYPE_UPSTREAM:
		case PCI_EXP_TYPE_LEG_END:
		case PCI_EXP_TYPE_RC_END:
		if (!pdev->multifunction)
		break;

		acs_flags &= (PCI_ACS_RR \| PCI_ACS_CR \|
		PCI_ACS_EC \| PCI_ACS_DT);

		if (pci_pcie_type(pdev) == PCI_EXP_TYPE_DOWNSTREAM \|\|
		pci_pcie_type(pdev) == 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 pci_acs_flags_enabled(pdev, acs_flags);
		}

		/*
		* PCIe 3.0, 6.12.1.3 specifies no ACS capabilties are applicable
		* to single function devices with the exception of downstream ports.
		*/
		return true;
		}

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