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Commit 7ce3f912 authored by Sinan Kaya's avatar Sinan Kaya Committed by Bjorn Helgaas
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PCI: Enable PASID only if entire path supports End-End TLP prefixes 



A PCIe endpoint carries the process address space identifier (PASID) in
the TLP prefix as part of the memory read/write transaction. The address
information in the TLP is relevant only for a given PASID context.

An IOMMU takes PASID value and the address information from the
TLP to look up the physical address in the system.

PASID is an End-End TLP Prefix (PCIe r4.0, sec 6.20).  Sec 2.2.10.2 says

  It is an error to receive a TLP with an End-End TLP Prefix by a
  Receiver that does not support End-End TLP Prefixes. A TLP in
  violation of this rule is handled as a Malformed TLP. This is a
  reported error associated with the Receiving Port (see Section 6.2).

Prevent error condition by proactively requiring End-End TLP prefix to be
supported on the entire data path between the endpoint and the root port
before enabling PASID.

Signed-off-by: default avatarSinan Kaya <okaya@codeaurora.org>
Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
parent ce397d21

drivers/pci/ats.c

+3 −0
Original line number Diff line number Diff line
@@ -273,6 +273,9 @@ int pci_enable_pasid(struct pci_dev *pdev, int features) 
	if (WARN_ON(pdev->pasid_enabled))

		return -EBUSY;



	if (!pdev->eetlp_prefix_path)

		return -EINVAL;



	pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_PASID);

	if (!pos)

		return -EINVAL;

drivers/pci/probe.c

+24 −0
Original line number Diff line number Diff line
@@ -2042,6 +2042,29 @@ static void pci_configure_ltr(struct pci_dev *dev) 
#endif

}



static void pci_configure_eetlp_prefix(struct pci_dev *dev)

{

#ifdef CONFIG_PCI_PASID

	struct pci_dev *bridge;

	u32 cap;



	if (!pci_is_pcie(dev))

		return;



	pcie_capability_read_dword(dev, PCI_EXP_DEVCAP2, &cap);

	if (!(cap & PCI_EXP_DEVCAP2_EE_PREFIX))

		return;



	if (pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT)

		dev->eetlp_prefix_path = 1;

	else {

		bridge = pci_upstream_bridge(dev);

		if (bridge && bridge->eetlp_prefix_path)

			dev->eetlp_prefix_path = 1;

	}

#endif

}



static void pci_configure_device(struct pci_dev *dev)

{

	struct hotplug_params hpp;
@@ -2051,6 +2074,7 @@ static void pci_configure_device(struct pci_dev *dev) 
	pci_configure_extended_tags(dev, NULL);

	pci_configure_relaxed_ordering(dev);

	pci_configure_ltr(dev);

	pci_configure_eetlp_prefix(dev);



	memset(&hpp, 0, sizeof(hpp));

	ret = pci_get_hp_params(dev, &hpp);

include/linux/pci.h

+1 −0
Original line number Diff line number Diff line
@@ -350,6 +350,7 @@ struct pci_dev { 
	unsigned int	ltr_path:1;	/* Latency Tolerance Reporting

					   supported from root to here */

#endif

	unsigned int	eetlp_prefix_path:1;	/* End-to-End TLP Prefix */



	pci_channel_state_t error_state;	/* Current connectivity state */

	struct device	dev;			/* Generic device interface */

include/uapi/linux/pci_regs.h

+1 −0
Original line number Diff line number Diff line
@@ -636,6 +636,7 @@ 
#define  PCI_EXP_DEVCAP2_OBFF_MASK	0x000c0000 /* OBFF support mechanism */

#define  PCI_EXP_DEVCAP2_OBFF_MSG	0x00040000 /* New message signaling */

#define  PCI_EXP_DEVCAP2_OBFF_WAKE	0x00080000 /* Re-use WAKE# for OBFF */

#define PCI_EXP_DEVCAP2_EE_PREFIX	0x00200000 /* End-End TLP Prefix */

#define PCI_EXP_DEVCTL2		40	/* Device Control 2 */

#define  PCI_EXP_DEVCTL2_COMP_TIMEOUT	0x000f	/* Completion Timeout Value */

#define  PCI_EXP_DEVCTL2_COMP_TMOUT_DIS	0x0010	/* Completion Timeout Disable */