On Sat, Jun 30, 2018 at 11:24:24AM -0400, Sinan Kaya wrote:
> 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-to-End TLP
> prefix to be supported on the entire data path between the endpoint and
> the root port before enabling PASID.
>
> Signed-off-by: Sinan Kaya <ok...@codeaurora.org>
Applied to pci/virtualization for v4.19, thanks!
> ---
> drivers/pci/ats.c | 3 +++
> drivers/pci/probe.c | 24 ++++++++++++++++++++++++
> include/linux/pci.h | 1 +
> include/uapi/linux/pci_regs.h | 1 +
> 4 files changed, 29 insertions(+)
>
> diff --git a/drivers/pci/ats.c b/drivers/pci/ats.c
> index 4923a2a..5b78f3b 100644
> --- a/drivers/pci/ats.c
> +++ b/drivers/pci/ats.c
> @@ -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;
> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
> index ac876e3..39fd3ac 100644
> --- a/drivers/pci/probe.c
> +++ b/drivers/pci/probe.c
> @@ -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_E2ETLP))
> + 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);
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 340029b..6ba8184 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -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 */
> diff --git a/include/uapi/linux/pci_regs.h b/include/uapi/linux/pci_regs.h
> index 4da87e2..a617ab2 100644
> --- a/include/uapi/linux/pci_regs.h
> +++ b/include/uapi/linux/pci_regs.h
> @@ -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_E2ETLP 0x00200000 /* End-to-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 */
> --
> 2.7.4
>
>
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