Re: [PATCH v13 4/8] PCI/DPC: Add Error Disconnect Recover (EDR) support

From: Bjorn Helgaas
Date: Fri Jan 24 2020 - 10:04:55 EST

Next message: Steven Rostedt: "Re: [PATCH] perf test: Test case 66 broken on s390 (lib/traceevent issue)"
Previous message: Jon Hunter: "[PATCH V2] serial: 8250_tegra: Create Tegra specific 8250 driver"
Next in thread: Kuppuswamy Sathyanarayanan: "Re: [PATCH v13 4/8] PCI/DPC: Add Error Disconnect Recover (EDR) support"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]

On Sat, Jan 18, 2020 at 08:00:33PM -0800, sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx wrote:
> From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>
>
> As per ACPI specification r6.3, sec 5.6.6, when firmware owns Downstream
> Port Containment (DPC), its expected to use the "Error Disconnect
> Recover" (EDR) notification to alert OSPM of a DPC event and if OS
> supports EDR, its expected to handle the software state invalidation and
> port recovery in OS, and also let firmware know the recovery status via
> _OST ACPI call. Related _OST status codes can be found in ACPI
> specification r6.3, sec 6.3.5.2.
>
> Also, as per PCI firmware specification r3.2 Downstream Port Containment
> Related Enhancements ECN, sec 4.5.1, table 4-6, If DPC is controlled by
> firmware (firmware first mode), firmware is responsible for
> configuring the DPC and OS is responsible for error recovery. Also, OS
> is allowed to modify DPC registers only during the EDR notification
> window. So with EDR support, OS should provide DPC port services even in
> firmware first mode.
>
> Cc: Keith Busch <keith.busch@xxxxxxxxx>
> Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>
> Acked-by: Keith Busch <keith.busch@xxxxxxxxx>
> Tested-by: Huong Nguyen <huong.nguyen@xxxxxxxx>
> Tested-by: Austin Bolen <Austin.Bolen@xxxxxxxx>
> ---
> drivers/pci/pci-acpi.c | 99 +++++++++++++++++++++++++++++++
> drivers/pci/pcie/Kconfig | 10 ++++
> drivers/pci/pcie/dpc.c | 123 ++++++++++++++++++++++++++++++++++++++-
> include/linux/pci-acpi.h | 13 +++++
> 4 files changed, 244 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
> index 0c02d500158f..920928f0d55c 100644
> --- a/drivers/pci/pci-acpi.c
> +++ b/drivers/pci/pci-acpi.c
> @@ -103,6 +103,105 @@ int acpi_get_rc_resources(struct device *dev, const char *hid, u16 segment,
> }
> #endif
>
> +#if defined(CONFIG_PCIE_DPC)
> +
> +/*
> + * _DSM wrapper function to enable/disable DPC port.
> + * @dpc : DPC device structure
> + * @enable: status of DPC port (0 or 1).
> + *
> + * returns 0 on success or errno on failure.
> + */
> +int acpi_enable_dpc_port(struct pci_dev *pdev, acpi_handle handle, bool enable)
> +{
> + union acpi_object *obj, argv4, req;
> + int status = 0;
> +
> + req.type = ACPI_TYPE_INTEGER;
> + req.integer.value = enable;
> +
> + argv4.type = ACPI_TYPE_PACKAGE;
> + argv4.package.count = 1;
> + argv4.package.elements = &req;
> +
> + /*
> + * Per the Downstream Port Containment Related Enhancements ECN to
> + * the PCI Firmware Specification r3.2, sec 4.6.12,
> + * EDR_PORT_ENABLE_DSM is optional. Return success if it's not
> + * implemented.
> + */
> + obj = acpi_evaluate_dsm(handle, &pci_acpi_dsm_guid, 5,
> + EDR_PORT_ENABLE_DSM, &argv4);
> + if (!obj)
> + return 0;
> +
> + if (obj->type != ACPI_TYPE_INTEGER || obj->integer.value != enable)
> + status = -EIO;
> +
> + ACPI_FREE(obj);
> +
> + return status;
> +}
> +
> +/*
> + * _DSM wrapper function to locate DPC port.
> + * @dpc : DPC device structure
> + *
> + * returns pci_dev or NULL.
> + */
> +struct pci_dev *acpi_locate_dpc_port(struct pci_dev *pdev, acpi_handle handle)
> +{
> + union acpi_object *obj;
> + u16 port;
> +
> + obj = acpi_evaluate_dsm(handle, &pci_acpi_dsm_guid, 5,
> + EDR_PORT_LOCATE_DSM, NULL);
> + if (!obj)
> + return pci_dev_get(pdev);
> +
> + if (obj->type != ACPI_TYPE_INTEGER) {
> + ACPI_FREE(obj);
> + return NULL;
> + }
> +
> + /*
> + * Firmware returns DPC port BDF details in following format:
> + * 15:8 = bus
> + * 7:3 = device
> + * 2:0 = function
> + */
> + port = obj->integer.value;
> +
> + ACPI_FREE(obj);
> +
> + return pci_get_domain_bus_and_slot(pci_domain_nr(pdev->bus),
> + PCI_BUS_NUM(port), port & 0xff);
> +}
> +
> +/*
> + * _OST wrapper function to let firmware know the status of EDR event.
> + * @dpc : DPC device structure.
> + * @status: Status of EDR event.
> + */
> +int acpi_send_edr_status(struct pci_dev *pdev, acpi_handle handle, u16 status)
> +{
> + u32 ost_status;
> +
> + pci_dbg(pdev, "Sending EDR status :%#x\n", status);
> +
> + ost_status = PCI_DEVID(pdev->bus->number, pdev->devfn);
> + ost_status = (ost_status << 16) | status;
> +
> + status = acpi_evaluate_ost(handle,
> + ACPI_NOTIFY_DISCONNECT_RECOVER,
> + ost_status, NULL);
> + if (ACPI_FAILURE(status))
> + return -EINVAL;
> +
> + return 0;
> +}
> +#endif /* CONFIG_PCIE_DPC */

I think we should try collecting all this stuff into a new pcie/edr.c
file. It could contain all the above, plus edr_handle_event() and
maybe something like a "pci_acpi_add_edr_notifier()" that could be
called from pci_acpi_setup() to install the notify handler.

I think the ACPI EDR stuff in dpc.c kind of clutters it up, especially
for the non-ACPI systems that use dpc.c.

Obviously this would require some sort of interface exported from
dpc.c to do the guts of edr_handle_event(), i.e., reading
PCI_EXP_DPC_STATUS and calling dpc_process_error().

> phys_addr_t acpi_pci_root_get_mcfg_addr(acpi_handle handle)
> {
> acpi_status status = AE_NOT_EXIST;
> diff --git a/drivers/pci/pcie/Kconfig b/drivers/pci/pcie/Kconfig
> index 6e3c04b46fb1..772b1f4cb19e 100644
> --- a/drivers/pci/pcie/Kconfig
> +++ b/drivers/pci/pcie/Kconfig
> @@ -140,3 +140,13 @@ config PCIE_BW
> This enables PCI Express Bandwidth Change Notification. If
> you know link width or rate changes occur only to correct
> unreliable links, you may answer Y.
> +
> +config PCIE_EDR
> + bool "PCI Express Error Disconnect Recover support"
> + depends on PCIE_DPC && ACPI
> + help
> + This option adds Error Disconnect Recover support as specified
> + in the Downstream Port Containment Related Enhancements ECN to
> + the PCI Firmware Specification r3.2. Enable this if you want to
> + support hybrid DPC model which uses both firmware and OS to
> + implement DPC.
> diff --git a/drivers/pci/pcie/dpc.c b/drivers/pci/pcie/dpc.c
> index 9f58e91f8852..8a8ee374d9b1 100644
> --- a/drivers/pci/pcie/dpc.c
> +++ b/drivers/pci/pcie/dpc.c
> @@ -13,6 +13,8 @@
> #include <linux/interrupt.h>
> #include <linux/init.h>
> #include <linux/pci.h>
> +#include <linux/acpi.h>
> +#include <linux/pci-acpi.h>
>
> #include "portdrv.h"
> #include "../pci.h"
> @@ -23,6 +25,11 @@ struct dpc_dev {
> bool rp_extensions;
> u8 rp_log_size;
> bool edr_enabled; /* EDR mode is supported */
> + pci_ers_result_t error_state;
> + struct mutex edr_lock;
> +#ifdef CONFIG_ACPI
> + struct acpi_device *adev;
> +#endif
> };
>
> static const char * const rp_pio_error_string[] = {
> @@ -161,6 +168,9 @@ static pci_ers_result_t dpc_reset_link(struct pci_dev *pdev)
> if (!pcie_wait_for_link(pdev, true))
> return PCI_ERS_RESULT_DISCONNECT;
>
> + /* Since the device recovery is done just update the error state */
> + dpc->error_state = PCI_ERS_RESULT_RECOVERED;
> +
> return PCI_ERS_RESULT_RECOVERED;
> }
>
> @@ -305,14 +315,94 @@ static irqreturn_t dpc_irq(int irq, void *context)
> return IRQ_HANDLED;
> }
>
> +static void dpc_error_resume(struct pci_dev *dev)
> +{
> + struct dpc_dev *dpc = to_dpc_dev(dev);
> +
> + dpc->error_state = PCI_ERS_RESULT_RECOVERED;
> +}
> +
> +#ifdef CONFIG_ACPI
> +
> +static void edr_handle_event(acpi_handle handle, u32 event, void *data)
> +{
> + struct dpc_dev *dpc = data;
> + struct pci_dev *pdev = dpc->dev->port;
> + u16 status;
> +
> + pci_info(pdev, "ACPI event %#x received\n", event);
> +
> + if (event != ACPI_NOTIFY_DISCONNECT_RECOVER)
> + return;
> +
> + /*
> + * Check if _DSM(0xD) is available, and if present locate the
> + * port which issued EDR event.
> + */
> + pdev = acpi_locate_dpc_port(pdev, dpc->adev->handle);
> + if (!pdev) {
> + pdev = dpc->dev->port;
> + pci_err(pdev, "No valid port found\n");

This message should include the bus/device/function that we looked for.

> + return;
> + }
> +
> + dpc = to_dpc_dev(pdev);
> + if (!dpc) {
> + pci_err(pdev, "DPC port is NULL\n");
> + goto done;
> + }
> +
> + mutex_lock(&dpc->edr_lock);
> +
> + dpc->error_state = PCI_ERS_RESULT_DISCONNECT;
> +
> + /*
> + * Check if the port supports DPC:
> + *
> + * If port supports DPC, then fall back to default error
> + * recovery.
> + */
> + if (dpc->cap_pos) {
> + /* Check if there is a valid DPC trigger */
> + pci_read_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_STATUS,
> + &status);
> + if ((status & PCI_EXP_DPC_STATUS_TRIGGER))
> + dpc_process_error(dpc);
> + else
> + pci_err(pdev, "Invalid DPC trigger %#010x\n", status);
> + }
> +
> + /*
> + * If recovery is successful, send _OST(0xF, BDF << 16 | 0x80)
> + * to firmware. If not successful, send _OST(0xF, BDF << 16 | 0x81).
> + */
> + if (dpc->error_state == PCI_ERS_RESULT_RECOVERED)
> + status = EDR_OST_SUCCESS;
> + else
> + status = EDR_OST_FAILED;
> +
> + /* Use ACPI handle of DPC event device for sending EDR status */
> + dpc = data;
> +
> + acpi_send_edr_status(pdev, dpc->adev->handle, status);
> +
> + mutex_unlock(&dpc->edr_lock);
> +done:
> + pci_dev_put(pdev);
> +}
> +#endif
> +
> #define FLAG(x, y) (((x) & (y)) ? '+' : '-')
> static int dpc_probe(struct pcie_device *dev)
> {
> struct dpc_dev *dpc;
> struct pci_dev *pdev = dev->port;
> struct device *device = &dev->device;
> - int status;
> + int status = 0;
> u16 ctl, cap;
> +#ifdef CONFIG_ACPI
> + struct acpi_device *adev = ACPI_COMPANION(&pdev->dev);
> +#endif
>
> dpc = devm_kzalloc(device, sizeof(*dpc), GFP_KERNEL);
> if (!dpc)
> @@ -321,6 +411,9 @@ static int dpc_probe(struct pcie_device *dev)
> dpc->cap_pos = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_DPC);
> dpc->dev = dev;
>
> + dpc->error_state = PCI_ERS_RESULT_NONE;
> + mutex_init(&dpc->edr_lock);
> +
> /*
> * As per PCIe r5.0, sec 6.2.10, implementation note titled
> * "Determination of DPC Control", to avoid conflicts over whether
> @@ -358,6 +451,33 @@ static int dpc_probe(struct pcie_device *dev)
> }
> }
>
> +#ifdef CONFIG_ACPI
> + if (pcie_aer_get_firmware_first(pdev) && adev) {

I'm not convinced about using pcie_aer_get_firmware_first() here yet.
AFAICT the spec doesn't actually say anything like this (I'm looking
at the ECN sec 4.5.1 description of "Error Disconnect Recover
Supported".

> + acpi_status astatus;
> +
> + dpc->adev = adev;
> +
> + astatus = acpi_install_notify_handler(adev->handle,
> + ACPI_SYSTEM_NOTIFY,
> + edr_handle_event,
> + dpc);

I think there are a couple issues with the ECN here:

- The ECN allows EDR notifications on host bridges (sec 4.5.1, table
4-4), but it does not allow the "Locate" _DSM under host bridges
(sec 4.6.13).

- The ECN allows EDR notifications on root ports or switch ports
that do not support DPC (sec 4.5.1), but it does not allow the
"Locate" _DSM on those ports (sec 4.6.13).

> + if (ACPI_FAILURE(astatus)) {
> + pci_err(pdev,
> + "Install ACPI_SYSTEM_NOTIFY handler failed\n");
> + return -EBUSY;
> + }
> +
> + status = acpi_enable_dpc_port(pdev, adev->handle, true);
> + if (status) {
> + pci_warn(pdev, "Enable DPC port failed\n");
> + acpi_remove_notify_handler(adev->handle,
> + ACPI_SYSTEM_NOTIFY,
> + edr_handle_event);
> + return status;
> + }
> + }
> +#endif
> pci_read_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_CAP, &cap);
> pci_read_config_word(pdev, dpc->cap_pos + PCI_EXP_DPC_CTL, &ctl);
>
> @@ -409,6 +529,7 @@ static struct pcie_port_service_driver dpcdriver = {
> .probe = dpc_probe,
> .remove = dpc_remove,
> .reset_link = dpc_reset_link,
> + .error_resume = dpc_error_resume,
> };
>
> int __init pcie_dpc_init(void)
> diff --git a/include/linux/pci-acpi.h b/include/linux/pci-acpi.h
> index 62b7fdcc661c..f4e0d5d984b0 100644
> --- a/include/linux/pci-acpi.h
> +++ b/include/linux/pci-acpi.h
> @@ -111,6 +111,19 @@ extern const guid_t pci_acpi_dsm_guid;
> #define DEVICE_LABEL_DSM 0x07
> #define RESET_DELAY_DSM 0x08
> #define FUNCTION_DELAY_DSM 0x09
> +#ifdef CONFIG_PCIE_DPC
> +#define EDR_PORT_ENABLE_DSM 0x0C
> +#define EDR_PORT_LOCATE_DSM 0x0D
> +#define EDR_OST_SUCCESS 0x80
> +#define EDR_OST_FAILED 0x81
> +
> +int acpi_enable_dpc_port(struct pci_dev *pdev, acpi_handle handle,
> + bool enable);
> +struct pci_dev *acpi_locate_dpc_port(struct pci_dev *pdev,
> + acpi_handle handle);
> +int acpi_send_edr_status(struct pci_dev *pdev,
> + acpi_handle handle, u16 status);
> +#endif /* CONFIG_PCIE_DPC */
>
> #else /* CONFIG_ACPI */
> static inline void acpi_pci_add_bus(struct pci_bus *bus) { }
> --
> 2.21.0
>

Next message: Steven Rostedt: "Re: [PATCH] perf test: Test case 66 broken on s390 (lib/traceevent issue)"
Previous message: Jon Hunter: "[PATCH V2] serial: 8250_tegra: Create Tegra specific 8250 driver"
Next in thread: Kuppuswamy Sathyanarayanan: "Re: [PATCH v13 4/8] PCI/DPC: Add Error Disconnect Recover (EDR) support"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]