[PATCH v4 2/3] PCI/DPC: Run recovery on device that detected the error

[Manivannan Sadhasivam]

On Mon, Feb 17, 2025 at 10:42:17AM +0800, Shuai Xue wrote:
> The current implementation of pcie_do_recovery() assumes that the
> recovery process is executed on the device that detected the error.

s/on/for

> However, the DPC driver currently passes the error port that experienced
> the DPC event to pcie_do_recovery().
> 
> Use the SOURCE ID register to correctly identify the device that
> detected the error. When passing the error device, the
> pcie_do_recovery() will find the upstream bridge and walk bridges
> potentially AER affected. And subsequent patches will be able to

s/patches/commits

> accurately access AER status of the error device.
> 
> Should not observe any functional changes.
> 
> Signed-off-by: Shuai Xue <xueshuai at linux.alibaba.com>
> ---
>  drivers/pci/pci.h      |  2 +-
>  drivers/pci/pcie/dpc.c | 28 ++++++++++++++++++++++++----
>  drivers/pci/pcie/edr.c |  7 ++++---
>  3 files changed, 29 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> index 01e51db8d285..870d2fbd6ff2 100644
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -572,7 +572,7 @@ struct rcec_ea {
>  void pci_save_dpc_state(struct pci_dev *dev);
>  void pci_restore_dpc_state(struct pci_dev *dev);
>  void pci_dpc_init(struct pci_dev *pdev);
> -void dpc_process_error(struct pci_dev *pdev);
> +struct pci_dev *dpc_process_error(struct pci_dev *pdev);
>  pci_ers_result_t dpc_reset_link(struct pci_dev *pdev);
>  bool pci_dpc_recovered(struct pci_dev *pdev);
>  unsigned int dpc_tlp_log_len(struct pci_dev *dev);
> diff --git a/drivers/pci/pcie/dpc.c b/drivers/pci/pcie/dpc.c
> index 1a54a0b657ae..ea3ea989afa7 100644
> --- a/drivers/pci/pcie/dpc.c
> +++ b/drivers/pci/pcie/dpc.c
> @@ -253,10 +253,20 @@ static int dpc_get_aer_uncorrect_severity(struct pci_dev *dev,
>  	return 1;
>  }
>  
> -void dpc_process_error(struct pci_dev *pdev)
> +/**
> + * dpc_process_error - handle the DPC error status
> + * @pdev: the port that experienced the containment event
> + *
> + * Return the device that detected the error.

s/Return/Return:

> + *
> + * NOTE: The device reference count is increased, the caller must decrement
> + * the reference count by calling pci_dev_put().
> + */
> +struct pci_dev *dpc_process_error(struct pci_dev *pdev)
>  {
>  	u16 cap = pdev->dpc_cap, status, source, reason, ext_reason;
>  	struct aer_err_info info;
> +	struct pci_dev *err_dev;
>  
>  	pci_read_config_word(pdev, cap + PCI_EXP_DPC_STATUS, &status);
>  	pci_read_config_word(pdev, cap + PCI_EXP_DPC_SOURCE_ID, &source);
> @@ -279,6 +289,13 @@ void dpc_process_error(struct pci_dev *pdev)
>  		 "software trigger" :
>  		 "reserved error");
>  
> +	if (reason == PCI_EXP_DPC_STATUS_TRIGGER_RSN_NFE ||
> +	    reason == PCI_EXP_DPC_STATUS_TRIGGER_RSN_FE)
> +		err_dev = pci_get_domain_bus_and_slot(pci_domain_nr(pdev->bus),
> +					    PCI_BUS_NUM(source), source & 0xff);
> +	else
> +		err_dev = pci_dev_get(pdev);
> +
>  	/* show RP PIO error detail information */
>  	if (pdev->dpc_rp_extensions &&
>  	    reason == PCI_EXP_DPC_STATUS_TRIGGER_RSN_IN_EXT &&
> @@ -291,6 +308,8 @@ void dpc_process_error(struct pci_dev *pdev)
>  		pci_aer_clear_nonfatal_status(pdev);
>  		pci_aer_clear_fatal_status(pdev);
>  	}
> +
> +	return err_dev;
>  }
>  
>  static void pci_clear_surpdn_errors(struct pci_dev *pdev)
> @@ -346,7 +365,7 @@ static bool dpc_is_surprise_removal(struct pci_dev *pdev)
>  
>  static irqreturn_t dpc_handler(int irq, void *context)
>  {
> -	struct pci_dev *err_port = context;
> +	struct pci_dev *err_port = context, *err_dev;
>  
>  	/*
>  	 * According to PCIe r6.0 sec 6.7.6, errors are an expected side effect
> @@ -357,10 +376,11 @@ static irqreturn_t dpc_handler(int irq, void *context)
>  		return IRQ_HANDLED;
>  	}
>  
> -	dpc_process_error(err_port);
> +	err_dev = dpc_process_error(err_port);
>  
>  	/* We configure DPC so it only triggers on ERR_FATAL */
> -	pcie_do_recovery(err_port, pci_channel_io_frozen, dpc_reset_link);
> +	pcie_do_recovery(err_dev, pci_channel_io_frozen, dpc_reset_link);
> +	pci_dev_put(err_dev);
>  
>  	return IRQ_HANDLED;
>  }
> diff --git a/drivers/pci/pcie/edr.c b/drivers/pci/pcie/edr.c
> index 521fca2f40cb..088f3e188f54 100644
> --- a/drivers/pci/pcie/edr.c
> +++ b/drivers/pci/pcie/edr.c
> @@ -150,7 +150,7 @@ static int acpi_send_edr_status(struct pci_dev *pdev, struct pci_dev *edev,
>  
>  static void edr_handle_event(acpi_handle handle, u32 event, void *data)
>  {
> -	struct pci_dev *pdev = data, *err_port;
> +	struct pci_dev *pdev = data, *err_port, *err_dev;
>  	pci_ers_result_t estate = PCI_ERS_RESULT_DISCONNECT;
>  	u16 status;
>  
> @@ -190,7 +190,7 @@ static void edr_handle_event(acpi_handle handle, u32 event, void *data)
>  		goto send_ost;
>  	}
>  
> -	dpc_process_error(err_port);
> +	err_dev = dpc_process_error(err_port);
>  	pci_aer_raw_clear_status(err_port);
>  
>  	/*
> @@ -198,7 +198,7 @@ static void edr_handle_event(acpi_handle handle, u32 event, void *data)
>  	 * or ERR_NONFATAL, since the link is already down, use the FATAL
>  	 * error recovery path for both cases.
>  	 */
> -	estate = pcie_do_recovery(err_port, pci_channel_io_frozen, dpc_reset_link);
> +	estate = pcie_do_recovery(err_dev, pci_channel_io_frozen, dpc_reset_link);
>  
>  send_ost:
>  
> @@ -216,6 +216,7 @@ static void edr_handle_event(acpi_handle handle, u32 event, void *data)
>  	}
>  
>  	pci_dev_put(err_port);
> +	pci_dev_put(err_dev);

err_dev is not a valid pointer before calling dpc_process_error(). So either
initialize it with NULL or only call it in error paths after
dpc_process_error().

And btw, pci_dev_put(err_dev) should come before pci_dev_put(err_port).

- Mani

-- 
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