linux-kernel - Re: [PATCH v12 16/25] CXL/PCI: Introduce PCI_ERS_RESULT

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Message-ID: <ba93061a-09dd-4132-bde0-6af319a56405@intel.com>
Date: Fri, 26 Sep 2025 14:26:00 -0700
From: Dave Jiang <dave.jiang@...el.com>
To: Terry Bowman <terry.bowman@....com>, dave@...olabs.net,
 jonathan.cameron@...wei.com, alison.schofield@...el.com,
 dan.j.williams@...el.com, bhelgaas@...gle.com, shiju.jose@...wei.com,
 ming.li@...omail.com, Smita.KoralahalliChannabasappa@....com,
 rrichter@....com, dan.carpenter@...aro.org,
 PradeepVineshReddy.Kodamati@....com, lukas@...ner.de,
 Benjamin.Cheatham@....com, sathyanarayanan.kuppuswamy@...ux.intel.com,
 linux-cxl@...r.kernel.org, alucerop@....com, ira.weiny@...el.com
Cc: linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org
Subject: Re: [PATCH v12 16/25] CXL/PCI: Introduce PCI_ERS_RESULT_PANIC



On 9/25/25 3:34 PM, Terry Bowman wrote:
> The CXL driver's error handling for uncorrectable errors (UCE) will be
> updated in the future. A required change is for the error handlers to
> to force a system panic when a UCE is detected.
> 
> Introduce PCI_ERS_RESULT_PANIC as a 'enum pci_ers_result' type. This will
> be used by CXL UCE fatal and non-fatal recovery in future patches. Update
> PCIe recovery documentation with details of PCI_ERS_RESULT_PANIC.
> 
> Signed-off-by: Terry Bowman <terry.bowman@....com>

Reviewed-by: Dave Jiang <dave.jiang@...el.com>
> 
> ---
> 
> Changes v11 -> v12:
> - Documentation requested by (Lukas)
> ---
>  Documentation/PCI/pci-error-recovery.rst | 6 ++++++
>  include/linux/pci.h                      | 3 +++
>  2 files changed, 9 insertions(+)
> 
> diff --git a/Documentation/PCI/pci-error-recovery.rst b/Documentation/PCI/pci-error-recovery.rst
> index 42e1e78353f3..f823a6c1fb23 100644
> --- a/Documentation/PCI/pci-error-recovery.rst
> +++ b/Documentation/PCI/pci-error-recovery.rst
> @@ -102,6 +102,8 @@ Possible return values are::
>  		PCI_ERS_RESULT_NEED_RESET,  /* Device driver wants slot to be reset. */
>  		PCI_ERS_RESULT_DISCONNECT,  /* Device has completely failed, is unrecoverable */
>  		PCI_ERS_RESULT_RECOVERED,   /* Device driver is fully recovered and operational */
> +		PCI_ERS_RESULT_NO_AER_DRIVER, /* No AER capabilities registered for the driver */
> +		PCI_ERS_RESULT_PANIC,       /* System is unstable, panic. Is CXL specific */
>  	};
>  
>  A driver does not have to implement all of these callbacks; however,
> @@ -116,6 +118,10 @@ The actual steps taken by a platform to recover from a PCI error
>  event will be platform-dependent, but will follow the general
>  sequence described below.
>  
> +PCI_ERS_RESULT_PANIC is currently unique to CXL and handled in CXL
> +cxl_do_recdovery(). The PCI pcie_do_recovery() routine does not report or
> +handle PCI_ERS_RESULT_PANIC.
> +
>  STEP 0: Error Event
>  -------------------
>  A PCI bus error is detected by the PCI hardware.  On powerpc, the slot
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 53a45e92c635..bc3a7b6d0f94 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -889,6 +889,9 @@ enum pci_ers_result {
>  
>  	/* No AER capabilities registered for the driver */
>  	PCI_ERS_RESULT_NO_AER_DRIVER = (__force pci_ers_result_t) 6,
> +
> +	/* System is unstable, panic. Is CXL specific */
> +	PCI_ERS_RESULT_PANIC = (__force pci_ers_result_t) 7,
>  };
>  
>  /* PCI bus error event callbacks */