Re: [PATCH v18 09/13] cxl: Update CXL Endpoint AER handler

[Jonathan Cameron]

On Fri, 17 Jul 2026 17:27:02 -0500
Terry Bowman <terry.bowman@xxxxxxx> wrote:

> Rename cxl_error_detected() to cxl_pci_error_detected() and rename
> the struct pci_error_handlers instance to cxl_pci_error_handlers to
> avoid shadowing the struct type tag.
> 
> Document the unconditional CXL RAS read policy: on a dead link,
> readl() returns 0xFFFFFFFF which is interpreted as UCE bits set and
> triggers a panic. If RAS registers are not mapped the read is
> skipped and the frozen/perm_failure switch cases defer to AER
> recovery for devices without active CXL.mem traffic.
> 
> Signed-off-by: Terry Bowman <terry.bowman@xxxxxxx>
> 
A couple of trivial things inline.

Reviewed-by: Jonathan Cameron <jonathan.cameron@xxxxxxxxxxxxxxxx>

>  drivers/cxl/core/ras.c | 24 +++++++++++++++---------
>  drivers/cxl/cxlpci.h   |  8 ++++----
>  drivers/cxl/pci.c      | 12 ++++++------
>  3 files changed, 25 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/cxl/core/ras.c b/drivers/cxl/core/ras.c
> index 6f4a3c1b0bb85..d5dc2c22565da 100644
> --- a/drivers/cxl/core/ras.c
> +++ b/drivers/cxl/core/ras.c
> @@ -328,10 +328,8 @@ bool cxl_handle_ras(struct cxl_port *port, struct cxl_dport *dport, void __iomem
>  	return true;
>  }
>  
> -
> -

This white space removal should be in patch 7 I think.

> -pci_ers_result_t cxl_error_detected(struct pci_dev *pdev,
> -				    pci_channel_state_t state)
> +pci_ers_result_t cxl_pci_error_detected(struct pci_dev *pdev,
> +					pci_channel_state_t state)
>  {
>  	struct cxl_port *port __free(put_cxl_port) = find_cxl_port_by_uport(&pdev->dev);
>  	bool ue = false;
> @@ -349,10 +347,18 @@ pci_ers_result_t cxl_error_detected(struct pci_dev *pdev,
>  		}
>  
>  		/*
> -		 * A frozen channel indicates an impending reset which is fatal to
> -		 * CXL.mem operation, and will likely crash the system. On the off
> -		 * chance the situation is recoverable dump the status of the RAS
> -		 * capability registers and bounce the active state of the memdev.
> +		 * The CXL RAS read is unconditional regardless of channel

Keep the 80 char wrap for comments. Also local style is single space after .
(I'm terrible at not following style on that stuff but do as I say not as
I do!)

> +		 * state.  Any uncorrectable error bit set in the CXL RAS
> +		 * status register triggers a panic because CXL.mem cache
> +		 * coherency is already lost; continuing risks silent data
> +		 * corruption across interleaved HDM regions.
> +		 *
> +		 * On a dead link readl() returns 0xFFFFFFFF which sets all
> +		 * UCE bits and also triggers the panic - this is intentional.
> +		 * If RAS registers are not mapped the read is skipped, the
> +		 * panic is not reached, and the frozen/perm_failure switch
> +		 * cases below handle AER recovery for devices without active
> +		 * CXL.mem traffic.

Now this comment I like. Good and clear and explaining the non obvious decision.

>  		 */
>  		ue = cxl_handle_ras(port, NULL, to_ras_base(port, NULL));

> diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
> index 5c21db36073fe..6cf1db7b85020 100644
> --- a/drivers/cxl/pci.c
> +++ b/drivers/cxl/pci.c
> @@ -1000,18 +1000,18 @@ static void cxl_reset_done(struct pci_dev *pdev)
>  	}
>  }
>  
> -static const struct pci_error_handlers cxl_error_handlers = {
> -	.error_detected	= cxl_error_detected,
> -	.slot_reset	= cxl_slot_reset,
> -	.resume		= cxl_error_resume,
> -	.reset_done	= cxl_reset_done,
> +static const struct pci_error_handlers cxl_pci_error_handlers = {
> +	.error_detected		= cxl_pci_error_detected,
> +	.slot_reset		= cxl_slot_reset,
> +	.resume			= cxl_error_resume,
> +	.reset_done		= cxl_reset_done,

Do we need the re-indent?  Nice to make it more obvious what didn't change.

>  };