Re: [PATCH v3 1/3] cxl/pci: Fix appropriate checking for _OSC while handling CXL RAS registers

[Jonathan Cameron <Jonathan.Cameron@Huawei.com>]

On Thu, 3 Aug 2023 23:01:27 +0000
Smita Koralahalli <Smita.KoralahalliChannabasappa@amd.com> wrote:

> According to Section 9.17.2, Table 9-26 of CXL Specification [1], owner
> of AER should also own CXL Protocol Error Management as there is no
> explicit control of CXL Protocol error. And the CXL RAS Cap registers
> reported on Protocol errors should check for AER _OSC rather than CXL
> Memory Error Reporting Control _OSC.
> 
> The CXL Memory Error Reporting Control _OSC specifically highlights
> handling Memory Error Logging and Signaling Enhancements. These kinds of
> errors are reported through a device's mailbox and can be managed
> independently from CXL Protocol Errors.
> 
> This change fixes handling and reporting CXL Protocol Errors and RAS
> registers natively with native AER and FW-First CXL Memory Error Reporting
> Control.
> 
> [1] Compute Express Link (CXL) Specification, Revision 3.1, Aug 1 2022.
> 
> Fixes: 248529edc86f ("cxl: add RAS status unmasking for CXL")
> Signed-off-by: Smita Koralahalli <Smita.KoralahalliChannabasappa@amd.com>
> Reviewed-by: Robert Richter <rrichter@amd.com>

I'd be tempted to add a comment on why this returns 0 rather than an
error.  I think that makes sense but it isn't immediately obvious from
the local context.

Otherwise LGTM

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>


> ---
> v2:
> 	Added fixes tag.
> 	Included what the patch fixes in commit message.
> v3:
> 	Added "Reviewed-by" tag.
> ---
>  drivers/cxl/pci.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
> index 1cb1494c28fe..2323169b6e5f 100644
> --- a/drivers/cxl/pci.c
> +++ b/drivers/cxl/pci.c
> @@ -541,9 +541,9 @@ static int cxl_pci_ras_unmask(struct pci_dev *pdev)
>  		return 0;
>  	}
>  
> -	/* BIOS has CXL error control */
> -	if (!host_bridge->native_cxl_error)
> -		return -ENXIO;
> +	/* BIOS has PCIe AER error control */
> +	if (!host_bridge->native_aer)
> +		return 0;
>  
>  	rc = pcie_capability_read_word(pdev, PCI_EXP_DEVCTL, &cap);
>  	if (rc)