linux-kernel - Re: [PATCH 2/2] cxl/pci: Fix appropriate checking for

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Date:   Wed, 19 Jul 2023 13:39:23 -0700
From:   Sathyanarayanan Kuppuswamy 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>
To:     Smita Koralahalli <Smita.KoralahalliChannabasappa@....com>,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-cxl@...r.kernel.org
Cc:     Bjorn Helgaas <bhelgaas@...gle.com>, oohall@...il.com,
        Lukas Wunner <lukas@...ner.de>,
        Mahesh J Salgaonkar <mahesh@...ux.ibm.com>,
        Alison Schofield <alison.schofield@...el.com>,
        Vishal Verma <vishal.l.verma@...el.com>,
        Ira Weiny <ira.weiny@...el.com>,
        Ben Widawsky <bwidawsk@...nel.org>,
        Dan Williams <dan.j.williams@...el.com>,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        Yazen Ghannam <yazen.ghannam@....com>,
        Terry Bowman <terry.bowman@....com>,
        Robert Richter <rrichter@....com>
Subject: Re: [PATCH 2/2] cxl/pci: Fix appropriate checking for _OSC while
 handling CXL RAS registers



On 7/19/23 12:23 PM, Smita Koralahalli 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.

Does it fix any issue? If yes, please include that in the commit log.

Since you are removing some change, maybe it needs Fixes: tag?
> 
> [1] Compute Express Link (CXL) Specification, Revision 3.1, Aug 1 2022.
> 
> Signed-off-by: Smita Koralahalli <Smita.KoralahalliChannabasappa@....com>
> ---
>  drivers/cxl/pci.c | 7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
> index 1cb1494c28fe..44a21ab7add5 100644
> --- a/drivers/cxl/pci.c
> +++ b/drivers/cxl/pci.c
> @@ -529,7 +529,6 @@ static int cxl_pci_setup_regs(struct pci_dev *pdev, enum cxl_regloc_type type,
>  
>  static int cxl_pci_ras_unmask(struct pci_dev *pdev)
>  {
> -	struct pci_host_bridge *host_bridge = pci_find_host_bridge(pdev->bus);
>  	struct cxl_dev_state *cxlds = pci_get_drvdata(pdev);
>  	void __iomem *addr;
>  	u32 orig_val, val, mask;
> @@ -541,9 +540,9 @@ 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 (!pcie_aer_is_native(pdev))
> +		return 0;
>  
>  	rc = pcie_capability_read_word(pdev, PCI_EXP_DEVCTL, &cap);
>  	if (rc)

-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer