linux-kernel - Re: [PATCH v6 2/2] acpi: apei: Do not panic() on PCIe errors reported through GHES

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Date:   Mon, 21 May 2018 10:27:49 -0400
From:   Tyler Baicar <tbaicar@...eaurora.org>
To:     Alexandru Gagniuc <mr.nuke.me@...il.com>, bp@...en8.de
Cc:     alex_gagniuc@...lteam.com, austin_bolen@...l.com,
        shyam_iyer@...l.com, "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>, Tony Luck <tony.luck@...el.com>,
        Will Deacon <will.deacon@....com>,
        James Morse <james.morse@....com>,
        Shiju Jose <shiju.jose@...wei.com>,
        "Jonathan (Zhixiong) Zhang" <zjzhang@...eaurora.org>,
        Dongjiu Geng <gengdongjiu@...wei.com>,
        linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 2/2] acpi: apei: Do not panic() on PCIe errors reported
 through GHES

On 5/21/2018 9:49 AM, Alexandru Gagniuc wrote:
> +/* PCIe errors should not cause a panic. */
> +static int ghes_sec_pcie_severity(struct acpi_hest_generic_data *gdata)
> +{
> +	struct cper_sec_pcie *pcie_err = acpi_hest_get_payload(gdata);
> +
> +	if (pcie_err->validation_bits & CPER_PCIE_VALID_DEVICE_ID &&
> +	    pcie_err->validation_bits & CPER_PCIE_VALID_AER_INFO &&
> +	    IS_ENABLED(CONFIG_ACPI_APEI_PCIEAER))
> +		return GHES_SEV_RECOVERABLE;
> +
> +	return ghes_cper_severity(gdata->error_severity);
> +}
> +
> +/*
> + * The severity field in the status block is an unreliable metric for the
> + * severity. A more reliable way is to look at each subsection and see how safe
> + * it is to call the approproate error handler.
> + * We're not conerned with handling the error. We're concerned with being able
> + * to notify an error handler by crossing the NMI/IRQ boundary, being able to
> + * schedule_work, and so forth.
> + *   - SEC_PCIE: All PCIe errors can be handled by AER.
> + */
> +static int ghes_severity(struct ghes *ghes)
> +{
> +	int worst_sev, sec_sev;
> +	struct acpi_hest_generic_data *gdata;
> +	const guid_t *section_type;
> +	const struct acpi_hest_generic_status *estatus = ghes->estatus;
> +
> +	worst_sev = GHES_SEV_NO;
> +	apei_estatus_for_each_section(estatus, gdata) {
> +		section_type = (guid_t *)gdata->section_type;
> +		sec_sev = ghes_cper_severity(gdata->error_severity);
> +
> +		if (guid_equal(section_type, &CPER_SEC_PCIE))
> +			sec_sev = ghes_sec_pcie_severity(gdata);
> +
> +		worst_sev = max(worst_sev, sec_sev);
> +	}
> +
> +	return worst_sev;
> +}
> +
>   static void ghes_do_proc(struct ghes *ghes,
>   			 const struct acpi_hest_generic_status *estatus)
>   {
> @@ -944,7 +986,7 @@ static int ghes_notify_nmi(unsigned int cmd, struct pt_regs *regs)
>   			ret = NMI_HANDLED;
>   		}
>   
> -		sev = ghes_cper_severity(ghes->estatus->error_severity);
> +		sev = ghes_severity(ghes);
Hello Alex,

There is a compile warning if CONFIG_HAVE_ACPI_APEI_NMI is not selected.

   CC      drivers/acpi/apei/ghes.o
drivers/acpi/apei/ghes.c:483:12: warning: ‘ghes_severity’ defined but not used 
[-Wunused-function]
  static int ghes_severity(struct ghes *ghes)
             ^~~~~~~~~~~~~

Thanks,
Tyler

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