linux-kernel - Re: [PATCH] Re: [Patch] MCE, APEI: Don't enable CMCI when Firmware First mode is set in

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Message-ID: <20130616122030.GA12290@nazgul.tnic>
Date:	Sun, 16 Jun 2013 14:20:30 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	"Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>
Cc:	tony.luck@...el.com, ananth@...ibm.com, masbock@...ux.vnet.ibm.com,
	lcm@...ux.vnet.ibm.com, linux-kernel@...r.kernel.org,
	linux-acpi@...r.kernel.org, ying.huang@...el.com
Subject: Re: [PATCH] Re: [Patch] MCE, APEI: Don't enable CMCI when Firmware
 First mode is set in

On Fri, Jun 14, 2013 at 11:47:21PM +0530, Naveen N. Rao wrote:
> +static int __init hest_parse_cmc(struct acpi_hest_header *hest_hdr, void *data)
> +{
> +	int i;
> +	struct acpi_hest_ia_corrected *cmc;
> +	struct acpi_hest_ia_error_bank *mc_bank;
> +
> +	if (hest_hdr->type != ACPI_HEST_TYPE_IA32_CORRECTED_CHECK)
> +		return 0;
> +
> +	if (!((struct acpi_hest_generic *)hest_hdr)->enabled)
> +		return 0;
> +
> +	cmc = (struct acpi_hest_ia_corrected *)hest_hdr;
> +	if (!(cmc->flags & ACPI_HEST_FIRMWARE_FIRST))
> +		return 0;
> +
> +	/*
> +	 * We expect HEST to provide a list of MC banks that
> +	 * report errors through firmware first mode.
> +	 */
> +	if (cmc->num_hardware_banks <= 0)
> +		return 0;
> +
> +	pr_info("HEST: Enabling Firmware First mode for corrected errors\n");
> +
> +	mc_bank = (struct acpi_hest_ia_error_bank *)(cmc + 1);
> +	for (i = 0; i < cmc->num_hardware_banks; i++, mc_bank++)
> +		mce_disable_bank(mc_bank->bank_number);

One more thing: we never trust the BIOS so mce_disable_bank() should
sanity-check this mc_bank->bank_number against the number of the
actually available banks on the system before disabling anything.

Thanks.
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