linux-kernel - Re: [PATCH] ACPI, EINJ: Enhance error injection tolerance level

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Message-ID: <54854EAC.8090504@linaro.org>
Date:	Mon, 08 Dec 2014 08:09:32 +0100
From:	Tomasz Nowicki <tomasz.nowicki@...aro.org>
To:	"Luck, Tony" <tony.luck@...el.com>, linux-kernel@...r.kernel.org
CC:	Borislav Petkov <bp@...e.de>,
	Chen Gong <gong.chen@...ux.intel.com>,
	linux-acpi@...r.kernel.org
Subject: Re: [PATCH] ACPI, EINJ: Enhance error injection tolerance level

W dniu 03.12.2014 o 22:22, Luck, Tony pisze:
> From: "Chen, Gong" <gong.chen@...ux.intel.com>
>
> Some BIOSes utilize PCI MMCFG space read/write opertion to trigger
> specific errors. EINJ will report errors as below when hitting such
> cases:
>
> APEI: Can not request [mem 0x83f990a0-0x83f990a3] for APEI EINJ Trigger registers
>
> It is because on x86 platform ACPI based PCI MMCFG logic has
> reserved all MMCFG spaces so that EINJ can't reserve it again.
> We already trust the ACPI/APEI code when using the EINJ interface
> so it is not a big leap to also trust it to access the right
> MMCFG addresses. Skip address checking to allow the access.
>
> Signed-off-by: Chen, Gong <gong.chen@...ux.intel.com>
> Signed-off-by: Tony Luck <tony.luck@...el.com>
> ---
>   drivers/acpi/apei/apei-base.c | 58 ++++++++++++++++++++++++++++++++++++++-----
>   1 file changed, 52 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/acpi/apei/apei-base.c b/drivers/acpi/apei/apei-base.c
> index 2cd7bdd6c8b3..e809d3c4904d 100644
> --- a/drivers/acpi/apei/apei-base.c
> +++ b/drivers/acpi/apei/apei-base.c
> @@ -41,6 +41,9 @@
>   #include <linux/interrupt.h>
>   #include <linux/debugfs.h>
>   #include <asm/unaligned.h>
> +#ifdef CONFIG_PCI_MMCONFIG
> +#include <asm/pci_x86.h>
> +#endif
>
>   #include "apei-internal.h"
>
> @@ -449,7 +452,7 @@ int apei_resources_sub(struct apei_resources *resources1,
>   }
>   EXPORT_SYMBOL_GPL(apei_resources_sub);
>
> -static int apei_get_nvs_callback(__u64 start, __u64 size, void *data)
> +static int apei_get_res_callback(__u64 start, __u64 size, void *data)
>   {
>   	struct apei_resources *resources = data;
>   	return apei_res_add(&resources->iomem, start, size);
> @@ -457,9 +460,42 @@ static int apei_get_nvs_callback(__u64 start, __u64 size, void *data)
>
>   static int apei_get_nvs_resources(struct apei_resources *resources)
>   {
> -	return acpi_nvs_for_each_region(apei_get_nvs_callback, resources);
> +	return acpi_nvs_for_each_region(apei_get_res_callback, resources);
>   }
>
> +#ifdef CONFIG_PCI_MMCONFIG
> +static int pci_mmcfg_for_each_region(int (*func)(__u64 start, __u64 size,
> +				     void *data), void *data)
> +{
> +	struct pci_mmcfg_region *cfg;
> +	int rc;
> +
> +	if ((pci_probe & PCI_PROBE_MMCONF) == 0)
> +		return 0;
> +
> +	if (list_empty(&pci_mmcfg_list))
> +		return 0;
> +
> +	list_for_each_entry(cfg, &pci_mmcfg_list, list) {
> +		rc = func(cfg->res.start, resource_size(&cfg->res), data);
> +		if (rc)
> +			return rc;
> +	}
> +
> +	return 0;
> +}
> +
> +static int apei_get_mmcfg_resources(struct apei_resources *resources)
> +{
> +	return pci_mmcfg_for_each_region(apei_get_res_callback, resources);
> +}
> +#else
> +static int apei_get_mmcfg_resources(struct apei_resources *resources)
> +{
> +	return 0;
> +}
> +#endif
> +

If this is the case for x86 only, IMHO it should be wrapped into:
#if CONFIG_X86 && CONFIG_PCI_MMCONFIG or something similar.

If it solves problem related to ACPI, you should not use in this file:
 > +	if ((pci_probe & PCI_PROBE_MMCONF) == 0)
 > +		return 0;
This is very x86 specific. We are making a lot of effort to make 
MMCONFIG platform independent now.

Regards,
Tomasz
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