linux-kernel - Re: [PATCH 4/8] ACPI, APEI, Resolve false conflict between ACPI NVS and APEI

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Date:	Mon, 19 Sep 2011 20:09:14 -0600
From:	Bjorn Helgaas <bhelgaas@...gle.com>
To:	Huang Ying <ying.huang@...el.com>
Cc:	Len Brown <lenb@...nel.org>, linux-kernel@...r.kernel.org,
	Tony Luck <tony.luck@...el.com>, linux-acpi@...r.kernel.org,
	Yinghai Lu <yinghai@...nel.org>
Subject: Re: [PATCH 4/8] ACPI, APEI, Resolve false conflict between ACPI NVS
 and APEI

On Mon, Sep 19, 2011 at 7:38 PM, Huang Ying <ying.huang@...el.com> wrote:
> Some firmware will access memory in ACPI NVS region via APEI.  That
> is, instructions in APEI ERST/EINJ table will read/write ACPI NVS
> region.  The original resource conflict checking in APEI code will
> check memory/ioport accessed by APEI via general resource management
> mech.  But ACPI NVS region is marked as busy already, so that the
> false resource conflict will prevent APEI ERST/EINJ to work.
>
> To fix this, this patch excludes ACPI NVS regions when APEI components
> request resources.  So that they will not conflict with ACPI NVS
> regions.

I think this is much, much too complicated.

Yinghai's three-line e820.c patch to leave ACPI NVS regions in the
iomem_resource tree, but as not busy, is far better.

Bjorn

> Reported-and-tested-by: Pavel Ivanov <paivanof@...il.com>
> Signed-off-by: Huang Ying <ying.huang@...el.com>
> ---
>  drivers/acpi/apei/apei-base.c |   29 ++++++++++++++++++++++++++++-
>  1 file changed, 28 insertions(+), 1 deletion(-)
>
> --- a/drivers/acpi/apei/apei-base.c
> +++ b/drivers/acpi/apei/apei-base.c
> @@ -438,8 +438,19 @@ int apei_resources_sub(struct apei_resou
>  }
>  EXPORT_SYMBOL_GPL(apei_resources_sub);
>
> +static int apei_get_nvs_callback(__u64 start, __u64 size, void *data)
> +{
> +       struct apei_resources *resources = data;
> +       return apei_res_add(&resources->iomem, start, size);
> +}
> +
> +static int apei_get_nvs_resources(struct apei_resources *resources)
> +{
> +       return acpi_nvs_for_each_region(apei_get_nvs_callback, resources);
> +}
> +
>  /*
> - * IO memory/port rersource management mechanism is used to check
> + * IO memory/port resource management mechanism is used to check
>  * whether memory/port area used by GARs conflicts with normal memory
>  * or IO memory/port of devices.
>  */
> @@ -448,12 +459,26 @@ int apei_resources_request(struct apei_r
>  {
>        struct apei_res *res, *res_bak = NULL;
>        struct resource *r;
> +       struct apei_resources nvs_resources;
>        int rc;
>
>        rc = apei_resources_sub(resources, &apei_resources_all);
>        if (rc)
>                return rc;
>
> +       /*
> +        * Some firmware uses ACPI NVS region, that has been marked as
> +        * busy, so exclude it from APEI resources to avoid false
> +        * conflict.
> +        */
> +       apei_resources_init(&nvs_resources);
> +       rc = apei_get_nvs_resources(&nvs_resources);
> +       if (rc)
> +               goto res_fini;
> +       rc = apei_resources_sub(resources, &nvs_resources);
> +       if (rc)
> +               goto res_fini;
> +
>        rc = -EINVAL;
>        list_for_each_entry(res, &resources->iomem, list) {
>                r = request_mem_region(res->start, res->end - res->start,
> @@ -500,6 +525,8 @@ err_unmap_iomem:
>                        break;
>                release_mem_region(res->start, res->end - res->start);
>        }
> +res_fini:
> +       apei_resources_fini(&nvs_resources);
>        return rc;
>  }
>  EXPORT_SYMBOL_GPL(apei_resources_request);
> --
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