linux-kernel - Re: [PATCH v1 2/3] x86/PCI: trim _CRS windows when they conflict with previous reservations

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Message-ID: <4BA04BB9.2090501@jp.fujitsu.com>
Date:	Wed, 17 Mar 2010 12:25:45 +0900
From:	Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>
To:	Bjorn Helgaas <bjorn.helgaas@...com>
CC:	Jesse Barnes <jbarnes@...tuousgeek.org>, linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org, "Rafael J. Wysocki" <rjw@...k.pl>,
	Yanko Kaneti <yaneti@...lera.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Thomas Renninger <trenn@...e.de>, maciej.rutecki@...il.com
Subject: Re: [PATCH v1 2/3] x86/PCI: trim _CRS windows when they conflict
 with	previous reservations

Bjorn Helgaas wrote:
> Yanko's GA-MA78GM-S2H (BIOS F11) reports a host bridge window that overlaps
> system memory:
> 
>     PCI window: [mem 0xcff00000-0x10ed0ffff]
>     System RAM: [mem 0x100000000-0x22fffffff]
> 
> We can be pretty confident that the System RAM region is correct (if it
> were wrong, we'd crash as soon as we tried to use any memory in that area),
> so this patch tries to correct the PCI window by trimming it so it doesn't
> conflict with any previous reservations.
> 

Though I might misunderstand something, it looks Yanko's machine specific
workaround. I'm wondering if trimming _CRS is a generic workaround for
broken _CRS machine.

How about doing this when GA-MA78GM-S2H (BIOS F11) (and known machines
that have the same problem) is detected? Or how about switching nocrs
mode if the problem (resource conflict) is detected?

Thanks,
Kenji Kaneshige



> http://bugzilla.kernel.org/show_bug.cgi?id=15480
> 
> Signed-off-by: Bjorn Helgaas <bjorn.helgaas@...com>
> Reported-by: Yanko Kaneti <yaneti@...lera.com>
> ---
> 
>  arch/x86/pci/acpi.c |   48 +++++++++++++++++++++++++++++++++++-------------
>  1 files changed, 35 insertions(+), 13 deletions(-)
> 
> 
> diff --git a/arch/x86/pci/acpi.c b/arch/x86/pci/acpi.c
> index 6e22454..d255ce8 100644
> --- a/arch/x86/pci/acpi.c
> +++ b/arch/x86/pci/acpi.c
> @@ -114,11 +114,19 @@ align_resource(struct acpi_device *bridge, struct resource *res)
>  	}
>  }
>  
> +static bool
> +resource_contains(struct resource *res, resource_size_t n)
> +{
> +	if (n < res->start || n > res->end)
> +		return false;
> +	return true;
> +}
> +
>  static acpi_status
>  setup_resource(struct acpi_resource *acpi_res, void *data)
>  {
>  	struct pci_root_info *info = data;
> -	struct resource *res;
> +	struct resource *res, *conflict;
>  	struct acpi_resource_address64 addr;
>  	acpi_status status;
>  	unsigned long flags;
> @@ -157,21 +165,35 @@ setup_resource(struct acpi_resource *acpi_res, void *data)
>  		return AE_OK;
>  	}
>  
> -	if (insert_resource(root, res)) {
> +	conflict = insert_resource_conflict(root, res);
> +	while (conflict) {
>  		dev_err(&info->bridge->dev,
> -			"can't allocate host bridge window %pR\n", res);
> -	} else {
> -		pci_bus_add_resource(info->bus, res, 0);
> -		info->res_num++;
> -		if (addr.translation_offset)
> -			dev_info(&info->bridge->dev, "host bridge window %pR "
> -				 "(PCI address [%#llx-%#llx])\n",
> -				 res, res->start - addr.translation_offset,
> -				 res->end - addr.translation_offset);
> +		        "host bridge window %pR conflicts with %s %pR\n",
> +			res, conflict->name, conflict);
> +
> +		if (resource_contains(res, conflict->end))
> +			res->start = conflict->end + 1;
> +		else if (resource_contains(res, conflict->start))
> +			res->end = conflict->start - 1;
>  		else
> -			dev_info(&info->bridge->dev,
> -				 "host bridge window %pR\n", res);
> +			return AE_OK;
> +
> +		if (res->start >= res->end)
> +			return AE_OK;
> +
> +		conflict = insert_resource_conflict(root, res);
>  	}
> +
> +	pci_bus_add_resource(info->bus, res, 0);
> +	info->res_num++;
> +	if (addr.translation_offset)
> +		dev_info(&info->bridge->dev, "host bridge window %pR "
> +			 "(PCI address [%#llx-%#llx])\n",
> +			 res, res->start - addr.translation_offset,
> +			 res->end - addr.translation_offset);
> +	else
> +		dev_info(&info->bridge->dev,
> +			 "host bridge window %pR\n", res);
>  	return AE_OK;
>  }
>  
> 
> --
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> 
> 


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