linux-kernel - Re: [tip:x86/pci] x86, pci: Ignore any PCI BARs that match an HPET we already know about

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Date:	Wed, 22 Sep 2010 14:48:44 -0700
From:	Yinghai Lu <yinghai@...nel.org>
To:	mingo@...hat.com, hpa@...or.com, linux-kernel@...r.kernel.org,
	simon@...e.lp0.eu, tglx@...utronix.de, bjorn.helgaas@...com,
	hpa@...ux.intel.com
CC:	linux-tip-commits@...r.kernel.org
Subject: Re: [tip:x86/pci] x86, pci: Ignore any PCI BARs that match an HPET
 we already know about

On 09/22/2010 02:22 PM, tip-bot for Bjorn Helgaas wrote:
> Commit-ID:  e72a6c8f7ac715a9cdb473afbc30743348d0a1e2
> Gitweb:     http://git.kernel.org/tip/e72a6c8f7ac715a9cdb473afbc30743348d0a1e2
> Author:     Bjorn Helgaas <bjorn.helgaas@...com>
> AuthorDate: Wed, 22 Sep 2010 14:15:47 -0600
> Committer:  H. Peter Anvin <hpa@...ux.intel.com>
> CommitDate: Wed, 22 Sep 2010 13:29:39 -0700
> 
> x86, pci: Ignore any PCI BARs that match an HPET we already know about
> 
> We often discover the HPET early, via the static ACPI HPET table,
> before enumerating PCI devices.  If the HPET is implemented as a PCI
> function, we will discover it again during PCI device enumeration.  We
> must ignore the PCI function so we don't inadvertently move it out
> from under the driver.
> 
> I think it's better to ignore *any* PCI BAR that matches a previously
> discovered HPET; that way we don't need platform-specific knowledge,
> and we won't have to add more quirks for future machines.
> 
> This is for a regression from 2.6.34, but the reporter has been
> unable to test it yet.
> 
> [ hpa: if this fixes the regression, it should be promoted to x86/urgent ]
> 
> Reference: https://bugzilla.kernel.org/show_bug.cgi?id=18482
> Reported-by: Simon Arlott <simon@...e.lp0.eu>
> Signed-off-by: Bjorn Helgaas <bjorn.helgaas@...com>
> LKML-Reference: <20100922201547.3197.33702.stgit@....kio>
> Signed-off-by: H. Peter Anvin <hpa@...ux.intel.com>
> ---
>  arch/x86/kernel/quirks.c |   21 +++++++++++++++++++++
>  arch/x86/pci/fixup.c     |   28 ----------------------------
>  2 files changed, 21 insertions(+), 28 deletions(-)
> 
> diff --git a/arch/x86/kernel/quirks.c b/arch/x86/kernel/quirks.c
> index 939b9e9..99a7d4b 100644
> --- a/arch/x86/kernel/quirks.c
> +++ b/arch/x86/kernel/quirks.c
> @@ -507,6 +507,27 @@ static void force_disable_hpet_msi(struct pci_dev *unused)
>  DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_ATI, PCI_DEVICE_ID_ATI_SBX00_SMBUS,
>  			 force_disable_hpet_msi);
>  
> +static void disable_pci_hpet(struct pci_dev *dev)
> +{
> +	int i;
> +
> +	if (!hpet_address)
> +		return;
> +
> +	for (i = 0; i < 6; i++) {
> +		struct resource *res = &dev->resource[i];
> +
> +		if (resource_type(res) == IORESOURCE_MEM &&
> +		    res->start == hpet_address) {
> +			dev_info(&dev->dev, "BAR %d: %pR is an HPET we found earlier; ignoring this BAR\n",
> +				 i, res);
> +			res->flags = 0;
> +			res->start = 0;
> +			res->end = 0;
> +		}
> +	}
> +}

It seems there is some problem here:

hpet_res is inserted to resource with late_initcall().
so if you don't touch that hpet address in bar and not put in the resource.
kernel could allocate that address to other devices that doesn't get resource from BIOS.

Yinghai


> +DECLARE_PCI_FIXUP_HEADER(PCI_ANY_ID, PCI_ANY_ID, disable_pci_hpet);
>  #endif
>  
>  #if defined(CONFIG_PCI) && defined(CONFIG_NUMA)
> diff --git a/arch/x86/pci/fixup.c b/arch/x86/pci/fixup.c
> index 6dd8955..08eba69 100644
> --- a/arch/x86/pci/fixup.c
> +++ b/arch/x86/pci/fixup.c
> @@ -493,31 +493,3 @@ static void __devinit pci_siemens_interrupt_controller(struct pci_dev *dev)
>  }
>  DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_SIEMENS, 0x0015,
>  			  pci_siemens_interrupt_controller);
> -
> -/*
> - * SB600: Disable BAR1 on device 14.0 to avoid HPET resources from
> - * confusing the PCI engine:
> - */
> -static void sb600_disable_hpet_bar(struct pci_dev *dev)
> -{
> -	u8 val;
> -
> -	/*
> -	 * The SB600 and SB700 both share the same device
> -	 * ID, but the PM register 0x55 does something different
> -	 * for the SB700, so make sure we are dealing with the
> -	 * SB600 before touching the bit:
> -	 */
> -
> -	pci_read_config_byte(dev, 0x08, &val);
> -
> -	if (val < 0x2F) {
> -		outb(0x55, 0xCD6);
> -		val = inb(0xCD7);
> -
> -		/* Set bit 7 in PM register 0x55 */
> -		outb(0x55, 0xCD6);
> -		outb(val | 0x80, 0xCD7);
> -	}
> -}
> -DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_ATI, 0x4385, sb600_disable_hpet_bar);
> --
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