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From: ebiederm@xmission.com (Eric W. Biederman)
To: Neil Horman <nhorman@tuxdriver.com>
Cc: Neil Horman <nhorman@redhat.com>, Yinghai Lu <yhlu.kernel@gmail.com>,
       Ben Woodard <woodard@redhat.com>, kexec@lists.infradead.org,
       linux-kernel@vger.kernel.org, Andi Kleen <ak@suse.de>, hbabu@us.ibm.com,
       Andi Kleen <andi@firstfloor.org>
Subject: Re: [PATCH] kexec: force x86_64 arches to boot kdump kernels on boot cpu
References: <20071130144250.GC23810@redhat.com>
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	<20071211034349.GA3635@localhost.localdomain>
Date: Mon, 10 Dec 2007 21:48:11 -0700
In-Reply-To: <20071211034349.GA3635@localhost.localdomain> (Neil Horman's
	message of "Mon, 10 Dec 2007 22:43:49 -0500")
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Neil Horman <nhorman@tuxdriver.com> writes:

Almost there.


> On Mon, Dec 10, 2007 at 06:08:03PM -0700, Eric W. Biederman wrote:
>> Neil Horman <nhorman@tuxdriver.com> writes:
>> 
> <snip>
>> 
>> Ok.  This test is broken.  Please remove the == 1.  You are looking
>> for == (1 << 18).  So just saying: "if (htcfg & (1 << 18))" should be clearer.
>> 
> Fixed.  Thanks!
>
>> > + printk(KERN_INFO "Detected use of extended apic ids on hypertransport
> bus\n");
>> > +		if ((htcfg & (1 << 17)) == 0) {
>> > + printk(KERN_INFO "Enabling hypertransport extended apic interrupt
>> > broadcast\n");
>> > +			htcfg |= (1 << 17);
>> > +			write_pci_config(num, slot, func, 0x68, htcfg);
>> > +		}
>> > +	}
>> > +	
>> > +}
>> 
>> The rest of this quirk looks fine, include the fact it is only intended
>> to be applied to PCI_VENDOR_ID_AMD PCI_DEVICE_ID_AMD_K8_NB.
>> 
> Copy that.
>
>> 
>> For what is below I don't like the way the infrastructure has been
>> extended as what you are doing quickly devolves into a big mess.
>> 
>> Please extend struct chipset to be something like:
>> struct chipset {
>> 	u16 vendor;
>> 	u16 device;
>>         u32 class, class_mask;
>> 	void (*f)(void);
>> };
>> 
>> And then the test for matching the chipset can be something like:
>> 	if ((id->vendor == PCI_ANY_ID || id->vendor == dev->vendor) &&
>> 	    (id->device == PCI_ANY_ID || id->device == dev->device) &&
>> 	    !((id->class ^ dev->class) & id->class_mask))
>> 
>> Essentially a subset of pci_match_one_device from drivers/pci/pci.h
>> 
>> That way you don't need to increase the number of tables or the
>> number of passes through the pci busses, just update the early_qrk
>> table with a few more bits of information.
>> 
> copy that.  Fixed.  Thanks!
>
>> The extended form should be much more maintainable in the long
>> run.  Given that we may want this before we enable the timer
>> which is very early doing this in the pci early quirks seems
>> to make sense.
>> 
>> Eric
>
>
> New patch attached, with suggestions incorporated.
>
> Thanks & regards
> Neil
>
> Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
>
>
>  early-quirks.c | 82 ++++++++++++++++++++++++++++++++++++++++++++++++++-------
>  1 file changed, 73 insertions(+), 9 deletions(-)
>
>
>
> diff --git a/arch/x86/kernel/early-quirks.c b/arch/x86/kernel/early-quirks.c
> index 88bb83e..4b0cee1 100644
> --- a/arch/x86/kernel/early-quirks.c
> +++ b/arch/x86/kernel/early-quirks.c
> @@ -44,6 +44,50 @@ static int __init nvidia_hpet_check(struct acpi_table_header
> *header)
>  #endif /* CONFIG_X86_IO_APIC */
>  #endif /* CONFIG_ACPI */
>  
> +static void __init fix_hypertransport_config(int num, int slot, int func)
> +{
> +	u32 htcfg;
> +	/*
> +	 *we found a hypertransport bus
> +	 *make sure that are broadcasting
> +	 *interrupts to all cpus on the ht bus
> +	 *if we're using extended apic ids
> +	 */
> +	htcfg = read_pci_config(num, slot, func, 0x68);
> +	if (htcfg & (1 << 18)) {	
> + printk(KERN_INFO "Detected use of extended apic ids on hypertransport bus\n");
> +		if ((htcfg & (1 << 17)) == 0) {
> + printk(KERN_INFO "Enabling hypertransport extended apic interrupt
> broadcast\n");
> +			htcfg |= (1 << 17);
> +			write_pci_config(num, slot, func, 0x68, htcfg);
> +		}
> +	}
> +	
> +}
> +
> +static void __init check_hypertransport_config()
> +{
> +	int num, slot, func;
> +	u32 device, vendor;
> +	func = 0;
> +	for (num = 0; num < 32; num++) {
> +		for (slot = 0; slot < 32; slot++) {
> +			vendor = read_pci_config(num,slot,func,
> +						PCI_VENDOR_ID); 
> +			device = read_pci_config(num,slot,func,
> +						PCI_DEVICE_ID);
> +			vendor &= 0x0000ffff;
> +			device >>= 16;
> +			if ((vendor == PCI_VENDOR_ID_AMD) &&
> +			    (device == PCI_DEVICE_ID_AMD_K8_NB))
> +				fix_hypertransport_config(num,slot,func);
> +		}
> +	}
> +
> +	return;
> +
> +}

We should not need check_hypertransport_config as the generic loop
now does the work for us.
> +
>  static void __init nvidia_bugs(void)
>  {
>  #ifdef CONFIG_ACPI
> @@ -83,15 +127,25 @@ static void __init ati_bugs(void)
>  #endif
>  }
>  
> +static void __init amd_host_bugs(void)
> +{
> +	printk(KERN_CRIT "IN AMD_HOST_BUGS\n");
> +	check_hypertransport_config();
> +}

Likewise this function is unneeded and the printk is likely confusing
for users.

>  struct chipset {
>  	u16 vendor;
> +	u16 device;
> +	u32 class;
> +	u32 class_mask;
>  	void (*f)(void);
>  };
>  
>  static struct chipset early_qrk[] __initdata = {
> -	{ PCI_VENDOR_ID_NVIDIA, nvidia_bugs },
> -	{ PCI_VENDOR_ID_VIA, via_bugs },
> -	{ PCI_VENDOR_ID_ATI, ati_bugs },
> + { PCI_VENDOR_ID_NVIDIA, PCI_ANY_ID, PCI_CLASS_BRIDGE_PCI, PCI_ANY_ID,
> nvidia_bugs },
> + { PCI_VENDOR_ID_VIA, PCI_ANY_ID, PCI_CLASS_BRIDGE_PCI, PCI_ANY_ID, via_bugs },
> + { PCI_VENDOR_ID_ATI, PCI_ANY_ID, PCI_CLASS_BRIDGE_PCI, PCI_ANY_ID, ati_bugs },
> + { PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_K8_NB, PCI_CLASS_BRIDGE_HOST,
> PCI_ANY_ID, amd_host_bugs },
>  	{}
So make that fix_hypertransport_config and we should be good.
>  };
>  
> @@ -108,25 +162,35 @@ void __init early_quirks(void)
>  			for (func = 0; func < 8; func++) {
>  				u32 class;
>  				u32 vendor;
> +				u32 device;
>  				u8 type;
>  				int i;
> +
>  				class = read_pci_config(num,slot,func,
>  							PCI_CLASS_REVISION);
>  				if (class == 0xffffffff)
>  					break;
>  
> -				if ((class >> 16) != PCI_CLASS_BRIDGE_PCI)
> -					continue;
> +				class >>= 16;

>  
>  				vendor = read_pci_config(num, slot, func,
>  							 PCI_VENDOR_ID);
>  				vendor &= 0xffff;
>  
> -				for (i = 0; early_qrk[i].f; i++)
> -					if (early_qrk[i].vendor == vendor) {
> -						early_qrk[i].f();
> -						return;
> +				device = read_pci_config(num, slot, func,
> +							PCI_DEVICE_ID);
> +				device >>= 16;

We don't need to shift device.  Although we can do:
device_vendor = read_pci_config(num, slot, func, PCI_VENDOR_ID);
device = device_vendor >> 16;
vendor = device_vendor & 0xffff;

Assuming the early read_pci_config is limited to 32bit reads.

> +				for(i=0;early_qrk[i].f != NULL;i++) {
> + if (((early_qrk[i].vendor == PCI_ANY_ID) ||
> +					    (early_qrk[i].vendor == vendor)) &&
> + ((early_qrk[i].device == PCI_ANY_ID) ||
> +					    (early_qrk[i].device == device)) &&
> +					   ((early_qrk[i].class ^ class) & 
> +					     early_qrk[i].class_mask)) {
> +						early_qrk[i].f();
>  					}
> +				}
>  
>  				type = read_pci_config_byte(num, slot, func,
>  							    PCI_HEADER_TYPE);