linux-kernel - Re: [PATCH 2/3 V2] EDAC, AMD64_EDAC: Add relevant condition checks as F15h M30h does not support GART or L3.

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Date:	Tue, 6 Aug 2013 22:19:25 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	Aravind Gopalakrishnan <Aravind.Gopalakrishnan@....com>
Cc:	tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
	dougthompson@...ssion.com, bhelgaas@...gle.com, jbeulich@...e.com,
	linux-kernel@...r.kernel.org, linux-edac@...r.kernel.org,
	linux-pci@...r.kernel.org
Subject: Re: [PATCH 2/3 V2] EDAC, AMD64_EDAC: Add relevant condition checks
 as F15h M30h does not support GART or L3.

On Fri, Aug 02, 2013 at 05:43:03PM -0500, Aravind Gopalakrishnan wrote:
> Adding code to check for specific model (F15h, M30h) and if yes,
> do not add flag AMD_NB_GART. Also check cpuid_edx(0x80000006) for
> prescence of L3. If no L3, do not add any L3 flags.
> 
> Signed-off-by: Aravind Gopalakrishnan <Aravind.Gopalakrishnan@....com>
> 
> diff --git a/arch/x86/kernel/amd_nb.c b/arch/x86/kernel/amd_nb.c
> index 3048ded..3ee7a4d 100644
> --- a/arch/x86/kernel/amd_nb.c
> +++ b/arch/x86/kernel/amd_nb.c
> @@ -20,6 +20,7 @@ const struct pci_device_id amd_nb_misc_ids[] = {
>  	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_10H_NB_MISC) },
>  	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_15H_NB_F3) },
>  	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_15H_M10H_F3) },
> +	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_15H_M30H_NB_F3) },
>  	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_16H_NB_F3) },
>  	{}
>  };
> @@ -27,6 +28,7 @@ EXPORT_SYMBOL(amd_nb_misc_ids);
>  
>  static const struct pci_device_id amd_nb_link_ids[] = {
>  	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_15H_NB_F4) },
> +	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_15H_M30H_NB_F4) },
>  	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_16H_NB_F4) },
>  	{}
>  };
> @@ -81,13 +83,21 @@ int amd_cache_northbridges(void)
>  			next_northbridge(misc, amd_nb_misc_ids);
>  		node_to_amd_nb(i)->link = link =
>  			next_northbridge(link, amd_nb_link_ids);
> -        }
> +	}
>  
> +	/* GART present only on Fam15h upto model 0fh */
>  	if (boot_cpu_data.x86 == 0xf || boot_cpu_data.x86 == 0x10 ||
> -	    boot_cpu_data.x86 == 0x15)
> +	    (boot_cpu_data.x86 == 0x15 && boot_cpu_data.x86_model < 0x10))
>  		amd_northbridges.flags |= AMD_NB_GART;
>  
>  	/*
> +	 * Check CPUID Fn8000_0006_EDX: L3 Cache Identifiers.
> +	 * If == 0, then no need to proceed as there is no L3.

This comment explains the code. Just sit down and think about it: does
it make any sense to have that in a comment?

> +	 */
> +	if (cpuid_edx(0x80000006) == 0)
> +		return 0;
> +
> +	/*
>  	 * Some CPU families support L3 Cache Index Disable. There are some
>  	 * limitations because of E382 and E388 on family 0x10.
>  	 */
> --

I fixed it up like this:

commit a0cb1bab68823648def0fda19bf307ad08eb25d2
Author: Aravind Gopalakrishnan <Aravind.Gopalakrishnan@....com>
Date:   Fri Aug 2 17:43:03 2013 -0500

    x86, amd_nb: Clarify F15h, model 30h GART and L3 support
    
    F15h, models 0x30 and later don't have a GART. Note that. Also check
    cpuid_edx(0x80000006) for prescence of L3 because there are models which
    don't sport an L3.
    
    Signed-off-by: Aravind Gopalakrishnan <Aravind.Gopalakrishnan@....com>
    [ Boris: rewrite commit message, cleanup comments. ]
    Signed-off-by: Borislav Petkov <bp@...e.de>

diff --git a/arch/x86/kernel/amd_nb.c b/arch/x86/kernel/amd_nb.c
index 3048ded1b598..59554dca96ec 100644
--- a/arch/x86/kernel/amd_nb.c
+++ b/arch/x86/kernel/amd_nb.c
@@ -20,6 +20,7 @@ const struct pci_device_id amd_nb_misc_ids[] = {
 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_10H_NB_MISC) },
 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_15H_NB_F3) },
 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_15H_M10H_F3) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_15H_M30H_NB_F3) },
 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_16H_NB_F3) },
 	{}
 };
@@ -27,6 +28,7 @@ EXPORT_SYMBOL(amd_nb_misc_ids);
 
 static const struct pci_device_id amd_nb_link_ids[] = {
 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_15H_NB_F4) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_15H_M30H_NB_F4) },
 	{ PCI_DEVICE(PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_16H_NB_F4) },
 	{}
 };
@@ -81,13 +83,20 @@ int amd_cache_northbridges(void)
 			next_northbridge(misc, amd_nb_misc_ids);
 		node_to_amd_nb(i)->link = link =
 			next_northbridge(link, amd_nb_link_ids);
-        }
+	}
 
+	/* GART present only on Fam15h upto model 0fh */
 	if (boot_cpu_data.x86 == 0xf || boot_cpu_data.x86 == 0x10 ||
-	    boot_cpu_data.x86 == 0x15)
+	    (boot_cpu_data.x86 == 0x15 && boot_cpu_data.x86_model < 0x10))
 		amd_northbridges.flags |= AMD_NB_GART;
 
 	/*
+	 * Check for L3 cache presence.
+	 */
+	if (!cpuid_edx(0x80000006))
+		return 0;
+
+	/*
 	 * Some CPU families support L3 Cache Index Disable. There are some
 	 * limitations because of E382 and E388 on family 0x10.
 	 */



-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
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