linux-kernel - Re: x86, amd: Get multi-node CPU info from NodeId MSR instead of PCI config space

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20091016123853.GA15393@elte.hu>
Date:	Fri, 16 Oct 2009 14:38:53 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Andreas Herrmann <herrmann.der.user@...glemail.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org,
	Yinghai Lu <yinghai@...nel.org>
Subject: Re: x86, amd: Get multi-node CPU info from NodeId MSR instead of
	PCI config space


* Andreas Herrmann <herrmann.der.user@...glemail.com> wrote:

> Use newly introduced NodeId MSR to get NodeId and number of nodes per 
> processor.

What will happen on CPUs that dont have this MSR and got this info from 
the PCI config space:

>  static void __cpuinit amd_fixup_dcm(struct cpuinfo_x86 *c)
>  {
> -#ifdef CONFIG_PCI
> -	u32 t, cpn;
> -	u8 n, n_id;
>  	int cpu = smp_processor_id();
>  
>  	/* fixup topology information only once for a core */
>  	if (cpu_has(c, X86_FEATURE_AMD_DCM))
>  		return;
>  
> -	/* check for multi-node processor on boot cpu */
> -	t = read_pci_config(0, 24, 3, 0xe8);
> -	if (!(t & (1 << 29)))
>  		return;
>  
>  	set_cpu_cap(c, X86_FEATURE_AMD_DCM);

are there any such CPUs? I.e. we want to know the effect of this patch 
on various models of AMD CPUs - is the change really .32 safe? Does it 
solve any problem that makes it .32 material versus being for .33?

	Ingo
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/