linux-kernel - Re: [PATCH v5 03/16] x86/mtrr: get MTRR number and support TOP

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Date:   Tue, 4 Sep 2018 10:02:41 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Pu Wen <puwen@...on.cn>
Cc:     tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
        x86@...nel.org, thomas.lendacky@....com, pbonzini@...hat.com,
        linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org
Subject: Re: [PATCH v5 03/16] x86/mtrr: get MTRR number and support TOP_MEM2

On Tue, Sep 04, 2018 at 11:02:41AM +0800, Pu Wen wrote:
> > > -	if (!((boot_cpu_data.x86_vendor == X86_VENDOR_AMD) &&
> > > -	      (boot_cpu_data.x86 >= 0x0f)))
> > > +	if (!((boot_cpu_data.x86_vendor == X86_VENDOR_AMD &&
> > > +	       boot_cpu_data.x86 >= 0x0f) ||
> > > +	       boot_cpu_data.x86_vendor == X86_VENDOR_HYGON))
> > 
> > Why are you even touching this statement? The function returns early on
> > !X86_VENDOR_AMD.
> 
> The statement is briefly equal to !(X86_VENDOR_AMD || X86_VENDOR_HYGON).
> So the function will not return early on !X86_VENDOR_AMD. :-)

I meant the *original* version - not yours!

My question is why are you even touching a K8-old BIOS workaround?! Your
commit message says:

    The MtrrFixDramModEn bit on Hygon platform should also be set to 1
    during BIOS initialization of the fixed MTRRs, then cleared to 0 for
    operation.

Is your BIOS already broken?

Searching the net for

                pr_err(FW_WARN "MTRR: CPU %u: SYSCFG[MtrrFixDramModEn]"
                       " not cleared by BIOS, clearing this bit\n",

shows only old mails so I'm going to assume this got fixed, finally! And
you probably have received a *fixed* BIOS even, allegedly.

So what's up?

-- 
Regards/Gruss,
    Boris.

Good mailing practices for 400: avoid top-posting and trim the reply.