Re: [PATCH 1/2] x86/mm/pat: Change pat_disable() to emulate PAT table

From: "Luis R. Rodriguez" <mcgrof@kernel.org>
To: Borislav Petkov <bp@alien8.de>
Cc: Toshi Kani <toshi.kani@hpe.com>,
	"mingo@kernel.org" <mingo@kernel.org>,
	"hpa@zytor.com" <hpa@zytor.com>,
	"tglx@linutronix.de" <tglx@linutronix.de>,
	"jgross@suse.com" <jgross@suse.com>,
	"paul.gortmaker@windriver.com" <paul.gortmaker@windriver.com>,
	"x86@kernel.org" <x86@kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	xen-devel@lists.xenproject.org, boris.ostrovsky@oracle.com
Subject: Re: [PATCH 1/2] x86/mm/pat: Change pat_disable() to emulate PAT table
Date: Tue, 15 Mar 2016 01:29:21 +0100	[thread overview]
Message-ID: <20160315002921.GG25147@wotan.suse.de> (raw)
In-Reply-To: <20160312115544.GA23410@pd.tnic>

I like this approach more as it stuff more PAT setup on its own type
of calls, but:

On Sat, Mar 12, 2016 at 12:55:44PM +0100, Borislav Petkov wrote:
> diff --git a/arch/x86/kernel/cpu/mtrr/main.c b/arch/x86/kernel/cpu/mtrr/main.c
> index 10f8d4796240..5c442b4bd52a 100644
> --- a/arch/x86/kernel/cpu/mtrr/main.c
> +++ b/arch/x86/kernel/cpu/mtrr/main.c
> @@ -759,8 +761,11 @@ void __init mtrr_bp_init(void)
>  		}
>  	}
>  
> -	if (!mtrr_enabled())
> +	if (!__mtrr_enabled) {
>  		pr_info("MTRR: Disabled\n");
> +		pat_disable("PAT disabled by MTRR");
> +		pat_setup();
> +	}
>  }

This hunk would break PAT on Xen.

  Luis