linux-kernel - Re: [PATCH v6 00/16] x86/mtrr: fix handling with PAT but without MTRR

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Date:   Wed, 10 May 2023 01:36:41 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Juergen Gross <jgross@...e.com>
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org,
        linux-hyperv@...r.kernel.org, linux-doc@...r.kernel.org,
        mikelley@...rosoft.com, Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        "K. Y. Srinivasan" <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Wei Liu <wei.liu@...nel.org>, Dexuan Cui <decui@...rosoft.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        xen-devel@...ts.xenproject.org, Jonathan Corbet <corbet@....net>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH v6 00/16] x86/mtrr: fix handling with PAT but without MTRR

On Tue, May 09, 2023 at 10:14:37PM +0200, Borislav Petkov wrote:
> On Tue, May 02, 2023 at 02:09:15PM +0200, Juergen Gross wrote:
> > This series tries to fix the rather special case of PAT being available
> > without having MTRRs (either due to CONFIG_MTRR being not set, or
> > because the feature has been disabled e.g. by a hypervisor).
> 
> More weird stuff. With the series:

Yah, that was me.

That ->enabled thing is *two* bits. FFS.

More staring at this tomorrow, on a clear head.

diff --git a/arch/x86/include/uapi/asm/mtrr.h b/arch/x86/include/uapi/asm/mtrr.h
index a28e6bbd8f21..f476a1355182 100644
--- a/arch/x86/include/uapi/asm/mtrr.h
+++ b/arch/x86/include/uapi/asm/mtrr.h
@@ -84,7 +84,7 @@ typedef __u8 mtrr_type;
 struct mtrr_state_type {
 	struct mtrr_var_range var_ranges[MTRR_MAX_VAR_RANGES];
 	mtrr_type fixed_ranges[MTRR_NUM_FIXED_RANGES];
-	bool enabled;
+	unsigned char enabled;
 	bool have_fixed;
 	mtrr_type def_type;
 };

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette