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Subject: Re: [PATCH] x86/ldt: Fix support_pte_mask filtering in
 map_ldt_struct()
To: Joerg Roedel <joro@8bytes.org>, Borislav Petkov <bp@suse.de>
References: <1523871837-8378-1-git-send-email-joro@8bytes.org>
 <CALCETrVgQspiO3nnyhqiXi17iaGG7bRDsr3gpHwdDnYfFDZabQ@mail.gmail.com>
 <07e2c23e-10b7-b03f-5706-3d4b910537ba@linux.intel.com>
 <20180418121403.GA3434@pd.tnic> <20180419130011.GG3896@pd.tnic>
 <20180419141134.GI15462@8bytes.org>
Cc: Andy Lutomirski <luto@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Peter Zijlstra <peterz@infradead.org>,
        LKML <linux-kernel@vger.kernel.org>, Joerg Roedel <jroedel@suse.de>,
        "Rafael J. Wysocki" <rjw@rjwysocki.net>
From: Dave Hansen <dave.hansen@linux.intel.com>
Message-ID: <a47fd151-a691-6b11-597e-aad1f646fdef@linux.intel.com>
Date: Thu, 19 Apr 2018 12:22:40 -0700
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On 04/19/2018 07:11 AM, Joerg Roedel wrote:
> On Thu, Apr 19, 2018 at 03:00:11PM +0200, Borislav Petkov wrote:
>> fb43d6cb91ef x86/mm: Do not auto-massage page protections <--- NOT OK
> Hmm, that hunk from above patch looks suspicious:
> 
> -               set_pgd(pgd + pgd_index(restore_jump_address), __pgd(__pa(pud) | _KERNPG_TABLE));
> +               pgd_t new_pgd = __pgd(__pa(p4d) | pgprot_val(pgtable_prot));
> +               set_pgd(pgd + pgd_index(restore_jump_address), new_pgd);
> 
> The old code used __pa(pud) while the new one uses __pa(p4d).
> 
> Boris, can you change that back to __pa(pud) and test please?

That does look like the culprit.  I probably copy/pasted the p4d line
from above and missed that 'p4d' when converting it to pud.

Thanks for finding this, guys.