linux-kernel - Re: [tip:x86/urgent] x86/mm/32: Load a sane CR3 before cpu

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Message-ID: <20170920125258.GA3716@amd>
Date:   Wed, 20 Sep 2017 14:52:58 +0200
From:   Pavel Machek <pavel@....cz>
To:     mingo@...nel.org, bpetkov@...e.de, peterz@...radead.org,
        bp@...en8.de, tglx@...utronix.de, hpa@...or.com, luto@...nel.org,
        torvalds@...ux-foundation.org, pmenzel@...gen.mpg.de,
        linux-kernel@...r.kernel.org
Cc:     linux-tip-commits@...r.kernel.org
Subject: Re: [tip:x86/urgent] x86/mm/32: Load a sane CR3 before cpu_init() on
 secondary CPUs

On Sun 2017-09-17 11:19:53, tip-bot for Andy Lutomirski wrote:
> Commit-ID:  4ba55e65f471d011d3ba2ac2022180ea0877d68e
> Gitweb:     http://git.kernel.org/tip/4ba55e65f471d011d3ba2ac2022180ea0877d68e
> Author:     Andy Lutomirski <luto@...nel.org>
> AuthorDate: Sun, 17 Sep 2017 09:03:51 -0700
> Committer:  Ingo Molnar <mingo@...nel.org>
> CommitDate: Sun, 17 Sep 2017 18:59:09 +0200
> 
> x86/mm/32: Load a sane CR3 before cpu_init() on secondary CPUs
> 
> For unknown historical reasons (i.e. Borislav doesn't recall),
> 32-bit kernels invoke cpu_init() on secondary CPUs with
> initial_page_table loaded into CR3.  Then they set
> current->active_mm to &init_mm and call enter_lazy_tlb() before
> fixing CR3.  This means that the x86 TLB code gets invoked while CR3
> is inconsistent, and, with the improved PCID sanity checks I added,
> we warn.
> 
> Fix it by loading swapper_pg_dir (i.e. init_mm.pgd) earlier.
> 
> Reported-by: Paul Menzel <pmenzel@...gen.mpg.de>
> Reported-by: Pavel Machek <pavel@....cz>

4.14.0-rc1-next-20170919 does not produce the warning during bootup.

									Pavel

Tested-by: Pavel Machek <pavel@....cz>


-- 
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