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    Subject[PATCH 1/5] x86, pti: fix boot problems from Global-bit setting
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    From: Dave Hansen <dave.hansen@linux.intel.com>

    Part of the global bit _setting_ patches also includes clearing the
    Global bit when we do not want it. That is done with
    set_memory_nonglobal(), which uses change_page_attr_clear() in
    pageattr.c under the covers.

    The TLB flushing code inside pageattr.c has has checks like
    BUG_ON(irqs_disabled()), looking for interrupt disabling that might
    cause deadlocks. But, these also trip in early boot on certain
    preempt configurations. Just copy the existing BUG_ON() sequence from
    cpa_flush_range() to the other two sites and check for early boot.

    Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
    Fixes: 39114b7a7 (x86/pti: Never implicitly clear _PAGE_GLOBAL for kernel image)
    Reported-by: Mariusz Ceier <mceier@gmail.com>
    Reported-by: Aaro Koskinen <aaro.koskinen@nokia.com>
    Cc: Andrea Arcangeli <aarcange@redhat.com>
    Cc: Andy Lutomirski <luto@kernel.org>
    Cc: Arjan van de Ven <arjan@linux.intel.com>
    Cc: Borislav Petkov <bp@alien8.de>
    Cc: Dan Williams <dan.j.williams@intel.com>
    Cc: David Woodhouse <dwmw2@infradead.org>
    Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    Cc: Hugh Dickins <hughd@google.com>
    Cc: Josh Poimboeuf <jpoimboe@redhat.com>
    Cc: Juergen Gross <jgross@suse.com>
    Cc: Kees Cook <keescook@google.com>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Nadav Amit <namit@vmware.com>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: linux-mm@kvack.org
    ---

    b/arch/x86/mm/pageattr.c | 4 ++--
    1 file changed, 2 insertions(+), 2 deletions(-)

    diff -puN arch/x86/mm/pageattr.c~pti-glb-boot-problem-fix arch/x86/mm/pageattr.c
    --- a/arch/x86/mm/pageattr.c~pti-glb-boot-problem-fix 2018-04-20 14:10:01.086749169 -0700
    +++ b/arch/x86/mm/pageattr.c 2018-04-20 14:10:01.090749169 -0700
    @@ -172,7 +172,7 @@ static void __cpa_flush_all(void *arg)

    static void cpa_flush_all(unsigned long cache)
    {
    - BUG_ON(irqs_disabled());
    + BUG_ON(irqs_disabled() && !early_boot_irqs_disabled);

    on_each_cpu(__cpa_flush_all, (void *) cache, 1);
    }
    @@ -236,7 +236,7 @@ static void cpa_flush_array(unsigned lon
    unsigned long do_wbinvd = cache && numpages >= 1024; /* 4M threshold */
    #endif

    - BUG_ON(irqs_disabled());
    + BUG_ON(irqs_disabled() && !early_boot_irqs_disabled);

    on_each_cpu(__cpa_flush_all, (void *) do_wbinvd, 1);

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