Commit 10a70416 authored by Andi Kleen's avatar Andi Kleen Committed by Thomas Gleixner

x86/speculation/l1tf: Make sure the first page is always reserved

The L1TF workaround doesn't make any attempt to mitigate speculate accesses
to the first physical page for zeroed PTEs. Normally it only contains some
data from the early real mode BIOS.

It's not entirely clear that the first page is reserved in all
configurations, so add an extra reservation call to make sure it is really
reserved. In most configurations (e.g.  with the standard reservations)
it's likely a nop.
Signed-off-by: default avatarAndi Kleen <ak@linux.intel.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Acked-by: default avatarDave Hansen <dave.hansen@intel.com>
parent 6b28baca
...@@ -823,6 +823,12 @@ void __init setup_arch(char **cmdline_p) ...@@ -823,6 +823,12 @@ void __init setup_arch(char **cmdline_p)
memblock_reserve(__pa_symbol(_text), memblock_reserve(__pa_symbol(_text),
(unsigned long)__bss_stop - (unsigned long)_text); (unsigned long)__bss_stop - (unsigned long)_text);
/*
* Make sure page 0 is always reserved because on systems with
* L1TF its contents can be leaked to user processes.
*/
memblock_reserve(0, PAGE_SIZE);
early_reserve_initrd(); early_reserve_initrd();
/* /*
......
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