diff options
| author | Mikulas Patocka <mpatocka@redhat.com> | 2017-07-04 19:04:23 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-07-15 11:57:50 +0200 |
| commit | 646b65808b0da1fb2f72daf4dabdd9bc8e398f49 (patch) | |
| tree | 54ca9fe37ae97e92429ab8fc096ef24f97f6caaf /arch/x86/kernel/setup.c | |
| parent | ad5a88c54cd299f3bb2bf53810dd5bb5805369c3 (diff) | |
x86/mm/pat: Don't report PAT on CPUs that don't support it
commit 99c13b8c8896d7bcb92753bf0c63a8de4326e78d upstream.
The pat_enabled() logic is broken on CPUs which do not support PAT and
where the initialization code fails to call pat_init(). Due to that the
enabled flag stays true and pat_enabled() returns true wrongfully.
As a consequence the mappings, e.g. for Xorg, are set up with the wrong
caching mode and the required MTRR setups are omitted.
To cure this the following changes are required:
1) Make pat_enabled() return true only if PAT initialization was
invoked and successful.
2) Invoke init_cache_modes() unconditionally in setup_arch() and
remove the extra callsites in pat_disable() and the pat disabled
code path in pat_init().
Also rename __pat_enabled to pat_disabled to reflect the real purpose of
this variable.
Fixes: 9cd25aac1f44 ("x86/mm/pat: Emulate PAT when it is disabled")
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Bernhard Held <berny156@gmx.de>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: "Luis R. Rodriguez" <mcgrof@suse.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/alpine.LRH.2.02.1707041749300.3456@file01.intranet.prod.int.rdu2.redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/x86/kernel/setup.c')
| -rw-r--r-- | arch/x86/kernel/setup.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index d2bbe343fda7..e67b834279b2 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -1048,6 +1048,13 @@ void __init setup_arch(char **cmdline_p) if (mtrr_trim_uncached_memory(max_pfn)) max_pfn = e820_end_of_ram_pfn(); + /* + * This call is required when the CPU does not support PAT. If + * mtrr_bp_init() invoked it already via pat_init() the call has no + * effect. + */ + init_cache_modes(); + #ifdef CONFIG_X86_32 /* max_low_pfn get updated here */ find_low_pfn_range(); |