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authorMikulas Patocka <mpatocka@redhat.com>2017-07-04 19:04:23 -0400
committerThomas Gleixner <tglx@linutronix.de>2017-07-05 09:01:24 +0200
commit99c13b8c8896d7bcb92753bf0c63a8de4326e78d (patch)
treeb8f8cf4f4fba6e34ba7d090dbdb852b9588d0e5d /arch/x86/kernel
parent5122daa017578ebc4818de8fb3c9d0e131f8b335 (diff)
downloadop-kernel-dev-99c13b8c8896d7bcb92753bf0c63a8de4326e78d.zip
op-kernel-dev-99c13b8c8896d7bcb92753bf0c63a8de4326e78d.tar.gz
x86/mm/pat: Don't report PAT on CPUs that don't support it
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> Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/alpine.LRH.2.02.1707041749300.3456@file01.intranet.prod.int.rdu2.redhat.com
Diffstat (limited to 'arch/x86/kernel')
-rw-r--r--arch/x86/kernel/setup.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 65622f0..3486d04 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -1076,6 +1076,13 @@ void __init setup_arch(char **cmdline_p)
max_possible_pfn = max_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();
+
+ /*
* Define random base addresses for memory sections after max_pfn is
* defined and before each memory section base is used.
*/
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