x86/mm: Disable PCID on 32-bit kernels

32-bit kernels on new hardware will see PCID in CPUID, but PCID can
only be used in 64-bit mode.  Rather than making all PCID code
conditional, just disable the feature on 32-bit builds.

Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Nadav Amit <nadav.amit@gmail.com>
Reviewed-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/2e391769192a4d31b808410c383c6bf0734bc6ea.1498751203.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/arch/x86/include/asm/disabled-features.h b/arch/x86/include/asm/disabled-features.h
index 5dff775..c10c912 100644 (file)
--- a/arch/x86/include/asm/disabled-features.h
+++ b/arch/x86/include/asm/disabled-features.h
@@ -21,11 +21,13 @@
 # define DISABLE_K6_MTRR       (1<<(X86_FEATURE_K6_MTRR & 31))
 # define DISABLE_CYRIX_ARR     (1<<(X86_FEATURE_CYRIX_ARR & 31))
 # define DISABLE_CENTAUR_MCR   (1<<(X86_FEATURE_CENTAUR_MCR & 31))
+# define DISABLE_PCID          0
 #else
 # define DISABLE_VME           0
 # define DISABLE_K6_MTRR       0
 # define DISABLE_CYRIX_ARR     0
 # define DISABLE_CENTAUR_MCR   0
+# define DISABLE_PCID          (1<<(X86_FEATURE_PCID & 31))
 #endif /* CONFIG_X86_64 */
 
 #ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
@@ -49,7 +51,7 @@
 #define DISABLED_MASK1 0
 #define DISABLED_MASK2 0
 #define DISABLED_MASK3 (DISABLE_CYRIX_ARR|DISABLE_CENTAUR_MCR|DISABLE_K6_MTRR)
-#define DISABLED_MASK4 0
+#define DISABLED_MASK4 (DISABLE_PCID)
 #define DISABLED_MASK5 0
 #define DISABLED_MASK6 0
 #define DISABLED_MASK7 0

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 0af86d9..db68488 100644 (file)
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -21,6 +21,14 @@
 
 void __init check_bugs(void)
 {
+#ifdef CONFIG_X86_32
+       /*
+        * Regardless of whether PCID is enumerated, the SDM says
+        * that it can't be enabled in 32-bit mode.
+        */
+       setup_clear_cpu_cap(X86_FEATURE_PCID);
+#endif
+
        identify_boot_cpu();
 
        if (!IS_ENABLED(CONFIG_SMP)) {