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authorPeter Zijlstra <peterz@infradead.org>2016-07-18 11:41:10 -0700
committerIngo Molnar <mingo@kernel.org>2016-07-20 09:48:40 +0200
commit08e237fa56a1d95c1372033bc29c4a2517b3c0fa (patch)
tree516f04cfcd11fafd8d801c7ce0ed60ca660d26d0 /arch/x86/include/asm
parent4fffe71dd913cca5532da594e2f48a0db6b494dc (diff)
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x86/cpu: Add workaround for MONITOR instruction erratum on Goldmont based CPUs
Monitored cached line may not wake up from mwait on certain Goldmont based CPUs. This patch will avoid calling current_set_polling_and_test() and thereby not set the TIF_ flag. The result is that we'll always send IPIs for wakeups. Signed-off-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Len Brown <lenb@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1468867270-18493-1-git-send-email-jacob.jun.pan@linux.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/include/asm')
-rw-r--r--arch/x86/include/asm/cpufeatures.h2
-rw-r--r--arch/x86/include/asm/mwait.h2
2 files changed, 2 insertions, 2 deletions
diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index c64b1e9c5d1a..19ecc6e11f4f 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -310,5 +310,5 @@
#endif
#define X86_BUG_NULL_SEG X86_BUG(10) /* Nulling a selector preserves the base */
#define X86_BUG_SWAPGS_FENCE X86_BUG(11) /* SWAPGS without input dep on GS */
-
+#define X86_BUG_MONITOR X86_BUG(12) /* IPI required to wake up remote CPU */
#endif /* _ASM_X86_CPUFEATURES_H */
diff --git a/arch/x86/include/asm/mwait.h b/arch/x86/include/asm/mwait.h
index 0deeb2d26df7..f37f2d8a2989 100644
--- a/arch/x86/include/asm/mwait.h
+++ b/arch/x86/include/asm/mwait.h
@@ -97,7 +97,7 @@ static inline void __sti_mwait(unsigned long eax, unsigned long ecx)
*/
static inline void mwait_idle_with_hints(unsigned long eax, unsigned long ecx)
{
- if (!current_set_polling_and_test()) {
+ if (static_cpu_has_bug(X86_BUG_MONITOR) || !current_set_polling_and_test()) {
if (static_cpu_has_bug(X86_BUG_CLFLUSH_MONITOR)) {
mb();
clflush((void *)&current_thread_info()->flags);