x86: prevent C-states hang on AMD C1E enabled machines

Impact: System hang when AMD C1E machines switch into C2/C3

AMD C1E enabled systems do not work with normal ACPI C-states 
even if the BIOS is advertising them. Limit the C-states to 
C1 for the ACPI processor idle code.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

2 files changed, 3 insertions, 0 deletions

diff --git a/include/asm-x86/acpi.h b/include/asm-x86/acpi.h
index 635d764dc13e..35d1743b57ac 100644
--- a/include/asm-x86/acpi.h
+++ b/include/asm-x86/acpi.h
@@ -140,6 +140,8 @@ static inline unsigned int acpi_processor_cstate_check(unsigned int max_cstate)
             boot_cpu_data.x86_model <= 0x05 &&
             boot_cpu_data.x86_mask < 0x0A)
                 return 1;
+        else if (boot_cpu_has(X86_FEATURE_AMDC1E))
+                return 1;
         else
                 return max_cstate;
 }
diff --git a/include/asm-x86/cpufeature.h b/include/asm-x86/cpufeature.h
index 9489283a4bcf..cfcfb0a806ba 100644
--- a/include/asm-x86/cpufeature.h
+++ b/include/asm-x86/cpufeature.h
@@ -81,6 +81,7 @@
 #define X86_FEATURE_LFENCE_RDTSC (3*32+18) /* Lfence synchronizes RDTSC */
 #define X86_FEATURE_11AP        (3*32+19) /* Bad local APIC aka 11AP */
 #define X86_FEATURE_NOPL        (3*32+20) /* The NOPL (0F 1F) instructions */
+#define X86_FEATURE_AMDC1E      (3*32+21) /* AMD C1E detected */
 
 /* Intel-defined CPU features, CPUID level 0x00000001 (ecx), word 4 */
 #define X86_FEATURE_XMM3        (4*32+ 0) /* Streaming SIMD Extensions-3 */