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Diffstat (limited to 'arch/x86/kernel/acpi/cstate.c')
-rw-r--r--arch/x86/kernel/acpi/cstate.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/arch/x86/kernel/acpi/cstate.c b/arch/x86/kernel/acpi/cstate.c
index 5812404a0d4..4b28159e042 100644
--- a/arch/x86/kernel/acpi/cstate.c
+++ b/arch/x86/kernel/acpi/cstate.c
@@ -14,6 +14,7 @@
#include <acpi/processor.h>
#include <asm/acpi.h>
#include <asm/mwait.h>
+#include <asm/special_insns.h>
/*
* Initialize bm_flags based on the CPU cache properties
@@ -86,7 +87,9 @@ static long acpi_processor_ffh_cstate_probe_cpu(void *_cx)
num_cstate_subtype = edx_part & MWAIT_SUBSTATE_MASK;
retval = 0;
- if (num_cstate_subtype < (cx->address & MWAIT_SUBSTATE_MASK)) {
+ /* If the HW does not support any sub-states in this C-state */
+ if (num_cstate_subtype == 0) {
+ pr_warn(FW_BUG "ACPI MWAIT C-state 0x%x not supported by HW (0x%x)\n", cx->address, edx_part);
retval = -1;
goto out;
}