[PATCH] x86/cstate: fix mwait hint target cstate calc

[He Rongguang <herongguang@linux.alibaba.com>]

According to x86 manual (Intel SDM Vol 2, Table 4-11. MWAIT Hints
Register (EAX) and AMD manual Vol 3, MWAIT), mwait hint[7:4] adds 1 is
the corresponding cstate, and 0xF means C0, so fix the handling of
0xF -> C0.

Intel: "Value of 0 means C1; 1 means C2 and so on
Value of 01111B means C0".

AMD: "The processor C-state is EAX[7:4]+1, so to request C0 is to place
the value F in EAX[7:4] and to request C1 is to place the value 0 in
EAX[7:4].".

Signed-off-by: He Rongguang <herongguang@linux.alibaba.com>
---
  arch/x86/kernel/acpi/cstate.c | 4 ++--
  drivers/idle/intel_idle.c     | 3 ++-
  2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/acpi/cstate.c b/arch/x86/kernel/acpi/cstate.c
index 401808b47af3..f3ffd0a3a012 100644
--- a/arch/x86/kernel/acpi/cstate.c
+++ b/arch/x86/kernel/acpi/cstate.c
@@ -131,8 +131,8 @@ static long acpi_processor_ffh_cstate_probe_cpu(void 
*_cx)
         cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &edx);

         /* Check whether this particular cx_type (in CST) is supported 
or not */
-       cstate_type = ((cx->address >> MWAIT_SUBSTATE_SIZE) &
-                       MWAIT_CSTATE_MASK) + 1;
+       cstate_type = (((cx->address >> MWAIT_SUBSTATE_SIZE) &
+                       MWAIT_CSTATE_MASK) + 1) & MWAIT_CSTATE_MASK;
         edx_part = edx >> (cstate_type * MWAIT_SUBSTATE_SIZE);
         num_cstate_subtype = edx_part & MWAIT_SUBSTATE_MASK;

diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c
index bcf1198e8991..e486027f8b07 100644
--- a/drivers/idle/intel_idle.c
+++ b/drivers/idle/intel_idle.c
@@ -1934,7 +1934,8 @@ static void __init spr_idle_state_table_update(void)

  static bool __init intel_idle_verify_cstate(unsigned int mwait_hint)
  {
-       unsigned int mwait_cstate = MWAIT_HINT2CSTATE(mwait_hint) + 1;
+       unsigned int mwait_cstate = (MWAIT_HINT2CSTATE(mwait_hint) + 1) &
+                                       MWAIT_CSTATE_MASK;
         unsigned int num_substates = (mwait_substates >> mwait_cstate * 
4) &
                                         MWAIT_SUBSTATE_MASK;

--
2.43.0