[PATCH v3 2/3] intel_idle: Sync up the SPEC_CTRL MSR value to x86_spec_ctrl_current

[Waiman Long <longman@redhat.com>]

When intel_idle_ibrs() is called, it modifies the SPEC_CTRL MSR to
0 in order disable IBRS. However, the new MSR value isn't reflected
in x86_spec_ctrl_current which is at odd with the other code that
keep track of its state in that percpu variable. Fix that by updating
x86_spec_ctrl_current percpu value to always match the content of the
SPEC_CTRL MSR.

Signed-off-by: Waiman Long <longman@redhat.com>
---
 drivers/idle/intel_idle.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c
index aa2d19db2b1d..07fa23707b3c 100644
--- a/drivers/idle/intel_idle.c
+++ b/drivers/idle/intel_idle.c
@@ -181,13 +181,17 @@ static __cpuidle int intel_idle_ibrs(struct cpuidle_device *dev,
 	u64 spec_ctrl = spec_ctrl_current();
 	int ret;
 
-	if (smt_active)
+	if (smt_active) {
+		__this_cpu_write(x86_spec_ctrl_current, 0);
 		native_wrmsrl(MSR_IA32_SPEC_CTRL, 0);
+	}
 
 	ret = __intel_idle(dev, drv, index);
 
-	if (smt_active)
+	if (smt_active) {
 		native_wrmsrl(MSR_IA32_SPEC_CTRL, spec_ctrl);
+		__this_cpu_write(x86_spec_ctrl_current, spec_ctrl);
+	}
 
 	return ret;
 }
-- 
2.31.1