[PATCH 01/62] kvm: Make pi_enable_wakeup_handler() easier to analyze

[Bart Van Assche]

From: Bart Van Assche <bvanassche@xxxxxxx>

The Clang thread-safety analyzer does not support comparing expressions
that use per_cpu(). Hence introduce a new local variable to capture the
address of a per-cpu spinlock. This patch prepares for enabling the
Clang thread-safety analyzer.

Cc: Sean Christopherson <seanjc@xxxxxxxxxx>
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: kvm@xxxxxxxxxxxxxxx
Signed-off-by: Bart Van Assche <bvanassche@xxxxxxx>
---
 arch/x86/kvm/vmx/posted_intr.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/vmx/posted_intr.c b/arch/x86/kvm/vmx/posted_intr.c
index 4a6d9a17da23..f8711b7b85a8 100644
--- a/arch/x86/kvm/vmx/posted_intr.c
+++ b/arch/x86/kvm/vmx/posted_intr.c
@@ -164,6 +164,7 @@ static void pi_enable_wakeup_handler(struct kvm_vcpu *vcpu)
 	struct pi_desc *pi_desc = vcpu_to_pi_desc(vcpu);
 	struct vcpu_vt *vt = to_vt(vcpu);
 	struct pi_desc old, new;
+	raw_spinlock_t *wakeup_lock;
 
 	lockdep_assert_irqs_disabled();
 
@@ -179,11 +180,11 @@ static void pi_enable_wakeup_handler(struct kvm_vcpu *vcpu)
 	 * entirety of the sched_out critical section, i.e. the wakeup handler
 	 * can't run while the scheduler locks are held.
 	 */
-	raw_spin_lock_nested(&per_cpu(wakeup_vcpus_on_cpu_lock, vcpu->cpu),
-			     PI_LOCK_SCHED_OUT);
+	wakeup_lock = &per_cpu(wakeup_vcpus_on_cpu_lock, vcpu->cpu);
+	raw_spin_lock_nested(wakeup_lock, PI_LOCK_SCHED_OUT);
 	list_add_tail(&vt->pi_wakeup_list,
 		      &per_cpu(wakeup_vcpus_on_cpu, vcpu->cpu));
-	raw_spin_unlock(&per_cpu(wakeup_vcpus_on_cpu_lock, vcpu->cpu));
+	raw_spin_unlock(wakeup_lock);
 
 	WARN(pi_test_sn(pi_desc), "PI descriptor SN field set before blocking");