When KVM_HINTS_REALTIME is set and KVM_FEATURE_PV_UNHALT is clear,
currently guest will use virt_spin_lock.
Since KVM_HINTS_REALTIME is set, use native qspinlock should be safe
and have better performance than virt_spin_lock.
Signed-off-by: Liangyan <liangyan.peng@xxxxxxxxxxxxx>
---
arch/x86/kernel/kvm.c | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index 921c1c783bc1..9080544a4007 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -1072,6 +1072,15 @@ static void kvm_wait(u8 *ptr, u8 val)
*/
void __init kvm_spinlock_init(void)
{
+ /*
+ * Disable PV spinlocks and use native qspinlock when dedicated pCPUs
+ * are available.
+ */
+ if (kvm_para_has_hint(KVM_HINTS_REALTIME)) {
+ pr_info("PV spinlocks disabled with KVM_HINTS_REALTIME hints\n");
+ goto out;
+ }
+
/*
* In case host doesn't support KVM_FEATURE_PV_UNHALT there is still an
* advantage of keeping virt_spin_lock_key enabled: virt_spin_lock() is
@@ -1082,15 +1091,6 @@ void __init kvm_spinlock_init(void)
return;
}
- /*
- * Disable PV spinlocks and use native qspinlock when dedicated pCPUs
- * are available.
- */
- if (kvm_para_has_hint(KVM_HINTS_REALTIME)) {
- pr_info("PV spinlocks disabled with KVM_HINTS_REALTIME hints\n");
- goto out;
- }
-
if (num_possible_cpus() == 1) {
pr_info("PV spinlocks disabled, single CPU\n");
goto out;
--
2.39.3 (Apple Git-145)
