[PATCH v7 2/3] LoongArch: KVM: Implement function kvm_para_has_feature

[Bibo Mao]

Function kvm_para_has_feature() is to detect supported paravirt features,
it can be used by device driver to detect and enable paravirt features,
such as extioi irqchip driver can detect KVM_FEATURE_VIRT_EXTIOI and do
some optimization.

Signed-off-by: Bibo Mao <maob...@loongson.cn>
---
 arch/loongarch/include/asm/kvm_para.h | 10 +++++++++
 arch/loongarch/kernel/paravirt.c      | 31 ++++++++++++++-------------
 2 files changed, 26 insertions(+), 15 deletions(-)

diff --git a/arch/loongarch/include/asm/kvm_para.h 
b/arch/loongarch/include/asm/kvm_para.h
index 39d7483ab8fd..2174fb53c2e7 100644
--- a/arch/loongarch/include/asm/kvm_para.h
+++ b/arch/loongarch/include/asm/kvm_para.h
@@ -155,10 +155,20 @@ static __always_inline long kvm_hypercall5(u64 fid,
        return ret;
 }
 
+#ifdef CONFIG_PARAVIRT
+bool kvm_para_available(void);
+unsigned int kvm_arch_para_features(void);
+#else
+static inline bool kvm_para_available(void)
+{
+       return false;
+}
+
 static inline unsigned int kvm_arch_para_features(void)
 {
        return 0;
 }
+#endif
 
 static inline unsigned int kvm_arch_para_hints(void)
 {
diff --git a/arch/loongarch/kernel/paravirt.c b/arch/loongarch/kernel/paravirt.c
index cc6bf096cb88..dc3cebcb550a 100644
--- a/arch/loongarch/kernel/paravirt.c
+++ b/arch/loongarch/kernel/paravirt.c
@@ -151,11 +151,14 @@ static void pv_init_ipi(void)
 }
 #endif
 
-static bool kvm_para_available(void)
+bool kvm_para_available(void)
 {
        int config;
        static int hypervisor_type;
 
+       if (!cpu_has_hypervisor)
+               return false;
+
        if (!hypervisor_type) {
                config = read_cpucfg(CPUCFG_KVM_SIG);
                if (!memcmp(&config, KVM_SIGNATURE, 4))
@@ -165,17 +168,21 @@ static bool kvm_para_available(void)
        return hypervisor_type == HYPERVISOR_KVM;
 }
 
-int __init pv_ipi_init(void)
+unsigned int kvm_arch_para_features(void)
 {
-       int feature;
+       static int feature;
 
-       if (!cpu_has_hypervisor)
-               return 0;
        if (!kvm_para_available())
                return 0;
 
-       feature = read_cpucfg(CPUCFG_KVM_FEATURE);
-       if (!(feature & BIT(KVM_FEATURE_IPI)))
+       if (!feature)
+               feature = read_cpucfg(CPUCFG_KVM_FEATURE);
+       return feature;
+}
+
+int __init pv_ipi_init(void)
+{
+       if (!kvm_para_has_feature(KVM_FEATURE_IPI))
                return 0;
 
 #ifdef CONFIG_SMP
@@ -258,15 +265,9 @@ static struct notifier_block pv_reboot_nb = {
 
 int __init pv_time_init(void)
 {
-       int r, feature;
-
-       if (!cpu_has_hypervisor)
-               return 0;
-       if (!kvm_para_available())
-               return 0;
+       int r;
 
-       feature = read_cpucfg(CPUCFG_KVM_FEATURE);
-       if (!(feature & BIT(KVM_FEATURE_STEAL_TIME)))
+       if (!kvm_para_has_feature(KVM_FEATURE_STEAL_TIME))
                return 0;
 
        has_steal_clock = 1;
-- 
2.39.3