LoongArch: KVM: Implement function kvm_para_has_feature()

Implement function kvm_para_has_feature() to detect supported paravirt
features. It can be used by device driver to detect and enable paravirt
features, such as the EIOINTC irqchip driver is able to detect feature
KVM_FEATURE_VIRT_EXTIOI and do some optimization.

Signed-off-by: Bibo Mao <maobibo@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

diff --git a/arch/loongarch/include/asm/kvm_para.h b/arch/loongarch/include/asm/kvm_para.h
index d0f087870628a13a2633eccff2470d1c4ee8ad82..c4e84227280dc1ec74a362723972cb3de6830092 100644 (file)
--- a/arch/loongarch/include/asm/kvm_para.h
+++ b/arch/loongarch/include/asm/kvm_para.h
@@ -156,10 +156,20 @@ 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 1306ad830ae2d99ca55adf99a09872c9267db1db..708eda025ed880ca4ae6dcd795cd01fb38a10c06 100644 (file)
--- a/arch/loongarch/kernel/paravirt.c
+++ b/arch/loongarch/kernel/paravirt.c
@@ -152,11 +152,14 @@ 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))
@@ -166,17 +169,22 @@ 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 unsigned 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
@@ -259,15 +267,9 @@ 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;