[PATCH v4 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 <mao...@loongson.cn>
---
arch/loongarch/include/asm/kvm_para.h | 10 ++++++++++
arch/loongarch/kernel/paravirt.c | 28 +++++++++++++++------------
2 files changed, 26 insertions(+), 12 deletions(-)

diff --git a/arch/loongarch/include/asm/kvm_para.h b/arch/loongarch/include/asm/kvm_para.h
index 9814d56b8d0e..327f331d5237 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..10683e25b6b3 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 (!feature)
+ feature = read_cpucfg(CPUCFG_KVM_FEATURE);
+ return feature;
+}
+
+int __init pv_ipi_init(void)
+{
if (!kvm_para_available())
return 0;

- feature = read_cpucfg(CPUCFG_KVM_FEATURE);
- if (!(feature & BIT(KVM_FEATURE_IPI)))
+ if (!kvm_para_has_feature(KVM_FEATURE_IPI))
return 0;

#ifdef CONFIG_SMP
@@ -258,15 +265,12 @@ static struct notifier_block pv_reboot_nb = {

int __init pv_time_init(void)
{
- int r, feature;
+ int r;

- if (!cpu_has_hypervisor)
- return 0;
if (!kvm_para_available())
return 0;

- 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