From 1c300a40772dae829b91dad634999a6a522c0829 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Mon, 27 Jan 2014 14:49:40 +0100 Subject: [PATCH] x86, kvm: cache the base of the KVM cpuid leaves It is unnecessary to go through hypervisor_cpuid_base every time a leaf is found (which will be every time a feature is requested after the next patch). Fixes: 1085ba7f552d84aa8ac0ae903fa8d0cc2ff9f79d Cc: stable@vger.kernel.org Cc: mtosatti@redhat.com Signed-off-by: Paolo Bonzini --- arch/x86/include/asm/kvm_para.h | 22 ++++++---------------- arch/x86/kernel/kvm.c | 27 +++++++++++++++++++++++++++ 2 files changed, 33 insertions(+), 16 deletions(-) diff --git a/arch/x86/include/asm/kvm_para.h b/arch/x86/include/asm/kvm_para.h index 1df1159..1679cc7 100644 --- a/arch/x86/include/asm/kvm_para.h +++ b/arch/x86/include/asm/kvm_para.h @@ -85,28 +85,13 @@ static inline long kvm_hypercall4(unsigned int nr, unsigned long p1, return ret; } -static inline uint32_t kvm_cpuid_base(void) -{ - if (boot_cpu_data.cpuid_level < 0) - return 0; /* So we don't blow up on old processors */ - - if (cpu_has_hypervisor) - return hypervisor_cpuid_base("KVMKVMKVM\0\0\0", 0); - - return 0; -} - -static inline bool kvm_para_available(void) -{ - return kvm_cpuid_base() != 0; -} - static inline unsigned int kvm_arch_para_features(void) { return cpuid_eax(KVM_CPUID_FEATURES); } #ifdef CONFIG_KVM_GUEST +bool kvm_para_available(void); void __init kvm_guest_init(void); void kvm_async_pf_task_wait(u32 token); void kvm_async_pf_task_wake(u32 token); @@ -126,6 +111,11 @@ static inline void kvm_spinlock_init(void) #define kvm_async_pf_task_wait(T) do {} while(0) #define kvm_async_pf_task_wake(T) do {} while(0) +static inline bool kvm_para_available(void) +{ + return 0; +} + static inline u32 kvm_read_and_reset_pf_reason(void) { return 0; diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c index 6dd802c..0823003 100644 --- a/arch/x86/kernel/kvm.c +++ b/arch/x86/kernel/kvm.c @@ -500,6 +500,33 @@ void __init kvm_guest_init(void) #endif } +static noinline uint32_t __kvm_cpuid_base(void) +{ + if (boot_cpu_data.cpuid_level < 0) + return 0; /* So we don't blow up on old processors */ + + if (cpu_has_hypervisor) + return hypervisor_cpuid_base("KVMKVMKVM\0\0\0", 0); + + return 0; +} + +static inline uint32_t kvm_cpuid_base(void) +{ + static int kvm_cpuid_base = -1; + + if (kvm_cpuid_base == -1) + kvm_cpuid_base = __kvm_cpuid_base(); + + return kvm_cpuid_base; +} + +bool kvm_para_available(void) +{ + return kvm_cpuid_base() != 0; +} +EXPORT_SYMBOL_GPL(kvm_para_available); + static uint32_t __init kvm_detect(void) { return kvm_cpuid_base(); -- 2.7.4