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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: 1085ba7f55
Cc: stable@vger.kernel.org
Cc: mtosatti@redhat.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2014-01-27 14:49:40 +01:00
parent 5f66b62095
commit 1c300a4077
2 changed files with 33 additions and 16 deletions
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22
arch/x86/include/asm/kvm_para.h
View File

@ -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;

27
arch/x86/kernel/kvm.c
View File

@ -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();