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Commit 1c300a40 authored by Paolo Bonzini's avatar Paolo Bonzini
Browse files

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: 1085ba7f
Cc: stable@vger.kernel.org
Cc: mtosatti@redhat.com
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 5f66b620

arch/x86/include/asm/kvm_para.h

+6 −16
Original line number Diff line number Diff line
@@ -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;

arch/x86/kernel/kvm.c

+27 −0
Original line number Diff line number Diff line
@@ -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();