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Commit a4429e53 authored by Wanpeng Li's avatar Wanpeng Li Committed by Radim Krčmář
Browse files

KVM: Introduce paravirtualization hints and KVM_HINTS_DEDICATED 



This patch introduces kvm_para_has_hint() to query for hints about
the configuration of the guests.  The first hint KVM_HINTS_DEDICATED,
is set if the guest has dedicated physical CPUs for each vCPU (i.e.
pinning and no over-commitment).  This allows optimizing spinlocks
and tells the guest to avoid PV TLB flush.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: default avatarWanpeng Li <wanpengli@tencent.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarRadim Krčmář <rkrcmar@redhat.com>
parent d4c67a7a

Documentation/virtual/kvm/cpuid.txt

+13 −2
Original line number Diff line number Diff line
@@ -23,8 +23,8 @@ This function queries the presence of KVM cpuid leafs. 




function: define KVM_CPUID_FEATURES (0x40000001)

returns : ebx, ecx, edx = 0

          eax = and OR'ed group of (1 << flag), where each flags is:

returns : ebx, ecx

          eax = an OR'ed group of (1 << flag), where each flags is:





flag                               || value || meaning
@@ -66,3 +66,14 @@ KVM_FEATURE_CLOCKSOURCE_STABLE_BIT || 24 || host will warn if no guest-side 
                                   ||       || per-cpu warps are expected in

                                   ||       || kvmclock.

------------------------------------------------------------------------------



          edx = an OR'ed group of (1 << flag), where each flags is:





flag                               || value || meaning

==================================================================================

KVM_HINTS_DEDICATED                ||     0 || guest checks this feature bit to

                                   ||       || determine if there is vCPU pinning

                                   ||       || and there is no vCPU over-commitment,

                                   ||       || allowing optimizations

----------------------------------------------------------------------------------

arch/mips/include/asm/kvm_para.h

+5 −0
Original line number Diff line number Diff line
@@ -94,6 +94,11 @@ static inline unsigned int kvm_arch_para_features(void) 
	return 0;

}



static inline unsigned int kvm_arch_para_hints(void)

{

	return 0;

}



#ifdef CONFIG_MIPS_PARAVIRT

static inline bool kvm_para_available(void)

{

arch/powerpc/include/asm/kvm_para.h

+5 −0
Original line number Diff line number Diff line
@@ -61,6 +61,11 @@ static inline unsigned int kvm_arch_para_features(void) 
	return r;

}



static inline unsigned int kvm_arch_para_hints(void)

{

	return 0;

}



static inline bool kvm_check_and_clear_guest_paused(void)

{

	return false;

arch/s390/include/asm/kvm_para.h

+5 −0
Original line number Diff line number Diff line
@@ -193,6 +193,11 @@ static inline unsigned int kvm_arch_para_features(void) 
	return 0;

}



static inline unsigned int kvm_arch_para_hints(void)

{

	return 0;

}



static inline bool kvm_check_and_clear_guest_paused(void)

{

	return false;

arch/x86/include/asm/kvm_para.h

+6 −0
Original line number Diff line number Diff line
@@ -88,6 +88,7 @@ static inline long kvm_hypercall4(unsigned int nr, unsigned long p1, 
#ifdef CONFIG_KVM_GUEST

bool kvm_para_available(void);

unsigned int kvm_arch_para_features(void);

unsigned int kvm_arch_para_hints(void);

void kvm_async_pf_task_wait(u32 token, int interrupt_kernel);

void kvm_async_pf_task_wake(u32 token);

u32 kvm_read_and_reset_pf_reason(void);
@@ -115,6 +116,11 @@ static inline unsigned int kvm_arch_para_features(void) 
	return 0;

}



static inline unsigned int kvm_arch_para_hints(void)

{

	return 0;

}



static inline u32 kvm_read_and_reset_pf_reason(void)

{

	return 0;