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Commit 32b72ecc authored by Wanpeng Li's avatar Wanpeng Li Committed by Paolo Bonzini
Browse files

KVM: X86: Expose PV_SCHED_YIELD CPUID feature bit to guest 



Expose PV_SCHED_YIELD feature bit to guest, the guest can check this
feature bit before using paravirtualized sched yield.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Liran Alon <liran.alon@oracle.com>
Signed-off-by: default avatarWanpeng Li <wanpengli@tencent.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 71506297

Documentation/virtual/kvm/cpuid.txt

+4 −0
Original line number Diff line number Diff line
@@ -66,6 +66,10 @@ KVM_FEATURE_PV_SEND_IPI || 11 || guest checks this feature bit 
                                   ||       || before using paravirtualized

                                   ||       || send IPIs.

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

KVM_FEATURE_PV_SCHED_YIELD         ||    13 || guest checks this feature bit

                                   ||       || before using paravirtualized

                                   ||       || sched yield.

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

KVM_FEATURE_CLOCKSOURCE_STABLE_BIT ||    24 || host will warn if no guest-side

                                   ||       || per-cpu warps are expected in

                                   ||       || kvmclock.

arch/x86/kvm/cpuid.c

+2 −1
Original line number Diff line number Diff line
@@ -659,7 +659,8 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function, 
			     (1 << KVM_FEATURE_PV_TLB_FLUSH) |

			     (1 << KVM_FEATURE_ASYNC_PF_VMEXIT) |

			     (1 << KVM_FEATURE_PV_SEND_IPI) |

			     (1 << KVM_FEATURE_POLL_CONTROL);

			     (1 << KVM_FEATURE_POLL_CONTROL) |

			     (1 << KVM_FEATURE_PV_SCHED_YIELD);



		if (sched_info_on())

			entry->eax |= (1 << KVM_FEATURE_STEAL_TIME);