KVM: X86: Implement PV sched yield hypercall (71506297) · Commits · 戴 / test

The target vCPUs are in runnable state after vcpu_kick and suitable as a yield target. This patch implements the sched yield hypercall. 17% performance increasement of ebizzy benchmark can be observed in an over-subscribe environment. (w/ kvm-pv-tlb disabled, testing TLB flush call-function IPI-many since call-function is not easy to be trigged by userspace workload). Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Cc: Liran Alon <liran.alon@oracle.com> Signed-off-by:

Wanpeng Li <wanpengli@tencent.com> Signed-off-by:

Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/x86.c

+21 −0

Original line number	Diff line number	Diff line
		@@ -7193,6 +7193,23 @@ void kvm_vcpu_deactivate_apicv(struct kvm_vcpu *vcpu)
		kvm_x86_ops->refresh_apicv_exec_ctrl(vcpu);
		}

		static void kvm_sched_yield(struct kvm *kvm, unsigned long dest_id)
		{
		struct kvm_vcpu *target = NULL;
		struct kvm_apic_map *map;

		rcu_read_lock();
		map = rcu_dereference(kvm->arch.apic_map);

		if (likely(map) && dest_id <= map->max_apic_id && map->phys_map[dest_id])
		target = map->phys_map[dest_id]->vcpu;

		rcu_read_unlock();

		if (target)
		kvm_vcpu_yield_to(target);
		}

		int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
		{
		unsigned long nr, a0, a1, a2, a3, ret;
		@@ -7239,6 +7256,10 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
		case KVM_HC_SEND_IPI:
		ret = kvm_pv_send_ipi(vcpu->kvm, a0, a1, a2, a3, op_64_bit);
		break;
		case KVM_HC_SCHED_YIELD:
		kvm_sched_yield(vcpu->kvm, a0);
		ret = 0;
		break;
		default:
		ret = -KVM_ENOSYS;
		break;

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