KVM: VMX: Optimize handling of VM-Entry failures in vmx_vcpu_run() (873e1da1) · Commits · 戴 / test

Mark the VM-Fail, VM-Exit on VM-Enter, and #MC on VM-Enter paths as 'unlikely' so as to improve code generation so that it favors successful VM-Enter. The performance of successful VM-Enter is for more important, irrespective of whether or not success is actually likely. Signed-off-by:

Sean Christopherson <sean.j.christopherson@intel.com> Message-Id: <20200410174703.1138-2-sean.j.christopherson@intel.com> Signed-off-by:

Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/vmx/vmx.c

+8 −3

Original line number	Diff line number	Diff line
		@@ -6724,11 +6724,16 @@ static void vmx_vcpu_run(struct kvm_vcpu *vcpu)
		vmx->nested.nested_run_pending = 0;
		vmx->idt_vectoring_info = 0;

		vmx->exit_reason = vmx->fail ? 0xdead : vmcs_read32(VM_EXIT_REASON);
		if ((u16)vmx->exit_reason == EXIT_REASON_MCE_DURING_VMENTRY)
		if (unlikely(vmx->fail)) {
		vmx->exit_reason = 0xdead;
		return;
		}

		vmx->exit_reason = vmcs_read32(VM_EXIT_REASON);
		if (unlikely((u16)vmx->exit_reason == EXIT_REASON_MCE_DURING_VMENTRY))
		kvm_machine_check();

		if (vmx->fail \|\| (vmx->exit_reason & VMX_EXIT_REASONS_FAILED_VMENTRY))
		if (unlikely(vmx->exit_reason & VMX_EXIT_REASONS_FAILED_VMENTRY))
		return;

		vmx->loaded_vmcs->launched = 1;

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