Only reload debug register 6 if we're running with the guest's debug registers. Saves around 150 cycles from the guest lightweight exit path. Signed-off-by: Avi Kivity <avi@xxxxxxxxxx> --- arch/x86/kvm/vmx.c | 6 ++++-- 1 files changed, 4 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 05cd554..70b0c54 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -3629,7 +3629,8 @@ static void vmx_vcpu_run(struct kvm_vcpu *vcpu) */ vmcs_writel(HOST_CR0, read_cr0()); - set_debugreg(vcpu->arch.dr6, 6); + if (vcpu->arch.switch_db_regs) + set_debugreg(vcpu->arch.dr6, 6); asm( /* Store host registers */ @@ -3731,7 +3732,8 @@ static void vmx_vcpu_run(struct kvm_vcpu *vcpu) | (1 << VCPU_EXREG_PDPTR)); vcpu->arch.regs_dirty = 0; - get_debugreg(vcpu->arch.dr6, 6); + if (vcpu->arch.switch_db_regs) + get_debugreg(vcpu->arch.dr6, 6); vmx->idt_vectoring_info = vmcs_read32(IDT_VECTORING_INFO_FIELD); if (vmx->rmode.irq.pending) -- 1.6.4.1 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
