Avi Kivity wrote: > 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) That reduces the emulation quality as vcpu->arch.switch_db_regs is only set if some breakpoint is active while dr6 has its use also when that is not the case). Jan -- Siemens AG, Corporate Technology, CT SE 2 Corporate Competence Center Embedded Linux -- 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
