On 26/02/2016 11:42, Xiao Guangrong wrote: >> >> + vcpu->arch.switch_db_regs |= KVM_DEBUGREG_RELOAD; > > Er, i do not understand how it works. The BP is enabled in this test case so > the debug registers are always reloaded before entering guest as > KVM_DEBUGREG_BP_ENABLED bit is always set on switch_db_regs. What did i > miss? > > Another impact of this fix is when vcpu is rescheduled we need to always > reload debug registers even if guest does not enable it, it is really needed? Hi, I have looked further at the bug and the issue is that the lazy debug register optimization doesn't call kvm_update_dr7 and thus does not set KVM_DEBUGREG_BP_ENABLED. I will post a better patch shortly. However, I still think this one is simpler to have in stable kernel releases, because it doesn't have any dependencies. Paolo -- 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
