Am 03.04.2013 um 19:47 schrieb Bhushan Bharat-R65777 <[email protected]>:
>>>>>>>>> + dbg_reg =&(vcpu->arch.shadow_dbg_reg); >>>>>>>>> + >>>>>>>>> + /* >>>>>>>>> + * On BOOKE (e500v2); Set DBCR1 and DBCR2 to allow debug events >>>>>>>>> + * to occur when MSR.PR is set. >>>>>>>>> + * On BOOKE-HV (e500mc+); MSR.PR = 0 when guest is running. So we >>>>>>>>> + * should clear DBCR1 and DBCR2. >>>>>>>>> + */ >>>>>>>>> +#ifdef CONFIG_KVM_BOOKE_HV >>>>>>>>> + dbg_reg->dbcr1 = 0; >>>>>>>>> + dbg_reg->dbcr2 = 0; >>>>>>>> Does that mean we can't debug guest user space? >>>>>>> Yes >>>>>> This is wrong. >>>>> Really, So far I am assuming qemu debug stub is not mean for >>>>> debugging guest >>>> application. >>>> >>>> Ok, let me rephrase: This is confusing. You do trap in PR mode on >>>> e500v2. IIRC >>>> x86 also traps in kernel and user space. I don't see why e500 hv >>>> should be different. >>> >>> I am sorry, I think did not read the document correctly. >>> >>> DBCR1 = 0 ; means the "00 IAC1 debug conditions unaffected by >>> MSR[PR],MSR[GS]. >>> >>> Similarly for dbcr2. >>> >>> So yes the guest user space can be debugged. >> >> So why is this conditional on BOOKE_HV then? Wouldn't it make things easier >> to >> treat HV and PR identical? > > On BOOKE-HV we have to keep these to 0, so guest and guest application both > can be debugged. Also on HV we have EPCR.DUVD to control that debug events > will not come in hypervisor (GS = 0). > > On BOOKE; guest and guest application both runs in PR = 1 and hypervisor in > PR = 0. So with dbcr1/dbcr2 on booke we control debug exception not to come > in hypervisor mode still allow guest and its application debugging. Ah, can we group these 2 overrides next to each other with an #ifdef ... #else to make this obvious from the code? Alex > > Thanks > -Bharat > > > > > > -- > To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in > the body of a message to [email protected] > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
