> -----Original Message----- > From: Alexander Graf [mailto:ag...@suse.de] > Sent: Friday, May 03, 2013 6:00 PM > To: Bhushan Bharat-R65777 > Cc: kvm-...@vger.kernel.org; kvm@vger.kernel.org; Wood Scott-B07421 > Subject: Re: [PATCH 7/7 v3] KVM: PPC: Add userspace debug stub support > > > On 03.05.2013, at 13:08, Alexander Graf wrote: > > > > > > > Am 03.05.2013 um 12:48 schrieb Bhushan Bharat-R65777 <r65...@freescale.com>: > > > >>>>>> +static void kvmppc_booke_vcpu_load_debug_regs(struct kvm_vcpu > >>>>>> +*vcpu) { > >>>>>> + if (!vcpu->arch.debug_active) > >>>>>> + return; > >>>>>> + > >>>>>> + /* Disable all debug events and clead pending debug events */ > >>>>>> + mtspr(SPRN_DBCR0, 0x0); > >>>>>> + kvmppc_clear_dbsr(); > >>>>>> + > >>>>>> + /* > >>>>>> + * Check whether guest still need debug resource, if not then > >>>>>> there > >>>>>> + * is no need to restore guest context. > >>>>>> + */ > >>>>>> + if (!vcpu->arch.shadow_dbg_reg.dbcr0) > >>>>>> + return; > >>>>>> + > >>>>>> + /* Load Guest Context */ > >>>>>> + mtspr(SPRN_DBCR1, vcpu->arch.shadow_dbg_reg.dbcr1); > >>>>>> + mtspr(SPRN_DBCR2, vcpu->arch.shadow_dbg_reg.dbcr2); #ifdef > >>>>>> +CONFIG_KVM_E500MC > >>>>>> + mtspr(SPRN_DBCR4, vcpu->arch.shadow_dbg_reg.dbcr4); > >>>>> > >>>>> You need to make sure DBCR4 is 0 when you leave things back to > >>>>> normal user space. Otherwise guest debug can interfere with host debug. > >>>> > >>>> > >>>> ok > >>>> > >>>>> > >>>>>> +#endif > >>>>>> + mtspr(SPRN_IAC1, vcpu->arch.shadow_dbg_reg.iac[0]); > >>>>>> + mtspr(SPRN_IAC2, vcpu->arch.shadow_dbg_reg.iac[1]); > >>>>>> +#if CONFIG_PPC_ADV_DEBUG_IACS > 2 > >>>>>> + mtspr(SPRN_IAC3, vcpu->arch.shadow_dbg_reg.iac[2]); > >>>>>> + mtspr(SPRN_IAC4, vcpu->arch.shadow_dbg_reg.iac[3]); > >>>>>> +#endif > >>>>>> + mtspr(SPRN_DAC1, vcpu->arch.shadow_dbg_reg.dac[0]); > >>>>>> + mtspr(SPRN_DAC2, vcpu->arch.shadow_dbg_reg.dac[1]); > >>>>>> + > >>>>>> + /* Enable debug events after other debug registers restored */ > >>>>>> + mtspr(SPRN_DBCR0, vcpu->arch.shadow_dbg_reg.dbcr0); } > >>>>> > >>>>> All of the code above looks suspiciously similar to > >>>>> prime_debug_regs();. Can't we somehow reuse that? > >>>> > >>>> I think we can if > >>>> - Save thread->debug_regs in local data structure > >>> > >>> Yes, it can even be on the stack. > >>> > >>>> - Load vcpu->arch->debug_regs in thread->debug_regs > >>>> - Call prime_debug_regs(); > >>>> - Restore thread->debug_regs from local save values in first step > >>> > >>> On heavyweight exit, based on the values on stack, yes. > >> > >> This is how I think we can save/restore debug context. Please correct if I > >> am > missing something. > > > > Sounds about right :) > > Actually, what happens if a guest breakpoint is set to a kernel address that > happens to be within the scope of kvm code?
You mean address of kvm code in guest or host? If host, we already mentioned that we do not support that. Right? -Bharat > We do accept debug events between > vcpu_run and the assembly code, right? > > > Alex > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
