> -----Original Message----- > From: Alexander Graf [mailto:agraf@xxxxxxx] > Sent: Tuesday, April 02, 2013 9:11 PM > To: Bhushan Bharat-R65777 > Cc: kvm-ppc@xxxxxxxxxxxxxxx; kvm@xxxxxxxxxxxxxxx; Wood Scott-B07421 > Subject: Re: [PATCH 4/4 v2] KVM: PPC: Add userspace debug stub support > > On 04/02/2013 04:09 PM, Bhushan Bharat-R65777 wrote: > > > >> -----Original Message----- > >> From: Alexander Graf [mailto:agraf@xxxxxxx] > >> Sent: Tuesday, April 02, 2013 1:57 PM > >> To: Bhushan Bharat-R65777 > >> Cc: kvm-ppc@xxxxxxxxxxxxxxx; kvm@xxxxxxxxxxxxxxx; Wood Scott-B07421 > >> Subject: Re: [PATCH 4/4 v2] KVM: PPC: Add userspace debug stub > >> support > >> > >> > >> On 29.03.2013, at 07:04, Bhushan Bharat-R65777 wrote: > >> > >>> > >>>> -----Original Message----- > >>>> From: Alexander Graf [mailto:agraf@xxxxxxx] > >>>> Sent: Thursday, March 28, 2013 10:06 PM > >>>> To: Bhushan Bharat-R65777 > >>>> Cc: kvm-ppc@xxxxxxxxxxxxxxx; kvm@xxxxxxxxxxxxxxx; Wood > >>>> Scott-B07421; Bhushan > >>>> Bharat-R65777 > >>>> Subject: Re: [PATCH 4/4 v2] KVM: PPC: Add userspace debug stub > >>>> support > >>>> > >>>> > >>>> On 21.03.2013, at 07:25, Bharat Bhushan wrote: > >>>> > >>>>> From: Bharat Bhushan<bharat.bhushan@xxxxxxxxxxxxx> > >>>>> > >>>>> This patch adds the debug stub support on booke/bookehv. > >>>>> Now QEMU debug stub can use hw breakpoint, watchpoint and software > >>>>> breakpoint to debug guest. > >>>>> > >>>>> Debug registers are saved/restored on vcpu_put()/vcpu_get(). > >>>>> Also the debug registers are saved restored only if guest is using > >>>>> debug resources. > >>>>> > >>>>> Signed-off-by: Bharat Bhushan<bharat.bhushan@xxxxxxxxxxxxx> > >>>>> --- > >>>>> v2: > >>>>> - save/restore in vcpu_get()/vcpu_put() > >>>>> - some more minor cleanup based on review comments. > >>>>> > >>>>> arch/powerpc/include/asm/kvm_host.h | 10 ++ > >>>>> arch/powerpc/include/uapi/asm/kvm.h | 22 +++- > >>>>> arch/powerpc/kvm/booke.c | 252 > ++++++++++++++++++++++++++++++++- > >> -- > >>>>> arch/powerpc/kvm/e500_emulate.c | 10 ++ > >>>>> 4 files changed, 272 insertions(+), 22 deletions(-) > >>>>> > >>>>> diff --git a/arch/powerpc/include/asm/kvm_host.h > >>>>> b/arch/powerpc/include/asm/kvm_host.h > >>>>> index f4ba881..8571952 100644 > >>>>> --- a/arch/powerpc/include/asm/kvm_host.h > >>>>> +++ b/arch/powerpc/include/asm/kvm_host.h > >>>>> @@ -504,7 +504,17 @@ struct kvm_vcpu_arch { > >>>>> u32 mmucfg; > >>>>> u32 epr; > >>>>> u32 crit_save; > >>>>> + /* guest debug registers*/ > >>>>> struct kvmppc_booke_debug_reg dbg_reg; > >>>>> + /* shadow debug registers */ > >>>>> + struct kvmppc_booke_debug_reg shadow_dbg_reg; > >>>>> + /* host debug registers*/ > >>>>> + struct kvmppc_booke_debug_reg host_dbg_reg; > >>>>> + /* > >>>>> + * Flag indicating that debug registers are used by guest > >>>>> + * and requires save restore. > >>>>> + */ > >>>>> + bool debug_save_restore; > >>>>> #endif > >>>>> gpa_t paddr_accessed; > >>>>> gva_t vaddr_accessed; > >>>>> diff --git a/arch/powerpc/include/uapi/asm/kvm.h > >>>>> b/arch/powerpc/include/uapi/asm/kvm.h > >>>>> index 15f9a00..d7ce449 100644 > >>>>> --- a/arch/powerpc/include/uapi/asm/kvm.h > >>>>> +++ b/arch/powerpc/include/uapi/asm/kvm.h > >>>>> @@ -25,6 +25,7 @@ > >>>>> /* Select powerpc specific features in<linux/kvm.h> */ #define > >>>>> __KVM_HAVE_SPAPR_TCE #define __KVM_HAVE_PPC_SMT > >>>>> +#define __KVM_HAVE_GUEST_DEBUG > >>>>> > >>>>> struct kvm_regs { > >>>>> __u64 pc; > >>>>> @@ -267,7 +268,24 @@ struct kvm_fpu { > >>>>> __u64 fpr[32]; > >>>>> }; > >>>>> > >>>>> +/* > >>>>> + * Defines for h/w breakpoint, watchpoint (read, write or both) > >>>>> +and > >>>>> + * software breakpoint. > >>>>> + * These are used as "type" in KVM_SET_GUEST_DEBUG ioctl and "status" > >>>>> + * for KVM_DEBUG_EXIT. > >>>>> + */ > >>>>> +#define KVMPPC_DEBUG_NONE 0x0 > >>>>> +#define KVMPPC_DEBUG_BREAKPOINT (1UL<< 1) > >>>>> +#define KVMPPC_DEBUG_WATCH_WRITE (1UL<< 2) > >>>>> +#define KVMPPC_DEBUG_WATCH_READ (1UL<< 3) > >>>>> struct kvm_debug_exit_arch { > >>>>> + __u64 address; > >>>>> + /* > >>>>> + * exiting to userspace because of h/w breakpoint, watchpoint > >>>>> + * (read, write or both) and software breakpoint. > >>>>> + */ > >>>>> + __u32 status; > >>>>> + __u32 reserved; > >>>>> }; > >>>>> > >>>>> /* for KVM_SET_GUEST_DEBUG */ > >>>>> @@ -279,10 +297,6 @@ struct kvm_guest_debug_arch { > >>>>> * Type denotes h/w breakpoint, read watchpoint, write > >>>>> * watchpoint or watchpoint (both read and write). > >>>>> */ > >>>>> -#define KVMPPC_DEBUG_NOTYPE 0x0 > >>>>> -#define KVMPPC_DEBUG_BREAKPOINT (1UL<< 1) > >>>>> -#define KVMPPC_DEBUG_WATCH_WRITE (1UL<< 2) > >>>>> -#define KVMPPC_DEBUG_WATCH_READ (1UL<< 3) > >>>>> __u32 type; > >>>>> __u32 reserved; > >>>>> } bp[16]; > >>>>> diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c > >>>>> index > >>>>> 1de93a8..bf20056 100644 > >>>>> --- a/arch/powerpc/kvm/booke.c > >>>>> +++ b/arch/powerpc/kvm/booke.c > >>>>> @@ -133,6 +133,30 @@ static void kvmppc_vcpu_sync_fpu(struct > >>>>> kvm_vcpu > >>>>> *vcpu) #endif } > >>>>> > >>>>> +static void kvmppc_vcpu_sync_debug(struct kvm_vcpu *vcpu) { > >>>>> + /* Synchronize guest's desire to get debug interrupts into > >>>>> +shadow MSR */ #ifndef CONFIG_KVM_BOOKE_HV > >>>>> + vcpu->arch.shadow_msr&= ~MSR_DE; > >>>>> + vcpu->arch.shadow_msr |= vcpu->arch.shared->msr& MSR_DE; #endif > >>>>> + > >>>>> + /* Force enable debug interrupts when user space wants to debug */ > >>>>> + if (vcpu->guest_debug) { > >>>>> +#ifdef CONFIG_KVM_BOOKE_HV > >>>>> + /* > >>>>> + * Since there is no shadow MSR, sync MSR_DE into the guest > >>>>> + * visible MSR. Do not allow guest to change MSR[DE]. > >>>>> + */ > >>>>> + vcpu->arch.shared->msr |= MSR_DE; > >>>>> + mtspr(SPRN_MSRP, mfspr(SPRN_MSRP) | MSRP_DEP); > >>>> This mtspr should really just be a bit or in shadow_mspr when > >>>> guest_debug gets enabled. It should automatically get synchronized > >>>> as soon as the next > >>>> vpcu_load() happens. > >>> I think this is not required here as shadow_dbsr already have MSRP_DEP set. > >>> > >>> Will setup shadow_msrp when setting guest_debug and clear > >>> shadow_msrp when > >> guest_debug is cleared. > >>> But that will also not be sufficient as it not sure when vcpu_load() > >>> will be called after the shadow_msrp is changed. So > >>> > >>> When guest_debug is set in debug_ioctl() > >>> /* Set MSRP_DEP in shadow_msrp so that guest cannot change MSR.DE. > >>> As shadow_msrp is loaded on vcpu_load(), and it is not guaranteed > >>> that > >>> vcpu_load() will be called just after debug_ioctl(), so also set > >>> MSRP_DEP in SPRN_MSRP. */ > >> debug_ioctl is an ioctl. So while that ioctl is on, the vcpu is not running. > >> After that ioctl user space calls another VCPU_RUN ioctl which > >> invokes vcpu_load. > > That's good. I was not aware of vcpu_load() is being called before > > ioctl handling in KVM :) > > > >>> - shadow_msrp | MSRP_DEP; > >>> - change SPRN_MSRP.MSRP_DEP as you do not know when vcpu_load() will > >>> be > >> called? > >>> > >>> When guest_debug is cleared in debug_ioctl() > >>> /* Clear MSRP_DEP in shadow_msrp so that guest can change MSR.DE. As > >>> shadow_msrp is loaded on vcpu_load(), and it is not guaranteed that > >>> vcpu_load() will be called just after debug_ioctl(), so also clear > >>> MSRP_DEP in SPRN_MSRP. */ > >> Same thing here again. > >> > >>> - shadow_msrp | MSRP_DEP; > >>> - change SPRN_MSRP.MSRP_DEP as you do not know when vcpu_load() will > >>> be > >> called? > >>>> Also, what happens when user space disables guest_debug? > >>>> > >>>>> +#else > >>>>> + vcpu->arch.shadow_msr |= MSR_DE; > >>>>> + vcpu->arch.shared->msr&= ~MSR_DE; #endif > >>>>> + } > >>>>> +} > >>>>> + > >>>>> /* > >>>>> * Helper function for "full" MSR writes. No need to call this if > >>>>> only > >>>>> * EE/CE/ME/DE/RI are changing. > >>>>> @@ -150,6 +174,7 @@ void kvmppc_set_msr(struct kvm_vcpu *vcpu, u32 > new_msr) > >>>>> kvmppc_mmu_msr_notify(vcpu, old_msr); > >>>>> kvmppc_vcpu_sync_spe(vcpu); > >>>>> kvmppc_vcpu_sync_fpu(vcpu); > >>>>> + kvmppc_vcpu_sync_debug(vcpu); > >>>>> } > >>>>> > >>>>> static void kvmppc_booke_queue_irqprio(struct kvm_vcpu *vcpu, @@ > >>>>> -736,6 +761,9 @@ static int emulation_exit(struct kvm_run *run, > >>>>> struct > >>>> kvm_vcpu *vcpu) > >>>>> run->exit_reason = KVM_EXIT_DCR; > >>>>> return RESUME_HOST; > >>>>> > >>>>> + case EMULATE_EXIT_USER: > >>>>> + return RESUME_HOST; > >>>> This should get folded into the previous patch or be a separate one. > >>> ok > >>> > >>>>> + > >>>>> case EMULATE_FAIL: > >>>>> printk(KERN_CRIT "%s: emulation at %lx failed (%08x)\n", > >>>>> __func__, vcpu->arch.pc, vcpu->arch.last_inst); @@ -751,6 > >>>>> +779,30 @@ static int emulation_exit(struct kvm_run *run, struct > >>>>> +kvm_vcpu > >>>> *vcpu) > >>>>> } > >>>>> } > >>>>> > >>>>> +static int kvmppc_handle_debug(struct kvm_run *run, struct > >>>>> +kvm_vcpu > >>>>> +*vcpu) { > >>>>> + u32 dbsr = mfspr(SPRN_DBSR); > >>>>> + mtspr(SPRN_DBSR, dbsr); > >>>> This definitely deserves a comment :). > >>> Ok. > >>> > >>>> Also, are we non-preemptible here? > >>> This is called from kvmppc_handle_exit and interrupts are enabled, > >>> so I think > >> this can be preempted. > >>> But I do not think there is any issue as we clear DBSR in vpu_put(). > >> Ok, make clear_dbsr a function then that you call from both places. > >> That way it's more obvious. > > Ok > > > >>>>> + > >>>>> + run->debug.arch.status = 0; > >>>>> + run->debug.arch.address = vcpu->arch.pc; > >>>>> + > >>>>> + if (dbsr& (DBSR_IAC1 | DBSR_IAC2 | DBSR_IAC3 | DBSR_IAC4)) { > >>>>> + run->debug.arch.status |= KVMPPC_DEBUG_BREAKPOINT; > >>>>> + } else { > >>>>> + if (dbsr& (DBSR_DAC1W | DBSR_DAC2W)) > >>>>> + run->debug.arch.status |= KVMPPC_DEBUG_WATCH_WRITE; > >>>>> + else if (dbsr& (DBSR_DAC1R | DBSR_DAC2R)) > >>>>> + run->debug.arch.status |= KVMPPC_DEBUG_WATCH_READ; > >>>>> + if (dbsr& (DBSR_DAC1R | DBSR_DAC1W)) > >>>>> + run->debug.arch.address = vcpu- > >arch.shadow_dbg_reg.dac[0]; > >>>>> + else if (dbsr& (DBSR_DAC2R | DBSR_DAC2W)) > >>>>> + run->debug.arch.address = vcpu- > >arch.shadow_dbg_reg.dac[1]; > >>>>> + } > >>>>> + > >>>>> + return RESUME_HOST; > >>>> Shouldn't this check for guest_debug and only go to user space if > >>>> it asked for debugging? Can't you just leave it at the old code for > >> !guest_debug? > >>> Will add, I thought that it is redundant as of now as debug > >>> interrupt in guest > >> can come only when user space is debugging guest. > >> > >> The problem is that user space might not expect a guest debug exit. > > Ok > > > >>> clear DBSR > >>> if (!guest_debug) > >>> return RESUME_GUEST; > >> Can't you just do exactly what was done before when !guest_debug? We > >> usually try to change semantics one step at a time. > > What you mean by "done before" ? do you mean the removed code in "case > BOOKE_INTERRUPT_DEBUG" code in kvmppc_handle_exit() ? If yes then that code was > meaningless and not correct. > > Then change it in a separate patch. One patch, one change. Otherwise > bisectability suffers. > > > Right thing should be clear the pending exception and resume the > > guest. when no one is in state to handle the exception. May be we can > > have WARN_ON_ONCE() > > > >>>>> +} > >>>>> + > >>>>> static void kvmppc_fill_pt_regs(struct pt_regs *regs) { > >>>>> ulong r1, ip, msr, lr; > >>>>> @@ -1110,18 +1162,10 @@ int kvmppc_handle_exit(struct kvm_run > >>>>> *run, struct > >>>> kvm_vcpu *vcpu, > >>>>> } > >>>>> > >>>>> case BOOKE_INTERRUPT_DEBUG: { > >>>>> - u32 dbsr; > >>>>> - > >>>>> - vcpu->arch.pc = mfspr(SPRN_CSRR0); > >>>>> - > >>>>> - /* clear IAC events in DBSR register */ > >>>>> - dbsr = mfspr(SPRN_DBSR); > >>>>> - dbsr&= DBSR_IAC1 | DBSR_IAC2 | DBSR_IAC3 | DBSR_IAC4; > >>>>> - mtspr(SPRN_DBSR, dbsr); > >>>>> - > >>>>> - run->exit_reason = KVM_EXIT_DEBUG; > >>>>> + r = kvmppc_handle_debug(run, vcpu); > >>>>> + if (r == RESUME_HOST) > >>>>> + run->exit_reason = KVM_EXIT_DEBUG; > >>>>> kvmppc_account_exit(vcpu, DEBUG_EXITS); > >>>>> - r = RESUME_HOST; > >>>>> break; > >>>>> } > >>>>> > >>>>> @@ -1172,7 +1216,7 @@ int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu) > >>>>> kvmppc_set_msr(vcpu, 0); > >>>>> > >>>>> #ifndef CONFIG_KVM_BOOKE_HV > >>>>> - vcpu->arch.shadow_msr = MSR_USER | MSR_DE | MSR_IS | MSR_DS; > >>>>> + vcpu->arch.shadow_msr = MSR_USER | MSR_IS | MSR_DS; > >>>>> vcpu->arch.shadow_pid = 1; > >>>>> vcpu->arch.shared->msr = 0; > >>>>> #endif > >>>>> @@ -1527,12 +1571,6 @@ int kvm_vcpu_ioctl_set_one_reg(struct > >>>>> kvm_vcpu *vcpu, > >>>> struct kvm_one_reg *reg) > >>>>> return r; > >>>>> } > >>>>> > >>>>> -int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu, > >>>>> - struct kvm_guest_debug *dbg) > >>>>> -{ > >>>>> - return -EINVAL; > >>>>> -} > >>>>> - > >>>>> int kvm_arch_vcpu_ioctl_get_fpu(struct kvm_vcpu *vcpu, struct > >>>>> kvm_fpu > >>>>> *fpu) { > >>>>> return -ENOTSUPP; > >>>>> @@ -1638,16 +1676,194 @@ void kvmppc_decrementer_func(unsigned long data) > >>>>> kvmppc_set_tsr_bits(vcpu, TSR_DIS); } > >>>>> > >>>>> +static void kvmppc_booke_vcpu_put_debug_regs(struct kvm_vcpu *vcpu) { > >>>>> + if (!vcpu->arch.debug_save_restore) > >>>>> + return; > >>>>> + > >>>>> + /* Restore Host Context. Disable all debug events First */ > >>>>> + mtspr(SPRN_DBCR0, 0x0); > >>>>> + /* Disable pending debug event by Clearing DBSR */ > >>>>> + mtspr(SPRN_DBSR, mfspr(SPRN_DBSR)); > >>>>> + > >>>>> + mtspr(SPRN_DBCR1, vcpu->arch.host_dbg_reg.dbcr1); > >>>>> + mtspr(SPRN_DBCR2, vcpu->arch.host_dbg_reg.dbcr2); #ifdef > >>>>> +CONFIG_KVM_E500MC > >>>>> + mtspr(SPRN_DBCR4, vcpu->arch.host_dbg_reg.dbcr4); #endif > >>>>> + mtspr(SPRN_IAC1, vcpu->arch.host_dbg_reg.iac[0]); > >>>>> + mtspr(SPRN_IAC2, vcpu->arch.host_dbg_reg.iac[1]); #if > >>>>> +CONFIG_PPC_ADV_DEBUG_IACS> 2 > >>>>> + mtspr(SPRN_IAC3, vcpu->arch.host_dbg_reg.iac[2]); > >>>>> + mtspr(SPRN_IAC4, vcpu->arch.host_dbg_reg.iac[3]); #endif > >>>>> + mtspr(SPRN_DAC1, vcpu->arch.host_dbg_reg.dac[0]); > >>>>> + mtspr(SPRN_DAC2, vcpu->arch.host_dbg_reg.dac[1]); > >>>>> + > >>>>> + /* Enable debug events after all other debug registers restored */ > >>>>> + mtspr(SPRN_DBCR0, vcpu->arch.host_dbg_reg.dbcr0); > >>>> How does the normal debug register switching code work in Linux? > >>>> Can't we just reuse that? Or rely on it to restore working state > >>>> when another process gets scheduled in? > >>> Good point, I can see debug registers loading in function > >>> __switch_to()- > >>> switch_booke_debug_regs() in file arch/powerpc/kernel/process.c. > >>> So as long as assume that host will not use debug resources we can > >>> rely on > >> this restore. But I am not sure that this is a fare assumption. As > >> Scott earlier mentioned someone can use debug resource for kernel debugging > also. > >> > >> Someone in the kernel can also use floating point registers. But then > >> it's his responsibility to clean up the mess he leaves behind. > > I am neither convinced by what you said and nor even have much reason > > to oppose :) > > > > Scott, > > I remember you mentioned that host can use debug resources, you comment on > this ? > > > >>>>> + > >>>>> + /* Host debug register are restored */ > >>>>> + vcpu->arch.debug_save_restore = false; } > >>>>> + > >>>>> +static void kvmppc_booke_vcpu_load_debug_regs(struct kvm_vcpu > >>>>> +*vcpu) { > >>>>> + /* > >>>>> + * Check whether guest still need debug resource, if not then there > >>>>> + * is no need to resotre guest context. > >>>> restore > >>>> > >>>>> + */ > >>>>> + if (!vcpu->arch.shadow_dbg_reg.dbcr0) > >>>>> + return; > >>>> Are we guaranteed that debugging is disabled here? > >>> Ah, I should be clearing the hw DBCR0 and DBSR. > >>> > >>>> We don't want to get debug > >>>> exceptions that were meant for some other process. > >>>> > >>>>> + > >>>>> + /* > >>>>> + * Save Host debug register only after restore. If host debug > >>>>> + * registers are saved and not restored then do not save again. > >>>>> + */ > >>>>> + if (!vcpu->arch.debug_save_restore) { > >>>>> + /* Save Host context */ > >>>>> + vcpu->arch.host_dbg_reg.dbcr0 = mfspr(SPRN_DBCR0); > >>>>> + vcpu->arch.host_dbg_reg.dbcr1 = mfspr(SPRN_DBCR1); > >>>>> + vcpu->arch.host_dbg_reg.dbcr2 = mfspr(SPRN_DBCR2); #ifdef > >>>>> +CONFIG_KVM_E500MC > >>>>> + vcpu->arch.host_dbg_reg.dbcr4 = mfspr(SPRN_DBCR4); #endif > >>>>> + vcpu->arch.host_dbg_reg.iac[0] = mfspr(SPRN_IAC1); > >>>>> + vcpu->arch.host_dbg_reg.iac[1] = mfspr(SPRN_IAC2); #if > >>>>> +CONFIG_PPC_ADV_DEBUG_IACS> 2 > >>>>> + vcpu->arch.host_dbg_reg.iac[2] = mfspr(SPRN_IAC3); > >>>>> + vcpu->arch.host_dbg_reg.iac[3] = mfspr(SPRN_IAC4); #endif > >>>>> + vcpu->arch.host_dbg_reg.dac[0] = mfspr(SPRN_DAC1); > >>>>> + vcpu->arch.host_dbg_reg.dac[1] = mfspr(SPRN_DAC2); > >>>>> + vcpu->arch.debug_save_restore = true; > >>>>> + } > >>>>> + > >>>>> + /* Restore Guest Context. Disable all debug events First */ > >>>>> + mtspr(SPRN_DBCR0, 0x0); > >>>>> + /* Clear h/w DBSR */ > >>>>> + mtspr(SPRN_DBSR, mfspr(SPRN_DBSR)); > >>>>> + > >>>>> + 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); #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); } > >>>>> + > >>>>> +int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu, > >>>>> + struct kvm_guest_debug *dbg) { > >>>>> + struct kvmppc_booke_debug_reg *dbg_reg; > >>>>> + int n, b = 0, w = 0; > >>>>> + const u32 bp_code[] = { > >>>>> + DBCR0_IAC1 | DBCR0_IDM, > >>>>> + DBCR0_IAC2 | DBCR0_IDM, > >>>>> + DBCR0_IAC3 | DBCR0_IDM, > >>>>> + DBCR0_IAC4 | DBCR0_IDM > >>>>> + }; > >>>>> + const u32 wp_code[] = { > >>>>> + DBCR0_DAC1W | DBCR0_IDM, > >>>>> + DBCR0_DAC2W | DBCR0_IDM, > >>>>> + DBCR0_DAC1R | DBCR0_IDM, > >>>>> + DBCR0_DAC2R | DBCR0_IDM > >>>>> + }; > >>>>> + > >>>>> + if (!(dbg->control& KVM_GUESTDBG_ENABLE)) { > >>>>> + /* Clear All debug events */ > >>>>> + vcpu->arch.shadow_dbg_reg.dbcr0 = 0; > >>>>> + vcpu->guest_debug = 0; > >>>> Ah, this is where we disable guest_debug. This needs to enable > >>>> guest_debug for the guest again, so you need to remove the DE bit > >>>> from > >> shadow_msrp here. > >>>>> + return 0; > >>>>> + } > >>>>> + > >>>>> + vcpu->guest_debug = dbg->control; > >>>>> + vcpu->arch.shadow_dbg_reg.dbcr0 = 0; > >>>>> + /* Set DBCR0_EDM in guest visible DBCR0 register. */ > >>>>> + vcpu->arch.dbg_reg.dbcr0 = DBCR0_EDM; > >>>>> + > >>>>> + if (vcpu->guest_debug& KVM_GUESTDBG_SINGLESTEP) > >>>>> + vcpu->arch.shadow_dbg_reg.dbcr0 |= DBCR0_IDM | DBCR0_IC; > >>>>> + > >>>>> + if (!(vcpu->guest_debug& KVM_GUESTDBG_USE_HW_BP)) { > >>>>> + /* Code below handles only HW breakpoints */ > >>>>> + kvmppc_booke_vcpu_load_debug_regs(vcpu); > >>>>> + return 0; > >>>>> + } > >>>>> + > >>>>> + 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. Thanks -Bharat -- 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
