On 24.06.2013, at 13:22, Bhushan Bharat-R65777 wrote: > > >> -----Original Message----- >> From: Alexander Graf [mailto:agraf@xxxxxxx] >> Sent: Monday, June 24, 2013 4:13 PM >> To: Bhushan Bharat-R65777 >> Cc: kvm-ppc@xxxxxxxxxxxxxxx; kvm@xxxxxxxxxxxxxxx; Wood Scott-B07421; >> tiejun.chen@xxxxxxxxxxxxx; Bhushan Bharat-R65777 >> Subject: Re: [PATCH 6/6 v5] KVM: PPC: Add userspace debug stub support >> >> >> On 24.06.2013, at 11:08, Bharat Bhushan wrote: >> >>> 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. >>> >>> This is how we save/restore debug register context when switching >>> between guest, userspace and kernel user-process: >>> >>> When QEMU is running >>> -> thread->debug_reg == QEMU debug register context. >>> -> Kernel will handle switching the debug register on context switch. >>> -> no vcpu_load() called >>> >>> QEMU makes ioctls (except RUN) >>> -> This will call vcpu_load() >>> -> should not change context. >>> -> Some ioctls can change vcpu debug register, context saved in >>> -> vcpu->debug_regs >>> >>> QEMU Makes RUN ioctl >>> -> Save thread->debug_reg on STACK >>> -> Store thread->debug_reg == vcpu->debug_reg load thread->debug_reg >>> -> RUN VCPU ( So thread points to vcpu context ) >>> >>> Context switch happens When VCPU running >>> -> makes vcpu_load() should not load any context kernel loads the vcpu >>> -> context as thread->debug_regs points to vcpu context. >>> >>> On heavyweight_exit >>> -> Load the context saved on stack in thread->debug_reg >>> >>> Currently we do not support debug resource emulation to guest, On >>> debug exception, always exit to user space irrespective of user space >>> is expecting the debug exception or not. If this is unexpected >>> exception (breakpoint/watchpoint event not set by >>> userspace) then let us leave the action on user space. This is similar >>> to what it was before, only thing is that now we have proper exit >>> state available to user space. >>> >>> Signed-off-by: Bharat Bhushan <bharat.bhushan@xxxxxxxxxxxxx> >>> --- >>> arch/powerpc/include/asm/kvm_host.h | 3 + >>> arch/powerpc/include/uapi/asm/kvm.h | 1 + >>> arch/powerpc/kvm/booke.c | 233 ++++++++++++++++++++++++++++++++--- >>> arch/powerpc/kvm/booke.h | 5 + >>> 4 files changed, 224 insertions(+), 18 deletions(-) >>> >>> diff --git a/arch/powerpc/include/asm/kvm_host.h >>> b/arch/powerpc/include/asm/kvm_host.h >>> index 838a577..aeb490d 100644 >>> --- a/arch/powerpc/include/asm/kvm_host.h >>> +++ b/arch/powerpc/include/asm/kvm_host.h >>> @@ -524,7 +524,10 @@ struct kvm_vcpu_arch { >>> u32 eptcfg; >>> u32 epr; >>> u32 crit_save; >>> + /* guest debug registers*/ >>> struct debug_reg dbg_reg; >>> + /* hardware visible debug registers when in guest state */ >>> + struct debug_reg shadow_dbg_reg; >>> #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 ded0607..f5077c2 100644 >>> --- a/arch/powerpc/include/uapi/asm/kvm.h >>> +++ b/arch/powerpc/include/uapi/asm/kvm.h >>> @@ -27,6 +27,7 @@ >>> #define __KVM_HAVE_PPC_SMT >>> #define __KVM_HAVE_IRQCHIP >>> #define __KVM_HAVE_IRQ_LINE >>> +#define __KVM_HAVE_GUEST_DEBUG >>> >>> struct kvm_regs { >>> __u64 pc; >>> diff --git a/arch/powerpc/kvm/booke.c b/arch/powerpc/kvm/booke.c index >>> 3e9fc1d..8be3502 100644 >>> --- a/arch/powerpc/kvm/booke.c >>> +++ b/arch/powerpc/kvm/booke.c >>> @@ -133,6 +133,29 @@ 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. >>> + */ >>> + vcpu->arch.shared->msr |= MSR_DE; >>> +#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 +173,7 @@ 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, @@ >>> -655,6 +679,7 @@ int kvmppc_core_check_requests(struct kvm_vcpu *vcpu) >>> int kvmppc_vcpu_run(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu) { >>> int ret, s; >>> + struct thread_struct thread; >>> #ifdef CONFIG_PPC_FPU >>> unsigned int fpscr; >>> int fpexc_mode; >>> @@ -698,12 +723,21 @@ int kvmppc_vcpu_run(struct kvm_run *kvm_run, >>> struct kvm_vcpu *vcpu) >>> >>> kvmppc_load_guest_fp(vcpu); >>> #endif >>> + /* Switch to guest debug context */ >>> + thread.debug = vcpu->arch.shadow_dbg_reg; >>> + switch_booke_debug_regs(&thread); >>> + thread.debug = current->thread.debug; >>> + current->thread.debug = vcpu->arch.shadow_dbg_reg; >>> >>> ret = __kvmppc_vcpu_run(kvm_run, vcpu); >>> >>> /* No need for kvm_guest_exit. It's done in handle_exit. >>> We also get here with interrupts enabled. */ >>> >>> + /* Switch back to user space debug context */ >>> + switch_booke_debug_regs(&thread); >>> + current->thread.debug = thread.debug; >>> + >>> #ifdef CONFIG_PPC_FPU >>> kvmppc_save_guest_fp(vcpu); >>> >>> @@ -759,6 +793,30 @@ 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) { >>> + struct debug_reg *dbg_reg = &(vcpu->arch.shadow_dbg_reg); >>> + u32 dbsr = vcpu->arch.dbsr; >>> + >>> + 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 = dbg_reg->dac1; >>> + else if (dbsr & (DBSR_DAC2R | DBSR_DAC2W)) >>> + run->debug.arch.address = dbg_reg->dac2; >>> + } >>> + >>> + return RESUME_HOST; >>> +} >>> + >>> static void kvmppc_fill_pt_regs(struct pt_regs *regs) { >>> ulong r1, ip, msr, lr; >>> @@ -819,6 +877,11 @@ static void kvmppc_restart_interrupt(struct kvm_vcpu >> *vcpu, >>> case BOOKE_INTERRUPT_CRITICAL: >>> unknown_exception(®s); >>> break; >>> + case BOOKE_INTERRUPT_DEBUG: >>> + /* Save DBSR before preemption is enabled */ >>> + vcpu->arch.dbsr = mfspr(SPRN_DBSR); >>> + kvmppc_clear_dbsr(); >>> + break; >>> } >>> } >>> >>> @@ -1118,18 +1181,10 @@ 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; >>> } >>> >>> @@ -1180,7 +1235,7 @@ 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 >>> @@ -1557,12 +1612,6 @@ 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; >>> @@ -1668,6 +1717,151 @@ void kvmppc_decrementer_func(unsigned long data) >>> kvmppc_set_tsr_bits(vcpu, TSR_DIS); >>> } >>> >>> +static int kvmppc_booke_add_breakpoint(struct debug_reg *dbg_reg, >>> + uint64_t addr, int index) >>> +{ >>> + switch (index) { >>> + case 0: >>> + dbg_reg->dbcr0 |= DBCR0_IAC1; >>> + dbg_reg->iac1 = addr; >>> + break; >>> + case 1: >>> + dbg_reg->dbcr0 |= DBCR0_IAC2; >>> + dbg_reg->iac2 = addr; >>> + break; >>> +#if CONFIG_PPC_ADV_DEBUG_IACS > 2 >>> + case 2: >>> + dbg_reg->dbcr0 |= DBCR0_IAC3; >>> + dbg_reg->iac3 = addr; >>> + break; >>> + case 3: >>> + dbg_reg->dbcr0 |= DBCR0_IAC4; >>> + dbg_reg->iac4 = addr; >>> + break; >>> +#endif >>> + default: >>> + return -EINVAL; >>> + } >>> + >>> + dbg_reg->dbcr0 |= DBCR0_IDM; >>> + return 0; >>> +} >>> + >>> +static int kvmppc_booke_add_watchpoint(struct debug_reg *dbg_reg, uint64_t >> addr, >>> + int type, int index) >>> +{ >>> + switch (index) { >>> + case 0: >>> + if (type & KVMPPC_DEBUG_WATCH_READ) >>> + dbg_reg->dbcr0 |= DBCR0_DAC1R; >>> + if (type & KVMPPC_DEBUG_WATCH_WRITE) >>> + dbg_reg->dbcr0 |= DBCR0_DAC1W; >>> + dbg_reg->dac1 = addr; >>> + break; >>> + case 1: >>> + if (type & KVMPPC_DEBUG_WATCH_READ) >>> + dbg_reg->dbcr0 |= DBCR0_DAC2R; >>> + if (type & KVMPPC_DEBUG_WATCH_WRITE) >>> + dbg_reg->dbcr0 |= DBCR0_DAC2W; >>> + dbg_reg->dac2 = addr; >>> + break; >>> + default: >>> + return -EINVAL; >>> + } >>> + >>> + dbg_reg->dbcr0 |= DBCR0_IDM; >>> + return 0; >>> +} >>> + >>> +#ifdef CONFIG_KVM_BOOKE_HV >>> +void kvm_guest_may_change_msr_de(struct kvm_vcpu *vcpu, bool >>> +may_change) { >>> + if (may_change) >>> + /* Allow guest to change MSR.DE */ >>> + vcpu->arch.shadow_msrp &= ~MSRP_DEP; >>> + else >>> + /* Don't allow guest to change MSR.DE */ >>> + vcpu->arch.shadow_msrp |= MSRP_DEP; >>> + >>> +} >>> +#endif >> >> Could you please provide this function regardless of CONFIG_KVM_BOOKE_HV? For >> PR, just save a bool away somewhere and emulate the same behavior (guest may not >> modify MSR.DE). > > You mean modify kvmppc_set_msr() (kvmppc_vcpu_sync_debug()) to consider this bool to change/not_change msr.de? Yep :). Alex -- 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
