| Message ID | 1458658428-19566-1-git-send-email-lvivier@redhat.com |
|---|---|
| State | Superseded |
| Headers | show |
Ping? On 22/03/2016 15:53, Laurent Vivier wrote: > Until now, when we connect gdb to the QEMU gdb-server, the > single-step mode is not managed. > > This patch adds this, only for kvm-pr: > > If KVM_GUESTDBG_SINGLESTEP is set, we enable single-step trace bit in the > MSR (MSR_SE) just before the __kvmppc_vcpu_run(), and disable it just after. > In kvmppc_handle_exit_pr, instead of routing the interrupt to > the guest, we return to host, with KVM_EXIT_DEBUG reason. > > Signed-off-by: Laurent Vivier <lvivier@redhat.com> > --- > arch/powerpc/kvm/book3s_pr.c | 31 +++++++++++++++++++++++++++++-- > 1 file changed, 29 insertions(+), 2 deletions(-) > > diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c > index 95bceca..e6896f4 100644 > --- a/arch/powerpc/kvm/book3s_pr.c > +++ b/arch/powerpc/kvm/book3s_pr.c > @@ -882,6 +882,24 @@ void kvmppc_set_fscr(struct kvm_vcpu *vcpu, u64 fscr) > } > #endif > > +static void kvmppc_setup_debug(struct kvm_vcpu *vcpu) > +{ > + if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) { > + u64 msr = kvmppc_get_msr(vcpu); > + > + kvmppc_set_msr(vcpu, msr | MSR_SE); > + } > +} > + > +static void kvmppc_clear_debug(struct kvm_vcpu *vcpu) > +{ > + if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) { > + u64 msr = kvmppc_get_msr(vcpu); > + > + kvmppc_set_msr(vcpu, msr & ~MSR_SE); > + } > +} > + > int kvmppc_handle_exit_pr(struct kvm_run *run, struct kvm_vcpu *vcpu, > unsigned int exit_nr) > { > @@ -1208,8 +1226,13 @@ program_interrupt: > #endif > case BOOK3S_INTERRUPT_MACHINE_CHECK: > case BOOK3S_INTERRUPT_TRACE: > - kvmppc_book3s_queue_irqprio(vcpu, exit_nr); > - r = RESUME_GUEST; > + if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) { > + run->exit_reason = KVM_EXIT_DEBUG; > + r = RESUME_HOST; > + } else { > + kvmppc_book3s_queue_irqprio(vcpu, exit_nr); > + r = RESUME_GUEST; > + } > break; > default: > { > @@ -1479,6 +1502,8 @@ static int kvmppc_vcpu_run_pr(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu) > goto out; > } > > + kvmppc_setup_debug(vcpu); > + > /* > * Interrupts could be timers for the guest which we have to inject > * again, so let's postpone them until we're in the guest and if we > @@ -1501,6 +1526,8 @@ static int kvmppc_vcpu_run_pr(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu) > > ret = __kvmppc_vcpu_run(kvm_run, vcpu); > > + kvmppc_clear_debug(vcpu); > + > /* No need for kvm_guest_exit. It's done in handle_exit. > We also get here with interrupts enabled. */ > > -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 22.03.2016 15:53, Laurent Vivier wrote: > Until now, when we connect gdb to the QEMU gdb-server, the > single-step mode is not managed. > > This patch adds this, only for kvm-pr: > > If KVM_GUESTDBG_SINGLESTEP is set, we enable single-step trace bit in the > MSR (MSR_SE) just before the __kvmppc_vcpu_run(), and disable it just after. > In kvmppc_handle_exit_pr, instead of routing the interrupt to > the guest, we return to host, with KVM_EXIT_DEBUG reason. > > Signed-off-by: Laurent Vivier <lvivier@redhat.com> > --- > arch/powerpc/kvm/book3s_pr.c | 31 +++++++++++++++++++++++++++++-- > 1 file changed, 29 insertions(+), 2 deletions(-) > > diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c > index 95bceca..e6896f4 100644 > --- a/arch/powerpc/kvm/book3s_pr.c > +++ b/arch/powerpc/kvm/book3s_pr.c > @@ -882,6 +882,24 @@ void kvmppc_set_fscr(struct kvm_vcpu *vcpu, u64 fscr) > } > #endif > > +static void kvmppc_setup_debug(struct kvm_vcpu *vcpu) > +{ > + if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) { > + u64 msr = kvmppc_get_msr(vcpu); > + > + kvmppc_set_msr(vcpu, msr | MSR_SE); > + } > +} > + > +static void kvmppc_clear_debug(struct kvm_vcpu *vcpu) > +{ > + if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) { > + u64 msr = kvmppc_get_msr(vcpu); > + > + kvmppc_set_msr(vcpu, msr & ~MSR_SE); > + } > +} > + > int kvmppc_handle_exit_pr(struct kvm_run *run, struct kvm_vcpu *vcpu, > unsigned int exit_nr) > { > @@ -1208,8 +1226,13 @@ program_interrupt: > #endif > case BOOK3S_INTERRUPT_MACHINE_CHECK: > case BOOK3S_INTERRUPT_TRACE: > - kvmppc_book3s_queue_irqprio(vcpu, exit_nr); > - r = RESUME_GUEST; > + if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) { > + run->exit_reason = KVM_EXIT_DEBUG; > + r = RESUME_HOST; > + } else { > + kvmppc_book3s_queue_irqprio(vcpu, exit_nr); > + r = RESUME_GUEST; > + } Should the new code rather be limited to the BOOK3S_INTERRUPT_TRACE case only? I mean, this way, you never can deliver a machine check interrupt to the guest if singlestep debugging is enabled on the host, can you? Thomas -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 08/04/2016 08:23, Thomas Huth wrote: > On 22.03.2016 15:53, Laurent Vivier wrote: >> Until now, when we connect gdb to the QEMU gdb-server, the >> single-step mode is not managed. >> >> This patch adds this, only for kvm-pr: >> >> If KVM_GUESTDBG_SINGLESTEP is set, we enable single-step trace bit in the >> MSR (MSR_SE) just before the __kvmppc_vcpu_run(), and disable it just after. >> In kvmppc_handle_exit_pr, instead of routing the interrupt to >> the guest, we return to host, with KVM_EXIT_DEBUG reason. >> >> Signed-off-by: Laurent Vivier <lvivier@redhat.com> >> --- >> arch/powerpc/kvm/book3s_pr.c | 31 +++++++++++++++++++++++++++++-- >> 1 file changed, 29 insertions(+), 2 deletions(-) >> >> diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c >> index 95bceca..e6896f4 100644 >> --- a/arch/powerpc/kvm/book3s_pr.c >> +++ b/arch/powerpc/kvm/book3s_pr.c >> @@ -882,6 +882,24 @@ void kvmppc_set_fscr(struct kvm_vcpu *vcpu, u64 fscr) >> } >> #endif >> >> +static void kvmppc_setup_debug(struct kvm_vcpu *vcpu) >> +{ >> + if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) { >> + u64 msr = kvmppc_get_msr(vcpu); >> + >> + kvmppc_set_msr(vcpu, msr | MSR_SE); >> + } >> +} >> + >> +static void kvmppc_clear_debug(struct kvm_vcpu *vcpu) >> +{ >> + if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) { >> + u64 msr = kvmppc_get_msr(vcpu); >> + >> + kvmppc_set_msr(vcpu, msr & ~MSR_SE); >> + } >> +} >> + >> int kvmppc_handle_exit_pr(struct kvm_run *run, struct kvm_vcpu *vcpu, >> unsigned int exit_nr) >> { >> @@ -1208,8 +1226,13 @@ program_interrupt: >> #endif >> case BOOK3S_INTERRUPT_MACHINE_CHECK: >> case BOOK3S_INTERRUPT_TRACE: >> - kvmppc_book3s_queue_irqprio(vcpu, exit_nr); >> - r = RESUME_GUEST; >> + if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) { >> + run->exit_reason = KVM_EXIT_DEBUG; >> + r = RESUME_HOST; >> + } else { >> + kvmppc_book3s_queue_irqprio(vcpu, exit_nr); >> + r = RESUME_GUEST; >> + } > > Should the new code rather be limited to the BOOK3S_INTERRUPT_TRACE case > only? I mean, this way, you never can deliver a machine check interrupt > to the guest if singlestep debugging is enabled on the host, can you? You're right but it adds complexity and it would be only useful to single-step the single-step mode of the guest. It's hard to imagine a developer single-stepping the guest kernel while he is single-stepping a user application in the guest. It's why I have completely by-passed this case. Thanks, Laurent -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 08.04.2016 08:58, Laurent Vivier wrote: > > > On 08/04/2016 08:23, Thomas Huth wrote: >> On 22.03.2016 15:53, Laurent Vivier wrote: >>> Until now, when we connect gdb to the QEMU gdb-server, the >>> single-step mode is not managed. >>> >>> This patch adds this, only for kvm-pr: >>> >>> If KVM_GUESTDBG_SINGLESTEP is set, we enable single-step trace bit in the >>> MSR (MSR_SE) just before the __kvmppc_vcpu_run(), and disable it just after. >>> In kvmppc_handle_exit_pr, instead of routing the interrupt to >>> the guest, we return to host, with KVM_EXIT_DEBUG reason. >>> >>> Signed-off-by: Laurent Vivier <lvivier@redhat.com> >>> --- >>> arch/powerpc/kvm/book3s_pr.c | 31 +++++++++++++++++++++++++++++-- >>> 1 file changed, 29 insertions(+), 2 deletions(-) >>> >>> diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c >>> index 95bceca..e6896f4 100644 >>> --- a/arch/powerpc/kvm/book3s_pr.c >>> +++ b/arch/powerpc/kvm/book3s_pr.c >>> @@ -882,6 +882,24 @@ void kvmppc_set_fscr(struct kvm_vcpu *vcpu, u64 fscr) >>> } >>> #endif >>> >>> +static void kvmppc_setup_debug(struct kvm_vcpu *vcpu) >>> +{ >>> + if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) { >>> + u64 msr = kvmppc_get_msr(vcpu); >>> + >>> + kvmppc_set_msr(vcpu, msr | MSR_SE); >>> + } >>> +} >>> + >>> +static void kvmppc_clear_debug(struct kvm_vcpu *vcpu) >>> +{ >>> + if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) { >>> + u64 msr = kvmppc_get_msr(vcpu); >>> + >>> + kvmppc_set_msr(vcpu, msr & ~MSR_SE); >>> + } >>> +} >>> + >>> int kvmppc_handle_exit_pr(struct kvm_run *run, struct kvm_vcpu *vcpu, >>> unsigned int exit_nr) >>> { >>> @@ -1208,8 +1226,13 @@ program_interrupt: >>> #endif >>> case BOOK3S_INTERRUPT_MACHINE_CHECK: >>> case BOOK3S_INTERRUPT_TRACE: >>> - kvmppc_book3s_queue_irqprio(vcpu, exit_nr); >>> - r = RESUME_GUEST; >>> + if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) { >>> + run->exit_reason = KVM_EXIT_DEBUG; >>> + r = RESUME_HOST; >>> + } else { >>> + kvmppc_book3s_queue_irqprio(vcpu, exit_nr); >>> + r = RESUME_GUEST; >>> + } >> >> Should the new code rather be limited to the BOOK3S_INTERRUPT_TRACE case >> only? I mean, this way, you never can deliver a machine check interrupt >> to the guest if singlestep debugging is enabled on the host, can you? > > You're right but it adds complexity and it would be only useful to > single-step the single-step mode of the guest. > > It's hard to imagine a developer single-stepping the guest kernel while > he is single-stepping a user application in the guest. Hmm, not sure whether you've got me right ;-) I rather meant: What happens when a machine check is supposed to happen in the guest while single stepping is enabled at the host level? IMHO it would be better to shape the code like this: case BOOK3S_INTERRUPT_MACHINE_CHECK: kvmppc_book3s_queue_irqprio(vcpu, exit_nr); r = RESUME_GUEST; break; case BOOK3S_INTERRUPT_TRACE: if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) { run->exit_reason = KVM_EXIT_DEBUG; r = RESUME_HOST; } else { kvmppc_book3s_queue_irqprio(vcpu, exit_nr); r = RESUME_GUEST; } That means, split the two cases, to keep the old behavior for the MACHINE_CHECK case. That's also not too much of additional complexity, is it? Thomas -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 08/04/2016 09:44, Thomas Huth wrote: > On 08.04.2016 08:58, Laurent Vivier wrote: >> >> >> On 08/04/2016 08:23, Thomas Huth wrote: >>> On 22.03.2016 15:53, Laurent Vivier wrote: >>>> Until now, when we connect gdb to the QEMU gdb-server, the >>>> single-step mode is not managed. >>>> >>>> This patch adds this, only for kvm-pr: >>>> >>>> If KVM_GUESTDBG_SINGLESTEP is set, we enable single-step trace bit in the >>>> MSR (MSR_SE) just before the __kvmppc_vcpu_run(), and disable it just after. >>>> In kvmppc_handle_exit_pr, instead of routing the interrupt to >>>> the guest, we return to host, with KVM_EXIT_DEBUG reason. >>>> >>>> Signed-off-by: Laurent Vivier <lvivier@redhat.com> >>>> --- >>>> arch/powerpc/kvm/book3s_pr.c | 31 +++++++++++++++++++++++++++++-- >>>> 1 file changed, 29 insertions(+), 2 deletions(-) >>>> >>>> diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c >>>> index 95bceca..e6896f4 100644 >>>> --- a/arch/powerpc/kvm/book3s_pr.c >>>> +++ b/arch/powerpc/kvm/book3s_pr.c >>>> @@ -882,6 +882,24 @@ void kvmppc_set_fscr(struct kvm_vcpu *vcpu, u64 fscr) >>>> } >>>> #endif >>>> >>>> +static void kvmppc_setup_debug(struct kvm_vcpu *vcpu) >>>> +{ >>>> + if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) { >>>> + u64 msr = kvmppc_get_msr(vcpu); >>>> + >>>> + kvmppc_set_msr(vcpu, msr | MSR_SE); >>>> + } >>>> +} >>>> + >>>> +static void kvmppc_clear_debug(struct kvm_vcpu *vcpu) >>>> +{ >>>> + if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) { >>>> + u64 msr = kvmppc_get_msr(vcpu); >>>> + >>>> + kvmppc_set_msr(vcpu, msr & ~MSR_SE); >>>> + } >>>> +} >>>> + >>>> int kvmppc_handle_exit_pr(struct kvm_run *run, struct kvm_vcpu *vcpu, >>>> unsigned int exit_nr) >>>> { >>>> @@ -1208,8 +1226,13 @@ program_interrupt: >>>> #endif >>>> case BOOK3S_INTERRUPT_MACHINE_CHECK: >>>> case BOOK3S_INTERRUPT_TRACE: >>>> - kvmppc_book3s_queue_irqprio(vcpu, exit_nr); >>>> - r = RESUME_GUEST; >>>> + if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) { >>>> + run->exit_reason = KVM_EXIT_DEBUG; >>>> + r = RESUME_HOST; >>>> + } else { >>>> + kvmppc_book3s_queue_irqprio(vcpu, exit_nr); >>>> + r = RESUME_GUEST; >>>> + } >>> >>> Should the new code rather be limited to the BOOK3S_INTERRUPT_TRACE case >>> only? I mean, this way, you never can deliver a machine check interrupt >>> to the guest if singlestep debugging is enabled on the host, can you? >> >> You're right but it adds complexity and it would be only useful to >> single-step the single-step mode of the guest. >> >> It's hard to imagine a developer single-stepping the guest kernel while >> he is single-stepping a user application in the guest. > > Hmm, not sure whether you've got me right ;-) I rather meant: What Yes, I've missed what you mean. :( Thank you to try again :) > happens when a machine check is supposed to happen in the guest while > single stepping is enabled at the host level? IMHO it would be better to > shape the code like this: > > case BOOK3S_INTERRUPT_MACHINE_CHECK: > kvmppc_book3s_queue_irqprio(vcpu, exit_nr); > r = RESUME_GUEST; > break; > case BOOK3S_INTERRUPT_TRACE: > if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) { > run->exit_reason = KVM_EXIT_DEBUG; > r = RESUME_HOST; > } else { > kvmppc_book3s_queue_irqprio(vcpu, exit_nr); > r = RESUME_GUEST; > } > > That means, split the two cases, to keep the old behavior for the > MACHINE_CHECK case. That's also not too much of additional complexity, > is it? Yes, you're right. Thanks, Laurent -- To unsubscribe from this list: send the line "unsubscribe kvm-ppc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c index 95bceca..e6896f4 100644 --- a/arch/powerpc/kvm/book3s_pr.c +++ b/arch/powerpc/kvm/book3s_pr.c @@ -882,6 +882,24 @@ void kvmppc_set_fscr(struct kvm_vcpu *vcpu, u64 fscr) } #endif +static void kvmppc_setup_debug(struct kvm_vcpu *vcpu) +{ + if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) { + u64 msr = kvmppc_get_msr(vcpu); + + kvmppc_set_msr(vcpu, msr | MSR_SE); + } +} + +static void kvmppc_clear_debug(struct kvm_vcpu *vcpu) +{ + if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) { + u64 msr = kvmppc_get_msr(vcpu); + + kvmppc_set_msr(vcpu, msr & ~MSR_SE); + } +} + int kvmppc_handle_exit_pr(struct kvm_run *run, struct kvm_vcpu *vcpu, unsigned int exit_nr) { @@ -1208,8 +1226,13 @@ program_interrupt: #endif case BOOK3S_INTERRUPT_MACHINE_CHECK: case BOOK3S_INTERRUPT_TRACE: - kvmppc_book3s_queue_irqprio(vcpu, exit_nr); - r = RESUME_GUEST; + if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) { + run->exit_reason = KVM_EXIT_DEBUG; + r = RESUME_HOST; + } else { + kvmppc_book3s_queue_irqprio(vcpu, exit_nr); + r = RESUME_GUEST; + } break; default: { @@ -1479,6 +1502,8 @@ static int kvmppc_vcpu_run_pr(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu) goto out; } + kvmppc_setup_debug(vcpu); + /* * Interrupts could be timers for the guest which we have to inject * again, so let's postpone them until we're in the guest and if we @@ -1501,6 +1526,8 @@ static int kvmppc_vcpu_run_pr(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu) ret = __kvmppc_vcpu_run(kvm_run, vcpu); + kvmppc_clear_debug(vcpu); + /* No need for kvm_guest_exit. It's done in handle_exit. We also get here with interrupts enabled. */
Until now, when we connect gdb to the QEMU gdb-server, the single-step mode is not managed. This patch adds this, only for kvm-pr: If KVM_GUESTDBG_SINGLESTEP is set, we enable single-step trace bit in the MSR (MSR_SE) just before the __kvmppc_vcpu_run(), and disable it just after. In kvmppc_handle_exit_pr, instead of routing the interrupt to the guest, we return to host, with KVM_EXIT_DEBUG reason. Signed-off-by: Laurent Vivier <lvivier@redhat.com> --- arch/powerpc/kvm/book3s_pr.c | 31 +++++++++++++++++++++++++++++-- 1 file changed, 29 insertions(+), 2 deletions(-)