| Message ID | 1441191044-18777-1-git-send-email-mark.rutland@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, Sep 2, 2015 at 11:50 AM, Mark Rutland <mark.rutland@arm.com> wrote: > > When VCPU #0 exits (e.g. due to KVM_EXIT_SYSTEM_EVENT), it sends > SIGKVMEXIT to all other VCPUs, waits for them to exit, then tears down > any remaining context. The signalling of SIGKVMEXIT is critical to > forcing VCPUs to shut down in response to a system event (e.g. PSCI > SYSTEM_OFF). > > VCPUs other that VCPU #0 simply exit in kvm_cpu_thread without forcing > other CPUs to shut down. Thus if a system event is taken on a VCPU other > than VCPU #0, the remaining CPUs are left online. This results in KVM > tool not exiting as expected when a system event is taken on a VCPU > other than VCPU #0 (as may happen if the guest panics). > > Fix this by signalling SIGKVMEXIT to VCPU #0 when a system event is > taken on other CPUs, so that it may tear things down as usual. > > Signed-off-by: Mark Rutland <mark.rutland@arm.com> > Cc: Will Deacon <will.deacon@arm.com> > Cc: Marc Zyngier <marc.zyngier@arm.com> > --- > kvm-cpu.c | 15 +++++++++++---- > 1 file changed, 11 insertions(+), 4 deletions(-) > > diff --git a/kvm-cpu.c b/kvm-cpu.c > index 5d90664..f47e3db 100644 > --- a/kvm-cpu.c > +++ b/kvm-cpu.c > @@ -166,13 +166,20 @@ int kvm_cpu__start(struct kvm_cpu *cpu) > * treat all system events as shutdown request. > */ > switch (cpu->kvm_run->system_event.type) { > - case KVM_SYSTEM_EVENT_RESET: > - /* Fall through for now */ > - case KVM_SYSTEM_EVENT_SHUTDOWN: > - goto exit_kvm; > default: > pr_warning("unknown system event type %d", > cpu->kvm_run->system_event.type); > + /* fall through for now */ > + case KVM_SYSTEM_EVENT_RESET: > + /* Fall through for now */ > + case KVM_SYSTEM_EVENT_SHUTDOWN: > + /* > + * Ensure that VCPU #0 tears everything down if > + * the event was taken on a different VCPU. > + */ > + if (cpu->cpu_id != 0) > + pthread_kill(cpu->kvm->cpus[0]->thread, > + SIGKVMEXIT); Could we use kvm_cpu__reboot() instead ? That sends SIGKVMEXIT to all the VCPUs, and is used by the other paths which trigger a reboot/shutdown. Suzuki -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, Sep 03, 2015 at 11:24:29AM +0100, Suzuki Poulose wrote: > On Wed, Sep 2, 2015 at 11:50 AM, Mark Rutland <mark.rutland@arm.com> wrote: > > > > When VCPU #0 exits (e.g. due to KVM_EXIT_SYSTEM_EVENT), it sends > > SIGKVMEXIT to all other VCPUs, waits for them to exit, then tears down > > any remaining context. The signalling of SIGKVMEXIT is critical to > > forcing VCPUs to shut down in response to a system event (e.g. PSCI > > SYSTEM_OFF). > > > > VCPUs other that VCPU #0 simply exit in kvm_cpu_thread without forcing > > other CPUs to shut down. Thus if a system event is taken on a VCPU other > > than VCPU #0, the remaining CPUs are left online. This results in KVM > > tool not exiting as expected when a system event is taken on a VCPU > > other than VCPU #0 (as may happen if the guest panics). > > > > Fix this by signalling SIGKVMEXIT to VCPU #0 when a system event is > > taken on other CPUs, so that it may tear things down as usual. > > > > Signed-off-by: Mark Rutland <mark.rutland@arm.com> > > Cc: Will Deacon <will.deacon@arm.com> > > Cc: Marc Zyngier <marc.zyngier@arm.com> > > --- > > kvm-cpu.c | 15 +++++++++++---- > > 1 file changed, 11 insertions(+), 4 deletions(-) > > > > diff --git a/kvm-cpu.c b/kvm-cpu.c > > index 5d90664..f47e3db 100644 > > --- a/kvm-cpu.c > > +++ b/kvm-cpu.c > > @@ -166,13 +166,20 @@ int kvm_cpu__start(struct kvm_cpu *cpu) > > * treat all system events as shutdown request. > > */ > > switch (cpu->kvm_run->system_event.type) { > > - case KVM_SYSTEM_EVENT_RESET: > > - /* Fall through for now */ > > - case KVM_SYSTEM_EVENT_SHUTDOWN: > > - goto exit_kvm; > > default: > > pr_warning("unknown system event type %d", > > cpu->kvm_run->system_event.type); > > + /* fall through for now */ > > + case KVM_SYSTEM_EVENT_RESET: > > + /* Fall through for now */ > > + case KVM_SYSTEM_EVENT_SHUTDOWN: > > + /* > > + * Ensure that VCPU #0 tears everything down if > > + * the event was taken on a different VCPU. > > + */ > > + if (cpu->cpu_id != 0) > > + pthread_kill(cpu->kvm->cpus[0]->thread, > > + SIGKVMEXIT); > > Could we use kvm_cpu__reboot() instead ? > > That sends SIGKVMEXIT to all the VCPUs, and is used by the other > paths which trigger a reboot/shutdown. Sure; I'll spin a v2 with that and an updated comment. Thanks, Mark. -- To unsubscribe from this list: send the line "unsubscribe kvm" 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/kvm-cpu.c b/kvm-cpu.c index 5d90664..f47e3db 100644 --- a/kvm-cpu.c +++ b/kvm-cpu.c @@ -166,13 +166,20 @@ int kvm_cpu__start(struct kvm_cpu *cpu) * treat all system events as shutdown request. */ switch (cpu->kvm_run->system_event.type) { - case KVM_SYSTEM_EVENT_RESET: - /* Fall through for now */ - case KVM_SYSTEM_EVENT_SHUTDOWN: - goto exit_kvm; default: pr_warning("unknown system event type %d", cpu->kvm_run->system_event.type); + /* fall through for now */ + case KVM_SYSTEM_EVENT_RESET: + /* Fall through for now */ + case KVM_SYSTEM_EVENT_SHUTDOWN: + /* + * Ensure that VCPU #0 tears everything down if + * the event was taken on a different VCPU. + */ + if (cpu->cpu_id != 0) + pthread_kill(cpu->kvm->cpus[0]->thread, + SIGKVMEXIT); goto exit_kvm; }; break;
When VCPU #0 exits (e.g. due to KVM_EXIT_SYSTEM_EVENT), it sends SIGKVMEXIT to all other VCPUs, waits for them to exit, then tears down any remaining context. The signalling of SIGKVMEXIT is critical to forcing VCPUs to shut down in response to a system event (e.g. PSCI SYSTEM_OFF). VCPUs other that VCPU #0 simply exit in kvm_cpu_thread without forcing other CPUs to shut down. Thus if a system event is taken on a VCPU other than VCPU #0, the remaining CPUs are left online. This results in KVM tool not exiting as expected when a system event is taken on a VCPU other than VCPU #0 (as may happen if the guest panics). Fix this by signalling SIGKVMEXIT to VCPU #0 when a system event is taken on other CPUs, so that it may tear things down as usual. Signed-off-by: Mark Rutland <mark.rutland@arm.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Marc Zyngier <marc.zyngier@arm.com> --- kvm-cpu.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-)