* [KVMTOOL][PATCH] Handle KVM_EXIT_SYSTEM_EVENT on any VCPU
@ 2015-09-02 10:50 Mark Rutland
2015-09-03 10:24 ` Suzuki Poulose
0 siblings, 1 reply; 3+ messages in thread
From: Mark Rutland @ 2015-09-02 10:50 UTC (permalink / raw)
To: kvm; +Cc: Mark Rutland, Will Deacon, Marc Zyngier
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);
goto exit_kvm;
};
break;
--
1.9.1
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [KVMTOOL][PATCH] Handle KVM_EXIT_SYSTEM_EVENT on any VCPU
2015-09-02 10:50 [KVMTOOL][PATCH] Handle KVM_EXIT_SYSTEM_EVENT on any VCPU Mark Rutland
@ 2015-09-03 10:24 ` Suzuki Poulose
2015-09-03 10:48 ` Mark Rutland
0 siblings, 1 reply; 3+ messages in thread
From: Suzuki Poulose @ 2015-09-03 10:24 UTC (permalink / raw)
To: Mark Rutland; +Cc: kvm, Will Deacon, Marc Zyngier, suzuki.poulose
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
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [KVMTOOL][PATCH] Handle KVM_EXIT_SYSTEM_EVENT on any VCPU
2015-09-03 10:24 ` Suzuki Poulose
@ 2015-09-03 10:48 ` Mark Rutland
0 siblings, 0 replies; 3+ messages in thread
From: Mark Rutland @ 2015-09-03 10:48 UTC (permalink / raw)
To: Suzuki Poulose
Cc: kvm@vger.kernel.org, Will Deacon, Marc Zyngier, Suzuki Poulose
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.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2015-09-02 10:50 [KVMTOOL][PATCH] Handle KVM_EXIT_SYSTEM_EVENT on any VCPU Mark Rutland
2015-09-03 10:24 ` Suzuki Poulose
2015-09-03 10:48 ` Mark Rutland
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