On 07/18/2015 11:18 AM, Christoffer Dall wrote:
> On Mon, Jul 06, 2015 at 02:49:56PM +0200, Eric Auger wrote:
>> On halt, the guest is forced to exit and prevented from being
>> re-entered. This is synchronous.
>>
>> Those two operations will be needed for IRQ forwarding setting.
>>
>> Signed-off-by: Eric Auger <eric.au...@linaro.org>
>>
>> ---
>> RFC v1 -> v2:
>> - add __maybe_unused
>>
>> RFC:
>> - rename the function and this latter becomes static
>> - remove __KVM_HAVE_ARCH_HALT_GUEST
>>
>> v4 -> v5: add arm64 support
>> - also defines __KVM_HAVE_ARCH_HALT_GUEST for arm64
>> - add pause field
>> ---
>> arch/arm/include/asm/kvm_host.h | 3 +++
>> arch/arm/kvm/arm.c | 35 ++++++++++++++++++++++++++++++++---
>> arch/arm64/include/asm/kvm_host.h | 3 +++
>> 3 files changed, 38 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/arm/include/asm/kvm_host.h
>> b/arch/arm/include/asm/kvm_host.h
>> index 304004d..899ae27 100644
>> --- a/arch/arm/include/asm/kvm_host.h
>> +++ b/arch/arm/include/asm/kvm_host.h
>> @@ -132,6 +132,9 @@ struct kvm_vcpu_arch {
>> /* vcpu power-off state */
>> bool power_off;
>>
>> + /* Don't run the guest */
>> + bool pause;
>> +
>> /* IO related fields */
>> struct kvm_decode mmio_decode;
>>
>> diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
>> index 7537e68..46d4ef6 100644
>> --- a/arch/arm/kvm/arm.c
>> +++ b/arch/arm/kvm/arm.c
>> @@ -471,11 +471,39 @@ bool kvm_arch_intc_initialized(struct kvm *kvm)
>> return vgic_initialized(kvm);
>> }
>>
>> +static void kvm_arm_halt_guest(struct kvm *kvm) __maybe_unused;
>> +static void kvm_arm_resume_guest(struct kvm *kvm) __maybe_unused;
>> +
>> +static void kvm_arm_halt_guest(struct kvm *kvm)
>> +{
>> + int i;
>> + struct kvm_vcpu *vcpu;
>> +
>> + kvm_for_each_vcpu(i, vcpu, kvm)
>> + vcpu->arch.pause = true;
>> + force_vm_exit(cpu_all_mask);
>> +}
>> +
>> +static void kvm_arm_resume_guest(struct kvm *kvm)
>> +{
>> + int i;
>> + struct kvm_vcpu *vcpu;
>> +
>> + kvm_for_each_vcpu(i, vcpu, kvm) {
>> + wait_queue_head_t *wq = kvm_arch_vcpu_wq(vcpu);
>> +
>> + vcpu->arch.pause = false;
>> + wake_up_interruptible(wq);
>> + }
>> +}
>> +
>> +
>> static void vcpu_pause(struct kvm_vcpu *vcpu)
>> {
>> wait_queue_head_t *wq = kvm_arch_vcpu_wq(vcpu);
>>
>> - wait_event_interruptible(*wq, !vcpu->arch.power_off);
>> + wait_event_interruptible(*wq, ((!vcpu->arch.power_off) &&
>> + (!vcpu->arch.pause)));
>> }
>>
>> static int kvm_vcpu_initialized(struct kvm_vcpu *vcpu)
>> @@ -525,7 +553,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu,
>> struct kvm_run *run)
>>
>> update_vttbr(vcpu->kvm);
>>
>> - if (vcpu->arch.power_off)
>> + if (vcpu->arch.power_off || vcpu->arch.pause)
>> vcpu_pause(vcpu);
>
> These two changes really make me feel like kvm_arch_vcpu_runnable()
> should be changed to check for both flags and all thes eplaces should
> check for runnable instead.
>
> To make the runnable function more robust, perhaps it should check:
>
> 1. The vcpu is neither paused nor powered off
> 2. The vcpu is not in a WFI state (vcpu->arch.wfi_request) OR there are
> pending interrupts (the current check).
>
> Then the logic would fit the name of the function, instead of being a
> specific check only called through handle_wfx.
Reading this again, I reconsider what I said in previous comment answer
and this definitively makes sense to update the runnable function. I
was/am afraid by this vcpu_block function and I need to better undertand
it - I think what I said previously is not correct - .
I will investigate that direction.
Eric
>
>>
>> /*
>> @@ -551,7 +579,8 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu,
>> struct kvm_run *run)
>> run->exit_reason = KVM_EXIT_INTR;
>> }
>>
>> - if (ret <= 0 || need_new_vmid_gen(vcpu->kvm)) {
>> + if (ret <= 0 || need_new_vmid_gen(vcpu->kvm) ||
>> + vcpu->arch.pause) {
>
> so why do we need to re-check the pause flag, but not the power_off
> flag? That is non-trivial for sure, so if it's correct, deserves a
> comment. Also see my comment on the last patch.
>
>> local_irq_enable();
>> preempt_enable();
>> kvm_vgic_sync_hwstate(vcpu);
>> diff --git a/arch/arm64/include/asm/kvm_host.h
>> b/arch/arm64/include/asm/kvm_host.h
>> index 009da6b..69e3785 100644
>> --- a/arch/arm64/include/asm/kvm_host.h
>> +++ b/arch/arm64/include/asm/kvm_host.h
>> @@ -125,6 +125,9 @@ struct kvm_vcpu_arch {
>> /* vcpu power-off state */
>> bool power_off;
>>
>> + /* Don't run the guest */
>
> Probably need to be more clear about this being an implementation
> requirement rather than being guest visible or related to any
> architectural concept.
>
>> + bool pause;
>> +
>> /* IO related fields */
>> struct kvm_decode mmio_decode;
>>
>> --
>> 1.9.1
>>
>
> Thanks,
> -Christoffer
>
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