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Date: Mon, 31 Aug 2015 12:43:33 +0200
From: Christoffer Dall <christoffer.dall@...aro.org>
To: Eric Auger <eric.auger@...aro.org>
Cc: eric.auger@...com, marc.zyngier@....com, drjones@...hat.com,
linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
patches@...aro.org, pbonzini@...hat.com
Subject: Re: [PATCH v2 4/4] KVM: arm/arm64: implement
kvm_arm_[halt,resume]_guest
On Fri, Aug 07, 2015 at 06:08:33PM +0200, Eric Auger wrote:
> We introduce kvm_arm_halt_guest and resume functions. They
> will be used for IRQ forward state change.
>
> Halt is synchronous and prevents the guest from being re-entered.
> We use the same mechanism put in place for PSCI former pause,
> now renamed power_off. A new flag is introduced in arch vcpu state,
> pause, only meant to be used by those functions.
>
> Signed-off-by: Eric Auger <eric.auger@...aro.org>
>
> ---
> v1 -> v2:
> - check pause in kvm_arch_vcpu_runnable
> - we cannot use kvm_vcpu_block since this latter would exit on
> IRQ/FIQ and this is not what we want
> ---
> 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, 37 insertions(+), 4 deletions(-)
>
> diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
> index 304004d..dac85f6 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;
>
> + /* Exit and don't run the guest (internal implementation need) */
Why exit? I think it's slightly more correct to just say.
"Don't run the guest (internal implementation need)"
> + 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 cc404a8..0529b38 100644
> --- a/arch/arm/kvm/arm.c
> +++ b/arch/arm/kvm/arm.c
> @@ -348,7 +348,7 @@ int kvm_arch_vcpu_ioctl_set_mpstate(struct kvm_vcpu *vcpu,
> int kvm_arch_vcpu_runnable(struct kvm_vcpu *v)
> {
> return ((!!v->arch.irq_lines || kvm_vgic_vcpu_pending_irq(v))
> - && !v->arch.power_off);
> + && !v->arch.power_off && !v->arch.pause);
> }
>
> /* Just ensure a guest exit from a particular CPU */
> @@ -474,11 +474,38 @@ 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_sleep(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)
> @@ -528,7 +555,7 @@ 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_sleep(vcpu);
>
> /*
> @@ -556,7 +583,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
> }
>
> if (ret <= 0 || need_new_vmid_gen(vcpu->kvm) ||
> - vcpu->arch.power_off) {
> + vcpu->arch.power_off || vcpu->arch.pause) {
> local_irq_enable();
> kvm_vgic_sync_hwstate(vcpu);
> preempt_enable();
> 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 */
Can we have the same comment on the arm and arm64 version?
> + bool pause;
> +
> /* IO related fields */
> struct kvm_decode mmio_decode;
>
> --
> 1.9.1
>
Besides these commenting nits, I think this looks reasonable overall.
Reviewed-by: Christoffer Dall <christoffer.dall@...aro.org>
On the series.
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