Re: [PATCH v2] KVM: s390: Add new reset vcpu API

Cornelia Huck
2019-12-03T16:28:16Z

On Tue, 3 Dec 2019 11:20:55 -0500
Janosch Frank <frankja@linux.ibm.com> wrote:

> The architecture states that we need to reset local IRQs for all CPU
> resets. Because the old reset interface did not support the normal CPU
> reset we never did that.
>
> Now that we have a new interface, let's properly clear out local IRQs
> and let this commit be a reminder.

Well, the new interface did not appear magically, this patch introduces
it :) (The whole sentence is a bit confusing; what is this commit
supposed to remind us of?)

>
> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
> ---
> arch/s390/kvm/kvm-s390.c | 13 +++++++++++++
> include/uapi/linux/kvm.h | 4 ++++
> 2 files changed, 17 insertions(+)
>
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index d9e6bf3d54f0..602214c5616c 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -529,6 +529,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
> case KVM_CAP_S390_CMMA_MIGRATION:
> case KVM_CAP_S390_AIS:
> case KVM_CAP_S390_AIS_MIGRATION:
> + case KVM_CAP_S390_VCPU_RESETS:
> r = 1;
> break;
> case KVM_CAP_S390_HPAGE_1M:
> @@ -3287,6 +3288,13 @@ static int kvm_arch_vcpu_ioctl_set_one_reg(struct kvm_vcpu *vcpu,
> return r;
> }
>
> +static int kvm_arch_vcpu_ioctl_normal_reset(struct kvm_vcpu *vcpu)
> +{
> + kvm_clear_async_pf_completion_queue(vcpu);
> + kvm_s390_clear_local_irqs(vcpu);
> + return 0;
> +}
> +
> static int kvm_arch_vcpu_ioctl_initial_reset(struct kvm_vcpu *vcpu)
> {
> kvm_s390_vcpu_initial_reset(vcpu);
> @@ -4363,7 +4371,12 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
> r = kvm_arch_vcpu_ioctl_set_initial_psw(vcpu, psw);
> break;
> }
> + case KVM_S390_NORMAL_RESET:
> + r = kvm_arch_vcpu_ioctl_normal_reset(vcpu);
> + break;
> case KVM_S390_INITIAL_RESET:
> + /* fallthrough */
> + case KVM_S390_CLEAR_RESET:
> r = kvm_arch_vcpu_ioctl_initial_reset(vcpu);

The cover letter probably should also mention that clear reset falls
back to initial reset for now?

> break;
> case KVM_SET_ONE_REG:
> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> index 52641d8ca9e8..f4fc865775a5 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -1000,6 +1000,7 @@ struct kvm_ppc_resize_hpt {
> #define KVM_CAP_PMU_EVENT_FILTER 173
> #define KVM_CAP_ARM_IRQ_LINE_LAYOUT_2 174
> #define KVM_CAP_HYPERV_DIRECT_TLBFLUSH 175
> +#define KVM_CAP_S390_VCPU_RESETS 180
>
> #ifdef KVM_CAP_IRQ_ROUTING
>
> @@ -1461,6 +1462,9 @@ struct kvm_enc_region {
> /* Available with KVM_CAP_ARM_SVE */
> #define KVM_ARM_VCPU_FINALIZE _IOW(KVMIO, 0xc2, int)
>
> +#define KVM_S390_NORMAL_RESET _IO(KVMIO, 0xc3)
> +#define KVM_S390_CLEAR_RESET _IO(KVMIO, 0xc4)
> +
> /* Secure Encrypted Virtualization command */
> enum sev_cmd_id {
> /* Guest initialization commands */

Looks sane, but please also document the new ioctls and the new cap.