On 10/01/2020 11.19, Janosch Frank 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 on a normal reset.
>
> Let's implement an interface for the missing normal and clear resets
> and reset all local IRQs, registers and control structures as stated
> in the architecture.
>
> Userspace might already reset the registers via the vcpu run struct,
> but as we need the interface for the interrupt clearing part anyway,
> we implement the resets fully and don't rely on userspace to reset the
> rest.
>
> Signed-off-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
> ---
[...]
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index d9e6bf3d54f0..4936f9499291 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:
> @@ -2844,35 +2845,6 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
>
> }
>
> -static void kvm_s390_vcpu_initial_reset(struct kvm_vcpu *vcpu)
> -{
> - /* this equals initial cpu reset in pop, but we don't switch to ESA */
> - vcpu->arch.sie_block->gpsw.mask = 0UL;
> - vcpu->arch.sie_block->gpsw.addr = 0UL;
> - kvm_s390_set_prefix(vcpu, 0);
> - kvm_s390_set_cpu_timer(vcpu, 0);
> - vcpu->arch.sie_block->ckc = 0UL;
> - vcpu->arch.sie_block->todpr = 0;
> - memset(vcpu->arch.sie_block->gcr, 0, 16 * sizeof(__u64));
> - vcpu->arch.sie_block->gcr[0] = CR0_UNUSED_56 |
> - CR0_INTERRUPT_KEY_SUBMASK |
> - CR0_MEASUREMENT_ALERT_SUBMASK;
> - vcpu->arch.sie_block->gcr[14] = CR14_UNUSED_32 |
> - CR14_UNUSED_33 |
> - CR14_EXTERNAL_DAMAGE_SUBMASK;
> - /* make sure the new fpc will be lazily loaded */
> - save_fpu_regs();
> - current->thread.fpu.fpc = 0;
> - vcpu->arch.sie_block->gbea = 1;
> - vcpu->arch.sie_block->pp = 0;
> - vcpu->arch.sie_block->fpf &= ~FPF_BPBC;
> - vcpu->arch.pfault_token = KVM_S390_PFAULT_TOKEN_INVALID;
> - kvm_clear_async_pf_completion_queue(vcpu);
> - if (!kvm_s390_user_cpu_state_ctrl(vcpu->kvm))
> - kvm_s390_vcpu_stop(vcpu);
> - kvm_s390_clear_local_irqs(vcpu);
> -}
> -
> void kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu)
> {
> mutex_lock(&vcpu->kvm->lock);
> @@ -3287,10 +3259,78 @@ static int kvm_arch_vcpu_ioctl_set_one_reg(struct kvm_vcpu *vcpu,
> return r;
> }
>
> -static int kvm_arch_vcpu_ioctl_initial_reset(struct kvm_vcpu *vcpu)
> +static void kvm_arch_vcpu_ioctl_normal_reset(struct kvm_vcpu *vcpu)
> {
> - kvm_s390_vcpu_initial_reset(vcpu);
> - return 0;
> + vcpu->arch.sie_block->gpsw.mask = ~PSW_MASK_RI;
> + vcpu->arch.pfault_token = KVM_S390_PFAULT_TOKEN_INVALID;
> + memset(vcpu->run->s.regs.riccb, 0, sizeof(vcpu->run->s.regs.riccb));
> +
> + kvm_clear_async_pf_completion_queue(vcpu);
> + if (!kvm_s390_user_cpu_state_ctrl(vcpu->kvm))
> + kvm_s390_vcpu_stop(vcpu);
> + kvm_s390_clear_local_irqs(vcpu);
> +}
> +
> +static void kvm_arch_vcpu_ioctl_initial_reset(struct kvm_vcpu *vcpu)
> +{
> + /* Initial reset is a superset of the normal reset */
> + kvm_arch_vcpu_ioctl_normal_reset(vcpu);
> +
> + /* this equals initial cpu reset in pop, but we don't switch to ESA */
> + vcpu->arch.sie_block->gpsw.mask = 0UL;
> + vcpu->arch.sie_block->gpsw.addr = 0UL;
> + kvm_s390_set_prefix(vcpu, 0);
> + kvm_s390_set_cpu_timer(vcpu, 0);
> + vcpu->arch.sie_block->ckc = 0UL;
> + vcpu->arch.sie_block->todpr = 0;
> + memset(vcpu->arch.sie_block->gcr, 0, 16 * sizeof(__u64));
> + vcpu->arch.sie_block->gcr[0] = CR0_UNUSED_56 |
> + CR0_INTERRUPT_KEY_SUBMASK |
> + CR0_MEASUREMENT_ALERT_SUBMASK;
> + vcpu->arch.sie_block->gcr[14] = CR14_UNUSED_32 |
> + CR14_UNUSED_33 |
> + CR14_EXTERNAL_DAMAGE_SUBMASK;
> + /* make sure the new fpc will be lazily loaded */
> + save_fpu_regs();
> + current->thread.fpu.fpc = 0;
> + vcpu->arch.sie_block->gbea = 1;
> + vcpu->arch.sie_block->pp = 0;
> + vcpu->arch.sie_block->fpf &= ~FPF_BPBC;
> +}
> +
> +static void kvm_arch_vcpu_ioctl_clear_reset(struct kvm_vcpu *vcpu)
> +{
> + struct kvm_sync_regs *regs = &vcpu->run->s.regs;
> +
> + /* Clear reset is a superset of the initial reset */
> + kvm_arch_vcpu_ioctl_normal_reset(vcpu);
> +
> + memset(®s->gprs, 0, sizeof(regs->gprs));
> + /*
> + * Will be picked up via save_fpu_regs() in the initial reset
> + * fallthrough.
The word "fallthrough" now likely should be removed from the comment.
Also, I'm not an expert in this lazy-fpu stuff, but don't you rather
have to deal with current->thread.fpu.regs here instead?
> + */
> + memset(®s->vrs, 0, sizeof(regs->vrs));
> + memset(®s->acrs, 0, sizeof(regs->acrs));
> +
> + regs->etoken = 0;
> + regs->etoken_extension = 0;
> +
> + memset(®s->gscb, 0, sizeof(regs->gscb));
> + if (MACHINE_HAS_GS) {
> + preempt_disable();
> + __ctl_set_bit(2, 4);
> + if (current->thread.gs_cb) {
> + vcpu->arch.host_gscb = current->thread.gs_cb;
> + save_gs_cb(vcpu->arch.host_gscb);
> + }
> + if (vcpu->arch.gs_enabled) {
> + current->thread.gs_cb = (struct gs_cb *)
> + &vcpu->run->s.regs.gscb;
> + restore_gs_cb(current->thread.gs_cb);
> + }
> + preempt_enable();
> + }
> }
Thomas
