Re: [PATCH v9 3/6] KVM: s390: Add new reset vcpu API

Christian Borntraeger
2020-01-30T12:53:45Z

On 30.01.20 13:34, 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@linux.ibm.com>
> Reviewed-by: Cornelia Huck <cohuck@redhat.com>
> ---
> Documentation/virt/kvm/api.txt | 43 +++++++++++++++++++++++
> arch/s390/kvm/kvm-s390.c | 63 +++++++++++++++++++++++++++++++---
> include/uapi/linux/kvm.h | 5 +++
> 3 files changed, 107 insertions(+), 4 deletions(-)
>
> diff --git a/Documentation/virt/kvm/api.txt b/Documentation/virt/kvm/api.txt
> index ebb37b34dcfc..73448764f544 100644
> --- a/Documentation/virt/kvm/api.txt
> +++ b/Documentation/virt/kvm/api.txt
> @@ -4168,6 +4168,42 @@ This ioctl issues an ultravisor call to terminate the secure guest,
> unpins the VPA pages and releases all the device pages that are used to
> track the secure pages by hypervisor.
>
> +4.122 KVM_S390_NORMAL_RESET
> +
> +Capability: KVM_CAP_S390_VCPU_RESETS
> +Architectures: s390
> +Type: vcpu ioctl
> +Parameters: none
> +Returns: 0
> +
> +This ioctl resets VCPU registers and control structures according to
> +the cpu reset definition in the POP (Principles Of Operation).
> +
> +4.123 KVM_S390_INITIAL_RESET
> +
> +Capability: none
> +Architectures: s390
> +Type: vcpu ioctl
> +Parameters: none
> +Returns: 0
> +
> +This ioctl resets VCPU registers and control structures according to
> +the initial cpu reset definition in the POP. However, the cpu is not
> +put into ESA mode. This reset is a superset of the normal reset.
> +
> +4.124 KVM_S390_CLEAR_RESET
> +
> +Capability: KVM_CAP_S390_VCPU_RESETS
> +Architectures: s390
> +Type: vcpu ioctl
> +Parameters: none
> +Returns: 0
> +
> +This ioctl resets VCPU registers and control structures according to
> +the clear cpu reset definition in the POP. However, the cpu is not put
> +into ESA mode. This reset is a superset of the initial reset.
> +
> +
> 5. The kvm_run structure
> ------------------------
>
> @@ -5396,3 +5432,10 @@ handling by KVM (as some KVM hypercall may be mistakenly treated as TLB
> flush hypercalls by Hyper-V) so userspace should disable KVM identification
> in CPUID and only exposes Hyper-V identification. In this case, guest
> thinks it's running on Hyper-V and only use Hyper-V hypercalls.
> +
> +8.22 KVM_CAP_S390_VCPU_RESETS
> +
> +Architectures: s390
> +
> +This capability indicates that the KVM_S390_NORMAL_RESET and
> +KVM_S390_CLEAR_RESET ioctls are available.
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index e0a0799b384e..7ecc5c884840 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:
> @@ -3274,10 +3275,55 @@ 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 = 0;
> + vcpu->arch.sie_block->gpsw.addr = 0;
> + kvm_s390_set_prefix(vcpu, 0);
> + kvm_s390_set_cpu_timer(vcpu, 0);
> + vcpu->arch.sie_block->ckc = 0;
> + vcpu->arch.sie_block->todpr = 0;
> + memset(vcpu->arch.sie_block->gcr, 0, sizeof(vcpu->arch.sie_block->gcr));
> + vcpu->arch.sie_block->gcr[0] = CR0_INITIAL_MASK;
> + vcpu->arch.sie_block->gcr[14] = CR14_INITIAL_MASK;
> + /* make sure the new fpc will be lazily loaded */
> + save_fpu_regs();
> + current->thread.fpu.fpc = 0;

with that fixed up

Reviewed-by: Christian Borntraeger <borntraeger@de.ibm.com>

> + 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_initial_reset(vcpu);
> +
> + memset(&regs->gprs, 0, sizeof(regs->gprs));
> + memset(&regs->vrs, 0, sizeof(regs->vrs));
> + memset(&regs->acrs, 0, sizeof(regs->acrs));
> + memset(&regs->gscb, 0, sizeof(regs->gscb));
> +
> + regs->etoken = 0;
> + regs->etoken_extension = 0;
> }
>
> int kvm_arch_vcpu_ioctl_set_regs(struct kvm_vcpu *vcpu, struct kvm_regs *regs)
> @@ -4350,8 +4396,17 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
> r = kvm_arch_vcpu_ioctl_set_initial_psw(vcpu, psw);
> break;
> }
> + case KVM_S390_CLEAR_RESET:
> + r = 0;
> + kvm_arch_vcpu_ioctl_clear_reset(vcpu);
> + break;
> case KVM_S390_INITIAL_RESET:
> - r = kvm_arch_vcpu_ioctl_initial_reset(vcpu);
> + r = 0;
> + kvm_arch_vcpu_ioctl_initial_reset(vcpu);
> + break;
> + case KVM_S390_NORMAL_RESET:
> + r = 0;
> + kvm_arch_vcpu_ioctl_normal_reset(vcpu);
> break;
> case KVM_SET_ONE_REG:
> case KVM_GET_ONE_REG: {
> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> index f0a16b4adbbd..4b95f9a31a2f 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -1009,6 +1009,7 @@ struct kvm_ppc_resize_hpt {
> #define KVM_CAP_PPC_GUEST_DEBUG_SSTEP 176
> #define KVM_CAP_ARM_NISV_TO_USER 177
> #define KVM_CAP_ARM_INJECT_EXT_DABT 178
> +#define KVM_CAP_S390_VCPU_RESETS 179
>
> #ifdef KVM_CAP_IRQ_ROUTING
>
> @@ -1473,6 +1474,10 @@ struct kvm_enc_region {
> /* Available with KVM_CAP_ARM_SVE */
> #define KVM_ARM_VCPU_FINALIZE _IOW(KVMIO, 0xc2, int)
>
> +/* Available with KVM_CAP_S390_VCPU_RESETS */
> +#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 */
>