Re: [PATCH v8] s390x: protvirt: SCLP interpretation

[David Hildenbrand <david@redhat.com>]

On 10.03.20 09:42, Janosch Frank wrote:
> SCLP for a protected guest is done over the SIDAD, so we need to use
> the s390_cpu_pv_mem_* functions to access the SIDAD instead of guest
> memory when reading/writing SCBs.
> 
> To not confuse the sclp emulation, we set 0x4000 as the SCCB address,
> since the function that injects the sclp external interrupt would
> reject a zero sccb address.
> 
> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
> ---
>  hw/s390x/sclp.c         | 30 ++++++++++++++++++++++++++++++
>  include/hw/s390x/sclp.h |  2 ++
>  target/s390x/kvm.c      | 24 +++++++++++++++++++-----
>  3 files changed, 51 insertions(+), 5 deletions(-)
> 
> diff --git a/hw/s390x/sclp.c b/hw/s390x/sclp.c
> index af0bfbc2ec..15dd15099c 100644
> --- a/hw/s390x/sclp.c
> +++ b/hw/s390x/sclp.c
> @@ -193,6 +193,36 @@ static void sclp_execute(SCLPDevice *sclp, SCCB *sccb, uint32_t code)
>      }
>  }
>  
> +/*
> +* We only need the address to have something valid for the
> +* service_interrupt call.
> +*/
> +#define SCLP_PV_DUMMY_ADDR 0x4000
> +int sclp_service_call_protected(CPUS390XState *env, uint64_t sccb,
> +                                uint32_t code)
> +{
> +    SCLPDevice *sclp = get_sclp_device();
> +    SCLPDeviceClass *sclp_c = SCLP_GET_CLASS(sclp);
> +    SCCB work_sccb;
> +    hwaddr sccb_len = sizeof(SCCB);
> +
> +    /*
> +     * Only a very limited amount of calls is permitted by the
> +     * Ultravisor and we support all of them, so we don't check for
> +     * them. All other specification exceptions are also interpreted
> +     * by the Ultravisor and hence never cause an exit we need to
> +     * handle.
> +     *
> +     * Setting the CC is also done by the Ultravisor.
> +     */
> +    s390_cpu_pv_mem_read(env_archcpu(env), 0, &work_sccb, sccb_len);
> +    sclp_c->execute(sclp, &work_sccb, code);
> +    s390_cpu_pv_mem_write(env_archcpu(env), 0, &work_sccb,
> +                          be16_to_cpu(work_sccb.h.length));
> +    sclp_c->service_interrupt(sclp, SCLP_PV_DUMMY_ADDR);
> +    return 0;
> +}
> +
>  int sclp_service_call(CPUS390XState *env, uint64_t sccb, uint32_t code)
>  {
>      SCLPDevice *sclp = get_sclp_device();
> diff --git a/include/hw/s390x/sclp.h b/include/hw/s390x/sclp.h
> index c54413b78c..c0a3faa37d 100644
> --- a/include/hw/s390x/sclp.h
> +++ b/include/hw/s390x/sclp.h
> @@ -217,5 +217,7 @@ void s390_sclp_init(void);
>  void sclp_service_interrupt(uint32_t sccb);
>  void raise_irq_cpu_hotplug(void);
>  int sclp_service_call(CPUS390XState *env, uint64_t sccb, uint32_t code);
> +int sclp_service_call_protected(CPUS390XState *env, uint64_t sccb,
> +                                uint32_t code);
>  
>  #endif
> diff --git a/target/s390x/kvm.c b/target/s390x/kvm.c
> index 295ed12a38..78e1b34ad5 100644
> --- a/target/s390x/kvm.c
> +++ b/target/s390x/kvm.c
> @@ -1226,12 +1226,26 @@ static void kvm_sclp_service_call(S390CPU *cpu, struct kvm_run *run,
>      sccb = env->regs[ipbh0 & 0xf];
>      code = env->regs[(ipbh0 & 0xf0) >> 4];
>  
> -    r = sclp_service_call(env, sccb, code);
> -    if (r < 0) {
> -        kvm_s390_program_interrupt(cpu, -r);
> -        return;
> +    switch (run->s390_sieic.icptcode) {
> +    case ICPT_PV_INSTR_NOTIFICATION:
> +        g_assert(env->pv);
> +        /* The notification intercepts are currently handled by KVM */
> +        error_report("unexpected SCLP PV notification\n");
> +        exit(1);
> +        break;
> +    case ICPT_PV_INSTR:
> +        g_assert(env->pv);
> +        sclp_service_call_protected(env, sccb, code);
> +        break;
> +    case ICPT_INSTRUCTION:
> +        g_assert(!env->pv);
> +        r = sclp_service_call(env, sccb, code);
> +        if (r < 0) {
> +            kvm_s390_program_interrupt(cpu, -r);
> +            return;
> +        }
> +        setcc(cpu, r);
>      }
> -    setcc(cpu, r);
>  }
>  
>  static int handle_b2(S390CPU *cpu, struct kvm_run *run, uint8_t ipa1)
> 

Reviewed-by: David Hildenbrand <david@redhat.com>

-- 
Thanks,

David / dhildenb