Re: [PATCH v10 09/16] s390x: protvirt: SCLP interpretation

[Cornelia Huck <cohuck@redhat.com>]

On Wed, 18 Mar 2020 10:30:40 -0400
Janosch Frank <frankja@linux.ibm.com> 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>
> Reviewed-by: David Hildenbrand <david@redhat.com>
> Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
> ---
>  hw/s390x/sclp.c         | 65 ++++++++++++++++++++++++++++++++++-------
>  include/hw/s390x/sclp.h |  2 ++
>  target/s390x/kvm.c      | 25 ++++++++++++----
>  3 files changed, 76 insertions(+), 16 deletions(-)
> 
> diff --git a/hw/s390x/sclp.c b/hw/s390x/sclp.c
> index af0bfbc2eca74767..6486890fecea4b3c 100644
> --- a/hw/s390x/sclp.c
> +++ b/hw/s390x/sclp.c
> @@ -33,6 +33,22 @@ static inline SCLPDevice *get_sclp_device(void)
>      return sclp;
>  }
>  
> +static inline bool sclp_command_code_valid(uint32_t code)
> +{
> +    switch (code & SCLP_CMD_CODE_MASK) {
> +    case SCLP_CMDW_READ_SCP_INFO:
> +    case SCLP_CMDW_READ_SCP_INFO_FORCED:
> +    case SCLP_CMDW_READ_CPU_INFO:
> +    case SCLP_CMDW_CONFIGURE_IOA:
> +    case SCLP_CMDW_DECONFIGURE_IOA:
> +    case SCLP_CMD_READ_EVENT_DATA:
> +    case SCLP_CMD_WRITE_EVENT_DATA:
> +    case SCLP_CMD_WRITE_EVENT_MASK:
> +        return true;
> +    }
> +    return false;
> +}
> +
>  static void prepare_cpu_entries(SCLPDevice *sclp, CPUEntry *entry, int *count)
>  {
>      MachineState *ms = MACHINE(qdev_get_machine());
> @@ -193,6 +209,43 @@ 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 number of calls is permitted by the
> +     * Ultravisor and we support all of them, so we don't check for

This is no longer true, no?

> +     * 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);
> +
> +    if (!sclp_command_code_valid(code)) {
> +        work_sccb.h.response_code = cpu_to_be16(SCLP_RC_INVALID_SCLP_COMMAND);
> +        goto out_write;
> +    }
> +
> +    sclp_c->execute(sclp, &work_sccb, code);
> +out_write:
> +    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();