Re: [PATCH v4 02/16] s390x: protvirt: Add diag308 subcodes 8 - 10

[Cornelia Huck <cohuck@redhat.com>]

On Thu, 20 Feb 2020 07:56:24 -0500
Janosch Frank <frankja@linux.ibm.com> wrote:

> For diag308 subcodes 8 - 10 we have a new ipib of type 5. The ipib
> holds the address and length of the secure execution header, as well
> as a list of guest components.
> 
> Each component is a block of memory, for example kernel or initrd,
> which needs to be decrypted by the Ultravisor in order to run a
> protected VM. The secure execution header instructs the Ultravisor on
> how to handle the protected VM and its components.
> 
> Subcodes 8 and 9 are similiar to 5 and 6 and subcode 10 will finally
> start the protected guest.
> 
> Subcodes 8-10 are not valid in protected mode, we have to do a subcode
> 3 and then the 8 and 10 combination for a protected reboot.
> 
> Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
> ---
>  hw/s390x/ipl.c      | 48 ++++++++++++++++++++++++++++++++++++++++++---
>  hw/s390x/ipl.h      | 31 +++++++++++++++++++++++++++++
>  target/s390x/diag.c | 27 ++++++++++++++++++++++---
>  3 files changed, 100 insertions(+), 6 deletions(-)
> 
> diff --git a/hw/s390x/ipl.c b/hw/s390x/ipl.c
> index 7773499d7f..e92d989813 100644
> --- a/hw/s390x/ipl.c
> +++ b/hw/s390x/ipl.c
> @@ -538,15 +538,56 @@ static bool is_virtio_scsi_device(IplParameterBlock *iplb)
>      return is_virtio_ccw_device_of_type(iplb, VIRTIO_ID_SCSI);
>  }
>  
> +int s390_ipl_pv_check_components(IplParameterBlock *iplb)
> +{
> +    int i;
> +    IPLBlockPV *ipib_pv = &iplb->pv;
> +
> +    if (ipib_pv->num_comp == 0) {
> +        return -EINVAL;
> +    }
> +
> +    for (i = 0; i < ipib_pv->num_comp; i++) {
> +
> +        /* Addr must be 4k aligned */
> +        if (ipib_pv->components[i].addr & ~TARGET_PAGE_MASK) {
> +            return -EINVAL;
> +        }
> +
> +        /* Tweak prefix is monotonously increasing with each component */
> +        if (i < ipib_pv->num_comp - 1 &&
> +            ipib_pv->components[i].tweak_pref >
> +            ipib_pv->components[i + 1].tweak_pref) {
> +            return -EINVAL;
> +        }
> +    }
> +    return 1;

Any reason why you return 1 here? 0 vs negative error is the more usual
pattern.

> +}
> +

(...)

> @@ -117,7 +123,8 @@ void handle_diag_308(CPUS390XState *env, uint64_t r1, uint64_t r3, uintptr_t ra)
>  
>          cpu_physical_memory_read(addr, iplb, be32_to_cpu(iplb->len));
>  
> -        if (!iplb_valid_ccw(iplb) && !iplb_valid_fcp(iplb)) {
> +        if (!iplb_valid_ccw(iplb) && !iplb_valid_fcp(iplb) &&
> +            !(iplb_valid_pv(iplb) && s390_ipl_pv_check_components(iplb) >= 0)) {

!s390_ipl_pv_check_components() would also read nicer IMHO :)

>              env->regs[r1 + 1] = DIAG_308_RC_INVALID;
>              goto out;
>          }

Otherwise, looks good to me.