Re: [PATCH v8 2/2] s390/kvm: diagnose 0x318 sync and reset

Cornelia Huck
2020-06-22T10:25:16Z

On Thu, 18 Jun 2020 18:22:22 -0400
Collin Walling <walling@linux.ibm.com> wrote:

> DIAGNOSE 0x318 (diag318) sets information regarding the environment
> the VM is running in (Linux, z/VM, etc) and is observed via
> firmware/service events.
>
> This is a privileged s390x instruction that must be intercepted by
> SIE. Userspace handles the instruction as well as migration. Data
> is communicated via VCPU register synchronization.
>
> The Control Program Name Code (CPNC) is stored in the SIE block. The
> CPNC along with the Control Program Version Code (CPVC) are stored
> in the kvm_vcpu_arch struct.
>
> The CPNC is shadowed/unshadowed in VSIE.
>
> This data is reset on load normal and clear resets.
>
> Signed-off-by: Collin Walling <walling@linux.ibm.com>
> ---
> arch/s390/include/asm/kvm_host.h | 4 +++-
> arch/s390/include/uapi/asm/kvm.h | 5 ++++-
> arch/s390/kvm/kvm-s390.c | 11 ++++++++++-
> arch/s390/kvm/vsie.c | 3 +++
> include/uapi/linux/kvm.h | 1 +
> 5 files changed, 21 insertions(+), 3 deletions(-)
>

(...)

> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> index 4fdf30316582..35cdb4307904 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -1031,6 +1031,7 @@ struct kvm_ppc_resize_hpt {
> #define KVM_CAP_PPC_SECURE_GUEST 181
> #define KVM_CAP_HALT_POLL 182
> #define KVM_CAP_ASYNC_PF_INT 183
> +#define KVM_CAP_S390_DIAG318 184

Do we strictly need this new cap, or would checking against the sync
regs capabilities be enough?

>
> #ifdef KVM_CAP_IRQ_ROUTING
>