On Mon, 3 Feb 2020 08:19:36 -0500
Christian Borntraeger <borntraeger@xxxxxxxxxx> wrote:
> The sclp interrupt is kind of special. The ultravisor polices that we
> do not inject and sclp interrupt with payload if no sccb is outstanding.
> On the other hand we have "asynchronous" event interrupts, e.g. for
> console input.
> We separate both variants into sclp interrupt and sclp event interrupt.
> The sclp interrupt is masked until a previous servc instruction has
> finished (sie exit 108).
>
> Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
> ---
> arch/s390/include/asm/kvm_host.h | 6 ++-
> arch/s390/kvm/intercept.c | 25 +++++++++
> arch/s390/kvm/interrupt.c | 92 ++++++++++++++++++++++++++------
> arch/s390/kvm/kvm-s390.c | 2 +
> 4 files changed, 108 insertions(+), 17 deletions(-)
>
> diff --git a/arch/s390/kvm/intercept.c b/arch/s390/kvm/intercept.c
> index 4b3fbbde1674..c22214967214 100644
> --- a/arch/s390/kvm/intercept.c
> +++ b/arch/s390/kvm/intercept.c
> @@ -444,8 +444,33 @@ static int handle_operexc(struct kvm_vcpu *vcpu)
> return kvm_s390_inject_program_int(vcpu, PGM_OPERATION);
> }
>
> +static int handle_pv_sclp(struct kvm_vcpu *vcpu)
> +{
> + struct kvm_s390_float_interrupt *fi = &vcpu->kvm->arch.float_int;
> +
> + spin_lock(&fi->lock);
> + /*
> + * 2 cases:
> + * a: an sccb answering interrupt was already pending or in flight.
> + * As the sccb value is not used we can simply set some more bits
> + * and make sure that we deliver something
The sccb value is not used because the firmware handles this?
> + * b: an error sccb interrupt needs to be injected so we also inject
> + * something and let firmware do the right thing.
> + * This makes sure, that both errors and real sccb returns will only
> + * be delivered when we are unmasked.
What makes this sure? That we only unmask here?
> + */
> + fi->srv_signal.ext_params |= 0x43000;
> + set_bit(IRQ_PEND_EXT_SERVICE, &fi->pending_irqs);
> + clear_bit(IRQ_PEND_EXT_SERVICE, &fi->masked_irqs);
> + spin_unlock(&fi->lock);
> + return 0;
> +}
> +
> static int handle_pv_not(struct kvm_vcpu *vcpu)
> {
> + if (vcpu->arch.sie_block->ipa == 0xb220)
> + return handle_pv_sclp(vcpu);
> +
> return handle_instruction(vcpu);
> }
>
