On 05.02.20 13:22, Cornelia Huck wrote:
> 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?
Yes, the firmware will use its copy of the sccb value when we have something !=0
>
>> + * 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?
Yes, we unmask here at a notification intercept (instruction is complete)..
I will use:
/*
* 2 cases:
* a: an sccb answering interrupt was already pending or in flight.
* As the sccb value is not known we can simply set some value to
* trigger delivery of a saved SCCB. UV will then use its saved
* copy of the SCCB value.
* b: an error SCCB interrupt needs to be injected so we also inject
* a fake SCCB address. Firmware will use the proper one.
* This makes sure, that both errors and real sccb returns will only
* be delivered after a notification intercept (instruction has
* finished) but not after others.
*/
