linux-kernel - Re: [PATCH v5 05/15] KVM: s390: unify pending_irqs() and pending_irqs_no

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Date:   Thu, 20 Dec 2018 12:49:56 +0100
From:   Michael Mueller <mimu@...ux.ibm.com>
To:     Cornelia Huck <cohuck@...hat.com>
Cc:     KVM Mailing List <kvm@...r.kernel.org>,
        Linux-S390 Mailing List <linux-s390@...r.kernel.org>,
        linux-kernel@...r.kernel.org,
        Martin Schwidefsky <schwidefsky@...ibm.com>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        Christian Borntraeger <borntraeger@...ibm.com>,
        Janosch Frank <frankja@...ux.ibm.com>,
        David Hildenbrand <david@...hat.com>,
        Halil Pasic <pasic@...ux.ibm.com>,
        Pierre Morel <pmorel@...ux.ibm.com>
Subject: Re: [PATCH v5 05/15] KVM: s390: unify pending_irqs() and
 pending_irqs_no_gisa()



On 20.12.18 12:06, Cornelia Huck wrote:
> On Wed, 19 Dec 2018 20:17:46 +0100
> Michael Mueller <mimu@...ux.ibm.com> wrote:
> 
>> Use a single function with parameter irq_flags to differentiate
>> between cases.
>>
>> New irq flag:
>>     IRQ_FLAG_LOCAL: include vcpu local interruptions pending
>>     IRQ_FLAG_FLOATING: include vcpu floating interruptions pending
>>     IRQ_FLAG_GISA: include GISA interruptions pending in IPM
> 
> I presume that means that irqs may be in more than one set? Or are gisa
> irqs not considered floating irqs, because they use a different
> mechanism?

Currently, the interruptions managed in GISA are floating only. But
that might change in future. The idea is not to subsume IRQ_FLAG_GISA
in IRQ_FLAG_FLOATING but to be able to address the right set of 
procedures to determine the irq pending set for a given subset of irq
types that have different implementations.

There might be a better name for IRQ_FLAG_FLOATING then?

> 
>>
>> New irq masks:
>>     IRQ_MASK_ALL: include all types
>>     IRQ_MASK_NO_GISA: include all types but GISA
>>
>> Examples:
>>     pending_irqs(vcpu, IRQ_MASK_ALL)
>>     pending_irqs(vcpu, IRQ_MASK_NO_GISA)
>>
>> There will be more irq flags with upcoming patches.
>>
>> Signed-off-by: Michael Mueller <mimu@...ux.ibm.com>
>> ---
>>   arch/s390/kvm/interrupt.c | 33 +++++++++++++++++++++------------
>>   1 file changed, 21 insertions(+), 12 deletions(-)
>>
>> diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
>> index 093b568b6356..4ab20d2eb180 100644
>> --- a/arch/s390/kvm/interrupt.c
>> +++ b/arch/s390/kvm/interrupt.c
>> @@ -31,6 +31,13 @@
>>   #define PFAULT_DONE 0x0680
>>   #define VIRTIO_PARAM 0x0d00
>>   
>> +#define IRQ_FLAG_LOCAL    0x8000 /* include local interruption pending mask */
>> +#define IRQ_FLAG_FLOATING 0x4000 /* include float interruption pending mask */
>> +#define IRQ_FLAG_GISA     0x2000 /* include GISA interruption pending mask */
>> +
>> +#define IRQ_MASK_ALL      (IRQ_FLAG_LOCAL | IRQ_FLAG_FLOATING | IRQ_FLAG_GISA)
>> +#define IRQ_MASK_NO_GISA  (IRQ_MASK_ALL & ~IRQ_FLAG_GISA)
>> +
>>   /* handle external calls via sigp interpretation facility */
>>   static int sca_ext_call_pending(struct kvm_vcpu *vcpu, int *src_id)
>>   {
>> @@ -237,16 +244,18 @@ static inline int kvm_s390_gisa_tac_ipm_gisc(struct kvm_s390_gisa *gisa, u32 gis
>>   	return test_and_clear_bit_inv(IPM_BIT_OFFSET + gisc, (unsigned long *) gisa);
>>   }
>>   
>> -static inline unsigned long pending_irqs_no_gisa(struct kvm_vcpu *vcpu)
>> +static inline unsigned long pending_irqs(struct kvm_vcpu *vcpu, u16 irq_flags)
> 
> Any deeper reason why this is a u16? 16 bits should be enough for
> everyone? :)

I want to use the 8 bits for the IRQ type and the other 8 for additional 
controls, see: "KVM: s390: restore IAM in get_ipm() when IPM is clean"

> 
>>   {
>> -	return vcpu->kvm->arch.float_int.pending_irqs |
>> -		vcpu->arch.local_int.pending_irqs;
>> -}
>> +	unsigned long pending_irqs = 0;
>>   
>> -static inline unsigned long pending_irqs(struct kvm_vcpu *vcpu)
>> -{
>> -	return pending_irqs_no_gisa(vcpu) |
>> -		kvm_s390_gisa_get_ipm(vcpu->kvm->arch.gisa) << IRQ_PEND_IO_ISC_7;
>> +	if (irq_flags & IRQ_FLAG_LOCAL)
>> +		pending_irqs |= vcpu->arch.local_int.pending_irqs;
>> +	if (irq_flags & IRQ_FLAG_FLOATING)
>> +		pending_irqs |= vcpu->kvm->arch.float_int.pending_irqs;
>> +	if (irq_flags & IRQ_FLAG_GISA)
>> +		pending_irqs |= kvm_s390_gisa_get_ipm(vcpu->kvm->arch.gisa) <<
>> +			IRQ_PEND_IO_ISC_7;
>> +	return pending_irqs;
>>   }
>>   
>>   static inline int isc_to_irq_type(unsigned long isc)
>> @@ -275,7 +284,7 @@ static unsigned long deliverable_irqs(struct kvm_vcpu *vcpu)
>>   {
>>   	unsigned long active_mask;
>>   
>> -	active_mask = pending_irqs(vcpu);
>> +	active_mask = pending_irqs(vcpu, IRQ_MASK_ALL);
>>   	if (!active_mask)
>>   		return 0;
>>   
>> @@ -343,7 +352,7 @@ static void __reset_intercept_indicators(struct kvm_vcpu *vcpu)
>>   
>>   static void set_intercept_indicators_io(struct kvm_vcpu *vcpu)
>>   {
>> -	if (!(pending_irqs_no_gisa(vcpu) & IRQ_PEND_IO_MASK))
>> +	if (!(pending_irqs(vcpu, IRQ_MASK_NO_GISA) & IRQ_PEND_IO_MASK))
> 
> I/O interrupts are always floating, so you probably could check for
> only floating (excluding gisa) irqs here.

That's right.

> 
>>   		return;
>>   	else if (psw_ioint_disabled(vcpu))
>>   		kvm_s390_set_cpuflags(vcpu, CPUSTAT_IO_INT);Store Data
>> @@ -353,7 +362,7 @@ static void set_intercept_indicators_io(struct kvm_vcpu *vcpu)
>>