Re: [PATCH v5 05/15] KVM: s390: unify pending_irqs() and pending_irqs_no_gisa()

From: Michael Mueller
Date: Thu Dec 20 2018 - 07:33:24 EST

On 20.12.18 13:21, Cornelia Huck wrote:
On Thu, 20 Dec 2018 12:49:56 +0100
Michael Mueller <mimu@xxxxxxxxxxxxx> wrote:

On 20.12.18 12:06, Cornelia Huck wrote:
On Wed, 19 Dec 2018 20:17:46 +0100
Michael Mueller <mimu@xxxxxxxxxxxxx> 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

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?

So the split is:

- local interrupts that are pending via kvm structures;
- floating interrupts that are pending via kvm structures;
- interrupts that are pending via gisa?

If so, what about
- IRQ_FLAG_GISA (or maybe IRQ_FLAG_GISA_FLOATING, if you need to
distinguish those later on?)

yes, that's the split and I will go with:



The floating and local selection can be done by related masks


if required.


New irq masks:
IRQ_MASK_ALL: include all types
IRQ_MASK_NO_GISA: include all types but GISA

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@xxxxxxxxxxxxx>
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 */
/* 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"

Still need to look at that patch, but my question mainly was "why only
16 bits"? I would think making this local variable larger is cheap.

I will enlarge the flag mask to u32 with 16 bits for the IRQ types then.

- return vcpu->kvm->arch.float_int.pending_irqs |
- vcpu->arch.local_int.pending_irqs;

Mit freundlichen GrÃÃen / Kind regards
Michael MÃller

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