From: Halil Pasic <pasic@xxxxxxxxxxxxxxxxxx>
Introduce a FLIC operation for clearing I/O interrupts for a subchannel.
Rationale: According to the platform specification, pending I/O
interruption requests have to be revoked in certain situations. For
instance, according to the Principles of Operation (page 17-27), a
subchannel put into the installed parameters initialized state is in the
same state as after an I/O system reset (just parameters possibly changed).
This implies that any I/O interrupts for that subchannel are no longer
pending (as I/O system resets clear I/O interrupts). Therefore, we need an
interface to clear pending I/O interrupts.
Signed-off-by: Halil Pasic <pasic@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Cornelia Huck <cornelia.huck@xxxxxxxxxx>
Reviewed-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
Signed-off-by: Christian Borntraeger <borntraeger@xxxxxxxxxx>
Signed-off-by: Cornelia Huck <cornelia.huck@xxxxxxxxxx>
---
Documentation/virtual/kvm/devices/s390_flic.txt | 6 ++++++
arch/s390/include/uapi/asm/kvm.h | 1 +
arch/s390/kvm/interrupt.c | 25 +++++++++++++++++++++++++
3 files changed, 32 insertions(+)
diff --git a/Documentation/virtual/kvm/devices/s390_flic.txt b/Documentation/virtual/kvm/devices/s390_flic.txt
index 646f474..8478de1 100644
--- a/Documentation/virtual/kvm/devices/s390_flic.txt
+++ b/Documentation/virtual/kvm/devices/s390_flic.txt
@@ -11,6 +11,7 @@ FLIC provides support to
- add interrupts (KVM_DEV_FLIC_ENQUEUE)
- inspect currently pending interrupts (KVM_FLIC_GET_ALL_IRQS)
- purge all pending floating interrupts (KVM_DEV_FLIC_CLEAR_IRQS)
+- purge one pending floating I/O interrupt (KVM_DEV_FLIC_CLEAR_IO_IRQ)
- enable/disable for the guest transparent async page faults
- register and modify adapter interrupt sources (KVM_DEV_FLIC_ADAPTER_*)
@@ -40,6 +41,11 @@ Groups:
Simply deletes all elements from the list of currently pending floating
interrupts. No interrupts are injected into the guest.
+ KVM_DEV_FLIC_CLEAR_IO_IRQ
+ Deletes one (if any) I/O interrupt for a subchannel identified by the
+ subsystem identification word passed via the buffer specified by
+ attr->addr (address) and attr->attr (length).
+
KVM_DEV_FLIC_APF_ENABLE
Enables async page faults for the guest. So in case of a major page fault
the host is allowed to handle this async and continues the guest.
diff --git a/arch/s390/include/uapi/asm/kvm.h b/arch/s390/include/uapi/asm/kvm.h
index 347fe5a..3b8e99e 100644
--- a/arch/s390/include/uapi/asm/kvm.h
+++ b/arch/s390/include/uapi/asm/kvm.h
@@ -25,6 +25,7 @@
#define KVM_DEV_FLIC_APF_DISABLE_WAIT 5
#define KVM_DEV_FLIC_ADAPTER_REGISTER 6
#define KVM_DEV_FLIC_ADAPTER_MODIFY 7
+#define KVM_DEV_FLIC_CLEAR_IO_IRQ 8
/*
* We can have up to 4*64k pending subchannels + 8 adapter interrupts,
* as well as up to ASYNC_PF_PER_VCPU*KVM_MAX_VCPUS pfault done interrupts.
diff --git a/arch/s390/kvm/interrupt.c b/arch/s390/kvm/interrupt.c
index 4c2cdb2..e550404 100644
--- a/arch/s390/kvm/interrupt.c
+++ b/arch/s390/kvm/interrupt.c
@@ -2034,6 +2034,27 @@ static int modify_io_adapter(struct kvm_device *dev,
return ret;
}
+static int clear_io_irq(struct kvm *kvm, struct kvm_device_attr *attr)
+
+{
+ const u64 isc_mask = 0xffUL << 24; /* all iscs set */
+ u32 schid;
+
+ if (attr->flags)
+ return -EINVAL;
+ if (attr->attr != sizeof(schid))
+ return -EINVAL;
+ if (copy_from_user(&schid, (void __user *) attr->addr, sizeof(schid)))
+ return -EFAULT;
+ kfree(kvm_s390_get_io_int(kvm, isc_mask, schid));
+ /*
+ * If userspace is conforming to the architecture, we can have at most
+ * one pending I/O interrupt per subchannel, so this is effectively a
+ * clear all.
+ */
+ return 0;
+}
+
static int flic_set_attr(struct kvm_device *dev, struct kvm_device_attr *attr)
{
int r = 0;
@@ -2067,6 +2088,9 @@ static int flic_set_attr(struct kvm_device *dev, struct kvm_device_attr *attr)
case KVM_DEV_FLIC_ADAPTER_MODIFY:
r = modify_io_adapter(dev, attr);
break;
+ case KVM_DEV_FLIC_CLEAR_IO_IRQ:
+ r = clear_io_irq(dev->kvm, attr);
+ break;
default:
r = -EINVAL;
}
@@ -2085,6 +2109,7 @@ static int flic_has_attr(struct kvm_device *dev,
case KVM_DEV_FLIC_APF_DISABLE_WAIT:
case KVM_DEV_FLIC_ADAPTER_REGISTER:
case KVM_DEV_FLIC_ADAPTER_MODIFY:
+ case KVM_DEV_FLIC_CLEAR_IO_IRQ:
return 0;
}
return -ENXIO;
--
2.8.1
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