Commit 6d28f789 authored by Halil Pasic's avatar Halil Pasic Committed by Cornelia Huck
Browse files

KVM: s390: add clear I/O irq operation for FLIC 



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: default avatarHalil Pasic <pasic@linux.vnet.ibm.com>
Reviewed-by: default avatarCornelia Huck <cornelia.huck@de.ibm.com>
Reviewed-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: default avatarCornelia Huck <cornelia.huck@de.ibm.com>
parent dad7eefb

Documentation/virtual/kvm/devices/s390_flic.txt

+6 −0
Original line number Diff line number Diff line
@@ -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.

arch/s390/include/uapi/asm/kvm.h

+1 −0
Original line number Diff line number Diff line
@@ -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.

arch/s390/kvm/interrupt.c

+25 −0
Original line number Diff line number Diff line
@@ -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;

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