[v4 11/16] KVM: kvm-vfio: User API for VT-d Posted-Interrupts

[Feng Wu]

This patch adds and documents two new attributes
KVM_DEV_VFIO_DEVICE_POST_IRQ and KVM_DEV_VFIO_DEVICE_UNPOST_IRQ
in KVM_DEV_VFIO_DEVICE group. The new attributes are used for
VT-d Posted-Interrupts.

When guest OS changes the interrupt configuration for an
assigned device, such as, MSI/MSIx data/address fields,
QEMU will use this IRQ attribute to tell KVM to update the
related IRTE according the VT-d Posted-Interrrupts Specification,
such as, the guest vector should be updated in the related IRTE.

Signed-off-by: Feng Wu <feng.wu@xxxxxxxxx>
---
 Documentation/virtual/kvm/devices/vfio.txt | 9 +++++++++
 include/uapi/linux/kvm.h                   | 2 ++
 2 files changed, 11 insertions(+)

diff --git a/Documentation/virtual/kvm/devices/vfio.txt b/Documentation/virtual/kvm/devices/vfio.txt
index 6186e6d..34925e1 100644
--- a/Documentation/virtual/kvm/devices/vfio.txt
+++ b/Documentation/virtual/kvm/devices/vfio.txt
@@ -42,3 +42,12 @@ In such a situation, -EAGAIN is returned. It is advised to to set the
 forwarding before the VFIO signaling is set up, this avoids trial and errors.
 
 Unforwarding can happen at any time.
+
+  KVM_DEV_VFIO_DEVICE_POST_IRQ: set a VFIO device IRQ as posted
+  KVM_DEV_VFIO_DEVICE_UNPOST_IRQ: set a VFIO device IRQ as remapped
+For this attribute, kvm_device_attr.addr points to a kvm_vfio_dev_irq struct.
+
+When guest OS changes the interrupt configuration for an assigned device,
+such as, MSI/MSIx data/address fields, QEMU will use this IRQ attribute
+to tell KVM to update the related IRTE according the VT-d Posted-Interrrupts
+Specification, such as, the guest vector should be updated in the related IRTE.
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 798f3e4..6e17596 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1002,6 +1002,8 @@ struct kvm_device_attr {
 #define  KVM_DEV_VFIO_DEVICE			2
 #define   KVM_DEV_VFIO_DEVICE_FORWARD_IRQ			1
 #define   KVM_DEV_VFIO_DEVICE_UNFORWARD_IRQ			2
+#define   KVM_DEV_VFIO_DEVICE_POST_IRQ				3
+#define   KVM_DEV_VFIO_DEVICE_UNPOST_IRQ			4
 
 enum kvm_device_type {
 	KVM_DEV_TYPE_FSL_MPIC_20	= 1,
-- 
2.1.0

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