[PATCH v3 16/16] KVM: document KVM_REINJECT_CONTROL ioctl

[Radim KrÄmÃÅ]

From: Radim KrÄmÃÅ <rkrcmar@xxxxxxxxxx>

Signed-off-by: Radim KrÄmÃÅ <rkrcmar@xxxxxxxxxx>
---
 v3: new, one result of a long discussion with Paolo

 Documentation/virtual/kvm/api.txt | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index 4a661e555c09..777aefc77743 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -3035,6 +3035,30 @@ Returns: 0 on success, -1 on error
 
 Queues an SMI on the thread's vcpu.
 
+4.97 KVM_REINJECT_CONTROL
+
+Capability: KVM_CAP_REINJECT_CONTROL
+Architectures: x86
+Type: vm ioctl
+Parameters: struct kvm_reinject_control (in)
+Returns: 0 on success,
+         -EFAULT if struct kvm_reinject_control cannot be read,
+         -ENXIO if KVM_CREATE_PIT or KVM_CREATE_PIT2 didn't succeed earlier.
+
+i8254 (PIT) has two modes, reinject and !reinject.  The default is reinject,
+where KVM queues elapsed i8254 ticks and monitors completion of interrupt from
+vector(s) that i8254 injects.  Reinject mode dequeues a tick and injects its
+interrupt whenever there isn't a pending interrupt from i8254.
+!reinject mode injects an interrupt as soon as a tick arrives.
+
+struct kvm_reinject_control {
+	__u8 pit_reinject;
+	__u8 reserved[31];
+};
+
+pit_reinject = 0 (!reinject mode) is recommended.
+
+
 5. The kvm_run structure
 ------------------------
 
-- 
2.7.2