diff options
| author | Steve Rutherford <srutherford@google.com> | 2015-07-30 11:27:16 +0200 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2015-10-01 15:06:29 +0200 |
| commit | 1c1a9ce973a7863dd46767226bce2a5f12d48bc6 (patch) | |
| tree | c7234495a61db9dc9d26956853b7495f8910c581 /Documentation | |
| parent | b053b2aef25d00773fa6762dcd4b7f5c9c42d171 (diff) | |
KVM: x86: Add support for local interrupt requests from userspace
In order to enable userspace PIC support, the userspace PIC needs to
be able to inject local interrupts even when the APICs are in the
kernel.
KVM_INTERRUPT now supports sending local interrupts to an APIC when
APICs are in the kernel.
The ready_for_interrupt_request flag is now only set when the CPU/APIC
will immediately accept and inject an interrupt (i.e. APIC has not
masked the PIC).
When the PIC wishes to initiate an INTA cycle with, say, CPU0, it
kicks CPU0 out of the guest, and renedezvous with CPU0 once it arrives
in userspace.
When the CPU/APIC unmasks the PIC, a KVM_EXIT_IRQ_WINDOW_OPEN is
triggered, so that userspace has a chance to inject a PIC interrupt
if it had been pending.
Overall, this design can lead to a small number of spurious userspace
renedezvous. In particular, whenever the PIC transistions from low to
high while it is masked and whenever the PIC becomes unmasked while
it is low.
Note: this does not buffer more than one local interrupt in the
kernel, so the VMM needs to enter the guest in order to complete
interrupt injection before injecting an additional interrupt.
Compiles for x86.
Can pass the KVM Unit Tests.
Signed-off-by: Steve Rutherford <srutherford@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/virtual/kvm/api.txt | 14 |
1 files changed, 10 insertions, 4 deletions
diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt index 89e71648d748..e3e9c41721a2 100644 --- a/Documentation/virtual/kvm/api.txt +++ b/Documentation/virtual/kvm/api.txt @@ -401,10 +401,9 @@ Capability: basic Architectures: x86, ppc, mips Type: vcpu ioctl Parameters: struct kvm_interrupt (in) -Returns: 0 on success, -1 on error +Returns: 0 on success, negative on failure. -Queues a hardware interrupt vector to be injected. This is only -useful if in-kernel local APIC or equivalent is not used. +Queues a hardware interrupt vector to be injected. /* for KVM_INTERRUPT */ struct kvm_interrupt { @@ -414,7 +413,14 @@ struct kvm_interrupt { X86: -Note 'irq' is an interrupt vector, not an interrupt pin or line. +Returns: 0 on success, + -EEXIST if an interrupt is already enqueued + -EINVAL the the irq number is invalid + -ENXIO if the PIC is in the kernel + -EFAULT if the pointer is invalid + +Note 'irq' is an interrupt vector, not an interrupt pin or line. This +ioctl is useful if the in-kernel PIC is not used. PPC: |