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| author |   Steve Rutherford <srutherford@google.com> | 2015-07-29 23:32:35 -0700 |
|---|---|---|
| committer |   Paolo Bonzini <pbonzini@redhat.com> | 2015-10-01 15:06:28 +0200 |
| commit | b053b2aef25d00773fa6762dcd4b7f5c9c42d171 (patch) | |
| tree | 49455d15fd99d802135fed0d197989c3e7a2b62b /Documentation/virtual | |
| parent | KVM: x86: Add KVM exit for IOAPIC EOIs (diff) | |
| download | linux-dev-b053b2aef25d00773fa6762dcd4b7f5c9c42d171.tar.xz linux-dev-b053b2aef25d00773fa6762dcd4b7f5c9c42d171.zip | |
KVM: x86: Add EOI exit bitmap inference
In order to support a userspace IOAPIC interacting with an in kernel
APIC, the EOI exit bitmaps need to be configurable.
If the IOAPIC is in userspace (i.e. the irqchip has been split), the
EOI exit bitmaps will be set whenever the GSI Routes are configured.
In particular, for the low MSI routes are reservable for userspace
IOAPICs. For these MSI routes, the EOI Exit bit corresponding to the
destination vector of the route will be set for the destination VCPU.
The intention is for the userspace IOAPICs to use the reservable MSI
routes to inject interrupts into the guest.
This is a slight abuse of the notion of an MSI Route, given that MSIs
classically bypass the IOAPIC. It might be worthwhile to add an
additional route type to improve clarity.
Compile tested for Intel x86.
Signed-off-by: Steve Rutherford <srutherford@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'Documentation/virtual')
| -rw-r--r-- | Documentation/virtual/kvm/api.txt | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt index 0d14bf5db534..89e71648d748 100644 --- a/Documentation/virtual/kvm/api.txt +++ b/Documentation/virtual/kvm/api.txt @@ -3642,7 +3642,7 @@ KVM handlers should exit to userspace with rc = -EREMOTE. 7.5 KVM_CAP_SPLIT_IRQCHIP Architectures: x86 -Parameters: None +Parameters: args[0] - number of routes reserved for userspace IOAPICs Returns: 0 on success, -1 on error Create a local apic for each processor in the kernel. This can be used @@ -3650,8 +3650,11 @@ instead of KVM_CREATE_IRQCHIP if the userspace VMM wishes to emulate the IOAPIC and PIC (and also the PIT, even though this has to be enabled separately). -This supersedes KVM_CREATE_IRQCHIP, creating only local APICs, but no in kernel -IOAPIC or PIC. This also enables in kernel routing of interrupt requests. +This capability also enables in kernel routing of interrupt requests; +when KVM_CAP_SPLIT_IRQCHIP only routes of KVM_IRQ_ROUTING_MSI type are +used in the IRQ routing table. The first args[0] MSI routes are reserved +for the IOAPIC pins. Whenever the LAPIC receives an EOI for these routes, +a KVM_EXIT_IOAPIC_EOI vmexit will be reported to userspace. Fails if VCPU has already been created, or if the irqchip is already in the kernel (i.e. KVM_CREATE_IRQCHIP has already been called). |