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Diffstat (limited to 'Documentation/virtual/kvm/devices/xive.txt')
| -rw-r--r-- | Documentation/virtual/kvm/devices/xive.txt | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/Documentation/virtual/kvm/devices/xive.txt b/Documentation/virtual/kvm/devices/xive.txt index 69ee62d3d4dc..9a24a4525253 100644 --- a/Documentation/virtual/kvm/devices/xive.txt +++ b/Documentation/virtual/kvm/devices/xive.txt @@ -43,6 +43,25 @@ the legacy interrupt mode, referred as XICS (POWER7/8). manage the source: to trigger, to EOI, to turn off the source for instance. + 3. Device pass-through + + When a device is passed-through into the guest, the source + interrupts are from a different HW controller (PHB4) and the ESB + pages exposed to the guest should accommadate this change. + + The passthru_irq helpers, kvmppc_xive_set_mapped() and + kvmppc_xive_clr_mapped() are called when the device HW irqs are + mapped into or unmapped from the guest IRQ number space. The KVM + device extends these helpers to clear the ESB pages of the guest IRQ + number being mapped and then lets the VM fault handler repopulate. + The handler will insert the ESB page corresponding to the HW + interrupt of the device being passed-through or the initial IPI ESB + page if the device has being removed. + + The ESB remapping is fully transparent to the guest and the OS + device driver. All handling is done within VFIO and the above + helpers in KVM-PPC. + * Groups: 1. KVM_DEV_XIVE_GRP_CTRL |