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Diffstat (limited to 'Documentation/virtual')
| -rw-r--r-- | Documentation/virtual/kvm/api.txt | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt index 07e4cdf02407..da3943586a2b 100644 --- a/Documentation/virtual/kvm/api.txt +++ b/Documentation/virtual/kvm/api.txt @@ -3035,6 +3035,31 @@ Returns: 0 on success, -1 on error Queues an SMI on the thread's vcpu. +4.97 KVM_CAP_PPC_MULTITCE + +Capability: KVM_CAP_PPC_MULTITCE +Architectures: ppc +Type: vm + +This capability means the kernel is capable of handling hypercalls +H_PUT_TCE_INDIRECT and H_STUFF_TCE without passing those into the user +space. This significantly accelerates DMA operations for PPC KVM guests. +User space should expect that its handlers for these hypercalls +are not going to be called if user space previously registered LIOBN +in KVM (via KVM_CREATE_SPAPR_TCE or similar calls). + +In order to enable H_PUT_TCE_INDIRECT and H_STUFF_TCE use in the guest, +user space might have to advertise it for the guest. For example, +IBM pSeries (sPAPR) guest starts using them if "hcall-multi-tce" is +present in the "ibm,hypertas-functions" device-tree property. + +The hypercalls mentioned above may or may not be processed successfully +in the kernel based fast path. If they can not be handled by the kernel, +they will get passed on to user space. So user space still has to have +an implementation for these despite the in kernel acceleration. + +This capability is always enabled. + 5. The kvm_run structure ------------------------ |