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Diffstat (limited to 'Documentation/virtual')
| -rw-r--r-- | Documentation/virtual/kvm/api.txt | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt index a1d344d5ff4c..681871311d3e 100644 --- a/Documentation/virtual/kvm/api.txt +++ b/Documentation/virtual/kvm/api.txt @@ -180,6 +180,19 @@ KVM_CHECK_EXTENSION ioctl() to determine the value for max_vcpus at run-time. If the KVM_CAP_NR_VCPUS does not exist, you should assume that max_vcpus is 4 cpus max. +On powerpc using book3s_hv mode, the vcpus are mapped onto virtual +threads in one or more virtual CPU cores. (This is because the +hardware requires all the hardware threads in a CPU core to be in the +same partition.) The KVM_CAP_PPC_SMT capability indicates the number +of vcpus per virtual core (vcore). The vcore id is obtained by +dividing the vcpu id by the number of vcpus per vcore. The vcpus in a +given vcore will always be in the same physical core as each other +(though that might be a different physical core from time to time). +Userspace can control the threading (SMT) mode of the guest by its +allocation of vcpu ids. For example, if userspace wants +single-threaded guest vcpus, it should make all vcpu ids be a multiple +of the number of vcpus per vcore. + 4.8 KVM_GET_DIRTY_LOG (vm ioctl) Capability: basic |