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Diffstat (limited to 'Documentation/virtual/kvm/hypercalls.txt')
| -rw-r--r-- | Documentation/virtual/kvm/hypercalls.txt | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/Documentation/virtual/kvm/hypercalls.txt b/Documentation/virtual/kvm/hypercalls.txt index ea113b5d87a..c8d040e2704 100644 --- a/Documentation/virtual/kvm/hypercalls.txt +++ b/Documentation/virtual/kvm/hypercalls.txt @@ -17,6 +17,9 @@ S390: S390 uses diagnose instruction as hypercall (0x500) along with hypercall number in R1. + For further information on the S390 diagnose call as supported by KVM, + refer to Documentation/virtual/kvm/s390-diag.txt. + PowerPC: It uses R3-R10 and hypercall number in R11. R4-R11 are used as output registers. Return value is placed in R3. @@ -64,3 +67,17 @@ Purpose: To enable communication between the hypervisor and guest there is a shared page that contains parts of supervisor visible register state. The guest can map this shared page to access its supervisor register through memory using this hypercall. + +5. KVM_HC_KICK_CPU +------------------------ +Architecture: x86 +Status: active +Purpose: Hypercall used to wakeup a vcpu from HLT state +Usage example : A vcpu of a paravirtualized guest that is busywaiting in guest +kernel mode for an event to occur (ex: a spinlock to become available) can +execute HLT instruction once it has busy-waited for more than a threshold +time-interval. Execution of HLT instruction would cause the hypervisor to put +the vcpu to sleep until occurrence of an appropriate event. Another vcpu of the +same guest can wakeup the sleeping vcpu by issuing KVM_HC_KICK_CPU hypercall, +specifying APIC ID (a1) of the vcpu to be woken up. An additional argument (a0) +is used in the hypercall for future use. |