On Sun, Jun 02, 2013 at 12:56:24AM +0530, Raghavendra K T wrote: > Documentation/kvm : Add documentation on Hypercalls and features used for PV spinlock > > From: Raghavendra K T <raghavendra.kt@xxxxxxxxxxxxxxxxxx> > > KVM_HC_KICK_CPU hypercall added to wakeup halted vcpu in paravirtual spinlock > enabled guest. > > KVM_FEATURE_PV_UNHALT enables guest to check whether pv spinlock can be enabled > in guest. > > Thanks Vatsa for rewriting KVM_HC_KICK_CPU > > Signed-off-by: Srivatsa Vaddagiri <vatsa@xxxxxxxxxxxxxxxxxx> > Signed-off-by: Raghavendra K T <raghavendra.kt@xxxxxxxxxxxxxxxxxx> > --- > Documentation/virtual/kvm/cpuid.txt | 4 ++++ > Documentation/virtual/kvm/hypercalls.txt | 13 +++++++++++++ > 2 files changed, 17 insertions(+) > > diff --git a/Documentation/virtual/kvm/cpuid.txt b/Documentation/virtual/kvm/cpuid.txt > index 83afe65..654f43c 100644 > --- a/Documentation/virtual/kvm/cpuid.txt > +++ b/Documentation/virtual/kvm/cpuid.txt > @@ -43,6 +43,10 @@ KVM_FEATURE_CLOCKSOURCE2 || 3 || kvmclock available at msrs > KVM_FEATURE_ASYNC_PF || 4 || async pf can be enabled by > || || writing to msr 0x4b564d02 > ------------------------------------------------------------------------------ > +KVM_FEATURE_PV_UNHALT || 6 || guest checks this feature bit > + || || before enabling paravirtualized > + || || spinlock support. > +------------------------------------------------------------------------------ > KVM_FEATURE_CLOCKSOURCE_STABLE_BIT || 24 || host will warn if no guest-side > || || per-cpu warps are expected in > || || kvmclock. > diff --git a/Documentation/virtual/kvm/hypercalls.txt b/Documentation/virtual/kvm/hypercalls.txt > index ea113b5..2a4da11 100644 > --- a/Documentation/virtual/kvm/hypercalls.txt > +++ b/Documentation/virtual/kvm/hypercalls.txt > @@ -64,3 +64,16 @@ 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 occurence 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 of the vcpu to be wokenup. woken up. > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
