On 2012-05-02 12:09, Raghavendra K T wrote:
From: Raghavendra K T raghavendra...@linux.vnet.ibm.com
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 Alex for KVM_HC_FEATURES inputs and Vatsa for rewriting KVM_HC_KICK_CPU
This contains valuable documentation for features that are already
supported. Can you break them out and post as separate patch already?
One comment on them below.
Signed-off-by: Srivatsa Vaddagiri va...@linux.vnet.ibm.com
Signed-off-by: Raghavendra K T raghavendra...@linux.vnet.ibm.com
---
Documentation/virtual/kvm/cpuid.txt |4 ++
Documentation/virtual/kvm/hypercalls.txt | 60
++
2 files changed, 64 insertions(+), 0 deletions(-)
diff --git a/Documentation/virtual/kvm/cpuid.txt
b/Documentation/virtual/kvm/cpuid.txt
index 8820685..062dff9 100644
--- a/Documentation/virtual/kvm/cpuid.txt
+++ b/Documentation/virtual/kvm/cpuid.txt
@@ -39,6 +39,10 @@ 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
new file mode 100644
index 000..bc3f14a
--- /dev/null
+++ b/Documentation/virtual/kvm/hypercalls.txt
@@ -0,0 +1,60 @@
+KVM Hypercalls Documentation
+===
+The template for each hypercall is:
+1. Hypercall name, value.
+2. Architecture(s)
+3. Status (deprecated, obsolete, active)
+4. Purpose
+
+1. KVM_HC_VAPIC_POLL_IRQ
+
+Value: 1
+Architecture: x86
+Purpose: None
Purpose: Trigger guest exit so that the host can check for pending
interrupts on reentry.
+
+2. KVM_HC_MMU_OP
+
+Value: 2
+Architecture: x86
+Status: deprecated.
+Purpose: Support MMU operations such as writing to PTE,
+flushing TLB, release PT.
+
+3. KVM_HC_FEATURES
+
+Value: 3
+Architecture: PPC
+Status: active
+Purpose: Expose hypercall availability to the guest. On x86 platforms, cpuid
+used to enumerate which hypercalls are available. On PPC, either device tree
+based lookup ( which is also what EPAPR dictates) OR KVM specific enumeration
+mechanism (which is this hypercall) can be used.
+
+4. KVM_HC_PPC_MAP_MAGIC_PAGE
+
+Value: 4
+Architecture: PPC
+Status: active
+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
+
+Value: 5
+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.
+
+TODO:
+1. more information on input and output needed?
+2. Add more detail to purpose of hypercalls.
Thanks,
Jan
--
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux
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