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Date: Sat, 14 Jan 2012 23:57:11 +0530
From: Raghavendra K T <raghavendra.kt@...ux.vnet.ibm.com>
To: Jeremy Fitzhardinge <jeremy@...p.org>,
Randy Dunlap <rdunlap@...otime.net>, linux-doc@...r.kernel.org,
KVM <kvm@...r.kernel.org>,
Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
Glauber Costa <glommer@...hat.com>,
Jan Kiszka <jan.kiszka@...mens.com>,
Rik van Riel <riel@...hat.com>,
Dave Jiang <dave.jiang@...el.com>,
"H. Peter Anvin" <hpa@...or.com>,
Thomas Gleixner <tglx@...utronix.de>,
Rob Landley <rlandley@...allels.com>, X86 <x86@...nel.org>,
Gleb Natapov <gleb@...hat.com>, Avi Kivity <avi@...hat.com>,
Alexander Graf <agraf@...e.de>,
Stefano Stabellini <stefano.stabellini@...citrix.com>,
Paul Mackerras <paulus@...ba.org>,
Sedat Dilek <sedat.dilek@...il.com>,
Ingo Molnar <mingo@...hat.com>,
LKML <linux-kernel@...r.kernel.org>,
Greg Kroah-Hartman <gregkh@...e.de>,
Virtualization <virtualization@...ts.linux-foundation.org>,
Marcelo Tosatti <mtosatti@...hat.com>,
Xen <xen-devel@...ts.xensource.com>
Cc: Srivatsa Vaddagiri <vatsa@...ux.vnet.ibm.com>,
Peter Zijlstra <peterz@...radead.org>,
Raghavendra K T <raghavendra.kt@...ux.vnet.ibm.com>,
Sasha Levin <levinsasha928@...il.com>,
Suzuki Poulose <suzuki@...ux.vnet.ibm.com>,
Dave Hansen <dave@...ux.vnet.ibm.com>
Subject: [PATCH RFC V4 5/5] Documentation/kvm : Add documentation on Hypercalls and features used for PV spinlock
Add Documentation on CPUID, KVM_CAP_PVLOCK_KICK, and Hypercalls supported.
KVM_HC_KICK_CPU hypercall added to wakeup halted vcpu in
paravirtual spinlock enabled guest.
KVM_FEATURE_PVLOCK_KICK enables guest to check whether pv spinlock can
be enabled in guest. support in host is queried via
ioctl(KVM_CHECK_EXTENSION, KVM_CAP_PVLOCK_KICK)
A minimal Documentation and template is added for hypercalls.
Signed-off-by: Raghavendra K T <raghavendra.kt@...ux.vnet.ibm.com>
Signed-off-by: Srivatsa Vaddagiri <vatsa@...ux.vnet.ibm.com>
---
diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index e2a4b52..1583bc7 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -1109,6 +1109,13 @@ support. Instead it is reported via
if that returns true and you use KVM_CREATE_IRQCHIP, or if you emulate the
feature in userspace, then you can enable the feature for KVM_SET_CPUID2.
+Paravirtualized ticket spinlocks can be enabled in guest by checking whether
+support exists in host via,
+
+ ioctl(KVM_CHECK_EXTENSION, KVM_CAP_PVLOCK_KICK)
+
+if this call return true, guest can use the feature.
+
4.47 KVM_PPC_GET_PVINFO
Capability: KVM_CAP_PPC_GET_PVINFO
diff --git a/Documentation/virtual/kvm/cpuid.txt b/Documentation/virtual/kvm/cpuid.txt
index 8820685..c7fc0da 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_PVLOCK_KICK || 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 0000000..7872da5
--- /dev/null
+++ b/Documentation/virtual/kvm/hypercalls.txt
@@ -0,0 +1,54 @@
+KVM Hypercalls Documentation
+===========================
+Template for documentation is
+The documenenation for hypercalls should inlcude
+1. Hypercall name, value.
+2. Architecture(s)
+3. Purpose
+
+
+1. KVM_HC_VAPIC_POLL_IRQ
+------------------------
+value: 1
+Architecture: x86
+Purpose:
+
+2. KVM_HC_MMU_OP
+------------------------
+value: 2
+Architecture: x86
+Purpose: Support MMU operations such as writing to PTE,
+flushing TLB, release PT.
+
+3. KVM_HC_FEATURES
+------------------------
+value: 3
+Architecture: PPC
+Purpose:
+
+4. KVM_HC_PPC_MAP_MAGIC_PAGE
+------------------------
+value: 4
+Architecture: PPC
+Purpose: To enable communication between the hypervisor and guest there is a
+new shared page that contains parts of supervisor visible register state.
+The guest can map this shared page using this hypercall.
+
+5. KVM_HC_KICK_CPU
+------------------------
+value: 5
+Architecture: x86
+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 (unless yield_on_hlt=0) 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.
--
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