[PATCH 1/5] KVM: arm64: Document PV-lock interface

[yezengruan]

From: Zengruan Ye <yezengruan@xxxxxxxxxx>

Introduce a paravirtualization interface for KVM/arm64 to obtain the vcpu
is currently running or not.

A hypercall interface is provided for the guest to interrogate the
hypervisor's support for this interface and the location of the shared
memory structures.

Signed-off-by: Zengruan Ye <yezengruan@xxxxxxxxxx>
---
 Documentation/virt/kvm/arm/pvlock.rst | 31 +++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)
 create mode 100644 Documentation/virt/kvm/arm/pvlock.rst

diff --git a/Documentation/virt/kvm/arm/pvlock.rst b/Documentation/virt/kvm/arm/pvlock.rst
new file mode 100644
index 000000000000..eec0c36edf17
--- /dev/null
+++ b/Documentation/virt/kvm/arm/pvlock.rst
@@ -0,0 +1,31 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Paravirtualized lock support for arm64
+======================================
+
+KVM/arm64 provids some hypervisor service calls to support a paravirtualized
+guest obtaining the vcpu is currently running or not.
+
+Two new SMCCC compatible hypercalls are defined:
+
+* PV_LOCK_FEATURES:   0xC5000040
+* PV_LOCK_PREEMPTED:  0xC5000041
+
+The existence of the PV_LOCK hypercall should be probed using the SMCCC 1.1
+ARCH_FEATURES mechanism before calling it.
+
+PV_LOCK_FEATURES
+    ============= ========    ==========
+    Function ID:  (uint32)    0xC5000040
+    PV_call_id:   (uint32)    The function to query for support.
+    Return value: (int64)     NOT_SUPPORTED (-1) or SUCCESS (0) if the relevant
+                              PV-lock feature is supported by the hypervisor.
+    ============= ========    ==========
+
+PV_LOCK_PREEMPTED
+    ============= ========    ==========
+    Function ID:  (uint32)    0xC5000041
+    Return value: (int64)     NOT_SUPPORTED (-1) or SUCCESS (0) if the IPA of
+                              this vcpu's pv data structure is configured by
+                              the hypervisor.
+    ============= ========    ==========
-- 
2.19.1