Hi Usama,Will make it clearer in the next revision. Thanks.
Usama Arif <usama.arif@xxxxxxxxxxxxx> writes:
Introduce a paravirtualization interface for KVM/arm64 to obtain whether
the VCPU is currently running or not.
The PV lock structure of the guest is allocated by user space.
A hypercall interface is provided for the guest to interrogate the
location of the shared memory structures.
Signed-off-by: Zengruan Ye <yezengruan@xxxxxxxxxx>
Signed-off-by: Usama Arif <usama.arif@xxxxxxxxxxxxx>
---
Documentation/virt/kvm/arm/index.rst | 1 +
Documentation/virt/kvm/arm/pvlock.rst | 52 +++++++++++++++++++++++++
Documentation/virt/kvm/devices/vcpu.rst | 25 ++++++++++++
3 files changed, 78 insertions(+)
create mode 100644 Documentation/virt/kvm/arm/pvlock.rst
diff --git a/Documentation/virt/kvm/arm/index.rst b/Documentation/virt/kvm/arm/index.rst
index e84848432158..b8499dc00a6a 100644
--- a/Documentation/virt/kvm/arm/index.rst
+++ b/Documentation/virt/kvm/arm/index.rst
@@ -10,4 +10,5 @@ ARM
hyp-abi
hypercalls
pvtime
+ pvlock
ptp_kvm
diff --git a/Documentation/virt/kvm/arm/pvlock.rst b/Documentation/virt/kvm/arm/pvlock.rst
new file mode 100644
index 000000000000..d3c391b16d36
--- /dev/null
+++ b/Documentation/virt/kvm/arm/pvlock.rst
@@ -0,0 +1,52 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Paravirtualized lock support for arm64
+======================================
+
+KVM/arm64 provides a hypervisor service call for paravirtualized guests to
+determine whether a VCPU is currently running or not.
+
+A new SMCCC compatible hypercall is defined:
+
+* ARM_SMCCC_VENDOR_HYP_KVM_PV_LOCK_FUNC_ID: 0xC6000002
+
+ARM_SMCCC_VENDOR_HYP_KVM_PV_LOCK_FUNC_ID
+
+ ============= ======== ==========================================
+ Function ID: (uint32) 0xC6000002
+ Return value: (int64) IPA of the pv lock data structure for this
+ VCPU. On failure:
+ NOT_SUPPORTED (-1)
+ ============= ======== ==========================================
+
+The IPA returned by PV_LOCK_PREEMPTED should be mapped by the guest as normal
+memory with inner and outer write back caching attributes, in the inner
+shareable domain.
+
+PV_LOCK_PREEMPTED returns the structure for the calling VCPU.
+
+PV lock state
+-------------
+
+The structure pointed to by the PV_LOCK_PREEMPTED hypercall is as follows:
+
++-----------+-------------+-------------+---------------------------------+
+| Field | Byte Length | Byte Offset | Description |
++===========+=============+=============+=================================+
+| preempted | 8 | 0 | Indicate if the VCPU that owns |
+| | | | this struct is running or not. |
+| | | | Non-zero values mean the VCPU |
+| | | | has been preempted. Zero means |
+| | | | the VCPU is not preempted. |
++-----------+-------------+-------------+---------------------------------+
+
+The preempted field will be updated to 1 by the hypervisor prior to scheduling
+a VCPU. When the VCPU is scheduled out, the preempted field will be updated
+to 0 by the hypervisor.
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