On 2020-11-11 06:22, Jianyong Wu wrote:
PTP_KVM implementation depends on hypercall using SMCCC. So we
introduce a new SMCCC service ID. This doc explains how does the
ID define and how does PTP_KVM works on arm/arm64.
Signed-off-by: Jianyong Wu <jianyong.wu@xxxxxxx>
---
Documentation/virt/kvm/api.rst | 9 +++++++
Documentation/virt/kvm/arm/index.rst | 1 +
Documentation/virt/kvm/arm/ptp_kvm.rst | 29 +++++++++++++++++++++
Documentation/virt/kvm/timekeeping.rst | 35 ++++++++++++++++++++++++++
4 files changed, 74 insertions(+)
create mode 100644 Documentation/virt/kvm/arm/ptp_kvm.rst
diff --git a/Documentation/virt/kvm/api.rst
b/Documentation/virt/kvm/api.rst
index 36d5f1f3c6dd..9843dbcbf770 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -6391,3 +6391,12 @@ When enabled, KVM will disable paravirtual
features provided to the
guest according to the bits in the KVM_CPUID_FEATURES CPUID leaf
(0x40000001). Otherwise, a guest may use the paravirtual features
regardless of what has actually been exposed through the CPUID leaf.
+
+8.27 KVM_CAP_PTP_KVM
+--------------------
+
+:Architectures: arm64
+
+This capability indicates that KVM virtual PTP service is supported in
host.
+It must company with the implementation of KVM virtual PTP service in
host
+so VMM can probe if there is the service in host by checking this
capability.
diff --git a/Documentation/virt/kvm/arm/index.rst
b/Documentation/virt/kvm/arm/index.rst
index 3e2b2aba90fc..78a9b670aafe 100644
--- a/Documentation/virt/kvm/arm/index.rst
+++ b/Documentation/virt/kvm/arm/index.rst
@@ -10,3 +10,4 @@ ARM
hyp-abi
psci
pvtime
+ ptp_kvm
diff --git a/Documentation/virt/kvm/arm/ptp_kvm.rst
b/Documentation/virt/kvm/arm/ptp_kvm.rst
new file mode 100644
index 000000000000..bb1e6cfefe44
--- /dev/null
+++ b/Documentation/virt/kvm/arm/ptp_kvm.rst
@@ -0,0 +1,29 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+PTP_KVM support for arm/arm64
+=============================
+
+PTP_KVM is used for time sync between guest and host in a high
precision.
+It needs to get the wall time and counter value from the host and
transfer these
+to guest via hypercall service. So one more hypercall service has been
added.
+
+This new SMCCC hypercall is defined as:
+
+* ARM_SMCCC_HYP_KVM_PTP_FUNC_ID: 0x86000001
+
+As both 32 and 64-bits ptp_kvm client should be supported, we choose
SMC32/HVC32
+calling convention.
+
+ARM_SMCCC_HYP_KVM_PTP_FUNC_ID:
+
+ ============= ========== ==========
+ Function ID: (uint32) 0x86000001
+ Arguments: (uint32) ARM_PTP_PHY_COUNTER(1) or
ARM_PTP_VIRT_COUNTER(0)
+ which indicate acquiring physical
counter or
+ virtual counter respectively.
+ return value: (uint32) NOT_SUPPORTED(-1) or val0 and val1
represent
+ wall clock time and val2 and val3
represent
+ counter cycle.
This needs a lot more description:
- Which word contains what part of the data (upper/lower part of the
64bit data)
- The endianness of the data returned
M.
--
Jazz is not dead. It just smells funny...
