From: Zengruan Ye yezengruan@huawei.com
euleros inclusion category: feature bugzilla: NA CVE: NA
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Introduce a paravirtualization interface for KVM/arm64 to PV-sched.
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@huawei.com Reviewed-by: zhanghailiang zhang.zhanghailiang@huawei.com Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- Documentation/virtual/kvm/arm/pvsched.txt | 56 +++++++++++++++++++++++ 1 file changed, 56 insertions(+) create mode 100644 Documentation/virtual/kvm/arm/pvsched.txt
diff --git a/Documentation/virtual/kvm/arm/pvsched.txt b/Documentation/virtual/kvm/arm/pvsched.txt new file mode 100644 index 000000000000..1d5aefc290ec --- /dev/null +++ b/Documentation/virtual/kvm/arm/pvsched.txt @@ -0,0 +1,56 @@ +Paravirtualized sched support for arm64 +======================================= + +KVM/arm64 provides some hypervisor service calls to support a paravirtualized +sched. + +Some SMCCC compatible hypercalls are defined: + +* PV_SCHED_FEATURES: 0xC5000090 +* PV_SCHED_IPA_INIT: 0xC5000091 +* PV_SCHED_IPA_RELEASE: 0xC5000092 + +The existence of the PV_SCHED hypercall should be probed using the SMCCC 1.1 +ARCH_FEATURES mechanism before calling it. + +PV_SCHED_FEATURES + ============= ======== ========== + Function ID: (uint32) 0xC5000090 + PV_call_id: (uint32) The function to query for support. + Return value: (int64) NOT_SUPPORTED (-1) or SUCCESS (0) if the relevant + PV-sched feature is supported by the hypervisor. + ============= ======== ========== + +PV_SCHED_IPA_INIT + ============= ======== ========== + Function ID: (uint32) 0xC5000091 + Return value: (int64) NOT_SUPPORTED (-1) or SUCCESS (0) if the IPA of + this vCPU's PV data structure is shared to the + hypervisor. + ============= ======== ========== + +PV_SCHED_IPA_RELEASE + ============= ======== ========== + Function ID: (uint32) 0xC5000092 + Return value: (int64) NOT_SUPPORTED (-1) or SUCCESS (0) if the IPA of + this vCPU's PV data structure is released. + ============= ======== ========== + +PV sched state +-------------- + +The structure pointed to by the PV_SCHED_IPA hypercall is as follows: + ++-----------+-------------+-------------+-----------------------------------+ +| Field | Byte Length | Byte Offset | Description | ++===========+=============+=============+===================================+ +| preempted | 4 | 0 | Indicates that 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 0 by the hypervisor prior to scheduling +a vCPU. When the vCPU is scheduled out, the preempted field will be updated +to 1 by the hypervisor.