59 lines
2.4 KiB
ReStructuredText
59 lines
2.4 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0
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Paravirtualized sched support for arm64
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=======================================
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KVM/arm64 provides some hypervisor service calls to support a paravirtualized
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sched.
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Some SMCCC compatible hypercalls are defined:
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* PV_SCHED_FEATURES: 0xC5000090
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* PV_SCHED_IPA_INIT: 0xC5000091
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* PV_SCHED_IPA_RELEASE: 0xC5000092
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The existence of the PV_SCHED hypercall should be probed using the SMCCC 1.1
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ARCH_FEATURES mechanism before calling it.
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PV_SCHED_FEATURES
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============= ======== ==========
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Function ID: (uint32) 0xC5000090
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PV_call_id: (uint32) The function to query for support.
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Return value: (int64) NOT_SUPPORTED (-1) or SUCCESS (0) if the relevant
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PV-sched feature is supported by the hypervisor.
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============= ======== ==========
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PV_SCHED_IPA_INIT
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============= ======== ==========
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Function ID: (uint32) 0xC5000091
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Return value: (int64) NOT_SUPPORTED (-1) or SUCCESS (0) if the IPA of
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this vCPU's PV data structure is shared to the
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hypervisor.
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============= ======== ==========
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PV_SCHED_IPA_RELEASE
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============= ======== ==========
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Function ID: (uint32) 0xC5000092
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Return value: (int64) NOT_SUPPORTED (-1) or SUCCESS (0) if the IPA of
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this vCPU's PV data structure is released.
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============= ======== ==========
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PV sched state
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--------------
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The structure pointed to by the PV_SCHED_IPA hypercall is as follows:
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+-----------+-------------+-------------+-----------------------------------+
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| Field | Byte Length | Byte Offset | Description |
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+===========+=============+=============+===================================+
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| preempted | 4 | 0 | Indicates that the vCPU that owns |
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| | | | this struct is running or not. |
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| | | | Non-zero values mean the vCPU has |
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| | | | been preempted. Zero means the |
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| | | | vCPU is not preempted. |
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+-----------+-------------+-------------+-----------------------------------+
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The preempted field will be updated to 0 by the hypervisor prior to scheduling
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a vCPU. When the vCPU is scheduled out, the preempted field will be updated
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to 1 by the hypervisor.
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