lkml.org 
[lkml]   [2022]   [Nov]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [v2 1/6] KVM: arm64: Document PV-lock interface
Date
Hi Usama,

Usama Arif <usama.arif@bytedance.com> 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@huawei.com>
> Signed-off-by: Usama Arif <usama.arif@bytedance.com>
> ---
> 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.

The text above doesn't match the description in the table. Please update
the texts to align them with the code.

[...]

\
 
 \ /
  Last update: 2022-11-07 19:02    [W:0.149 / U:0.228 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site