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SubjectRe: [External] Re: [RFC 1/6] KVM: arm64: Document PV-lock interface
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Hi,

Thanks for the review. I will include the changes in the next version I
send for pvlock. I have sent a patch to fix pvtime here
https://lore.kernel.org/all/20221103131210.3603385-1-usama.arif@bytedance.com/.

Usama

On 03/11/2022 03:50, Bagas Sanjaya wrote:
> On Wed, Nov 02, 2022 at 04:13:35PM +0000, Usama Arif wrote:
>> + ============= ======== ==========
>> + Function ID: (uint32) 0xC6000020
>> + PV_call_id: (uint32) The function to query for support.
>> + Currently only PV_LOCK_PREEMPTED is supported.
>> + Return value: (int64) NOT_SUPPORTED (-1) or SUCCESS (0) if the relevant
>> + PV-lock feature is supported by the hypervisor.
>> + ============= ======== ==========
>> +
>> +PV_LOCK_PREEMPTED
>> + ============= ======== ==========
>> + Function ID: (uint32) 0xC6000021
>> + Return value: (int64) IPA of the pv lock data structure for this
>> + VCPU. On failure:
>> + NOT_SUPPORTED (-1)
>> + ============= ======== ==========
>> +
>
> You need to fix up these tables above:
>
> ---- >8 ----
>
> diff --git a/Documentation/virt/kvm/arm/pvlock.rst b/Documentation/virt/kvm/arm/pvlock.rst
> index 766aeef50b2d31..940a1cb221bc90 100644
> --- a/Documentation/virt/kvm/arm/pvlock.rst
> +++ b/Documentation/virt/kvm/arm/pvlock.rst
> @@ -15,21 +15,23 @@ The existence of the PV_LOCK hypercall should be probed using the SMCCC 1.1
> ARCH_FEATURES mechanism before calling it.
>
> PV_LOCK_FEATURES
> - ============= ======== ==========
> +
> + ============= ======== =================================================
> Function ID: (uint32) 0xC6000020
> PV_call_id: (uint32) The function to query for support.
> Currently only PV_LOCK_PREEMPTED is supported.
> Return value: (int64) NOT_SUPPORTED (-1) or SUCCESS (0) if the relevant
> PV-lock feature is supported by the hypervisor.
> - ============= ======== ==========
> + ============= ======== =================================================
>
> PV_LOCK_PREEMPTED
> - ============= ======== ==========
> +
> + ============= ======== ==========================================
> Function ID: (uint32) 0xC6000021
> 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
>
> The similar fixup should also be made to the tables in
> Documentation/virt/kvm/arm/pvtime.rst, though.
>
>> +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 structure will be present within a reserved region of the normal memory
>> +given to the guest. The guest should not attempt to write into this memory.
>> +There is a structure per VCPU of the guest.
>> +
>> +For the user space interface see Documentation/virt/kvm/devices/vcpu.rst
>> +section "4. GROUP: KVM_ARM_VCPU_PVLOCK_CTRL".
>
> Use reST labels for cross-referencing to the documentation section:
>
> ---- >8 ----
>
> diff --git a/Documentation/virt/kvm/arm/pvlock.rst b/Documentation/virt/kvm/arm/pvlock.rst
> index 940a1cb221bc90..4e9d09b76ef033 100644
> --- a/Documentation/virt/kvm/arm/pvlock.rst
> +++ b/Documentation/virt/kvm/arm/pvlock.rst
> @@ -62,5 +62,5 @@ The structure will be present within a reserved region of the normal memory
> given to the guest. The guest should not attempt to write into this memory.
> There is a structure per VCPU of the guest.
>
> -For the user space interface see Documentation/virt/kvm/devices/vcpu.rst
> -section "4. GROUP: KVM_ARM_VCPU_PVLOCK_CTRL".
> +For the user space interface see :ref:`KVM_VCPU_TSC_CTRL in Generic vcpu
> +interface documentation <kvm-vcpu-tsc-ctrl>`.
> diff --git a/Documentation/virt/kvm/devices/vcpu.rst b/Documentation/virt/kvm/devices/vcpu.rst
> index 223ac2fe62f01f..6532f61073a39c 100644
> --- a/Documentation/virt/kvm/devices/vcpu.rst
> +++ b/Documentation/virt/kvm/devices/vcpu.rst
> @@ -194,6 +194,8 @@ base address must be 64 byte aligned and exist within a valid guest memory
> region. See Documentation/virt/kvm/arm/pvtime.rst for more information
> including the layout of the stolen time structure.
>
> +.. _kvm-vcpu-tsc-ctrl:
> +
> 4. GROUP: KVM_VCPU_TSC_CTRL
> ===========================
>
>
> Also, you need to add the documentation to table of contents (index):
>
> ---- >8 ----
>
> diff --git a/Documentation/virt/kvm/arm/index.rst b/Documentation/virt/kvm/arm/index.rst
> index e8484843215808..b8499dc00a6a96 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
>
> Thanks.
>

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