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 <[email protected]>
Signed-off-by: Usama Arif <[email protected]>
---
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 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
+:ref:`Documentation/virt/kvm/devices/vcpu.rst <kvm_arm_vcpu_pvlock_ctrl>`.
\ No newline at end of file
diff --git a/Documentation/virt/kvm/devices/vcpu.rst b/Documentation/virt/kvm/devices/vcpu.rst
index 716aa3edae14..ea81b98f0e19 100644
--- a/Documentation/virt/kvm/devices/vcpu.rst
+++ b/Documentation/virt/kvm/devices/vcpu.rst
@@ -263,3 +263,28 @@ From the destination VMM process:
7. Write the KVM_VCPU_TSC_OFFSET attribute for every vCPU with the
respective value derived in the previous step.
+
+.. _kvm_arm_vcpu_pvlock_ctrl:
+
+5. GROUP: KVM_ARM_VCPU_PVLOCK_CTRL
+==================================
+
+:Architectures: ARM64
+
+5.1 ATTRIBUTE: KVM_ARM_VCPU_PVLOCK_IPA
+--------------------------------------
+
+:Parameters: 64-bit base address
+
+Returns:
+
+ ======= ======================================
+ -ENXIO PV lock not implemented
+ -EEXIST Base address already set for this VCPU
+ -EINVAL Base address not 64 byte aligned
+ ======= ======================================
+
+Specifies the base address of the pv lock structure for this VCPU. The
+base address must be 64 byte aligned and exist within a valid guest memory
+region. See Documentation/virt/kvm/arm/pvlock.rst for more information
+including the layout of the pv lock structure.
--
2.25.1
Hi Usama,
Usama Arif <[email protected]> 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 <[email protected]>
> Signed-off-by: Usama Arif <[email protected]>
> ---
> 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.
[...]
On 07/11/2022 17:56, Punit Agrawal wrote:
> Hi Usama,
>
> Usama Arif <[email protected]> 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 <[email protected]>
>> Signed-off-by: Usama Arif <[email protected]>
>> ---
>> 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.
>
Will make it clearer in the next revision. Thanks.
> [...]
>