| Message ID | 20221104062105.4119003-2-usama.arif@bytedance.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: arm64: implement vcpu_is_preempted check | expand |
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. [...]
On 07/11/2022 17:56, Punit Agrawal wrote: > 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. > Will make it clearer in the next revision. Thanks. > [...] >
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.