62 lines
3.0 KiB
Plaintext
62 lines
3.0 KiB
Plaintext
KVM implements the PSCI (Power State Coordination Interface)
|
|
specification in order to provide services such as CPU on/off, reset
|
|
and power-off to the guest.
|
|
|
|
The PSCI specification is regularly updated to provide new features,
|
|
and KVM implements these updates if they make sense from a virtualization
|
|
point of view.
|
|
|
|
This means that a guest booted on two different versions of KVM can
|
|
observe two different "firmware" revisions. This could cause issues if
|
|
a given guest is tied to a particular PSCI revision (unlikely), or if
|
|
a migration causes a different PSCI version to be exposed out of the
|
|
blue to an unsuspecting guest.
|
|
|
|
In order to remedy this situation, KVM exposes a set of "firmware
|
|
pseudo-registers" that can be manipulated using the GET/SET_ONE_REG
|
|
interface. These registers can be saved/restored by userspace, and set
|
|
to a convenient value if required.
|
|
|
|
The following register is defined:
|
|
|
|
* KVM_REG_ARM_PSCI_VERSION:
|
|
|
|
- Only valid if the vcpu has the KVM_ARM_VCPU_PSCI_0_2 feature set
|
|
(and thus has already been initialized)
|
|
- Returns the current PSCI version on GET_ONE_REG (defaulting to the
|
|
highest PSCI version implemented by KVM and compatible with v0.2)
|
|
- Allows any PSCI version implemented by KVM and compatible with
|
|
v0.2 to be set with SET_ONE_REG
|
|
- Affects the whole VM (even if the register view is per-vcpu)
|
|
|
|
* KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1:
|
|
Holds the state of the firmware support to mitigate CVE-2017-5715, as
|
|
offered by KVM to the guest via a HVC call. The workaround is described
|
|
under SMCCC_ARCH_WORKAROUND_1 in [1].
|
|
Accepted values are:
|
|
KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_NOT_AVAIL: KVM does not offer
|
|
firmware support for the workaround. The mitigation status for the
|
|
guest is unknown.
|
|
KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_AVAIL: The workaround HVC call is
|
|
available to the guest and required for the mitigation.
|
|
KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_1_NOT_REQUIRED: The workaround HVC call
|
|
is available to the guest, but it is not needed on this VCPU.
|
|
|
|
* KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2:
|
|
Holds the state of the firmware support to mitigate CVE-2018-3639, as
|
|
offered by KVM to the guest via a HVC call. The workaround is described
|
|
under SMCCC_ARCH_WORKAROUND_2 in [1].
|
|
Accepted values are:
|
|
KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_AVAIL: A workaround is not
|
|
available. KVM does not offer firmware support for the workaround.
|
|
KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_UNKNOWN: The workaround state is
|
|
unknown. KVM does not offer firmware support for the workaround.
|
|
KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_AVAIL: The workaround is available,
|
|
and can be disabled by a vCPU. If
|
|
KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_ENABLED is set, it is active for
|
|
this vCPU.
|
|
KVM_REG_ARM_SMCCC_ARCH_WORKAROUND_2_NOT_REQUIRED: The workaround is
|
|
always active on this vCPU or it is not needed.
|
|
|
|
[1] https://developer.arm.com/-/media/developer/pdf/ARM_DEN_0070A_Firmware_interfaces_for_mitigating_CVE-2017-5715.pdf
|