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Diffstat (limited to 'Documentation/virt/kvm/arm/psci.txt')
| -rw-r--r-- | Documentation/virt/kvm/arm/psci.txt | 61 |
1 files changed, 0 insertions, 61 deletions
diff --git a/Documentation/virt/kvm/arm/psci.txt b/Documentation/virt/kvm/arm/psci.txt deleted file mode 100644 index 559586fc9d37..000000000000 --- a/Documentation/virt/kvm/arm/psci.txt +++ /dev/null @@ -1,61 +0,0 @@ -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 |