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author | Takashi Iwai <tiwai@suse.de> | 2019-09-10 14:03:08 +0300 |
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committer | Takashi Iwai <tiwai@suse.de> | 2019-09-10 14:03:08 +0300 |
commit | 7711fb7dac1ab77fd1b4d948f4647a569e4a1ae2 (patch) | |
tree | dd35ad21e0eb13572757dab279ae41f6d953baed /Documentation/virt/kvm/arm/psci.txt | |
parent | 789492f0c86505e63369907bcb1afdf52dec9366 (diff) | |
parent | bb831786117519fc16dfd3eaa7b84e4f6bbb8d99 (diff) | |
download | linux-7711fb7dac1ab77fd1b4d948f4647a569e4a1ae2.tar.xz |
Merge tag 'asoc-v5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound into for-next
ASoC: Updates for v5.4
Quite a big update this time around, particularly in the core
where we've had a lot of cleanups from Morimoto-san - there's
not much functional change but quite a bit of modernization
going on. We've also seen a lot of driver work, a lot of it
cleanups but also some particular drivers.
- Lots and lots of cleanups from Morimoto-san and Yue Haibing.
- Lots of cleanups and enhancements to the Freescale, sunxi dnd
Intel rivers.
- Initial Sound Open Firmware suppot for i.MX8.
- Removal of w90x900 and nuc900 drivers as the platforms are
being removed.
- New support for Cirrus Logic CS47L15 and CS47L92, Freescale
i.MX 7ULP and 8MQ, Meson G12A and NXP UDA1334
Diffstat (limited to 'Documentation/virt/kvm/arm/psci.txt')
-rw-r--r-- | Documentation/virt/kvm/arm/psci.txt | 61 |
1 files changed, 61 insertions, 0 deletions
diff --git a/Documentation/virt/kvm/arm/psci.txt b/Documentation/virt/kvm/arm/psci.txt new file mode 100644 index 000000000000..559586fc9d37 --- /dev/null +++ b/Documentation/virt/kvm/arm/psci.txt @@ -0,0 +1,61 @@ +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 |