diff options
Diffstat (limited to 'Documentation/virtual/kvm/arm')
-rw-r--r-- | Documentation/virtual/kvm/arm/hyp-abi.txt | 53 | ||||
-rw-r--r-- | Documentation/virtual/kvm/arm/psci.txt | 30 |
2 files changed, 0 insertions, 83 deletions
diff --git a/Documentation/virtual/kvm/arm/hyp-abi.txt b/Documentation/virtual/kvm/arm/hyp-abi.txt deleted file mode 100644 index a20a0bee268d..000000000000 --- a/Documentation/virtual/kvm/arm/hyp-abi.txt +++ /dev/null @@ -1,53 +0,0 @@ -* Internal ABI between the kernel and HYP - -This file documents the interaction between the Linux kernel and the -hypervisor layer when running Linux as a hypervisor (for example -KVM). It doesn't cover the interaction of the kernel with the -hypervisor when running as a guest (under Xen, KVM or any other -hypervisor), or any hypervisor-specific interaction when the kernel is -used as a host. - -On arm and arm64 (without VHE), the kernel doesn't run in hypervisor -mode, but still needs to interact with it, allowing a built-in -hypervisor to be either installed or torn down. - -In order to achieve this, the kernel must be booted at HYP (arm) or -EL2 (arm64), allowing it to install a set of stubs before dropping to -SVC/EL1. These stubs are accessible by using a 'hvc #0' instruction, -and only act on individual CPUs. - -Unless specified otherwise, any built-in hypervisor must implement -these functions (see arch/arm{,64}/include/asm/virt.h): - -* r0/x0 = HVC_SET_VECTORS - r1/x1 = vectors - - Set HVBAR/VBAR_EL2 to 'vectors' to enable a hypervisor. 'vectors' - must be a physical address, and respect the alignment requirements - of the architecture. Only implemented by the initial stubs, not by - Linux hypervisors. - -* r0/x0 = HVC_RESET_VECTORS - - Turn HYP/EL2 MMU off, and reset HVBAR/VBAR_EL2 to the initials - stubs' exception vector value. This effectively disables an existing - hypervisor. - -* r0/x0 = HVC_SOFT_RESTART - r1/x1 = restart address - x2 = x0's value when entering the next payload (arm64) - x3 = x1's value when entering the next payload (arm64) - x4 = x2's value when entering the next payload (arm64) - - Mask all exceptions, disable the MMU, move the arguments into place - (arm64 only), and jump to the restart address while at HYP/EL2. This - hypercall is not expected to return to its caller. - -Any other value of r0/x0 triggers a hypervisor-specific handling, -which is not documented here. - -The return value of a stub hypercall is held by r0/x0, and is 0 on -success, and HVC_STUB_ERR on error. A stub hypercall is allowed to -clobber any of the caller-saved registers (x0-x18 on arm64, r0-r3 and -ip on arm). It is thus recommended to use a function call to perform -the hypercall. diff --git a/Documentation/virtual/kvm/arm/psci.txt b/Documentation/virtual/kvm/arm/psci.txt deleted file mode 100644 index aafdab887b04..000000000000 --- a/Documentation/virtual/kvm/arm/psci.txt +++ /dev/null @@ -1,30 +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) |