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Diffstat (limited to 'Documentation/virt/kvm/api.rst')
| -rw-r--r-- | Documentation/virt/kvm/api.rst | 33 |
1 files changed, 29 insertions, 4 deletions
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index 192adcb61add..42403dfe9496 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -6256,15 +6256,40 @@ to the byte array. __u64 nr; __u64 args[6]; __u64 ret; - __u32 longmode; - __u32 pad; + __u64 flags; } hypercall; -Unused. This was once used for 'hypercall to userspace'. To implement -such functionality, use KVM_EXIT_IO (x86) or KVM_EXIT_MMIO (all except s390). + +It is strongly recommended that userspace use ``KVM_EXIT_IO`` (x86) or +``KVM_EXIT_MMIO`` (all except s390) to implement functionality that +requires a guest to interact with host userpace. .. note:: KVM_EXIT_IO is significantly faster than KVM_EXIT_MMIO. +For arm64: +---------- + +SMCCC exits can be enabled depending on the configuration of the SMCCC +filter. See the Documentation/virt/kvm/devices/vm.rst +``KVM_ARM_SMCCC_FILTER`` for more details. + +``nr`` contains the function ID of the guest's SMCCC call. Userspace is +expected to use the ``KVM_GET_ONE_REG`` ioctl to retrieve the call +parameters from the vCPU's GPRs. + +Definition of ``flags``: + - ``KVM_HYPERCALL_EXIT_SMC``: Indicates that the guest used the SMC + conduit to initiate the SMCCC call. If this bit is 0 then the guest + used the HVC conduit for the SMCCC call. + + - ``KVM_HYPERCALL_EXIT_16BIT``: Indicates that the guest used a 16bit + instruction to initiate the SMCCC call. If this bit is 0 then the + guest used a 32bit instruction. An AArch64 guest always has this + bit set to 0. + +At the point of exit, PC points to the instruction immediately following +the trapping instruction. + :: /* KVM_EXIT_TPR_ACCESS */ |