1.. SPDX-License-Identifier: GPL-2.0 2 3PTP_KVM support for arm/arm64 4============================= 5 6PTP_KVM is used for high precision time sync between host and guests. 7It relies on transferring the wall clock and counter value from the 8host to the guest using a KVM-specific hypercall. 9 10* ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID: 0x86000001 11 12This hypercall uses the SMC32/HVC32 calling convention: 13 14ARM_SMCCC_VENDOR_HYP_KVM_PTP_FUNC_ID 15 ============== ======== ===================================== 16 Function ID: (uint32) 0x86000001 17 Arguments: (uint32) KVM_PTP_VIRT_COUNTER(0) 18 KVM_PTP_PHYS_COUNTER(1) 19 Return Values: (int32) NOT_SUPPORTED(-1) on error, or 20 (uint32) Upper 32 bits of wall clock time (r0) 21 (uint32) Lower 32 bits of wall clock time (r1) 22 (uint32) Upper 32 bits of counter (r2) 23 (uint32) Lower 32 bits of counter (r3) 24 Endianness: No Restrictions. 25 ============== ======== ===================================== 26