1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * ucall support. A ucall is a "hypercall to userspace". 4 * 5 * Copyright (C) 2018, Red Hat, Inc. 6 */ 7 #include "kvm_util.h" 8 9 #define UCALL_PIO_PORT ((uint16_t)0x1000) 10 11 void ucall_init(struct kvm_vm *vm, void *arg) 12 { 13 } 14 15 void ucall_uninit(struct kvm_vm *vm) 16 { 17 } 18 19 void ucall(uint64_t cmd, int nargs, ...) 20 { 21 struct ucall uc = { 22 .cmd = cmd, 23 }; 24 va_list va; 25 int i; 26 27 nargs = min(nargs, UCALL_MAX_ARGS); 28 29 va_start(va, nargs); 30 for (i = 0; i < nargs; ++i) 31 uc.args[i] = va_arg(va, uint64_t); 32 va_end(va); 33 34 asm volatile("in %[port], %%al" 35 : : [port] "d" (UCALL_PIO_PORT), "D" (&uc) : "rax", "memory"); 36 } 37 38 uint64_t get_ucall(struct kvm_vcpu *vcpu, struct ucall *uc) 39 { 40 struct kvm_run *run = vcpu->run; 41 struct ucall ucall = {}; 42 43 if (uc) 44 memset(uc, 0, sizeof(*uc)); 45 46 if (run->exit_reason == KVM_EXIT_IO && run->io.port == UCALL_PIO_PORT) { 47 struct kvm_regs regs; 48 49 vcpu_regs_get(vcpu, ®s); 50 memcpy(&ucall, addr_gva2hva(vcpu->vm, (vm_vaddr_t)regs.rdi), 51 sizeof(ucall)); 52 53 vcpu_run_complete_io(vcpu); 54 if (uc) 55 memcpy(uc, &ucall, sizeof(ucall)); 56 } 57 58 return ucall.cmd; 59 } 60