root/tools/testing/selftests/kvm/lib/x86_64/ucall.c

DEFINITIONS

1. ucall_init
2. ucall_uninit
3. ucall
4. get_ucall

   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 = nargs <= UCALL_MAX_ARGS ? 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_vm *vm, uint32_t vcpu_id, struct ucall *uc)
  39 {
  40         struct kvm_run *run = vcpu_state(vm, vcpu_id);
  41         struct ucall ucall = {};
  42 
  43         if (run->exit_reason == KVM_EXIT_IO && run->io.port == UCALL_PIO_PORT) {
  44                 struct kvm_regs regs;
  45 
  46                 vcpu_regs_get(vm, vcpu_id, &regs);
  47                 memcpy(&ucall, addr_gva2hva(vm, (vm_vaddr_t)regs.rdi),
  48                        sizeof(ucall));
  49 
  50                 vcpu_run_complete_io(vm, vcpu_id);
  51                 if (uc)
  52                         memcpy(uc, &ucall, sizeof(ucall));
  53         }
  54 
  55         return ucall.cmd;
  56 }