LXR linux/tools/testing/selftests/kvm/lib/x86

   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
  11void ucall_init(struct kvm_vm *vm, void *arg)
  12{
  13}
  14
  15void ucall_uninit(struct kvm_vm *vm)
  16{
  17}
  18
  19void 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
  38uint64_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 (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(vm, vcpu_id, &regs);
  50                memcpy(&ucall, addr_gva2hva(vm, (vm_vaddr_t)regs.rdi),
  51                       sizeof(ucall));
  52
  53                vcpu_run_complete_io(vm, vcpu_id);
  54                if (uc)
  55                        memcpy(uc, &ucall, sizeof(ucall));
  56        }
  57
  58        return ucall.cmd;
  59}
  60