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
ucall_init(struct kvm_vm * vm,void * arg)11 void ucall_init(struct kvm_vm *vm, void *arg)
12 {
13 }
14
ucall_uninit(struct kvm_vm * vm)15 void ucall_uninit(struct kvm_vm *vm)
16 {
17 }
18
ucall(uint64_t cmd,int nargs,...)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
get_ucall(struct kvm_vm * vm,uint32_t vcpu_id,struct ucall * uc)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 (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, ®s);
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