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 /*
10 * ucall_exit_mmio_addr holds per-VM values (global data is duplicated by each
11 * VM), it must not be accessed from host code.
12 */
13 static vm_vaddr_t *ucall_exit_mmio_addr;
14
ucall_arch_init(struct kvm_vm * vm,vm_paddr_t mmio_gpa)15 void ucall_arch_init(struct kvm_vm *vm, vm_paddr_t mmio_gpa)
16 {
17 vm_vaddr_t mmio_gva = vm_vaddr_unused_gap(vm, vm->page_size, KVM_UTIL_MIN_VADDR);
18
19 virt_map(vm, mmio_gva, mmio_gpa, 1);
20
21 vm->ucall_mmio_addr = mmio_gpa;
22
23 write_guest_global(vm, ucall_exit_mmio_addr, (vm_vaddr_t *)mmio_gva);
24 }
25
ucall_arch_do_ucall(vm_vaddr_t uc)26 void ucall_arch_do_ucall(vm_vaddr_t uc)
27 {
28 WRITE_ONCE(*ucall_exit_mmio_addr, uc);
29 }
30
ucall_arch_get_ucall(struct kvm_vcpu * vcpu)31 void *ucall_arch_get_ucall(struct kvm_vcpu *vcpu)
32 {
33 struct kvm_run *run = vcpu->run;
34
35 if (run->exit_reason == KVM_EXIT_MMIO &&
36 run->mmio.phys_addr == vcpu->vm->ucall_mmio_addr) {
37 TEST_ASSERT(run->mmio.is_write && run->mmio.len == sizeof(uint64_t),
38 "Unexpected ucall exit mmio address access");
39 return (void *)(*((uint64_t *)run->mmio.data));
40 }
41
42 return NULL;
43 }
44