ucall.c

 1// SPDX-License-Identifier: GPL-2.0
 2/*
 3 * ucall support. A ucall is a "hypercall to userspace".
 4 *
 5 */
 6#include "kvm_util.h"
 7
 8/*
 9 * ucall_exit_mmio_addr holds per-VM values (global data is duplicated by each
10 * VM), it must not be accessed from host code.
11 */
12vm_vaddr_t *ucall_exit_mmio_addr;
13
14void ucall_arch_init(struct kvm_vm *vm, vm_paddr_t mmio_gpa)
15{
16	vm_vaddr_t mmio_gva = vm_vaddr_unused_gap(vm, vm->page_size, KVM_UTIL_MIN_VADDR);
17
18	virt_map(vm, mmio_gva, mmio_gpa, 1);
19
20	vm->ucall_mmio_addr = mmio_gpa;
21
22	write_guest_global(vm, ucall_exit_mmio_addr, (vm_vaddr_t *)mmio_gva);
23}
24
25void *ucall_arch_get_ucall(struct kvm_vcpu *vcpu)
26{
27	struct kvm_run *run = vcpu->run;
28
29	if (run->exit_reason == KVM_EXIT_MMIO &&
30	    run->mmio.phys_addr == vcpu->vm->ucall_mmio_addr) {
31		TEST_ASSERT(run->mmio.is_write && run->mmio.len == sizeof(uint64_t),
32			    "Unexpected ucall exit mmio address access");
33
34		return (void *)(*((uint64_t *)run->mmio.data));
35	}
36
37	return NULL;
38}