1 files changed, 112 insertions, 0 deletions
diff --git a/tools/testing/selftests/kvm/lib/aarch64/ucall.c b/tools/testing/selftests/kvm/lib/aarch64/ucall.c
new file mode 100644
index 000000000000..6cd91970fbad
--- /dev/null
+++ b/tools/testing/selftests/kvm/lib/aarch64/ucall.c
@@ -0,0 +1,112 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ucall support. A ucall is a "hypercall to userspace".
+ *
+ * Copyright (C) 2018, Red Hat, Inc.
+ */
+#include "kvm_util.h"
+#include "../kvm_util_internal.h"
+
+static vm_vaddr_t *ucall_exit_mmio_addr;
+
+static bool ucall_mmio_init(struct kvm_vm *vm, vm_paddr_t gpa)
+{
+	if (kvm_userspace_memory_region_find(vm, gpa, gpa + 1))
+		return false;
+
+	virt_pg_map(vm, gpa, gpa, 0);
+
+	ucall_exit_mmio_addr = (vm_vaddr_t *)gpa;
+	sync_global_to_guest(vm, ucall_exit_mmio_addr);
+
+	return true;
+}
+
+void ucall_init(struct kvm_vm *vm, void *arg)
+{
+	vm_paddr_t gpa, start, end, step, offset;
+	unsigned int bits;
+	bool ret;
+
+	if (arg) {
+		gpa = (vm_paddr_t)arg;
+		ret = ucall_mmio_init(vm, gpa);
+		TEST_ASSERT(ret, "Can't set ucall mmio address to %lx", gpa);
+		return;
+	}
+
+	/*
+	 * Find an address within the allowed physical and virtual address
+	 * spaces, that does _not_ have a KVM memory region associated with
+	 * it. Identity mapping an address like this allows the guest to
+	 * access it, but as KVM doesn't know what to do with it, it
+	 * will assume it's something userspace handles and exit with
+	 * KVM_EXIT_MMIO. Well, at least that's how it works for AArch64.
+	 * Here we start with a guess that the addresses around 5/8th
+	 * of the allowed space are unmapped and then work both down and
+	 * up from there in 1/16th allowed space sized steps.
+	 *
+	 * Note, we need to use VA-bits - 1 when calculating the allowed
+	 * virtual address space for an identity mapping because the upper
+	 * half of the virtual address space is the two's complement of the
+	 * lower and won't match physical addresses.
+	 */
+	bits = vm->va_bits - 1;
+	bits = vm->pa_bits < bits ? vm->pa_bits : bits;
+	end = 1ul << bits;
+	start = end * 5 / 8;
+	step = end / 16;
+	for (offset = 0; offset < end - start; offset += step) {
+		if (ucall_mmio_init(vm, start - offset))
+			return;
+		if (ucall_mmio_init(vm, start + offset))
+			return;
+	}
+	TEST_ASSERT(false, "Can't find a ucall mmio address");
+}
+
+void ucall_uninit(struct kvm_vm *vm)
+{
+	ucall_exit_mmio_addr = 0;
+	sync_global_to_guest(vm, ucall_exit_mmio_addr);
+}
+
+void ucall(uint64_t cmd, int nargs, ...)
+{
+	struct ucall uc = {
+		.cmd = cmd,
+	};
+	va_list va;
+	int i;
+
+	nargs = nargs <= UCALL_MAX_ARGS ? nargs : UCALL_MAX_ARGS;
+
+	va_start(va, nargs);
+	for (i = 0; i < nargs; ++i)
+		uc.args[i] = va_arg(va, uint64_t);
+	va_end(va);
+
+	*ucall_exit_mmio_addr = (vm_vaddr_t)&uc;
+}
+
+uint64_t get_ucall(struct kvm_vm *vm, uint32_t vcpu_id, struct ucall *uc)
+{
+	struct kvm_run *run = vcpu_state(vm, vcpu_id);
+	struct ucall ucall = {};
+
+	if (run->exit_reason == KVM_EXIT_MMIO &&
+	    run->mmio.phys_addr == (uint64_t)ucall_exit_mmio_addr) {
+		vm_vaddr_t gva;
+
+		TEST_ASSERT(run->mmio.is_write && run->mmio.len == 8,
+			    "Unexpected ucall exit mmio address access");
+		memcpy(&gva, run->mmio.data, sizeof(gva));
+		memcpy(&ucall, addr_gva2hva(vm, gva), sizeof(ucall));
+
+		vcpu_run_complete_io(vm, vcpu_id);
+		if (uc)
+			memcpy(uc, &ucall, sizeof(ucall));
+	}
+
+	return ucall.cmd;
+}