KVM: selftests: Make memslot_perf_test arch independent

memslot_perf_test uses ucalls for synchronization between guest and
host. Ucalls API is architecture independent: tests do not need to know
details like what kind of exit they generate on a specific arch.  More
specifically, there is no need to check whether an exit is KVM_EXIT_IO
in x86 for the host to know that the exit is ucall related, as
get_ucall() already makes that check.

Change memslot_perf_test to not require specifying what exit does a
ucall generate. Also add a missing ucall_init.

Signed-off-by: Ricardo Koller <ricarkol@google.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Reviewed-by: Oliver Upton <oupton@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210907180957.609966-2-ricarkol@google.com

Author: Ricardo Koller

tools/testing/selftests/kvm/memslot_perf_test.c

@@ -127,43 +127,54 @@ static bool verbose;
 			pr_info(__VA_ARGS__);	\
 	} while (0)
 
+static void check_mmio_access(struct vm_data *vm, struct kvm_run *run)
+{
+	TEST_ASSERT(vm->mmio_ok, "Unexpected mmio exit");
+	TEST_ASSERT(run->mmio.is_write, "Unexpected mmio read");
+	TEST_ASSERT(run->mmio.len == 8,
+		    "Unexpected exit mmio size = %u", run->mmio.len);
+	TEST_ASSERT(run->mmio.phys_addr >= vm->mmio_gpa_min &&
+		    run->mmio.phys_addr <= vm->mmio_gpa_max,
+		    "Unexpected exit mmio address = 0x%llx",
+		    run->mmio.phys_addr);
+}
+
 static void *vcpu_worker(void *data)
 {
 	struct vm_data *vm = data;
 	struct kvm_run *run;
 	struct ucall uc;
-	uint64_t cmd;
 
 	run = vcpu_state(vm->vm, VCPU_ID);
 	while (1) {
 		vcpu_run(vm->vm, VCPU_ID);
 
-		if (run->exit_reason == KVM_EXIT_IO) {
-			cmd = get_ucall(vm->vm, VCPU_ID, &uc);
-			if (cmd != UCALL_SYNC)
-				break;
-
+		switch (get_ucall(vm->vm, VCPU_ID, &uc)) {
+		case UCALL_SYNC:
+			TEST_ASSERT(uc.args[1] == 0,
+				"Unexpected sync ucall, got %lx",
+				(ulong)uc.args[1]);
 			sem_post(&vcpu_ready);
 			continue;
-		}
-
-		if (run->exit_reason != KVM_EXIT_MMIO)
+		case UCALL_NONE:
+			if (run->exit_reason == KVM_EXIT_MMIO)
+				check_mmio_access(vm, run);
+			else
+				goto done;
 			break;
-
-		TEST_ASSERT(vm->mmio_ok, "Unexpected mmio exit");
-		TEST_ASSERT(run->mmio.is_write, "Unexpected mmio read");
-		TEST_ASSERT(run->mmio.len == 8,
-			    "Unexpected exit mmio size = %u", run->mmio.len);
-		TEST_ASSERT(run->mmio.phys_addr >= vm->mmio_gpa_min &&
-			    run->mmio.phys_addr <= vm->mmio_gpa_max,
-			    "Unexpected exit mmio address = 0x%llx",
-			    run->mmio.phys_addr);
+		case UCALL_ABORT:
+			TEST_FAIL("%s at %s:%ld, val = %lu",
+					(const char *)uc.args[0],
+					__FILE__, uc.args[1], uc.args[2]);
+			break;
+		case UCALL_DONE:
+			goto done;
+		default:
+			TEST_FAIL("Unknown ucall %lu", uc.cmd);
+		}
 	}
 
-	if (run->exit_reason == KVM_EXIT_IO && cmd == UCALL_ABORT)
-		TEST_FAIL("%s at %s:%ld, val = %lu", (const char *)uc.args[0],
-			  __FILE__, uc.args[1], uc.args[2]);
-
+done:
 	return NULL;
 }
 
@@ -268,6 +279,7 @@ static bool prepare_vm(struct vm_data *data, int nslots, uint64_t *maxslots,
 	TEST_ASSERT(data->hva_slots, "malloc() fail");
 
 	data->vm = vm_create_default(VCPU_ID, mempages, guest_code);
+	ucall_init(data->vm, NULL);
 
 	pr_info_v("Adding slots 1..%i, each slot with %"PRIu64" pages + %"PRIu64" extra pages last\n",
 		max_mem_slots - 1, data->pages_per_slot, rempages);