tests/tcg/aarch64: add SVE iotcl test

This is a fairly bare-bones test of setting the various vector sizes
for SVE which will only fail if the PR_SVE_SET_VL can't reduce the
user-space vector length by powers of 2.

However we will also be able to use it in a future test which
exercises the GDB stub.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20200316172155.971-25-alex.bennee@linaro.org>

tests/tcg/aarch64/Makefile.target

@@ -47,6 +47,10 @@ ifneq ($(DOCKER_IMAGE)$(CROSS_CC_HAS_SVE),)
 AARCH64_TESTS += sysregs
 sysregs: CFLAGS+=-march=armv8.1-a+sve
 
+# SVE ioctl test
+AARCH64_TESTS += sve-ioctls
+sve-ioctls: CFLAGS+=-march=armv8.1-a+sve
+
 ifneq ($(HAVE_GDB_BIN),)
 GDB_SCRIPT=$(SRC_PATH)/tests/guest-debug/run-test.py
 

tests/tcg/aarch64/sve-ioctls.c

@@ -0,0 +1,70 @@
+/*
+ * SVE ioctls tests
+ *
+ * Test the SVE width setting ioctls work and provide a base for
+ * testing the gdbstub.
+ *
+ * Copyright (c) 2019 Linaro Ltd
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+#include <sys/prctl.h>
+#include <asm/hwcap.h>
+#include <stdio.h>
+#include <sys/auxv.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+#ifndef HWCAP_CPUID
+#define HWCAP_CPUID (1 << 11)
+#endif
+
+#define SVE_MAX_QUADS  (2048 / 128)
+#define BYTES_PER_QUAD (128 / 8)
+
+#define get_cpu_reg(id) ({                                      \
+            unsigned long __val;                                \
+            asm("mrs %0, "#id : "=r" (__val));                  \
+            __val;                                              \
+        })
+
+static int do_sve_ioctl_test(void)
+{
+    int i, res, init_vq;
+
+    res = prctl(PR_SVE_GET_VL, 0, 0, 0, 0);
+    if (res < 0) {
+        printf("FAILED to PR_SVE_GET_VL (%d)", res);
+        return -1;
+    }
+    init_vq = res & PR_SVE_VL_LEN_MASK;
+
+    for (i = init_vq; i > 15; i /= 2) {
+        printf("Checking PR_SVE_SET_VL=%d\n", i);
+        res = prctl(PR_SVE_SET_VL, i, 0, 0, 0, 0);
+        if (res < 0) {
+            printf("FAILED to PR_SVE_SET_VL (%d)", res);
+            return -1;
+        }
+        asm("index z0.b, #0, #1\n"
+            ".global __sve_ld_done\n"
+            "__sve_ld_done:\n"
+            "mov z0.b, #0\n"
+            : /* no outputs kept */
+            : /* no inputs */
+            : "memory", "z0");
+    }
+    printf("PASS\n");
+    return 0;
+}
+
+int main(int argc, char **argv)
+{
+    /* we also need to probe for the ioctl support */
+    if (getauxval(AT_HWCAP) & HWCAP_SVE) {
+        return do_sve_ioctl_test();
+    } else {
+        printf("SKIP: no HWCAP_SVE on this system\n");
+        return 0;
+    }
+}