[kvm-unit-tests PATCH 06/24] riscv: Add initial SBI support

[Andrew Jones <andrew.jones@linux.dev>]

Add an SBI call function and immediately apply it to properly
exiting the test (instead of hanging) by invoking SBI shutdown
from exit(). Also seed an SBI test file with a simple SBI test
that checks mvendorid is correctly extracted.

Run with e.g.
  qemu-system-riscv64 -nographic -M virt \
      -kernel riscv/sbi.flat \
      -cpu rv64,mvendorid=45 \
      -initrd sbi-env

and be happy that ctrl-a c q is no longer necessary to return to
the shell prompt. sbi-env has MVENDORID=45 in it.

Signed-off-by: Andrew Jones <andrew.jones@linux.dev>
---
 lib/riscv/asm/sbi.h | 32 ++++++++++++++++++++++++++++++++
 lib/riscv/io.c      |  2 ++
 lib/riscv/sbi.c     | 35 +++++++++++++++++++++++++++++++++++
 riscv/Makefile      |  2 ++
 riscv/sbi.c         | 41 +++++++++++++++++++++++++++++++++++++++++
 5 files changed, 112 insertions(+)
 create mode 100644 lib/riscv/asm/sbi.h
 create mode 100644 lib/riscv/sbi.c
 create mode 100644 riscv/sbi.c

diff --git a/lib/riscv/asm/sbi.h b/lib/riscv/asm/sbi.h
new file mode 100644
index 000000000000..aeff07f6f1a8
--- /dev/null
+++ b/lib/riscv/asm/sbi.h
@@ -0,0 +1,32 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef _ASMRISCV_SBI_H_
+#define _ASMRISCV_SBI_H_
+
+enum sbi_ext_id {
+	SBI_EXT_BASE = 0x10,
+	SBI_EXT_SRST = 0x53525354,
+};
+
+enum sbi_ext_base_fid {
+	SBI_EXT_BASE_GET_SPEC_VERSION = 0,
+	SBI_EXT_BASE_GET_IMP_ID,
+	SBI_EXT_BASE_GET_IMP_VERSION,
+	SBI_EXT_BASE_PROBE_EXT,
+	SBI_EXT_BASE_GET_MVENDORID,
+	SBI_EXT_BASE_GET_MARCHID,
+	SBI_EXT_BASE_GET_MIMPID,
+};
+
+struct sbiret {
+	long error;
+	long value;
+};
+
+struct sbiret sbi_ecall(int ext, int fid, unsigned long arg0,
+			unsigned long arg1, unsigned long arg2,
+			unsigned long arg3, unsigned long arg4,
+			unsigned long arg5);
+
+void sbi_shutdown(void);
+
+#endif /* _ASMRISCV_SBI_H_ */
diff --git a/lib/riscv/io.c b/lib/riscv/io.c
index aeda74be61ee..b3f587bb68ca 100644
--- a/lib/riscv/io.c
+++ b/lib/riscv/io.c
@@ -9,6 +9,7 @@
 #include <config.h>
 #include <devicetree.h>
 #include <asm/io.h>
+#include <asm/sbi.h>
 #include <asm/setup.h>
 #include <asm/spinlock.h>
 
@@ -90,6 +91,7 @@ void halt(int code);
 void exit(int code)
 {
 	printf("\nEXIT: STATUS=%d\n", ((code) << 1) | 1);
+	sbi_shutdown();
 	halt(code);
 	__builtin_unreachable();
 }
diff --git a/lib/riscv/sbi.c b/lib/riscv/sbi.c
new file mode 100644
index 000000000000..fd758555b888
--- /dev/null
+++ b/lib/riscv/sbi.c
@@ -0,0 +1,35 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <libcflat.h>
+#include <asm/sbi.h>
+
+struct sbiret sbi_ecall(int ext, int fid, unsigned long arg0,
+			unsigned long arg1, unsigned long arg2,
+			unsigned long arg3, unsigned long arg4,
+			unsigned long arg5)
+{
+	register uintptr_t a0 asm ("a0") = (uintptr_t)(arg0);
+	register uintptr_t a1 asm ("a1") = (uintptr_t)(arg1);
+	register uintptr_t a2 asm ("a2") = (uintptr_t)(arg2);
+	register uintptr_t a3 asm ("a3") = (uintptr_t)(arg3);
+	register uintptr_t a4 asm ("a4") = (uintptr_t)(arg4);
+	register uintptr_t a5 asm ("a5") = (uintptr_t)(arg5);
+	register uintptr_t a6 asm ("a6") = (uintptr_t)(fid);
+	register uintptr_t a7 asm ("a7") = (uintptr_t)(ext);
+	struct sbiret ret;
+
+	asm volatile (
+		"ecall"
+		: "+r" (a0), "+r" (a1)
+		: "r" (a2), "r" (a3), "r" (a4), "r" (a5), "r" (a6), "r" (a7)
+		: "memory");
+	ret.error = a0;
+	ret.value = a1;
+
+	return ret;
+}
+
+void sbi_shutdown(void)
+{
+	sbi_ecall(SBI_EXT_SRST, 0, 0, 0, 0, 0, 0, 0);
+	puts("SBI shutdown failed!\n");
+}
diff --git a/riscv/Makefile b/riscv/Makefile
index ddf2a0e016a8..4e7fcc538ba1 100644
--- a/riscv/Makefile
+++ b/riscv/Makefile
@@ -11,6 +11,7 @@ exe = flat
 endif
 
 tests =
+tests += $(TEST_DIR)/sbi.$(exe)
 tests += $(TEST_DIR)/selftest.$(exe)
 #tests += $(TEST_DIR)/sieve.$(exe)
 
@@ -25,6 +26,7 @@ cflatobjs += lib/alloc_phys.o
 cflatobjs += lib/devicetree.o
 cflatobjs += lib/riscv/bitops.o
 cflatobjs += lib/riscv/io.o
+cflatobjs += lib/riscv/sbi.o
 cflatobjs += lib/riscv/setup.o
 cflatobjs += lib/riscv/smp.o
 
diff --git a/riscv/sbi.c b/riscv/sbi.c
new file mode 100644
index 000000000000..ffb07a256ff6
--- /dev/null
+++ b/riscv/sbi.c
@@ -0,0 +1,41 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * SBI verification
+ *
+ * Copyright (C) 2023, Ventana Micro Systems Inc., Andrew Jones <ajones@ventanamicro.com>
+ */
+#include <libcflat.h>
+#include <stdlib.h>
+#include <asm/sbi.h>
+
+static void help(void)
+{
+	puts("Test SBI\n");
+	puts("An environ must be provided where expected values are given.\n");
+}
+
+int main(int argc, char **argv)
+{
+	struct sbiret ret;
+	long expected;
+
+	if (argc > 1 && !strcmp(argv[1], "-h")) {
+		help();
+		exit(0);
+	}
+
+	report_prefix_push("sbi");
+
+	if (!getenv("MVENDORID")) {
+		report_skip("mvendorid: missing MVENDORID environment variable");
+		goto done;
+	}
+	expected = strtol(getenv("MVENDORID"), NULL, 0);
+
+	ret = sbi_ecall(SBI_EXT_BASE, SBI_EXT_BASE_GET_MVENDORID, 0, 0, 0, 0, 0, 0);
+	report(!ret.error, "mvendorid: no error");
+	report(ret.value == expected, "mvendorid");
+
+done:
+	return report_summary();
+}
-- 
2.43.0