[kvm-unit-tests PATCH 1/1] s390x: stsi: Define vm_is_kvm to be used in different tests

[Pierre Morel <pmorel@linux.ibm.com>]

Several tests are in need of a way to check on which hypervisor
and virtualization level they are running on to be able to fence
certain tests. This patch adds functions that return true if a
vm is running under KVM, LPAR or generally as a level 2 guest.

To check if we're running under KVM we use the STSI 3.2.2
instruction, let's define it's response structure in a central
header.

Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
---
 lib/s390x/stsi.h | 32 ++++++++++++++++++++++++++++
 lib/s390x/vm.c   | 55 ++++++++++++++++++++++++++++++++++++++++++++++--
 lib/s390x/vm.h   |  3 +++
 s390x/stsi.c     | 23 ++------------------
 4 files changed, 90 insertions(+), 23 deletions(-)
 create mode 100644 lib/s390x/stsi.h

diff --git a/lib/s390x/stsi.h b/lib/s390x/stsi.h
new file mode 100644
index 00000000..bebc492d
--- /dev/null
+++ b/lib/s390x/stsi.h
@@ -0,0 +1,32 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Structures used to Store System Information
+ *
+ * Copyright IBM Corp. 2022
+ */
+
+#ifndef _S390X_STSI_H_
+#define _S390X_STSI_H_
+
+struct sysinfo_3_2_2 {
+	uint8_t reserved[31];
+	uint8_t count;
+	struct {
+		uint8_t reserved2[4];
+		uint16_t total_cpus;
+		uint16_t conf_cpus;
+		uint16_t standby_cpus;
+		uint16_t reserved_cpus;
+		uint8_t name[8];
+		uint32_t caf;
+		uint8_t cpi[16];
+		uint8_t reserved5[3];
+		uint8_t ext_name_encoding;
+		uint32_t reserved3;
+		uint8_t uuid[16];
+	} vm[8];
+	uint8_t reserved4[1504];
+	uint8_t ext_names[8][256];
+};
+
+#endif  /* _S390X_STSI_H_ */
diff --git a/lib/s390x/vm.c b/lib/s390x/vm.c
index a5b92863..91acd05b 100644
--- a/lib/s390x/vm.c
+++ b/lib/s390x/vm.c
@@ -12,6 +12,7 @@
 #include <alloc_page.h>
 #include <asm/arch_def.h>
 #include "vm.h"
+#include "stsi.h"
 
 /**
  * Detect whether we are running with TCG (instead of KVM)
@@ -26,9 +27,13 @@ bool vm_is_tcg(void)
 	if (initialized)
 		return is_tcg;
 
+	if (!vm_is_vm()) {
+		initialized = true;
+		return is_tcg;
+	}
+
 	buf = alloc_page();
-	if (!buf)
-		return false;
+	assert(buf);
 
 	if (stsi(buf, 1, 1, 1))
 		goto out;
@@ -43,3 +48,49 @@ out:
 	free_page(buf);
 	return is_tcg;
 }
+
+/**
+ * Detect whether we are running with KVM
+ */
+bool vm_is_kvm(void)
+{
+	/* EBCDIC for "KVM/" */
+	const uint8_t kvm_ebcdic[] = { 0xd2, 0xe5, 0xd4, 0x61 };
+	static bool initialized;
+	static bool is_kvm;
+	struct sysinfo_3_2_2 *stsi_322;
+
+	if (initialized)
+		return is_kvm;
+
+	if (!vm_is_vm() || vm_is_tcg()) {
+		initialized = true;
+		return is_kvm;
+	}
+
+	stsi_322 = alloc_page();
+	assert(stsi_322);
+
+	if (stsi(stsi_322, 3, 2, 2))
+		goto out;
+
+	/*
+	 * If the manufacturer string is "KVM/" in EBCDIC, then we
+	 * are on KVM.
+	 */
+	is_kvm = !memcmp(&stsi_322->vm[0].cpi, kvm_ebcdic, sizeof(kvm_ebcdic));
+	initialized = true;
+out:
+	free_page(stsi_322);
+	return is_kvm;
+}
+
+bool vm_is_lpar(void)
+{
+	return stsi_get_fc() == 2;
+}
+
+bool vm_is_vm(void)
+{
+	return stsi_get_fc() == 3;
+}
diff --git a/lib/s390x/vm.h b/lib/s390x/vm.h
index 7abba0cc..3aaf76af 100644
--- a/lib/s390x/vm.h
+++ b/lib/s390x/vm.h
@@ -9,5 +9,8 @@
 #define _S390X_VM_H_
 
 bool vm_is_tcg(void);
+bool vm_is_kvm(void);
+bool vm_is_vm(void);
+bool vm_is_lpar(void);
 
 #endif  /* _S390X_VM_H_ */
diff --git a/s390x/stsi.c b/s390x/stsi.c
index 391f8849..dccc53e7 100644
--- a/s390x/stsi.c
+++ b/s390x/stsi.c
@@ -13,27 +13,8 @@
 #include <asm/asm-offsets.h>
 #include <asm/interrupt.h>
 #include <smp.h>
+#include <stsi.h>
 
-struct stsi_322 {
-	uint8_t reserved[31];
-	uint8_t count;
-	struct {
-		uint8_t reserved2[4];
-		uint16_t total_cpus;
-		uint16_t conf_cpus;
-		uint16_t standby_cpus;
-		uint16_t reserved_cpus;
-		uint8_t name[8];
-		uint32_t caf;
-		uint8_t cpi[16];
-		uint8_t reserved5[3];
-		uint8_t ext_name_encoding;
-		uint32_t reserved3;
-		uint8_t uuid[16];
-	} vm[8];
-	uint8_t reserved4[1504];
-	uint8_t ext_names[8][256];
-};
 static uint8_t pagebuf[PAGE_SIZE * 2] __attribute__((aligned(PAGE_SIZE * 2)));
 
 static void test_specs(void)
@@ -91,7 +72,7 @@ static void test_3_2_2(void)
 	/* EBCDIC for "KVM/" */
 	const uint8_t cpi_kvm[] = { 0xd2, 0xe5, 0xd4, 0x61 };
 	const char vm_name_ext[] = "kvm-unit-test";
-	struct stsi_322 *data = (void *)pagebuf;
+	struct sysinfo_3_2_2 *data = (void *)pagebuf;
 
 	report_prefix_push("3.2.2");
 
-- 
2.27.0