[kvm-unit-tests PATCH v1 1/1] s390x: stsi: Define vm_is_kvm to be used in different tests

Pierre Morel
2022-02-16T12:32:00Z

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 | 51 ++++++++++++++++++++++++++++++++++++++++++++++--
lib/s390x/vm.h | 2 ++
s390x/stsi.c | 23 ++--------------------
4 files changed, 85 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..33fb1c45 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 (stsi_get_fc() != 3) {
+ initialized = true;
+ return is_tcg;
+ }
+
buf = alloc_page();
- if (!buf)
- return false;
+ assert(buf);

if (stsi(buf, 1, 1, 1))
goto out;
@@ -43,3 +48,45 @@ 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 (stsi_get_fc() != 3 || 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;
+}
+
diff --git a/lib/s390x/vm.h b/lib/s390x/vm.h
index 7abba0cc..4456b48c 100644
--- a/lib/s390x/vm.h
+++ b/lib/s390x/vm.h
@@ -9,5 +9,7 @@
#define _S390X_VM_H_

bool vm_is_tcg(void);
+bool vm_is_kvm(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