[kvm-unit-tests PATCH v3 5/7] s390x: Add library functions for exiting from snippet

[Nina Schoetterl-Glausch <nsg@linux.ibm.com>]

It is useful to be able to force an exit to the host from the snippet,
as well as do so while returning a value.
Add this functionality, also add helper functions for the host to check
for an exit and get or check the value.
Use diag 0x44 and 0x9c for this.
Add a guest specific snippet header file and rename snippet.h to reflect
that it is host specific.

Signed-off-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
---
 s390x/Makefile                          |  1 +
 lib/s390x/asm/arch_def.h                | 13 ++++++++
 lib/s390x/snippet-guest.h               | 26 +++++++++++++++
 lib/s390x/{snippet.h => snippet-host.h} | 10 ++++--
 lib/s390x/snippet-host.c                | 42 +++++++++++++++++++++++++
 lib/s390x/uv.c                          |  2 +-
 s390x/mvpg-sie.c                        |  2 +-
 s390x/pv-diags.c                        |  2 +-
 s390x/pv-icptcode.c                     |  2 +-
 s390x/pv-ipl.c                          |  2 +-
 s390x/sie-dat.c                         |  2 +-
 s390x/spec_ex-sie.c                     |  2 +-
 s390x/uv-host.c                         |  2 +-
 13 files changed, 97 insertions(+), 11 deletions(-)
 create mode 100644 lib/s390x/snippet-guest.h
 rename lib/s390x/{snippet.h => snippet-host.h} (92%)
 create mode 100644 lib/s390x/snippet-host.c

diff --git a/s390x/Makefile b/s390x/Makefile
index 23342bd6..12445fb5 100644
--- a/s390x/Makefile
+++ b/s390x/Makefile
@@ -111,6 +111,7 @@ cflatobjs += lib/s390x/css_lib.o
 cflatobjs += lib/s390x/malloc_io.o
 cflatobjs += lib/s390x/uv.o
 cflatobjs += lib/s390x/sie.o
+cflatobjs += lib/s390x/snippet-host.o
 cflatobjs += lib/s390x/fault.o
 
 OBJDIRS += lib/s390x
diff --git a/lib/s390x/asm/arch_def.h b/lib/s390x/asm/arch_def.h
index 745a3387..db04deca 100644
--- a/lib/s390x/asm/arch_def.h
+++ b/lib/s390x/asm/arch_def.h
@@ -504,4 +504,17 @@ static inline uint32_t get_prefix(void)
 	return current_prefix;
 }
 
+static inline void diag44(void)
+{
+	asm volatile("diag	0,0,0x44\n");
+}
+
+static inline void diag9c(uint64_t val)
+{
+	asm volatile("diag	%[val],0,0x9c\n"
+		:
+		: [val] "d"(val)
+	);
+}
+
 #endif
diff --git a/lib/s390x/snippet-guest.h b/lib/s390x/snippet-guest.h
new file mode 100644
index 00000000..3cc098e1
--- /dev/null
+++ b/lib/s390x/snippet-guest.h
@@ -0,0 +1,26 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Snippet functionality for the guest.
+ *
+ * Copyright IBM Corp. 2023
+ */
+
+#ifndef _S390X_SNIPPET_GUEST_H_
+#define _S390X_SNIPPET_GUEST_H_
+
+#include <asm/arch_def.h>
+#include <asm/barrier.h>
+
+static inline void force_exit(void)
+{
+	diag44();
+	mb(); /* allow host to modify guest memory */
+}
+
+static inline void force_exit_value(uint64_t val)
+{
+	diag9c(val);
+	mb(); /* allow host to modify guest memory */
+}
+
+#endif /* _S390X_SNIPPET_GUEST_H_ */
diff --git a/lib/s390x/snippet.h b/lib/s390x/snippet-host.h
similarity index 92%
rename from lib/s390x/snippet.h
rename to lib/s390x/snippet-host.h
index 910849aa..230b25b0 100644
--- a/lib/s390x/snippet.h
+++ b/lib/s390x/snippet-host.h
@@ -1,13 +1,13 @@
 /* SPDX-License-Identifier: GPL-2.0-only */
 /*
- * Snippet definitions
+ * Snippet functionality for the host.
  *
  * Copyright IBM Corp. 2021
  * Author: Janosch Frank <frankja@linux.ibm.com>
  */
 
-#ifndef _S390X_SNIPPET_H_
-#define _S390X_SNIPPET_H_
+#ifndef _S390X_SNIPPET_HOST_H_
+#define _S390X_SNIPPET_HOST_H_
 
 #include <sie.h>
 #include <uv.h>
@@ -144,4 +144,8 @@ static inline void snippet_setup_guest(struct vm *vm, bool is_pv)
 	}
 }
 
+bool snippet_is_force_exit(struct vm *vm);
+bool snippet_is_force_exit_value(struct vm *vm);
+uint64_t snippet_get_force_exit_value(struct vm *vm);
+void snippet_check_force_exit_value(struct vm *vm, uint64_t exit_exp);
 #endif
diff --git a/lib/s390x/snippet-host.c b/lib/s390x/snippet-host.c
new file mode 100644
index 00000000..44a60bb9
--- /dev/null
+++ b/lib/s390x/snippet-host.c
@@ -0,0 +1,42 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Snippet functionality for the host.
+ *
+ * Copyright IBM Corp. 2023
+ */
+
+#include <libcflat.h>
+#include <snippet-host.h>
+#include <sie.h>
+
+bool snippet_is_force_exit(struct vm *vm)
+{
+	return sie_is_diag_icpt(vm, 0x44);
+}
+
+bool snippet_is_force_exit_value(struct vm *vm)
+{
+	return sie_is_diag_icpt(vm, 0x9c);
+}
+
+uint64_t snippet_get_force_exit_value(struct vm *vm)
+{
+	struct kvm_s390_sie_block *sblk = vm->sblk;
+
+	assert(snippet_is_force_exit_value(vm));
+
+	return vm->save_area.guest.grs[(sblk->ipa & 0xf0) >> 4];
+}
+
+void snippet_check_force_exit_value(struct vm *vm, uint64_t value_exp)
+{
+	uint64_t value;
+
+	if (snippet_is_force_exit_value(vm)) {
+		value = snippet_get_force_exit_value(vm);
+		report(value == value_exp, "guest forced exit with value (0x%lx == 0x%lx)",
+		       value, value_exp);
+	} else {
+		report_fail("guest forced exit with value");
+	}
+}
diff --git a/lib/s390x/uv.c b/lib/s390x/uv.c
index 723bb4f2..c9fffbfc 100644
--- a/lib/s390x/uv.c
+++ b/lib/s390x/uv.c
@@ -18,7 +18,7 @@
 #include <asm/uv.h>
 #include <uv.h>
 #include <sie.h>
-#include <snippet.h>
+#include <snippet-host.h>
 
 static struct uv_cb_qui uvcb_qui = {
 	.header.cmd = UVC_CMD_QUI,
diff --git a/s390x/mvpg-sie.c b/s390x/mvpg-sie.c
index d182b49a..3aec9d71 100644
--- a/s390x/mvpg-sie.c
+++ b/s390x/mvpg-sie.c
@@ -19,7 +19,7 @@
 #include <alloc_page.h>
 #include <sclp.h>
 #include <sie.h>
-#include <snippet.h>
+#include <snippet-host.h>
 
 static struct vm vm;
 
diff --git a/s390x/pv-diags.c b/s390x/pv-diags.c
index 6ebe469a..a686c688 100644
--- a/s390x/pv-diags.c
+++ b/s390x/pv-diags.c
@@ -8,7 +8,7 @@
  *  Janosch Frank <frankja@linux.ibm.com>
  */
 #include <libcflat.h>
-#include <snippet.h>
+#include <snippet-host.h>
 #include <sie.h>
 #include <sclp.h>
 #include <asm/facility.h>
diff --git a/s390x/pv-icptcode.c b/s390x/pv-icptcode.c
index bc90df1e..82fd4246 100644
--- a/s390x/pv-icptcode.c
+++ b/s390x/pv-icptcode.c
@@ -12,7 +12,7 @@
 #include <sie.h>
 #include <smp.h>
 #include <sclp.h>
-#include <snippet.h>
+#include <snippet-host.h>
 #include <asm/facility.h>
 #include <asm/barrier.h>
 #include <asm/sigp.h>
diff --git a/s390x/pv-ipl.c b/s390x/pv-ipl.c
index cd49bd95..2acf7d0a 100644
--- a/s390x/pv-ipl.c
+++ b/s390x/pv-ipl.c
@@ -10,7 +10,7 @@
 #include <libcflat.h>
 #include <sie.h>
 #include <sclp.h>
-#include <snippet.h>
+#include <snippet-host.h>
 #include <asm/facility.h>
 #include <asm/uv.h>
 
diff --git a/s390x/sie-dat.c b/s390x/sie-dat.c
index f0257770..9e60f26e 100644
--- a/s390x/sie-dat.c
+++ b/s390x/sie-dat.c
@@ -16,7 +16,7 @@
 #include <alloc_page.h>
 #include <sclp.h>
 #include <sie.h>
-#include <snippet.h>
+#include <snippet-host.h>
 #include "snippets/c/sie-dat.h"
 
 static struct vm vm;
diff --git a/s390x/spec_ex-sie.c b/s390x/spec_ex-sie.c
index fe2f23ee..0ad7ec08 100644
--- a/s390x/spec_ex-sie.c
+++ b/s390x/spec_ex-sie.c
@@ -13,7 +13,7 @@
 #include <asm/arch_def.h>
 #include <alloc_page.h>
 #include <sie.h>
-#include <snippet.h>
+#include <snippet-host.h>
 #include <hardware.h>
 
 static struct vm vm;
diff --git a/s390x/uv-host.c b/s390x/uv-host.c
index 55b46446..87d108b6 100644
--- a/s390x/uv-host.c
+++ b/s390x/uv-host.c
@@ -15,7 +15,7 @@
 #include <sclp.h>
 #include <smp.h>
 #include <uv.h>
-#include <snippet.h>
+#include <snippet-host.h>
 #include <mmu.h>
 #include <asm/page.h>
 #include <asm/pgtable.h>
-- 
2.44.0