[PATCH kvm-unit-tests v3 06/11] s390x: detect installed memory

[David Hildenbrand <david@redhat.com>]

Unfortunately, there is no easy way to simply read out the amount
of installed memory. We have to probe (via TEST PROTECTION) for installed
memory in a given range.

Reviewed-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
 lib/s390x/asm/arch_def.h  | 12 ++++++++++
 lib/s390x/asm/interrupt.h |  1 +
 lib/s390x/interrupt.c     | 11 +++++++++
 lib/s390x/io.c            |  1 +
 lib/s390x/sclp.c          | 58 +++++++++++++++++++++++++++++++++++++++++++++++
 lib/s390x/sclp.h          |  1 +
 s390x/Makefile            |  1 +
 7 files changed, 85 insertions(+)
 create mode 100644 lib/s390x/sclp.c

diff --git a/lib/s390x/asm/arch_def.h b/lib/s390x/asm/arch_def.h
index 72e5c60..ee4c96f 100644
--- a/lib/s390x/asm/arch_def.h
+++ b/lib/s390x/asm/arch_def.h
@@ -151,4 +151,16 @@ struct cpuid {
 	uint64_t reserved : 15;
 };
 
+static inline int tprot(unsigned long addr)
+{
+	int cc;
+
+	asm volatile(
+		"	tprot	0(%1),0\n"
+		"	ipm	%0\n"
+		"	srl	%0,28\n"
+		: "=d" (cc) : "a" (addr) : "cc");
+	return cc;
+}
+
 #endif
diff --git a/lib/s390x/asm/interrupt.h b/lib/s390x/asm/interrupt.h
index 41be039..3ccc8e3 100644
--- a/lib/s390x/asm/interrupt.h
+++ b/lib/s390x/asm/interrupt.h
@@ -13,6 +13,7 @@
 
 void handle_pgm_int(void);
 void expect_pgm_int(void);
+uint16_t clear_pgm_int(void);
 void check_pgm_int_code(uint16_t code);
 
 /* Activate low-address protection */
diff --git a/lib/s390x/interrupt.c b/lib/s390x/interrupt.c
index 8d861a2..67d581b 100644
--- a/lib/s390x/interrupt.c
+++ b/lib/s390x/interrupt.c
@@ -23,6 +23,17 @@ void expect_pgm_int(void)
 	mb();
 }
 
+uint16_t clear_pgm_int(void)
+{
+	uint16_t code;
+
+	mb();
+	code = lc->pgm_int_code;
+	lc->pgm_int_code = 0;
+	pgm_int_expected = false;
+	return code;
+}
+
 void check_pgm_int_code(uint16_t code)
 {
 	mb();
diff --git a/lib/s390x/io.c b/lib/s390x/io.c
index 3121a78..eb4d171 100644
--- a/lib/s390x/io.c
+++ b/lib/s390x/io.c
@@ -43,6 +43,7 @@ void setup()
 	setup_args_progname(ipl_args);
 	setup_facilities();
 	sclp_ascii_setup();
+	sclp_memory_setup();
 }
 
 void exit(int code)
diff --git a/lib/s390x/sclp.c b/lib/s390x/sclp.c
new file mode 100644
index 0000000..199405c
--- /dev/null
+++ b/lib/s390x/sclp.c
@@ -0,0 +1,58 @@
+/*
+ * s390x SCLP driver
+ *
+ * Copyright (c) 2017 Red Hat Inc
+ *
+ * Authors:
+ *  David Hildenbrand <david@redhat.com>
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Library General Public License version 2.
+ */
+
+#include <libcflat.h>
+#include <asm/page.h>
+#include <asm/arch_def.h>
+#include <asm/interrupt.h>
+#include "sclp.h"
+
+static uint64_t storage_increment_size;
+static uint64_t max_ram_size;
+static uint64_t ram_size;
+
+void sclp_memory_setup(void)
+{
+	ReadInfo *ri = (void *)_sccb;
+	uint64_t rnmax, rnsize;
+	int cc;
+
+	ri->h.length = SCCB_SIZE;
+	sclp_service_call(SCLP_CMDW_READ_SCP_INFO_FORCED, ri);
+
+	/* calculate the storage increment size */
+	rnsize = ri->rnsize;
+	if (!rnsize) {
+		rnsize = ri->rnsize2;
+	}
+	storage_increment_size = rnsize << 20;
+
+	/* calculate the maximum memory size */
+	rnmax = ri->rnmax;
+	if (!rnmax) {
+		rnmax = ri->rnmax2;
+	}
+	max_ram_size = rnmax * storage_increment_size;
+
+	/* lowcore is always accessible, so the first increment is accessible */
+	ram_size = storage_increment_size;
+
+	/* probe for r/w memory up to max memory size */
+	while (ram_size < max_ram_size) {
+		expect_pgm_int();
+		cc = tprot(ram_size + storage_increment_size - 1);
+		/* stop once we receive an exception or have protected memory */
+		if (clear_pgm_int() || cc != 0)
+			break;
+		ram_size += storage_increment_size;
+	}
+}
diff --git a/lib/s390x/sclp.h b/lib/s390x/sclp.h
index d113cf8..21d482b 100644
--- a/lib/s390x/sclp.h
+++ b/lib/s390x/sclp.h
@@ -211,5 +211,6 @@ void sclp_ascii_setup(void);
 void sclp_print(const char *str);
 extern char _sccb[];
 int sclp_service_call(unsigned int command, void *sccb);
+void sclp_memory_setup(void);
 
 #endif /* SCLP_H */
diff --git a/s390x/Makefile b/s390x/Makefile
index f585faf..ce63dd1 100644
--- a/s390x/Makefile
+++ b/s390x/Makefile
@@ -24,6 +24,7 @@ cflatobjs += lib/util.o
 cflatobjs += lib/alloc_phys.o
 cflatobjs += lib/s390x/io.o
 cflatobjs += lib/s390x/stack.o
+cflatobjs += lib/s390x/sclp.o
 cflatobjs += lib/s390x/sclp-ascii.o
 cflatobjs += lib/s390x/interrupt.o
 
-- 
2.14.3