[kvm-unit-tests PATCH v4 3/9] s390x: SCLP feature checking

[Janosch Frank <frankja@linux.ibm.com>]

Availability of SIE is announced via a feature bit in a SCLP info CPU
entry. Let's add a framework that allows us to easily check for such
facilities.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
---
 lib/s390x/io.c   |  1 +
 lib/s390x/sclp.c | 25 +++++++++++++++++++++++++
 lib/s390x/sclp.h | 13 ++++++++++++-
 3 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/lib/s390x/io.c b/lib/s390x/io.c
index 6a1da63..ef9f59e 100644
--- a/lib/s390x/io.c
+++ b/lib/s390x/io.c
@@ -35,6 +35,7 @@ void setup(void)
 	setup_args_progname(ipl_args);
 	setup_facilities();
 	sclp_read_info();
+	sclp_facilities_setup();
 	sclp_console_setup();
 	sclp_memory_setup();
 	smp_setup();
diff --git a/lib/s390x/sclp.c b/lib/s390x/sclp.c
index 12916f5..06819a6 100644
--- a/lib/s390x/sclp.c
+++ b/lib/s390x/sclp.c
@@ -25,6 +25,7 @@ static uint64_t max_ram_size;
 static uint64_t ram_size;
 char _read_info[PAGE_SIZE] __attribute__((__aligned__(PAGE_SIZE)));
 static ReadInfo *read_info;
+struct sclp_facilities sclp_facilities;
 
 char _sccb[PAGE_SIZE] __attribute__((__aligned__(4096)));
 static volatile bool sclp_busy;
@@ -128,6 +129,30 @@ CPUEntry *sclp_get_cpu_entries(void)
 	return (CPUEntry *)(_read_info + read_info->offset_cpu);
 }
 
+void sclp_facilities_setup(void)
+{
+	unsigned short cpu0_addr = stap();
+	CPUEntry *cpu;
+	int i;
+
+	assert(read_info);
+
+	cpu = sclp_get_cpu_entries();
+	for (i = 0; i < read_info->entries_cpu; i++, cpu++) {
+		/*
+		 * The logic for only reading the facilities from the
+		 * boot cpu comes from the kernel. I haven't yet found
+		 * documentation that explains why this is necessary
+		 * but I figure there's a reason behind doing it this
+		 * way.
+		 */
+		if (cpu->address == cpu0_addr) {
+			sclp_facilities.has_sief2 = cpu->feat_sief2;
+			break;
+		}
+	}
+}
+
 /* Perform service call. Return 0 on success, non-zero otherwise. */
 int sclp_service_call(unsigned int command, void *sccb)
 {
diff --git a/lib/s390x/sclp.h b/lib/s390x/sclp.h
index acd86d5..6c86037 100644
--- a/lib/s390x/sclp.h
+++ b/lib/s390x/sclp.h
@@ -92,12 +92,22 @@ typedef struct SCCBHeader {
 typedef struct CPUEntry {
     uint8_t address;
     uint8_t reserved0;
-    uint8_t features[SCCB_CPU_FEATURE_LEN];
+    uint8_t : 4;
+    uint8_t feat_sief2 : 1;
+    uint8_t : 3;
+    uint8_t features_res2 [SCCB_CPU_FEATURE_LEN - 1];
     uint8_t reserved2[6];
     uint8_t type;
     uint8_t reserved1;
 } __attribute__((packed)) CPUEntry;
 
+extern struct sclp_facilities sclp_facilities;
+
+struct sclp_facilities {
+	uint64_t has_sief2 : 1;
+	uint64_t : 63;
+};
+
 typedef struct ReadInfo {
     SCCBHeader h;
     uint16_t rnmax;
@@ -271,6 +281,7 @@ void sclp_print(const char *str);
 void sclp_read_info(void);
 int sclp_get_cpu_num(void);
 CPUEntry *sclp_get_cpu_entries(void);
+void sclp_facilities_setup(void);
 int sclp_service_call(unsigned int command, void *sccb);
 void sclp_memory_setup(void);
 uint64_t get_ram_size(void);
-- 
2.25.1