[kvm-unit-tests PATCH v4 2/2] s390x: sclp: Implement SCLP_RC_INSUFFICIENT_SCCB_LENGTH

[Pierre Morel <pmorel@xxxxxxxxxxxxx>]

If SCLP_CMDW_READ_SCP_INFO fails due to a short buffer, retry
with a greater buffer.

Signed-off-by: Pierre Morel <pmorel@xxxxxxxxxxxxx>
---
 lib/s390x/sclp.c | 58 +++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 50 insertions(+), 8 deletions(-)

diff --git a/lib/s390x/sclp.c b/lib/s390x/sclp.c
index 34a31da..9d51ca4 100644
--- a/lib/s390x/sclp.c
+++ b/lib/s390x/sclp.c
@@ -17,13 +17,14 @@
 #include "sclp.h"
 #include <alloc_phys.h>
 #include <alloc_page.h>
+#include <asm/facility.h>
 
 extern unsigned long stacktop;
 
 static uint64_t storage_increment_size;
 static uint64_t max_ram_size;
 static uint64_t ram_size;
-char _read_info[PAGE_SIZE] __attribute__((__aligned__(PAGE_SIZE)));
+char _read_info[2 * PAGE_SIZE] __attribute__((__aligned__(PAGE_SIZE)));
 static ReadInfo *read_info;
 struct sclp_facilities sclp_facilities;
 
@@ -89,10 +90,41 @@ void sclp_clear_busy(void)
 	spin_unlock(&sclp_lock);
 }
 
-static void sclp_read_scp_info(ReadInfo *ri, int length)
+static bool sclp_read_scp_info_extended(unsigned int command, ReadInfo *ri)
+{
+	int cc;
+
+	if (!test_facility(140)) {
+		report_abort("S390_FEAT_EXTENDED_LENGTH_SCCB missing");
+		return false;
+	}
+	if (ri->h.length > (2 * PAGE_SIZE)) {
+		report_abort("SCLP_READ_INFO expected size too big");
+		return false;
+	}
+
+	sclp_mark_busy();
+	memset(&ri->h, 0, sizeof(ri->h));
+	ri->h.length = 2 * PAGE_SIZE;
+
+	cc = sclp_service_call(command, ri);
+	if (cc) {
+		report_abort("SCLP_READ_INFO error");
+		return false;
+	}
+	if (ri->h.response_code != SCLP_RC_NORMAL_READ_COMPLETION) {
+		report_abort("SCLP_READ_INFO error %02x", ri->h.response_code);
+		return false;
+	}
+
+	return true;
+}
+
+static void sclp_read_scp_info(ReadInfo *ri)
 {
 	unsigned int commands[] = { SCLP_CMDW_READ_SCP_INFO_FORCED,
 				    SCLP_CMDW_READ_SCP_INFO };
+	int length = PAGE_SIZE;
 	int i, cc;
 
 	for (i = 0; i < ARRAY_SIZE(commands); i++) {
@@ -101,19 +133,29 @@ static void sclp_read_scp_info(ReadInfo *ri, int length)
 		ri->h.length = length;
 
 		cc = sclp_service_call(commands[i], ri);
-		if (cc)
-			break;
-		if (ri->h.response_code == SCLP_RC_NORMAL_READ_COMPLETION)
+		if (cc) {
+			report_abort("SCLP_READ_INFO error");
 			return;
-		if (ri->h.response_code != SCLP_RC_INVALID_SCLP_COMMAND)
+		}
+
+		switch (ri->h.response_code) {
+		case SCLP_RC_NORMAL_READ_COMPLETION:
+			return;
+		case SCLP_RC_INVALID_SCLP_COMMAND:
 			break;
+		case SCLP_RC_INSUFFICIENT_SCCB_LENGTH:
+			sclp_read_scp_info_extended(commands[i], ri);
+			return;
+		default:
+			report_abort("READ_SCP_INFO failed");
+			return;
+		}
 	}
-	report_abort("READ_SCP_INFO failed");
 }
 
 void sclp_read_info(void)
 {
-	sclp_read_scp_info((void *)_read_info, SCCB_SIZE);
+	sclp_read_scp_info((void *)_read_info);
 	read_info = (ReadInfo *)_read_info;
 }
 
-- 
2.31.1