s390/sclp: provide extended sccb support

As the number of cpus increases, the sccb response can exceed 4k for
read cpu and read scp info sclp commands. Hence, all cpu info entries
cant be embedded within a sccb response

Solution:
To overcome this limitation, extended sccb facility is provided by sclp.

1. Check if the extended sccb facility is installed.
2. If extended sccb is installed, perform the read scp and read cpu
   command considering a max sccb length of three page size. This max
   length is based on factors like max cpus, sccb header.
3. If extended sccb is not installed, perform the read scp and read cpu
   sclp command considering a max sccb length of one page size.

Signed-off-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Reviewed-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

4 files changed, 19 insertions, 8 deletions

diff --git a/drivers/s390/char/sclp.h b/drivers/s390/char/sclp.h
index 448ed25bf6b8..6de919944a39 100644
--- a/drivers/s390/char/sclp.h
+++ b/drivers/s390/char/sclp.h
@@ -156,7 +156,11 @@ struct read_cpu_info_sccb {
 	u16	offset_configured;
 	u16	nr_standby;
 	u16	offset_standby;
-	u8	reserved[4096 - 16];
+	/*
+	 * Without ext sccb, struct size is PAGE_SIZE.
+	 * With ext sccb, struct size is EXT_SCCB_READ_CPU.
+	 */
+	u8	reserved[];
 } __attribute__((packed, aligned(PAGE_SIZE)));
 
 struct read_info_sccb {
@@ -199,7 +203,7 @@ struct read_info_sccb {
 	u8	byte_134;			/* 134 */
 	u8	cpudirq;		/* 135 */
 	u16	cbl;			/* 136-137 */
-	u8	_pad_138[4096 - 138];	/* 138-4095 */
+	u8	_pad_138[EXT_SCCB_READ_SCP - 138];
 } __packed __aligned(PAGE_SIZE);
 
 struct read_storage_sccb {
diff --git a/drivers/s390/char/sclp_cmd.c b/drivers/s390/char/sclp_cmd.c
index f6e97f0830f6..7ebe89890a9b 100644
--- a/drivers/s390/char/sclp_cmd.c
+++ b/drivers/s390/char/sclp_cmd.c
@@ -27,6 +27,7 @@
 #include <asm/page.h>
 #include <asm/sclp.h>
 #include <asm/numa.h>
+#include <asm/facility.h>
 
 #include "sclp.h"
 
@@ -87,14 +88,17 @@ out:
 int _sclp_get_core_info(struct sclp_core_info *info)
 {
 	int rc;
+	int length = test_facility(140) ? EXT_SCCB_READ_CPU : PAGE_SIZE;
 	struct read_cpu_info_sccb *sccb;
 
 	if (!SCLP_HAS_CPU_INFO)
 		return -EOPNOTSUPP;
-	sccb = (void *) get_zeroed_page(GFP_KERNEL | GFP_DMA);
+
+	sccb = (void *)__get_free_pages(GFP_KERNEL | GFP_DMA | __GFP_ZERO, get_order(length));
 	if (!sccb)
 		return -ENOMEM;
-	sccb->header.length = sizeof(*sccb);
+	sccb->header.length = length;
+	sccb->header.control_mask[2] = 0x80;
 	rc = sclp_sync_request_timeout(SCLP_CMDW_READ_CPU_INFO, sccb,
 				       SCLP_QUEUE_INTERVAL);
 	if (rc)
@@ -107,7 +111,7 @@ int _sclp_get_core_info(struct sclp_core_info *info)
 	}
 	sclp_fill_core_info(info, sccb);
 out:
-	free_page((unsigned long) sccb);
+	free_pages((unsigned long) sccb, get_order(length));
 	return rc;
 }
 
diff --git a/drivers/s390/char/sclp_early.c b/drivers/s390/char/sclp_early.c
index cc78b538acbf..2f3515fa242a 100644
--- a/drivers/s390/char/sclp_early.c
+++ b/drivers/s390/char/sclp_early.c
@@ -14,6 +14,7 @@
 #include <asm/sclp.h>
 #include <asm/ipl.h>
 #include <asm/setup.h>
+#include <asm/facility.h>
 #include "sclp_sdias.h"
 #include "sclp.h"
 
@@ -114,7 +115,7 @@ void __init sclp_early_get_ipl_info(struct sclp_ipl_info *info)
 int __init sclp_early_get_core_info(struct sclp_core_info *info)
 {
 	struct read_cpu_info_sccb *sccb;
-	int length = PAGE_SIZE;
+	int length = test_facility(140) ? EXT_SCCB_READ_CPU : PAGE_SIZE;
 	int rc = 0;
 
 	if (!SCLP_HAS_CPU_INFO)
diff --git a/drivers/s390/char/sclp_early_core.c b/drivers/s390/char/sclp_early_core.c
index d4fb61c10d7c..ec9f8ad5341c 100644
--- a/drivers/s390/char/sclp_early_core.c
+++ b/drivers/s390/char/sclp_early_core.c
@@ -11,6 +11,7 @@
 #include <asm/irq.h>
 #include <asm/sections.h>
 #include <asm/mem_detect.h>
+#include <asm/facility.h>
 #include "sclp.h"
 #include "sclp_rw.h"
 
@@ -237,13 +238,14 @@ void sclp_early_printk(const char *str)
 int __init sclp_early_read_info(void)
 {
 	int i;
+	int length = test_facility(140) ? EXT_SCCB_READ_SCP : PAGE_SIZE;
 	struct read_info_sccb *sccb = &sclp_info_sccb;
 	sclp_cmdw_t commands[] = {SCLP_CMDW_READ_SCP_INFO_FORCED,
 				  SCLP_CMDW_READ_SCP_INFO};
 
 	for (i = 0; i < ARRAY_SIZE(commands); i++) {
-		memset(sccb, 0, sizeof(*sccb));
-		sccb->header.length = sizeof(*sccb);
+		memset(sccb, 0, length);
+		sccb->header.length = length;
 		sccb->header.function_code = 0x80;
 		sccb->header.control_mask[2] = 0x80;
 		if (sclp_early_cmd(commands[i], sccb))