s390/cio: rework channel-utilization-block handling

JIRA: https://issues.redhat.com/browse/RHEL-50790

commit a817d98
Author: Peter Oberparleiter <oberpar@linux.ibm.com>
Date:   Tue Mar 26 17:03:20 2024 +0100

    s390/cio: rework channel-utilization-block handling

    Convert channel-utilization-block (CUB) address variables from separate
    named fields to arrays of addresses. Also simplify error handling and
    introduce named constants. This is done in preparation of introducing
    additional CUBs.

    Note: With this change the __packed annotation of secm_area is required
    to prevent an alignment hole that would otherwise occur due to the
    switch from u32 to dma64_t.

    Reviewed-by: Vineeth Vijayan <vneethv@linux.ibm.com>
    Acked-by: Heiko Carstens <hca@linux.ibm.com>
    Signed-off-by: Peter Oberparleiter <oberpar@linux.ibm.com>
    Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>

Signed-off-by: Mete Durlu <mdurlu@redhat.com>

Author: Mete Durlu

drivers/s390/cio/chp.c

@@ -161,12 +161,12 @@ static void chp_measurement_copy_block(struct cmg_entry *buf,
 	struct cmg_entry *entry, reference_buf;
 	int idx;
 
-	if (chpid.id < 128) {
-		area = css->cub_addr1;
+	if (chpid.id < CSS_CUES_PER_PAGE) {
+		area = css->cub[0];
 		idx = chpid.id;
 	} else {
-		area = css->cub_addr2;
-		idx = chpid.id - 128;
+		area = css->cub[1];
+		idx = chpid.id - CSS_CUES_PER_PAGE;
 	}
 	entry = area + (idx * sizeof(struct cmg_entry));
 	do {

drivers/s390/cio/chsc.c

@@ -860,19 +860,16 @@ int __chsc_do_secm(struct channel_subsystem *css, int enable)
 		u32 : 30;
 		u32 key : 4;
 		u32 : 28;
-		u32 zeroes1;
-		dma32_t cub_addr1;
-		u32 zeroes2;
-		dma32_t cub_addr2;
+		dma64_t cub[CSS_NUM_CUB_PAGES];
 		u32 reserved[13];
 		struct chsc_header response;
 		u32 status : 8;
 		u32 : 4;
 		u32 fmt : 4;
 		u32 : 16;
-	} *secm_area;
+	} __packed *secm_area;
 	unsigned long flags;
-	int ret, ccode;
+	int ret, ccode, i;
 
 	spin_lock_irqsave(&chsc_page_lock, flags);
 	memset(chsc_page, 0, PAGE_SIZE);
@@ -881,8 +878,9 @@ int __chsc_do_secm(struct channel_subsystem *css, int enable)
 	secm_area->request.code = 0x0016;
 
 	secm_area->key = PAGE_DEFAULT_KEY >> 4;
-	secm_area->cub_addr1 = virt_to_dma32(css->cub_addr1);
-	secm_area->cub_addr2 = virt_to_dma32(css->cub_addr2);
+
+	for (i = 0; i < CSS_NUM_CUB_PAGES; i++)
+		secm_area->cub[i] = (__force dma64_t)virt_to_dma32(css->cub[i]);
 
 	secm_area->operation_code = enable ? 0 : 1;
 
@@ -908,19 +906,38 @@ int __chsc_do_secm(struct channel_subsystem *css, int enable)
 	return ret;
 }
 
+static int cub_alloc(struct channel_subsystem *css)
+{
+	int i;
+
+	for (i = 0; i < CSS_NUM_CUB_PAGES; i++) {
+		css->cub[i] = (void *)get_zeroed_page(GFP_KERNEL | GFP_DMA);
+		if (!css->cub[i])
+			return -ENOMEM;
+	}
+
+	return 0;
+}
+
+static void cub_free(struct channel_subsystem *css)
+{
+	int i;
+
+	for (i = 0; i < CSS_NUM_CUB_PAGES; i++) {
+		free_page((unsigned long)css->cub[i]);
+		css->cub[i] = NULL;
+	}
+}
+
 int
 chsc_secm(struct channel_subsystem *css, int enable)
 {
 	int ret;
 
 	if (enable && !css->cm_enabled) {
-		css->cub_addr1 = (void *)get_zeroed_page(GFP_KERNEL | GFP_DMA);
-		css->cub_addr2 = (void *)get_zeroed_page(GFP_KERNEL | GFP_DMA);
-		if (!css->cub_addr1 || !css->cub_addr2) {
-			free_page((unsigned long)css->cub_addr1);
-			free_page((unsigned long)css->cub_addr2);
-			return -ENOMEM;
-		}
+		ret = cub_alloc(css);
+		if (ret)
+			goto out;
 	}
 	ret = __chsc_do_secm(css, enable);
 	if (!ret) {
@@ -934,10 +951,11 @@ chsc_secm(struct channel_subsystem *css, int enable)
 		} else
 			chsc_remove_cmg_attr(css);
 	}
-	if (!css->cm_enabled) {
-		free_page((unsigned long)css->cub_addr1);
-		free_page((unsigned long)css->cub_addr2);
-	}
+
+out:
+	if (!css->cm_enabled)
+		cub_free(css);
+
 	return ret;
 }
 

drivers/s390/cio/css.h

@@ -34,6 +34,13 @@
 #define SNID_STATE3_MULTI_PATH	   1
 #define SNID_STATE3_SINGLE_PATH	   0
 
+/*
+ * Miscellaneous constants
+ */
+
+#define CSS_NUM_CUB_PAGES		2
+#define CSS_CUES_PER_PAGE		128
+
 /*
  * Conditions used to specify which subchannels need evaluation
  */
@@ -122,8 +129,7 @@ struct channel_subsystem {
 	struct mutex mutex;
 	/* channel measurement related */
 	int cm_enabled;
-	void *cub_addr1;
-	void *cub_addr2;
+	void *cub[CSS_NUM_CUB_PAGES];
 	/* for orphaned ccw devices */
 	struct subchannel *pseudo_subchannel;
 };