Subject: [PATCH 2/3] powerpc/pseries/htmdump: Fix the offset value used in processor configuration dump

From: Athira Rajeev <[email-masked]>
Date: Sat, 14 Mar 2026 18:54:31 +0530

H_HTM call is invoked using three parameters specifying
the address of the buffer, size of the buffer and offset
where to read from. offset used was always zero.
"offset" is value from output buffer header that points
to next entry to dump. zero is the first entry to dump.
next entry is read from the output bufferbyte offset 0x8.
Update htminfo_read() function to use right offset. Return
when offset points to -1

Fixes: dea7384e14e7 ("powerpc/pseries/htmdump: Add htm info support to htmdump module")
Signed-off-by: Athira Rajeev <[email-masked]>
---
 arch/powerpc/platforms/pseries/htmdump.c | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/htmdump.c b/arch/powerpc/platforms/pseries/htmdump.c
index 93f0cc2dc7fb..34978a794eba 100644
--- a/arch/powerpc/platforms/pseries/htmdump.c
+++ b/arch/powerpc/platforms/pseries/htmdump.c
@@ -277,15 +277,26 @@ static ssize_t htminfo_read(struct file *filp, char __user *ubuf,
 	long rc, ret;
 	u64 *num_entries;
 	u64 to_copy;
+	loff_t offset = 0;
+	u64 info_offset = 0;
 
 	/*
 	 * Invoke H_HTM call with:
 	 * - operation as htm status (H_HTM_OP_STATUS)
 	 * - last three values as addr, size and offset
+	 *   "offset" is value from output buffer header
+	 *   that points to next entry to dump. 0 is the first
+	 *   entry to dump. next entry is read from the output
+	 *   bufferbyte offset 0x8.
 	 */
+	if (*ppos) {
+		info_offset = *(u64 *)(htm_info_data + 0x8);
+		if (info_offset == -1)
+			return 0;
+	}
 	rc = htm_hcall_wrapper(htmflags, nodeindex, nodalchipindex, coreindexonchip,
 				   htmtype, H_HTM_OP_DUMP_SYSPROC_CONF, virt_to_phys(htm_info_data),
-				   PAGE_SIZE, 0);
+				   PAGE_SIZE, be64_to_cpu(info_offset));
 
 	ret = htm_return_check(rc);
 	if (ret <= 0) {
@@ -303,7 +314,9 @@ static ssize_t htminfo_read(struct file *filp, char __user *ubuf,
 	 */
 	num_entries = htm_info_data + 0x10;
 	to_copy = 32 + (be64_to_cpu(*num_entries) * 16);
-	return simple_read_from_buffer(ubuf, count, ppos, htm_info_data, to_copy);
+
+	*ppos += to_copy;
+	return simple_read_from_buffer(ubuf, count, &offset, htm_info_data, to_copy);
 }
 
 static ssize_t htmcaps_read(struct file *filp, char __user *ubuf,
-- 
2.47.3