powerpc/pseries/htmdump: Add htm capabilities support to htmdump module

Support dumping HTM capabilities information from Hardware
Trace Macro (HTM) function via debugfs interface. Under
debugfs folder "/sys/kernel/debug/powerpc/htmdump", add
file "htmcaps".

The interface allows only read of this file which will present the
content of HTM buffer from the hcall.

Signed-off-by: Athira Rajeev <atrajeev@linux.ibm.com>
Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20250420180844.53128-9-atrajeev@linux.ibm.com

diff --git a/arch/powerpc/platforms/pseries/htmdump.c b/arch/powerpc/platforms/pseries/htmdump.c
index dc5cdcd8c3c3a1036556237c98d64ad5742141d7..af15d50c924b051d2b506627c6fafb4a7549ef4e 100644 (file)
--- a/arch/powerpc/platforms/pseries/htmdump.c
+++ b/arch/powerpc/platforms/pseries/htmdump.c
@@ -14,6 +14,7 @@
 static void *htm_buf;
 static void *htm_status_buf;
 static void *htm_info_buf;
+static void *htm_caps_buf;
 static u32 nodeindex;
 static u32 nodalchipindex;
 static u32 coreindexonchip;
@@ -304,12 +305,43 @@ static ssize_t htminfo_read(struct file *filp, char __user *ubuf,
        return simple_read_from_buffer(ubuf, count, ppos, htm_info_buf, to_copy);
 }
 
+static ssize_t htmcaps_read(struct file *filp, char __user *ubuf,
+                            size_t count, loff_t *ppos)
+{
+       void *htm_caps_buf = filp->private_data;
+       long rc, ret;
+
+       /*
+        * Invoke H_HTM call with:
+        * - operation as htm capabilities (H_HTM_OP_CAPABILITIES)
+        * - last three values as addr, size (0x80 for Capabilities Output Buffer
+        *   and zero
+        */
+       rc = htm_hcall_wrapper(htmflags, nodeindex, nodalchipindex, coreindexonchip,
+                                  htmtype, H_HTM_OP_CAPABILITIES, virt_to_phys(htm_caps_buf),
+                                  0x80, 0);
+
+       ret = htm_return_check(rc);
+       if (ret <= 0) {
+               pr_debug("H_HTM hcall failed for op: H_HTM_OP_CAPABILITIES, returning %ld\n", ret);
+               return ret;
+       }
+
+       return simple_read_from_buffer(ubuf, count, ppos, htm_caps_buf, 0x80);
+}
+
 static const struct file_operations htminfo_fops = {
        .llseek = NULL,
        .read   = htminfo_read,
        .open   = simple_open,
 };
 
+static const struct file_operations htmcaps_fops = {
+       .llseek = NULL,
+       .read   = htmcaps_read,
+       .open   = simple_open,
+};
+
 static int  htmsetup_set(void *data, u64 val)
 {
        long rc, ret;
@@ -417,8 +449,16 @@ static int htmdump_init_debugfs(void)
                return -ENOMEM;
        }
 
+       /* Debugfs interface file to present HTM capabilities */
+       htm_caps_buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
+       if (!htm_caps_buf) {
+               pr_err("Failed to allocate htm caps buf\n");
+               return -ENOMEM;
+       }
+
        debugfs_create_file("htmstatus", 0400, htmdump_debugfs_dir, htm_status_buf, &htmstatus_fops);
        debugfs_create_file("htminfo", 0400, htmdump_debugfs_dir, htm_info_buf, &htminfo_fops);
+       debugfs_create_file("htmcaps", 0400, htmdump_debugfs_dir, htm_caps_buf, &htmcaps_fops);
 
        return 0;
 }