powerpc/pseries/htmdump: Add htm_hcall_wrapper to integrate other htm operations

H_HTM (Hardware Trace Macro) hypervisor call is an HCALL to export data
from Hardware Trace Macro (HTM) function. The debugfs interface to
export the HTM function data in an lpar currently supports only dumping
of HTM data in an lpar. To add support for setup, configuration and
control of HTM function via debugfs interface, update the hcall wrapper
function. Rename and update htm_get_dump_hardware to htm_hcall_wrapper()
so that it can be used for other HTM operations as well. Additionally
include parameter "htm_op". Update htmdump module to check the return
code of hcall in a separate function so that it can be reused for other
option too. Add check to disable the interface in guest environment.

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/20250420180844.53128-2-atrajeev@linux.ibm.com

1 files changed, 50 insertions, 13 deletions

diff --git a/arch/powerpc/platforms/pseries/htmdump.c b/arch/powerpc/platforms/pseries/htmdump.c
index 57fc1700f604..604fde6a0559 100644
--- a/arch/powerpc/platforms/pseries/htmdump.c
+++ b/arch/powerpc/platforms/pseries/htmdump.c
@@ -18,20 +18,19 @@ static u32 coreindexonchip;
 static u32 htmtype;
 static struct dentry *htmdump_debugfs_dir;
 
-static ssize_t htmdump_read(struct file *filp, char __user *ubuf,
-			     size_t count, loff_t *ppos)
+/*
+ * Check the return code for H_HTM hcall.
+ * Return non-zero value (1) if either H_PARTIAL or H_SUCCESS
+ * is returned. For other return codes:
+ * Return zero if H_NOT_AVAILABLE.
+ * Return -EBUSY if hcall return busy.
+ * Return -EINVAL if any parameter or operation is not valid.
+ * Return -EPERM if HTM Virtualization Engine Technology code
+ * is not applied.
+ * Return -EIO if the HTM state is not valid.
+ */
+static ssize_t htm_return_check(long rc)
 {
-	void *htm_buf = filp->private_data;
-	unsigned long page, read_size, available;
-	loff_t offset;
-	long rc;
-
-	page = ALIGN_DOWN(*ppos, PAGE_SIZE);
-	offset = (*ppos) % PAGE_SIZE;
-
-	rc = htm_get_dump_hardware(nodeindex, nodalchipindex, coreindexonchip,
-				   htmtype, virt_to_phys(htm_buf), PAGE_SIZE, page);
-
 	switch (rc) {
 	case H_SUCCESS:
 	/* H_PARTIAL for the case where all available data can't be
@@ -65,6 +64,38 @@ static ssize_t htmdump_read(struct file *filp, char __user *ubuf,
 		return -EPERM;
 	}
 
+	/*
+	 * Return 1 for H_SUCCESS/H_PARTIAL
+	 */
+	return 1;
+}
+
+static ssize_t htmdump_read(struct file *filp, char __user *ubuf,
+			     size_t count, loff_t *ppos)
+{
+	void *htm_buf = filp->private_data;
+	unsigned long page, read_size, available;
+	loff_t offset;
+	long rc, ret;
+
+	page = ALIGN_DOWN(*ppos, PAGE_SIZE);
+	offset = (*ppos) % PAGE_SIZE;
+
+	/*
+	 * Invoke H_HTM call with:
+	 * - operation as htm dump (H_HTM_OP_DUMP_DATA)
+	 * - last three values are address, size and offset
+	 */
+	rc = htm_hcall_wrapper(nodeindex, nodalchipindex, coreindexonchip,
+				   htmtype, H_HTM_OP_DUMP_DATA, virt_to_phys(htm_buf),
+				   PAGE_SIZE, page);
+
+	ret = htm_return_check(rc);
+	if (ret <= 0) {
+		pr_debug("H_HTM hcall failed for op: H_HTM_OP_DUMP_DATA, returning %ld\n", ret);
+		return ret;
+	}
+
 	available = PAGE_SIZE;
 	read_size = min(count, available);
 	*ppos += read_size;
@@ -103,6 +134,12 @@ static int htmdump_init_debugfs(void)
 
 static int __init htmdump_init(void)
 {
+	/* Disable on kvm guest */
+	if (is_kvm_guest()) {
+		pr_info("htmdump not supported inside KVM guest\n");
+		return -EOPNOTSUPP;
+	}
+
 	if (htmdump_init_debugfs())
 		return -ENOMEM;