powerpc/pseries: Enable hvpipe with ibm,set-system-parameter RTAS

JIRA: https://issues.redhat.com/browse/RHEL-101959

commit 39a08a4
Author: Haren Myneni <haren@linux.ibm.com>
Date:   Tue Sep 9 01:44:00 2025 -0700

    powerpc/pseries: Enable hvpipe with ibm,set-system-parameter RTAS

    The partition uses “Hypervisor Pipe OS Enablement Notification”
    system parameter token (value = 64) to enable / disable hvpipe in
    the hypervisor. Once hvpipe is enabled, the hypervisor notifies
    OS if the payload is pending for that partition from any source.
    This system parameter token takes 1 byte length of data with
    1 = Enable and 0 = Disable.

    Enable hvpipe in the hypervisor with ibm,set-system-parameter
    RTAS after registering hvpipe event source interrupt.

    Signed-off-by: Haren Myneni <haren@linux.ibm.com>
    Tested-by: Shashank MS <shashank.gowda@in.ibm.com>
    Reviewed-by: Mahesh Salgaonkar <mahesh@linux.ibm.com>
    Reviewed-by: Tyrel Datwyler <tyreld@linux.ibm.com>
    Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
    Link: https://patch.msgid.link/20250909084402.1488456-9-haren@linux.ibm.com

Signed-off-by: Mamatha Inamdar <minamdar@redhat.com>

Author: Mamatha Inamdar

arch/powerpc/include/asm/papr-sysparm.h

@@ -21,6 +21,7 @@ typedef struct {
 #define PAPR_SYSPARM_COOP_MEM_OVERCOMMIT_ATTRS     mk_papr_sysparm(44)
 #define PAPR_SYSPARM_TLB_BLOCK_INVALIDATE_ATTRS    mk_papr_sysparm(50)
 #define PAPR_SYSPARM_LPAR_NAME                     mk_papr_sysparm(55)
+#define PAPR_SYSPARM_HVPIPE_ENABLE                 mk_papr_sysparm(64)
 
 /**
  * struct papr_sysparm_buf - RTAS work area layout for system parameter functions.

arch/powerpc/platforms/pseries/papr-hvpipe.c

@@ -15,6 +15,7 @@
 #include <asm/machdep.h>
 #include <asm/rtas.h>
 #include <asm/rtas-work-area.h>
+#include <asm/papr-sysparm.h>
 #include <uapi/asm/papr-hvpipe.h>
 #include "pseries.h"
 #include "papr-hvpipe.h"
@@ -648,6 +649,32 @@ static irqreturn_t hvpipe_event_interrupt(int irq, void *dev_id)
 	return IRQ_HANDLED;
 }
 
+/*
+ * Enable hvpipe by system parameter set with parameter
+ * token = 64 and with 1 byte buffer data:
+ * 0 = hvpipe not in use/disable
+ * 1 = hvpipe in use/enable
+ */
+static int set_hvpipe_sys_param(u8 val)
+{
+	struct papr_sysparm_buf *buf;
+	int ret;
+
+	buf = papr_sysparm_buf_alloc();
+	if (!buf)
+		return -ENOMEM;
+
+	buf->len = cpu_to_be16(1);
+	buf->val[0] = val;
+	ret = papr_sysparm_set(PAPR_SYSPARM_HVPIPE_ENABLE, buf);
+	if (ret)
+		pr_err("Can not enable hvpipe %d\n", ret);
+
+	papr_sysparm_buf_free(buf);
+
+	return ret;
+}
+
 static int __init enable_hvpipe_IRQ(void)
 {
 	struct device_node *np;
@@ -705,8 +732,11 @@ static int __init papr_hvpipe_init(void)
 	}
 
 	ret = enable_hvpipe_IRQ();
-	if (!ret)
-		ret = misc_register(&papr_hvpipe_dev);
+	if (!ret) {
+		ret = set_hvpipe_sys_param(1);
+		if (!ret)
+			ret = misc_register(&papr_hvpipe_dev);
+	}
 
 	if (!ret) {
 		pr_info("hvpipe feature is enabled\n");