[PATCH v3 0/9] powerpc/pseries: Add hypervisor pipe (HVPIPE) suport

[PATCH v3 0/9] powerpc/pseries: Add hypervisor pipe (HVPIPE) suport

[Haren Myneni]

On powerPC systems, the Hardware Management Console (HMC) is used
to create and manage logical partitions (LPAR)  and both HMC and
LPARs exchange information  over Ethernet which can expose security
implications. Hence the current method of communication is not
viable for secure boot configuration.  To overcome these concerns,
the hypervisor introduced new inband hypervisor channel called
“Hypervisor Pipe (HVPIPE)” which allows HMC and LPARs to exchange
information with ibm,send-hvpipe-msg and ibm,receive-hvpipe-msg
RTAS calls. Sources can be any target that the hypervisor supports,
but only HMC source is supported.

ibm,send-hvpipe-msg RTAS:  Inputs such as Source ID indicator of
which target the data is intended and the buffer list to hold the
payload, and returns the status. Each target represented by source
ID. For example, HMC1, HMC2 and etc.

ibm,receive-hvpipe-msg RTAS: Input buffer to hold the data and size
of the buffer, and returns the source ID of identifier of the target
providing the data, the bytes written in the buffer and the status.

The hypervisor defines HVPIPE with certain requirements and
constraints:
- The OS can determine HVPIPE feature availability with
  “ibm,hypervisor-pipe-capable” property in the /rtas node of the
  device tree.
- One pipe is assigned per partition and for all sources.
- Success return status of send HVPIPE means the payload is
  delivered to source.
- Success return status of send HVPIPE as ACK to source.
- Generate HVPIPE event message interrupt if the status of pipe is
  changed in the hypervisor such as payload is pending or pipe to
  the specific source is closed
- Then the partition issue check exception handler to retrieve the
   message which defines source ID of the pipe and its status.
- The hypervisor will not generate another HVPIPE event message
  until the partition obtains the payload with recv HVPIPE RTAS.
- Supports only 4088 bytes of maximum payload right now,

This patch series adds HVPIPE support and provides interfaces to
the user space to execute ibm,send-hvpipe-msg and
ibm,receive-hvpipe-msg RTAS calls. We already have RTAS calls
execution such as ibm,get-indices, ibm,platform-dump,
ibm,get/set-system-parameter, etc to the user space and following
the similar interfaces foe send and recv HVPIPE RTAS functions.

- Create /dev/papr-hvpipe entry if HVPIPE is enabled
- devfd = open("/dev/papr-hvpipe", ..)
- fd = ioctl(fd,HVPIPE_IOC_CREATE_HANDLE, &srcID) for each source.
- size = write(fd, buf, size)
  - Buffer contains papr_hvpipe_hdr and the payload and send the
    payload with  ibm,send-hvpipe-msg
  - Return the size if the RTAS is success, otherwise return the
    equivalent RTAS failure error code.
-  ret = poll(fd,..)
  - The user space waits for the payload from the source. OS wakes
    up FD whenever receives interrupt from the hypervisor
- size = read(fd, buf, size)
  -  Buffer should have the space to contain papr_hvpipe_hdr and
     the payload
  -  Each read() issue ibm,receive-hvpipe-msg and return the size
     for RTAS success. Otherwise return the equivalent RTAS failure
     error code.

This series consists of the following patches:
powerpc/pseries: Define papr-hvpipe ioctl
-provide HVPIPE_IOC_CREATE_HANDLE ioctl to the user space
powerpc/pseries: Define HVPIPE specific macros
– Define RTAS macros needed for ibm,send-hvpipe-msg and
  ibm,receive-hvpipe-msg RTAS
powerpc/pseries: Add papr-hvpipe char driver for HVPIPE interfaces
– Add devpapr-hvpipe user space interfaces
powerpc/pseries: Send payload with ibm,send-hvpipe-msg RTAS
– Add send HVPIPE RTAS execution from user space
powerpc/pseries: Receive payload with ibm,receive-hvpipe-msg RTAS
– Add recv HVPIPE RTAS execution from user space
powerpc/pseries: Wakeup hvpipe FD when the payload is pending
– The kernel wakes up user space FD when the payload is pending
  from the corresponding source
powerpc/pseries: Enable HVPIPE event message interrupt
– Enable HVPIPE interrupt and adds the handler
powerpc/pseries: Enable hvpipe with ibm,set-system-parameter RTAS
– Enable HVPIPE in the hypervisor
powerpc/pseries: HVPIPE changes to support migration
- LPM support

Changelog:

v2:
- Rebase to 6.17-rc1:
  Changes in Documentation/userspace-api/ioctl/ioctl-number.rst
- Fixed build warnings for uninitialized ret variable in
  papr_hvpipe_init() as reported by kernel test robot <lkp@intel.com>
- Execute migration handler only if the HVPIPE is enabled during
  bootup (papr_hvpipe_work is used).

v3:
The following changes based on comments from Mahesh Salgaonkar.
- Return -EPIPE for the send HVPIPE RTAS when the pipe is closed.
- Return -EALREADY when more than one process issue ioctl() concurrently
  for the same source ID.
- Fix typo error (4048 bytes instead of 4088 for the payload) in the
  commit log ("powerpc/pseries: Send payload with ibm,send-hvpipe-msg
  RTAS")

Haren Myneni (9):
  powerpc/pseries: Define papr-hvpipe ioctl
  powerpc/pseries: Define HVPIPE specific macros
  powerpc/pseries: Add papr-hvpipe char driver for HVPIPE interfaces
  powerpc/pseries: Send payload with ibm,send-hvpipe-msg RTAS
  powerpc/pseries: Receive payload with ibm,receive-hvpipe-msg RTAS
  powerpc/pseries: Wakeup hvpipe FD when the payload is pending
  powerpc/pseries: Enable HVPIPE event message interrupt
  powerpc/pseries: Enable hvpipe with ibm,set-system-parameter RTAS
  powerpc/pseries: HVPIPE changes to support migration

 .../userspace-api/ioctl/ioctl-number.rst      |   2 +
 arch/powerpc/include/asm/papr-sysparm.h       |   1 +
 arch/powerpc/include/asm/rtas.h               |   9 +
 arch/powerpc/include/uapi/asm/papr-hvpipe.h   |  33 +
 arch/powerpc/kernel/rtas.c                    |  24 +
 arch/powerpc/kernel/rtasd.c                   |   2 +
 arch/powerpc/platforms/pseries/Makefile       |   1 +
 arch/powerpc/platforms/pseries/mobility.c     |   3 +
 arch/powerpc/platforms/pseries/papr-hvpipe.c  | 819 ++++++++++++++++++
 arch/powerpc/platforms/pseries/papr-hvpipe.h  |  42 +
 10 files changed, 936 insertions(+)
 create mode 100644 arch/powerpc/include/uapi/asm/papr-hvpipe.h
 create mode 100644 arch/powerpc/platforms/pseries/papr-hvpipe.c
 create mode 100644 arch/powerpc/platforms/pseries/papr-hvpipe.h

-- 
2.50.1

[PATCH v3 1/9] powerpc/pseries: Define papr-hvpipe ioctl

[Haren Myneni]

PowerPC FW introduced HVPIPE RTAS calls such as
ibm,send-hvpipe-msg and ibm,receive-hvpipe-msg for the user space
to exchange information with different sources such as Hardware
Management Consoles (HMC).

HVPIPE_IOC_CREATE_HANDLE is defined to use /dev/papr-hvpipe
interface for ibm,send-hvpipe-msg and ibm,receive-hvpipe-msg
RTAS calls.

Also defined papr_hvpipe_hdr which will added in the payload
that is passed between the kernel and the user space.

Signed-off-by: Haren Myneni <haren@linux.ibm.com>
Reviewed-by: Mahesh Salgaonkar <mahesh@linux.ibm.com>
Tested-by: Shashank MS <shashank.gowda@in.ibm.com>
---
 .../userspace-api/ioctl/ioctl-number.rst      |  2 ++
 arch/powerpc/include/uapi/asm/papr-hvpipe.h   | 33 +++++++++++++++++++
 2 files changed, 35 insertions(+)
 create mode 100644 arch/powerpc/include/uapi/asm/papr-hvpipe.h

diff --git a/Documentation/userspace-api/ioctl/ioctl-number.rst b/Documentation/userspace-api/ioctl/ioctl-number.rst
index 406a9f4d0869..7c527a01d1cf 100644
--- a/Documentation/userspace-api/ioctl/ioctl-number.rst
+++ b/Documentation/userspace-api/ioctl/ioctl-number.rst
@@ -374,6 +374,8 @@ Code  Seq#    Include File                                             Comments
                                                                        <mailto:linuxppc-dev@lists.ozlabs.org>
 0xB2  08     arch/powerpc/include/uapi/asm/papr-physical-attestation.h powerpc/pseries Physical Attestation API
                                                                        <mailto:linuxppc-dev@lists.ozlabs.org>
+0xB2  09     arch/powerpc/include/uapi/asm/papr-hvpipe.h               powerpc/pseries HVPIPE API
+                                                                       <mailto:linuxppc-dev@lists.ozlabs.org>
 0xB3  00     linux/mmc/ioctl.h
 0xB4  00-0F  linux/gpio.h                                              <mailto:linux-gpio@vger.kernel.org>
 0xB5  00-0F  uapi/linux/rpmsg.h                                        <mailto:linux-remoteproc@vger.kernel.org>
diff --git a/arch/powerpc/include/uapi/asm/papr-hvpipe.h b/arch/powerpc/include/uapi/asm/papr-hvpipe.h
new file mode 100644
index 000000000000..459a7bb0e6c9
--- /dev/null
+++ b/arch/powerpc/include/uapi/asm/papr-hvpipe.h
@@ -0,0 +1,33 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+#ifndef _UAPI_PAPR_HVPIPE_H_
+#define _UAPI_PAPR_HVPIPE_H_
+
+#include <linux/types.h>
+#include <asm/ioctl.h>
+#include <asm/papr-miscdev.h>
+
+/*
+ * This header is included in payload between OS and the user
+ * space.
+ * flags: OS notifies the user space whether the hvpipe is
+ *        closed or the buffer has the payload.
+ */
+struct papr_hvpipe_hdr {
+	u8 version;
+	u8 reserved[3];
+	u32 flags;
+	u8 reserved2[40];
+};
+
+/*
+ * ioctl for /dev/papr-hvpipe
+ */
+#define PAPR_HVPIPE_IOC_CREATE_HANDLE	_IOW(PAPR_MISCDEV_IOC_ID, 9, __u32)
+
+/*
+ * hvpipe_hdr flags used for read()
+ */
+#define HVPIPE_MSG_AVAILABLE	0x01 /* Payload is available */
+#define HVPIPE_LOST_CONNECTION	0x02 /* Pipe connection is closed/unavailable */
+
+#endif /* _UAPI_PAPR_HVPIPE_H_ */
-- 
2.50.1

[PATCH v3 2/9] powerpc/pseries: Define HVPIPE specific macros

[Haren Myneni]

Define HVPIPE specific macros which are needed to support
ibm,send-hvpipe-msg and ibm,receive-hvpipe-msg RTAS calls
and used to handle HVPIPE message events.

Signed-off-by: Haren Myneni <haren@linux.ibm.com>
Reviewed-by: Mahesh Salgaonkar <mahesh@linux.ibm.com>
Tested-by: Shashank MS <shashank.gowda@in.ibm.com>
---
 arch/powerpc/include/asm/rtas.h |  9 +++++++++
 arch/powerpc/kernel/rtas.c      | 24 ++++++++++++++++++++++++
 arch/powerpc/kernel/rtasd.c     |  2 ++
 3 files changed, 35 insertions(+)

diff --git a/arch/powerpc/include/asm/rtas.h b/arch/powerpc/include/asm/rtas.h
index 75fa0293c508..d046bbd5017d 100644
--- a/arch/powerpc/include/asm/rtas.h
+++ b/arch/powerpc/include/asm/rtas.h
@@ -68,9 +68,11 @@ enum rtas_function_index {
 	RTAS_FNIDX__IBM_READ_PCI_CONFIG,
 	RTAS_FNIDX__IBM_READ_SLOT_RESET_STATE,
 	RTAS_FNIDX__IBM_READ_SLOT_RESET_STATE2,
+	RTAS_FNIDX__IBM_RECEIVE_HVPIPE_MSG,
 	RTAS_FNIDX__IBM_REMOVE_PE_DMA_WINDOW,
 	RTAS_FNIDX__IBM_RESET_PE_DMA_WINDOW,
 	RTAS_FNIDX__IBM_SCAN_LOG_DUMP,
+	RTAS_FNIDX__IBM_SEND_HVPIPE_MSG,
 	RTAS_FNIDX__IBM_SET_DYNAMIC_INDICATOR,
 	RTAS_FNIDX__IBM_SET_EEH_OPTION,
 	RTAS_FNIDX__IBM_SET_SLOT_RESET,
@@ -163,9 +165,11 @@ typedef struct {
 #define RTAS_FN_IBM_READ_PCI_CONFIG               rtas_fn_handle(RTAS_FNIDX__IBM_READ_PCI_CONFIG)
 #define RTAS_FN_IBM_READ_SLOT_RESET_STATE         rtas_fn_handle(RTAS_FNIDX__IBM_READ_SLOT_RESET_STATE)
 #define RTAS_FN_IBM_READ_SLOT_RESET_STATE2        rtas_fn_handle(RTAS_FNIDX__IBM_READ_SLOT_RESET_STATE2)
+#define RTAS_FN_IBM_RECEIVE_HVPIPE_MSG		  rtas_fn_handle(RTAS_FNIDX__IBM_RECEIVE_HVPIPE_MSG)
 #define RTAS_FN_IBM_REMOVE_PE_DMA_WINDOW          rtas_fn_handle(RTAS_FNIDX__IBM_REMOVE_PE_DMA_WINDOW)
 #define RTAS_FN_IBM_RESET_PE_DMA_WINDOW           rtas_fn_handle(RTAS_FNIDX__IBM_RESET_PE_DMA_WINDOW)
 #define RTAS_FN_IBM_SCAN_LOG_DUMP                 rtas_fn_handle(RTAS_FNIDX__IBM_SCAN_LOG_DUMP)
+#define RTAS_FN_IBM_SEND_HVPIPE_MSG		  rtas_fn_handle(RTAS_FNIDX__IBM_SEND_HVPIPE_MSG)
 #define RTAS_FN_IBM_SET_DYNAMIC_INDICATOR         rtas_fn_handle(RTAS_FNIDX__IBM_SET_DYNAMIC_INDICATOR)
 #define RTAS_FN_IBM_SET_EEH_OPTION                rtas_fn_handle(RTAS_FNIDX__IBM_SET_EEH_OPTION)
 #define RTAS_FN_IBM_SET_SLOT_RESET                rtas_fn_handle(RTAS_FNIDX__IBM_SET_SLOT_RESET)
@@ -217,6 +221,7 @@ typedef struct {
 #define RTAS_HARDWARE_ERROR             -1 /* Hardware or other unspecified error. */
 #define RTAS_BUSY                       -2 /* Retry immediately. */
 #define RTAS_INVALID_PARAMETER          -3 /* Invalid indicator/domain/sensor etc. */
+#define	RTAS_FUNC_NOT_SUPPORTED		-5 /* Function not supported */
 #define RTAS_UNEXPECTED_STATE_CHANGE    -7 /* Seems limited to EEH and slot reset. */
 #define RTAS_EXTENDED_DELAY_MIN       9900 /* Retry after delaying for ~1ms. */
 #define RTAS_EXTENDED_DELAY_MAX       9905 /* Retry after delaying for ~100s. */
@@ -233,6 +238,7 @@ typedef struct {
 #define RTAS_EPOW_WARNING		0x40000000 /* set bit 1 */
 #define RTAS_HOTPLUG_EVENTS		0x10000000 /* set bit 3 */
 #define RTAS_IO_EVENTS			0x08000000 /* set bit 4 */
+#define RTAS_HVPIPE_MSG_EVENTS		0x04000000 /* set bit 5 */
 #define RTAS_EVENT_SCAN_ALL_EVENTS	0xffffffff
 
 /* RTAS event severity */
@@ -282,6 +288,7 @@ typedef struct {
 #define RTAS_TYPE_DEALLOC		0xE3
 #define RTAS_TYPE_DUMP			0xE4
 #define RTAS_TYPE_HOTPLUG		0xE5
+#define RTAS_TYPE_HVPIPE		0xE6
 /* I don't add PowerMGM events right now, this is a different topic */
 #define RTAS_TYPE_PMGM_POWER_SW_ON	0x60
 #define RTAS_TYPE_PMGM_POWER_SW_OFF	0x61
@@ -374,6 +381,7 @@ inline uint32_t rtas_ext_event_company_id(struct rtas_ext_event_log_v6 *ext_log)
 #define PSERIES_ELOG_SECT_ID_HMC_ID		(('H' << 8) | 'M')
 #define PSERIES_ELOG_SECT_ID_EPOW		(('E' << 8) | 'P')
 #define PSERIES_ELOG_SECT_ID_IO_EVENT		(('I' << 8) | 'E')
+#define PSERIES_ELOG_SECT_ID_HVPIPE_EVENT	(('P' << 8) | 'E')
 #define PSERIES_ELOG_SECT_ID_MANUFACT_INFO	(('M' << 8) | 'I')
 #define PSERIES_ELOG_SECT_ID_CALL_HOME		(('C' << 8) | 'H')
 #define PSERIES_ELOG_SECT_ID_USER_DEF		(('U' << 8) | 'D')
@@ -519,6 +527,7 @@ extern struct mutex rtas_ibm_get_indices_lock;
 extern struct mutex rtas_ibm_set_dynamic_indicator_lock;
 extern struct mutex rtas_ibm_get_dynamic_sensor_state_lock;
 extern struct mutex rtas_ibm_physical_attestation_lock;
+extern struct mutex rtas_ibm_send_hvpipe_msg_lock;
 
 #define GLOBAL_INTERRUPT_QUEUE 9005
 
diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c
index e61245c4468e..8d81c1e7a8db 100644
--- a/arch/powerpc/kernel/rtas.c
+++ b/arch/powerpc/kernel/rtas.c
@@ -98,6 +98,8 @@ DEFINE_MUTEX(rtas_ibm_get_vpd_lock);
 DEFINE_MUTEX(rtas_ibm_get_indices_lock);
 DEFINE_MUTEX(rtas_ibm_set_dynamic_indicator_lock);
 DEFINE_MUTEX(rtas_ibm_get_dynamic_sensor_state_lock);
+DEFINE_MUTEX(rtas_ibm_receive_hvpipe_msg_lock);
+DEFINE_MUTEX(rtas_ibm_send_hvpipe_msg_lock);
 
 static struct rtas_function rtas_function_table[] __ro_after_init = {
 	[RTAS_FNIDX__CHECK_EXCEPTION] = {
@@ -373,6 +375,17 @@ static struct rtas_function rtas_function_table[] __ro_after_init = {
 	[RTAS_FNIDX__IBM_READ_SLOT_RESET_STATE2] = {
 		.name = "ibm,read-slot-reset-state2",
 	},
+	[RTAS_FNIDX__IBM_RECEIVE_HVPIPE_MSG] {
+		.name = "ibm,receive-hvpipe-msg",
+		.filter = &(const struct rtas_filter) {
+			.buf_idx1 = 0, .size_idx1 = 1,
+			.buf_idx2 = -1, .size_idx2 = -1,
+		},
+		/*
+		 * PAPR+ v2.13 R1–7.3.32.1
+		 */
+		.lock = &rtas_ibm_receive_hvpipe_msg_lock,
+	},
 	[RTAS_FNIDX__IBM_REMOVE_PE_DMA_WINDOW] = {
 		.name = "ibm,remove-pe-dma-window",
 	},
@@ -391,6 +404,17 @@ static struct rtas_function rtas_function_table[] __ro_after_init = {
 			.buf_idx2 = -1, .size_idx2 = -1,
 		},
 	},
+	[RTAS_FNIDX__IBM_SEND_HVPIPE_MSG] {
+		.name = "ibm,send-hvpipe-msg",
+		.filter = &(const struct rtas_filter) {
+			.buf_idx1 = 1, .size_idx1 = -1,
+			.buf_idx2 = -1, .size_idx2 = -1,
+		},
+		/*
+		 * PAPR+ v2.13 R1–7.3.32.2
+		 */
+		.lock = &rtas_ibm_send_hvpipe_msg_lock,
+	},
 	[RTAS_FNIDX__IBM_SET_DYNAMIC_INDICATOR] = {
 		.name = "ibm,set-dynamic-indicator",
 		.filter = &(const struct rtas_filter) {
diff --git a/arch/powerpc/kernel/rtasd.c b/arch/powerpc/kernel/rtasd.c
index 9bba469239fc..6336ec9aedd0 100644
--- a/arch/powerpc/kernel/rtasd.c
+++ b/arch/powerpc/kernel/rtasd.c
@@ -89,6 +89,8 @@ static char *rtas_event_type(int type)
 			return "Platform Resource Reassignment Event";
 		case RTAS_TYPE_HOTPLUG:
 			return "Hotplug Event";
+		case RTAS_TYPE_HVPIPE:
+			return "Hypervisor Pipe Notification event";
 	}
 
 	return rtas_type[0];
-- 
2.50.1

[PATCH v3 3/9] powerpc/pseries: Add papr-hvpipe char driver for HVPIPE interfaces

[Haren Myneni]

The hypervisor provides ibm,send-hvpipe-msg and
ibm,receive-hvpipe-msg RTAS calls which can be used by the
partition to communicate through an inband hypervisor channel with
different external sources such as Hardware Management Console
(HMC). The information exchanged, whether it be messages, raw or
formatted data, etc., is only known to between applications in the
OS and the source (HMC). This patch adds papr-hvpipe character
driver and provides the standard interfaces such as open / ioctl/
read / write to user space for exchanging information with HMC
using send/recevive HVPIPE RTAS functions.

PAPR (7.3.32 Hypervisor Pipe Information Exchange) defines the
HVPIPE usage:
- The hypervisor has one HVPIPE per partition for all sources.
- OS can determine this feature’s availability by detecting the
  “ibm,hypervisor-pipe-capable” property in the /rtas node of the
  device tree.
- Each source is represented by the source ID which is used in
  send / recv HVPIPE RTAS. (Ex: source ID is the target for the
  payload in send RTAS).
- Return status of ibm,send-hvpipe-msg can be considered as
  delivered the payload.
- Return status of ibm,receive-hvpipe-msg can be considered as
  ACK to source.
- The hypervisor generates hvpipe message event interrupt when
  the partition has the payload to receive.

Provide the interfaces to the user space with /dev/papr-hvpipe
character device using the following programming model:

int devfd = open("/dev/papr-hvpipe")
int fd = ioctl(devfd, PAPR_HVPIPE_IOC_CREATE_HANDLE, &srcID);
- Restrict the user space to use the same source ID and do not
  expect more than one process access with the same source.
char *buf = malloc(size);
- SIZE should be 4K and the buffer contains header and the
  payload.
length = write(fd, buf, size);
- OS issues ibm,send-hvpipe-msg RTAS and returns the RTAS status
  to the user space.
ret = poll(fd,...)
- The HVPIPE event message IRQ wakes up for any waiting FDs.
length = read(fd, buf, size);
- OS issues ibm,receive-hvpipe-msg to receive payload from the
  hypervisor.
release(fd);
- OS issues ibm,receive-hvpipe-msg if any payload is pending so
  that pipe is not blocked.

The actual implementation of these calls are added in the
next patches.

Signed-off-by: Haren Myneni <haren@linux.ibm.com>
Reviewed-by: Mahesh Salgaonkar <mahesh@linux.ibm.com>
Tested-by: Shashank MS <shashank.gowda@in.ibm.com>
---
 arch/powerpc/platforms/pseries/Makefile      |   1 +
 arch/powerpc/platforms/pseries/papr-hvpipe.c | 285 +++++++++++++++++++
 arch/powerpc/platforms/pseries/papr-hvpipe.h |  14 +
 3 files changed, 300 insertions(+)
 create mode 100644 arch/powerpc/platforms/pseries/papr-hvpipe.c
 create mode 100644 arch/powerpc/platforms/pseries/papr-hvpipe.h

diff --git a/arch/powerpc/platforms/pseries/Makefile b/arch/powerpc/platforms/pseries/Makefile
index 57222678bb3f..931ebaa474c8 100644
--- a/arch/powerpc/platforms/pseries/Makefile
+++ b/arch/powerpc/platforms/pseries/Makefile
@@ -5,6 +5,7 @@ obj-y			:= lpar.o hvCall.o nvram.o reconfig.o \
 			   of_helpers.o rtas-work-area.o papr-sysparm.o \
 			   papr-rtas-common.o papr-vpd.o papr-indices.o \
 			   papr-platform-dump.o papr-phy-attest.o \
+			   papr-hvpipe.o \
 			   setup.o iommu.o event_sources.o ras.o \
 			   firmware.o power.o dlpar.o mobility.o rng.o \
 			   pci.o pci_dlpar.o eeh_pseries.o msi.o \
diff --git a/arch/powerpc/platforms/pseries/papr-hvpipe.c b/arch/powerpc/platforms/pseries/papr-hvpipe.c
new file mode 100644
index 000000000000..0ce0e531e49b
--- /dev/null
+++ b/arch/powerpc/platforms/pseries/papr-hvpipe.c
@@ -0,0 +1,285 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#define pr_fmt(fmt) "papr-hvpipe: " fmt
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/delay.h>
+#include <linux/anon_inodes.h>
+#include <linux/miscdevice.h>
+#include <linux/file.h>
+#include <linux/fs.h>
+#include <linux/poll.h>
+#include <linux/of.h>
+#include <asm/machdep.h>
+#include <asm/rtas.h>
+#include <uapi/asm/papr-hvpipe.h>
+#include "pseries.h"
+#include "papr-hvpipe.h"
+
+static DEFINE_SPINLOCK(hvpipe_src_list_lock);
+static LIST_HEAD(hvpipe_src_list);
+
+/*
+ * New PowerPC FW provides support for partitions and various
+ * sources (Ex: remote hardware management console (HMC)) to
+ * exchange information through an inband hypervisor channel
+ * called HVPIPE. Only HMCs are supported right now and
+ * partitions can communicate with multiple HMCs and each
+ * source represented by source ID.
+ *
+ * FW introduces send HVPIPE and recv HVPIPE RTAS calls for
+ * partitions to send and receive payloads respectively.
+ *
+ * These RTAS functions have the following certain requirements
+ * / limitations:
+ * - One hvpipe per partition for all sources.
+ * - Assume the return status of send HVPIPE as delivered to source
+ * - Assume the return status of recv HVPIPE as ACK to source
+ * - Generates HVPIPE event message when the payload is ready
+ *   for the partition. The hypervisor will not deliver another
+ *   event until the partition read the previous payload which
+ *   means the pipe is blocked for any sources.
+ *
+ * Linux implementation:
+ * Follow the similar interfaces that the OS has for other RTAS calls.
+ * ex: /dev/papr-indices, /dev/papr-vpd, etc.
+ * - /dev/papr-hvpipe is available for the user space.
+ * - devfd = open("/dev/papr-hvpipe", ..)
+ * - fd = ioctl(fd,HVPIPE_IOC_CREATE_HANDLE,&srcID)-for each source
+ * - write(fd, buf, size) --> Issue send HVPIPE RTAS call and
+ *   returns size for success or the corresponding error for RTAS
+ *   return code for failure.
+ * - poll(fd,..) -> wakeup FD if the payload is available to read.
+ *   HVPIPE event message handler wakeup FD based on source ID in
+ *   the event message
+ * - read(fd, buf, size) --> Issue recv HVPIPE RTAS call and
+ *   returns size for success or the corresponding error for RTAS
+ *   return code for failure.
+ */
+
+static struct hvpipe_source_info *hvpipe_find_source(u32 srcID)
+{
+	struct hvpipe_source_info *src_info;
+
+	list_for_each_entry(src_info, &hvpipe_src_list, list)
+		if (src_info->srcID == srcID)
+			return src_info;
+
+	return NULL;
+}
+
+/*
+ * papr_hvpipe_handle_write -  Issue send HVPIPE RTAS and return
+ * the RTAS status to the user space
+ */
+static ssize_t papr_hvpipe_handle_write(struct file *file,
+	const char __user *buf, size_t size, loff_t *off)
+{
+	struct hvpipe_source_info *src_info = file->private_data;
+
+	if (!src_info)
+		return -EIO;
+
+	return 0;
+}
+
+/*
+ * papr_hvpipe_handle_read - If the payload for the specific
+ * source is pending in the hypervisor, issue recv HVPIPE RTAS
+ * and return the payload to the user space.
+ *
+ * When the payload is available for the partition, the
+ * hypervisor notifies HVPIPE event with the source ID
+ * and the event handler wakeup FD(s) that are waiting.
+ */
+static ssize_t papr_hvpipe_handle_read(struct file *file,
+		char __user *buf, size_t size, loff_t *off)
+{
+
+	struct hvpipe_source_info *src_info = file->private_data;
+
+	if (!src_info)
+		return -EIO;
+
+	return 0;
+}
+
+/*
+ * The user space waits for the payload to receive.
+ * The hypervisor sends HVPIPE event message to the partition
+ * when the payload is available. The event handler wakeup FD
+ * depends on the source ID in the message event.
+ */
+static unsigned int papr_hvpipe_handle_poll(struct file *filp,
+		struct poll_table_struct *wait)
+{
+	struct hvpipe_source_info *src_info = filp->private_data;
+
+	if (!src_info)
+		return -EIO;
+
+	return 0;
+}
+
+static int papr_hvpipe_handle_release(struct inode *inode,
+				struct file *file)
+{
+	struct hvpipe_source_info *src_info;
+
+	/*
+	 * Hold the lock, remove source from src_list, reset the
+	 * hvpipe status and release the lock to prevent any race
+	 * with message event IRQ.
+	 */
+	spin_lock(&hvpipe_src_list_lock);
+	src_info = file->private_data;
+	list_del(&src_info->list);
+	file->private_data = NULL;
+	spin_unlock(&hvpipe_src_list_lock);
+	kfree(src_info);
+	return 0;
+}
+
+static const struct file_operations papr_hvpipe_handle_ops = {
+	.read		=	papr_hvpipe_handle_read,
+	.write		=	papr_hvpipe_handle_write,
+	.release	=	papr_hvpipe_handle_release,
+	.poll		=	papr_hvpipe_handle_poll,
+};
+
+static int papr_hvpipe_dev_create_handle(u32 srcID)
+{
+	struct hvpipe_source_info *src_info;
+	struct file *file;
+	long err;
+	int fd;
+
+	spin_lock(&hvpipe_src_list_lock);
+	/*
+	 * Do not allow more than one process communicates with
+	 * each source.
+	 */
+	src_info = hvpipe_find_source(srcID);
+	if (src_info) {
+		spin_unlock(&hvpipe_src_list_lock);
+		pr_err("pid(%d) is already using the source(%d)\n",
+				src_info->tsk->pid, srcID);
+		return -EALREADY;
+	}
+	spin_unlock(&hvpipe_src_list_lock);
+
+	src_info = kzalloc(sizeof(*src_info), GFP_KERNEL_ACCOUNT);
+	if (!src_info)
+		return -ENOMEM;
+
+	src_info->srcID = srcID;
+	src_info->tsk = current;
+	init_waitqueue_head(&src_info->recv_wqh);
+
+	fd = get_unused_fd_flags(O_RDONLY | O_CLOEXEC);
+	if (fd < 0) {
+		err = fd;
+		goto free_buf;
+	}
+
+	file = anon_inode_getfile("[papr-hvpipe]",
+			&papr_hvpipe_handle_ops, (void *)src_info,
+			O_RDWR);
+	if (IS_ERR(file)) {
+		err = PTR_ERR(file);
+		goto free_fd;
+	}
+
+	spin_lock(&hvpipe_src_list_lock);
+	/*
+	 * If two processes are executing ioctl() for the same
+	 * source ID concurrently, prevent the second process to
+	 * acquire FD.
+	 */
+	if (hvpipe_find_source(srcID)) {
+		spin_unlock(&hvpipe_src_list_lock);
+		err = -EALREADY;
+		goto free_file;
+	}
+	list_add(&src_info->list, &hvpipe_src_list);
+	spin_unlock(&hvpipe_src_list_lock);
+
+	fd_install(fd, file);
+	return fd;
+
+free_file:
+	fput(file);
+free_fd:
+	put_unused_fd(fd);
+free_buf:
+	kfree(src_info);
+	return err;
+}
+
+/*
+ * Top-level ioctl handler for /dev/papr_hvpipe
+ *
+ * Use separate FD for each source (exa :HMC). So ioctl is called
+ * with source ID which returns FD.
+ */
+static long papr_hvpipe_dev_ioctl(struct file *filp, unsigned int ioctl,
+		unsigned long arg)
+{
+	u32 __user *argp = (void __user *)arg;
+	u32 srcID;
+	long ret;
+
+	if (get_user(srcID, argp))
+		return -EFAULT;
+
+	/*
+	 * Support only HMC source right now
+	 */
+	if (!(srcID & HVPIPE_HMC_ID_MASK))
+		return -EINVAL;
+
+	switch (ioctl) {
+	case PAPR_HVPIPE_IOC_CREATE_HANDLE:
+		ret = papr_hvpipe_dev_create_handle(srcID);
+		break;
+	default:
+		ret = -ENOIOCTLCMD;
+		break;
+	}
+
+	return ret;
+}
+
+static const struct file_operations papr_hvpipe_ops = {
+	.unlocked_ioctl	=	papr_hvpipe_dev_ioctl,
+};
+
+static struct miscdevice papr_hvpipe_dev = {
+	.minor	=	MISC_DYNAMIC_MINOR,
+	.name	=	"papr-hvpipe",
+	.fops	=	&papr_hvpipe_ops,
+};
+
+static int __init papr_hvpipe_init(void)
+{
+	int ret;
+
+	if (!of_find_property(rtas.dev, "ibm,hypervisor-pipe-capable",
+		NULL))
+		return -ENODEV;
+
+	if (!rtas_function_implemented(RTAS_FN_IBM_SEND_HVPIPE_MSG) ||
+		!rtas_function_implemented(RTAS_FN_IBM_RECEIVE_HVPIPE_MSG))
+		return -ENODEV;
+
+	ret = misc_register(&papr_hvpipe_dev);
+	if (ret) {
+		pr_err("misc-dev registration failed %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+machine_device_initcall(pseries, papr_hvpipe_init);
diff --git a/arch/powerpc/platforms/pseries/papr-hvpipe.h b/arch/powerpc/platforms/pseries/papr-hvpipe.h
new file mode 100644
index 000000000000..3b6f9e737913
--- /dev/null
+++ b/arch/powerpc/platforms/pseries/papr-hvpipe.h
@@ -0,0 +1,14 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef _PAPR_HVPIPE_H
+#define _PAPR_HVPIPE_H
+
+#define	HVPIPE_HMC_ID_MASK	0x02000000 /*02-HMC,00-reserved and HMC ID */
+
+struct hvpipe_source_info {
+	struct list_head list;	/* list of sources */
+	u32 srcID;
+	wait_queue_head_t recv_wqh;	 /* wake up poll() waitq */
+	struct task_struct *tsk;
+};
+
+#endif /* _PAPR_HVPIPE_H */
-- 
2.50.1

[PATCH v3 4/9] powerpc/pseries: Send payload with ibm,send-hvpipe-msg RTAS

[Haren Myneni]

ibm,send-hvpipe-msg RTAS call is used to send data to the source
(Ex: Hardware Management Console) over the hypervisor pipe. The
maximum data length of 4048 bytes is supported with this RTAS call
right now. The user space uses write() to send this payload which
invokes this RTAS. Then the write returns the buffer length
(including papr_hvpipe_hdr length) to the user space for success
or RTAS failure error.

ibm,send-hvpipe-msg call takes source ID as target and the buffer
in the form of buffer list. The buffer list format consists of
work area of size 4K to hold buffer list and number of 4K work
areas depends on buffers is as follows:

Length of Buffer List in bytes
Address of 4K buffer 1
Length of 4K buffer 1 used
...
Address of 4K buffer n
Length of 4K buffer n used

Only one buffer is used right now because of max payload size is
4048 bytes. writev() can be used in future when supported more
than one buffer.

Signed-off-by: Haren Myneni <haren@linux.ibm.com>
Reviewed-by: Mahesh Salgaonkar <mahesh@linux.ibm.com>
Tested-by: Shashank MS <shashank.gowda@in.ibm.com>
---
 arch/powerpc/platforms/pseries/papr-hvpipe.c | 120 ++++++++++++++++++-
 arch/powerpc/platforms/pseries/papr-hvpipe.h |   7 ++
 2 files changed, 126 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/platforms/pseries/papr-hvpipe.c b/arch/powerpc/platforms/pseries/papr-hvpipe.c
index 0ce0e531e49b..a7f0c49c7bdd 100644
--- a/arch/powerpc/platforms/pseries/papr-hvpipe.c
+++ b/arch/powerpc/platforms/pseries/papr-hvpipe.c
@@ -14,6 +14,7 @@
 #include <linux/of.h>
 #include <asm/machdep.h>
 #include <asm/rtas.h>
+#include <asm/rtas-work-area.h>
 #include <uapi/asm/papr-hvpipe.h>
 #include "pseries.h"
 #include "papr-hvpipe.h"
@@ -59,6 +60,51 @@ static LIST_HEAD(hvpipe_src_list);
  *   return code for failure.
  */
 
+/*
+ * ibm,send-hvpipe-msg RTAS call
+ * @area: Caller-provided work area buffer to send.
+ * @srcID: Target source for the send pipe message.
+ */
+static int rtas_ibm_send_hvpipe_msg(struct rtas_work_area *area, u32 srcID)
+{
+	const s32 token = rtas_function_token(RTAS_FN_IBM_SEND_HVPIPE_MSG);
+	s32 fwrc;
+	int ret;
+
+	if (token == RTAS_UNKNOWN_SERVICE)
+		return -ENOENT;
+
+	do {
+		fwrc = rtas_call(token, 2, 1, NULL, srcID,
+				rtas_work_area_phys(area));
+
+	} while (rtas_busy_delay(fwrc));
+
+	switch (fwrc) {
+	case RTAS_SUCCESS:
+		ret = 0;
+		break;
+	case RTAS_HARDWARE_ERROR:
+		ret = -EIO;
+		break;
+	case RTAS_INVALID_PARAMETER:
+		ret = -EINVAL;
+		break;
+	case RTAS_HVPIPE_CLOSED:
+		ret = -EPIPE;
+		break;
+	case RTAS_FUNC_NOT_SUPPORTED:
+		ret = -EOPNOTSUPP;
+		break;
+	default:
+		ret = -EIO;
+		pr_err_ratelimited("unexpected ibm,receive-hvpipe-msg status %d\n", fwrc);
+		break;
+	}
+
+	return ret;
+}
+
 static struct hvpipe_source_info *hvpipe_find_source(u32 srcID)
 {
 	struct hvpipe_source_info *src_info;
@@ -78,11 +124,83 @@ static ssize_t papr_hvpipe_handle_write(struct file *file,
 	const char __user *buf, size_t size, loff_t *off)
 {
 	struct hvpipe_source_info *src_info = file->private_data;
+	struct rtas_work_area *work_area, *work_buf;
+	unsigned long ret, len;
+	char *area_buf;
 
 	if (!src_info)
 		return -EIO;
 
-	return 0;
+	/*
+	 * Send HVPIPE RTAS is used to send payload to the specific
+	 * source with the input parameters source ID and the payload
+	 * as buffer list. Each entry in the buffer list contains
+	 * address/length pair of the buffer.
+	 *
+	 * The buffer list format is as follows:
+	 *
+	 * Header (length of address/length pairs and the header length)
+	 * Address of 4K buffer 1
+	 * Length of 4K buffer 1 used
+	 * ...
+	 * Address of 4K buffer n
+	 * Length of 4K buffer n used
+	 *
+	 * See PAPR 7.3.32.2 ibm,send-hvpipe-msg
+	 *
+	 * Even though can support max 1MB payload, the hypervisor
+	 * supports only 4048 bytes payload at present and also
+	 * just one address/length entry.
+	 *
+	 * writev() interface can be added in future when the
+	 * hypervisor supports multiple buffer list entries.
+	 */
+	/* HVPIPE_MAX_WRITE_BUFFER_SIZE = 4048 bytes */
+	if ((size > (HVPIPE_HDR_LEN + HVPIPE_MAX_WRITE_BUFFER_SIZE)) ||
+		(size <= HVPIPE_HDR_LEN))
+		return -EINVAL;
+
+	/*
+	 * The length of (address + length) pair + the length of header
+	 */
+	len = (2 * sizeof(u64)) + sizeof(u64);
+	size -= HVPIPE_HDR_LEN;
+	buf += HVPIPE_HDR_LEN;
+	mutex_lock(&rtas_ibm_send_hvpipe_msg_lock);
+	work_area = rtas_work_area_alloc(SZ_4K);
+	if (!work_area) {
+		ret = -ENOMEM;
+		goto out;
+	}
+	area_buf = rtas_work_area_raw_buf(work_area);
+	/* header */
+	*(u64 *)area_buf = cpu_to_be64(len);
+	area_buf += sizeof(u64);
+
+	work_buf = rtas_work_area_alloc(SZ_4K);
+	if (!area_buf) {
+		ret = -ENOMEM;
+		goto out_work;
+	}
+	/* First buffer address */
+	*(u64 *)area_buf = cpu_to_be64(rtas_work_area_phys(work_buf));
+	area_buf += sizeof(u64);
+	/* First buffer address length */
+	*(u64 *)area_buf = cpu_to_be64(size);
+
+	if (!copy_from_user(rtas_work_area_raw_buf(work_buf), buf, size)) {
+		ret = rtas_ibm_send_hvpipe_msg(work_area, src_info->srcID);
+		if (!ret)
+			ret = size + HVPIPE_HDR_LEN;
+	} else
+		ret = -EPERM;
+
+	rtas_work_area_free(work_buf);
+out_work:
+	rtas_work_area_free(work_area);
+out:
+	mutex_unlock(&rtas_ibm_send_hvpipe_msg_lock);
+	return ret;
 }
 
 /*
diff --git a/arch/powerpc/platforms/pseries/papr-hvpipe.h b/arch/powerpc/platforms/pseries/papr-hvpipe.h
index 3b6f9e737913..6f98da4ec45f 100644
--- a/arch/powerpc/platforms/pseries/papr-hvpipe.h
+++ b/arch/powerpc/platforms/pseries/papr-hvpipe.h
@@ -3,6 +3,13 @@
 #define _PAPR_HVPIPE_H
 
 #define	HVPIPE_HMC_ID_MASK	0x02000000 /*02-HMC,00-reserved and HMC ID */
+#define	HVPIPE_MAX_WRITE_BUFFER_SIZE	4048
+/*
+ * hvpipe specific RTAS return values
+ */
+#define	RTAS_HVPIPE_CLOSED		-4
+
+#define	HVPIPE_HDR_LEN	sizeof(struct papr_hvpipe_hdr)
 
 struct hvpipe_source_info {
 	struct list_head list;	/* list of sources */
-- 
2.50.1

[PATCH v3 5/9] powerpc/pseries: Receive payload with ibm,receive-hvpipe-msg RTAS

[Haren Myneni]

ibm,receive-hvpipe-msg RTAS call is used to receive data from the
source (Ex: Hardware Management Console) over the hypervisor
pipe. The hypervisor will signal the OS via a Hypervisor Pipe
Event external interrupt when data is available to be received
from the pipe and the event message has the source ID and the
message type such as payload or closed pipe to the specific
source. The hypervisor will not generate another interrupt for
the next payload until the partition reads the previous payload.
It means the hvpipe is blocked and will not deliver other events
for any source. The maximum data length of 4048 bytes is
supported with this RTAS call right now.

The user space uses read() to receive data from HMC which issues
ibm,receive-hvpipe-msg RTAS and the kernel returns the buffer
length (including papr_hvpipe_hdr length) to the user space for
success or RTAS failure error. If the message is regarding the
pipe closed, kernel just returns the  papr_hvpipe_hdr with
flags = HVPIPE_LOST_CONNECTION and expects the user space to
close FD for the corresponding source.

bm,receive-hvpipe-msg RTAS call passes the buffer and returns
the source ID from where this payload is received and the
payload length.

Signed-off-by: Haren Myneni <haren@linux.ibm.com>
Reviewed-by: Mahesh Salgaonkar <mahesh@linux.ibm.com>
Tested-by: Shashank MS <shashank.gowda@in.ibm.com>
---
 arch/powerpc/platforms/pseries/papr-hvpipe.c | 164 ++++++++++++++++++-
 arch/powerpc/platforms/pseries/papr-hvpipe.h |   1 +
 2 files changed, 163 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/papr-hvpipe.c b/arch/powerpc/platforms/pseries/papr-hvpipe.c
index a7f0c49c7bdd..eb1b5f1f976e 100644
--- a/arch/powerpc/platforms/pseries/papr-hvpipe.c
+++ b/arch/powerpc/platforms/pseries/papr-hvpipe.c
@@ -60,6 +60,54 @@ static LIST_HEAD(hvpipe_src_list);
  *   return code for failure.
  */
 
+/*
+ * ibm,receive-hvpipe-msg RTAS call.
+ * @area: Caller-provided work area buffer for results.
+ * @srcID: Source ID returned by the RTAS call.
+ * @bytesw: Bytes written by RTAS call to @area.
+ */
+static int rtas_ibm_receive_hvpipe_msg(struct rtas_work_area *area,
+					u32 *srcID, u32 *bytesw)
+{
+	const s32 token = rtas_function_token(RTAS_FN_IBM_RECEIVE_HVPIPE_MSG);
+	u32 rets[2];
+	s32 fwrc;
+	int ret;
+
+	if (token == RTAS_UNKNOWN_SERVICE)
+		return -ENOENT;
+
+	do {
+		fwrc = rtas_call(token, 2, 3, rets,
+				rtas_work_area_phys(area),
+				rtas_work_area_size(area));
+
+	} while (rtas_busy_delay(fwrc));
+
+	switch (fwrc) {
+	case RTAS_SUCCESS:
+		*srcID = rets[0];
+		*bytesw = rets[1];
+		ret = 0;
+		break;
+	case RTAS_HARDWARE_ERROR:
+		ret = -EIO;
+		break;
+	case RTAS_INVALID_PARAMETER:
+		ret = -EINVAL;
+		break;
+	case RTAS_FUNC_NOT_SUPPORTED:
+		ret = -EOPNOTSUPP;
+		break;
+	default:
+		ret = -EIO;
+		pr_err_ratelimited("unexpected ibm,receive-hvpipe-msg status %d\n", fwrc);
+		break;
+	}
+
+	return ret;
+}
+
 /*
  * ibm,send-hvpipe-msg RTAS call
  * @area: Caller-provided work area buffer to send.
@@ -116,9 +164,60 @@ static struct hvpipe_source_info *hvpipe_find_source(u32 srcID)
 	return NULL;
 }
 
+/*
+ * This work function collects receive buffer with recv HVPIPE
+ * RTAS call. Called from read()
+ * @buf: User specified buffer to copy the payload that returned
+ *       from recv HVPIPE RTAS.
+ * @size: Size of buffer user passed.
+ */
+static int hvpipe_rtas_recv_msg(char __user *buf, int size)
+{
+	struct rtas_work_area *work_area;
+	u32 srcID, bytes_written;
+	int ret;
+
+	work_area = rtas_work_area_alloc(SZ_4K);
+	if (!work_area) {
+		pr_err("Could not allocate RTAS buffer for recv pipe\n");
+		return -ENOMEM;
+	}
+
+	ret = rtas_ibm_receive_hvpipe_msg(work_area, &srcID,
+					&bytes_written);
+	if (!ret) {
+		/*
+		 * Recv HVPIPE RTAS is successful.
+		 * When releasing FD or no one is waiting on the
+		 * specific source, issue recv HVPIPE RTAS call
+		 * so that pipe is not blocked - this func is called
+		 * with NULL buf.
+		 */
+		if (buf) {
+			if (size < bytes_written) {
+				pr_err("Received the payload size = %d, but the buffer size = %d\n",
+					bytes_written, size);
+				bytes_written = size;
+			}
+			ret = copy_to_user(buf,
+					rtas_work_area_raw_buf(work_area),
+					bytes_written);
+			if (!ret)
+				ret = bytes_written;
+		}
+	} else {
+		pr_err("ibm,receive-hvpipe-msg failed with %d\n",
+				ret);
+	}
+
+	rtas_work_area_free(work_area);
+	return ret;
+}
+
 /*
  * papr_hvpipe_handle_write -  Issue send HVPIPE RTAS and return
- * the RTAS status to the user space
+ * the size (payload + HVPIPE_HDR_LEN) for RTAS success.
+ * Otherwise returns the status of RTAS to the user space
  */
 static ssize_t papr_hvpipe_handle_write(struct file *file,
 	const char __user *buf, size_t size, loff_t *off)
@@ -217,11 +316,72 @@ static ssize_t papr_hvpipe_handle_read(struct file *file,
 {
 
 	struct hvpipe_source_info *src_info = file->private_data;
+	struct papr_hvpipe_hdr hdr;
+	long ret;
 
 	if (!src_info)
 		return -EIO;
 
-	return 0;
+	/*
+	 * Max payload is 4048 (HVPIPE_MAX_WRITE_BUFFER_SIZE)
+	 */
+	if ((size > (HVPIPE_HDR_LEN + HVPIPE_MAX_WRITE_BUFFER_SIZE)) ||
+		(size < HVPIPE_HDR_LEN))
+		return -EINVAL;
+
+	/*
+	 * Payload is not available to receive or source pipe
+	 * is not closed.
+	 */
+	if (!src_info->hvpipe_status)
+		return 0;
+
+	hdr.version = 0;
+	hdr.flags = 0;
+
+	/*
+	 * In case if the hvpipe has payload and also the
+	 * hypervisor closed the pipe to the source, retrieve
+	 * the payload and return to the user space first and
+	 * then notify the userspace about the hvpipe close in
+	 * next read().
+	 */
+	if (src_info->hvpipe_status & HVPIPE_MSG_AVAILABLE)
+		hdr.flags = HVPIPE_MSG_AVAILABLE;
+	else if (src_info->hvpipe_status & HVPIPE_LOST_CONNECTION)
+		hdr.flags = HVPIPE_LOST_CONNECTION;
+	else
+		/*
+		 * Should not be here without one of the above
+		 * flags set
+		 */
+		return -EIO;
+
+	ret = copy_to_user(buf, &hdr, HVPIPE_HDR_LEN);
+	if (ret)
+		return ret;
+
+	/*
+	 * Message event has payload, so get the payload with
+	 * recv HVPIPE RTAS.
+	 */
+	if (hdr.flags & HVPIPE_MSG_AVAILABLE) {
+		ret = hvpipe_rtas_recv_msg(buf + HVPIPE_HDR_LEN,
+				size - HVPIPE_HDR_LEN);
+		if (ret > 0) {
+			src_info->hvpipe_status &= ~HVPIPE_MSG_AVAILABLE;
+			ret += HVPIPE_HDR_LEN;
+		}
+	} else if (hdr.flags & HVPIPE_LOST_CONNECTION) {
+		/*
+		 * Hypervisor is closing the pipe for the specific
+		 * source. So notify user space.
+		 */
+		src_info->hvpipe_status &= ~HVPIPE_LOST_CONNECTION;
+		ret = HVPIPE_HDR_LEN;
+	}
+
+	return ret;
 }
 
 /*
diff --git a/arch/powerpc/platforms/pseries/papr-hvpipe.h b/arch/powerpc/platforms/pseries/papr-hvpipe.h
index 6f98da4ec45f..125658e6b596 100644
--- a/arch/powerpc/platforms/pseries/papr-hvpipe.h
+++ b/arch/powerpc/platforms/pseries/papr-hvpipe.h
@@ -14,6 +14,7 @@
 struct hvpipe_source_info {
 	struct list_head list;	/* list of sources */
 	u32 srcID;
+	u32 hvpipe_status;
 	wait_queue_head_t recv_wqh;	 /* wake up poll() waitq */
 	struct task_struct *tsk;
 };
-- 
2.50.1

[PATCH v3 6/9] powerpc/pseries: Wakeup hvpipe FD when the payload is pending

[Haren Myneni]

The user space polls on the wait_queue for the payload from the
specific source. The hypervisor interrupts the OS when the pipe
status for the specific source is changed such as payload is
available for the partition or pipe to the source is closed. The
OS retrieves the HVPIPE event message with check-exception RTAS
and event message contains the source ID and the pipe status.
Then wakes up all FDs waiting on the wait_queue so that the user
space can read the payload or close the FD if the pipe to source
in the hypervisor is closed.

The hypervisor assigns one pipe per partition for all sources.
Hence issue  ibm,receive-hvpipe-msg() to read the pending
payload during release() before closing FD so that pipe to the
partition will not be blocked.

Signed-off-by: Haren Myneni <haren@linux.ibm.com>
Reviewed-by: Mahesh Salgaonkar <mahesh@linux.ibm.com>
Tested-by: Shashank MS <shashank.gowda@in.ibm.com>
---
 arch/powerpc/platforms/pseries/papr-hvpipe.c | 28 +++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/platforms/pseries/papr-hvpipe.c b/arch/powerpc/platforms/pseries/papr-hvpipe.c
index eb1b5f1f976e..1e7636c0b275 100644
--- a/arch/powerpc/platforms/pseries/papr-hvpipe.c
+++ b/arch/powerpc/platforms/pseries/papr-hvpipe.c
@@ -398,6 +398,21 @@ static unsigned int papr_hvpipe_handle_poll(struct file *filp,
 	if (!src_info)
 		return -EIO;
 
+	/*
+	 * If hvpipe already has pending payload, return so that
+	 * the user space can issue read().
+	 */
+	if (src_info->hvpipe_status)
+		return POLLIN | POLLRDNORM;
+
+	/*
+	 * Wait for the message event
+	 * hvpipe_event_interrupt() wakes up this wait_queue
+	 */
+	poll_wait(filp, &src_info->recv_wqh, wait);
+	if (src_info->hvpipe_status)
+		return POLLIN | POLLRDNORM;
+
 	return 0;
 }
 
@@ -415,7 +430,18 @@ static int papr_hvpipe_handle_release(struct inode *inode,
 	src_info = file->private_data;
 	list_del(&src_info->list);
 	file->private_data = NULL;
-	spin_unlock(&hvpipe_src_list_lock);
+	/*
+	 * If the pipe for this specific source has any pending
+	 * payload, issue recv HVPIPE RTAS so that pipe will not
+	 * be blocked.
+	 */
+	if (src_info->hvpipe_status & HVPIPE_MSG_AVAILABLE) {
+		src_info->hvpipe_status = 0;
+		spin_unlock(&hvpipe_src_list_lock);
+		hvpipe_rtas_recv_msg(NULL, 0);
+	} else
+		spin_unlock(&hvpipe_src_list_lock);
+
 	kfree(src_info);
 	return 0;
 }
-- 
2.50.1

[PATCH v3 7/9] powerpc/pseries: Enable HVPIPE event message interrupt

[Haren Myneni]

The hypervisor signals the OS via a Hypervisor Pipe Event external
interrupt when data is available to be received from the pipe.
Then the OS  should call RTAS check-exception and provide the input
Event Mask as defined for the ‘ibm,hvpipe-msg-events’. In response,
check-exception will return an event log containing an Pipe Events
message. This message contains the source ID for which this
message is intended to and the pipe status such as whether the
payload is pending in the hypervisor or pipe to source is closed.

If there is any user space process waiting in the wait_queue for
the payload from this source ID, wake up that process which can
issue read() to obtain payload with ibm,receive-hvpipe-msg RTAS
or close FD if the pipe to source is closed.

The hypervisor has one pipe per partition for all sources and it
will not deliver another hvpipe event message until the partition
reads the payload for the previous hvpipe event. So if the source
ID is not found in the source list, issue the dummy
ibm,receive-hvpipe-msg RTAS so that pipe will not blocked.

Register hvpipe event source interrupt based on entries from
/proc/device-tree//event-sources/ibm,hvpipe-msg-events property.

Signed-off-by: Haren Myneni <haren@linux.ibm.com>
Reviewed-by: Mahesh Salgaonkar <mahesh@linux.ibm.com>
Tested-by: Shashank MS <shashank.gowda@in.ibm.com>
---
 arch/powerpc/platforms/pseries/papr-hvpipe.c | 146 ++++++++++++++++++-
 arch/powerpc/platforms/pseries/papr-hvpipe.h |  14 ++
 2 files changed, 155 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/papr-hvpipe.c b/arch/powerpc/platforms/pseries/papr-hvpipe.c
index 1e7636c0b275..0969efb39d95 100644
--- a/arch/powerpc/platforms/pseries/papr-hvpipe.c
+++ b/arch/powerpc/platforms/pseries/papr-hvpipe.c
@@ -22,6 +22,11 @@
 static DEFINE_SPINLOCK(hvpipe_src_list_lock);
 static LIST_HEAD(hvpipe_src_list);
 
+static unsigned char hvpipe_ras_buf[RTAS_ERROR_LOG_MAX];
+static struct workqueue_struct *papr_hvpipe_wq;
+static struct work_struct *papr_hvpipe_work = NULL;
+static int hvpipe_check_exception_token;
+
 /*
  * New PowerPC FW provides support for partitions and various
  * sources (Ex: remote hardware management console (HMC)) to
@@ -556,6 +561,117 @@ static long papr_hvpipe_dev_ioctl(struct file *filp, unsigned int ioctl,
 	return ret;
 }
 
+/*
+ * papr_hvpipe_work_fn - called to issue recv HVPIPE RTAS for
+ * sources that are not monitored by user space so that pipe
+ * will not be blocked.
+ */
+static void papr_hvpipe_work_fn(struct work_struct *work)
+{
+	hvpipe_rtas_recv_msg(NULL, 0);
+}
+
+/*
+ * HVPIPE event message IRQ handler.
+ * The hypervisor sends event IRQ if the partition has payload
+ * and generates another event only after payload is read with
+ * recv HVPIPE RTAS.
+ */
+static irqreturn_t hvpipe_event_interrupt(int irq, void *dev_id)
+{
+	struct hvpipe_event_buf *hvpipe_event;
+	struct pseries_errorlog *pseries_log;
+	struct hvpipe_source_info *src_info;
+	struct rtas_error_log *elog;
+	int rc;
+
+	rc = rtas_call(hvpipe_check_exception_token, 6, 1, NULL,
+		RTAS_VECTOR_EXTERNAL_INTERRUPT, virq_to_hw(irq),
+		RTAS_HVPIPE_MSG_EVENTS, 1, __pa(&hvpipe_ras_buf),
+		rtas_get_error_log_max());
+
+	if (rc != 0) {
+		pr_err_ratelimited("unexpected hvpipe-event-notification failed %d\n", rc);
+		return IRQ_HANDLED;
+	}
+
+	elog = (struct rtas_error_log *)hvpipe_ras_buf;
+	if (unlikely(rtas_error_type(elog) != RTAS_TYPE_HVPIPE)) {
+		pr_warn_ratelimited("Unexpected event type %d\n",
+				rtas_error_type(elog));
+		return IRQ_HANDLED;
+	}
+
+	pseries_log = get_pseries_errorlog(elog,
+				PSERIES_ELOG_SECT_ID_HVPIPE_EVENT);
+	hvpipe_event = (struct hvpipe_event_buf *)pseries_log->data;
+
+	/*
+	 * The hypervisor notifies partition when the payload is
+	 * available to read with recv HVPIPE RTAS and it will not
+	 * notify another event for any source until the previous
+	 * payload is read. Means the pipe is blocked in the
+	 * hypervisor until the payload is read.
+	 *
+	 * If the source is ready to accept payload and wakeup the
+	 * corresponding FD. Hold lock and update hvpipe_status
+	 * and this lock is needed in case the user space process
+	 * is in release FD instead of poll() so that release()
+	 * reads the payload to unblock pipe before closing FD.
+	 *
+	 * otherwise (means no other user process waiting for the
+	 * payload, issue recv HVPIPE RTAS (papr_hvpipe_work_fn())
+	 * to unblock pipe.
+	 */
+	spin_lock(&hvpipe_src_list_lock);
+	src_info = hvpipe_find_source(be32_to_cpu(hvpipe_event->srcID));
+	if (src_info) {
+		u32 flags = 0;
+
+		if (hvpipe_event->event_type & HVPIPE_LOST_CONNECTION)
+			flags = HVPIPE_LOST_CONNECTION;
+		else if (hvpipe_event->event_type & HVPIPE_MSG_AVAILABLE)
+			flags = HVPIPE_MSG_AVAILABLE;
+
+		src_info->hvpipe_status |= flags;
+		wake_up(&src_info->recv_wqh);
+		spin_unlock(&hvpipe_src_list_lock);
+	} else {
+		spin_unlock(&hvpipe_src_list_lock);
+		/*
+		 * user space is not waiting on this source. So
+		 * execute receive pipe RTAS so that pipe will not
+		 * be blocked.
+		 */
+		if (hvpipe_event->event_type & HVPIPE_MSG_AVAILABLE)
+			queue_work(papr_hvpipe_wq, papr_hvpipe_work);
+	}
+
+	return IRQ_HANDLED;
+}
+
+static int __init enable_hvpipe_IRQ(void)
+{
+	struct device_node *np;
+
+	hvpipe_check_exception_token = rtas_function_token(RTAS_FN_CHECK_EXCEPTION);
+	if (hvpipe_check_exception_token  == RTAS_UNKNOWN_SERVICE)
+		return -ENODEV;
+
+	/* hvpipe events */
+	np = of_find_node_by_path("/event-sources/ibm,hvpipe-msg-events");
+	if (np != NULL) {
+		request_event_sources_irqs(np, hvpipe_event_interrupt,
+					"HPIPE_EVENT");
+		of_node_put(np);
+	} else {
+		pr_err("Can not enable hvpipe event IRQ\n");
+		return -ENODEV;
+	}
+
+	return 0;
+}
+
 static const struct file_operations papr_hvpipe_ops = {
 	.unlocked_ioctl	=	papr_hvpipe_dev_ioctl,
 };
@@ -578,12 +694,32 @@ static int __init papr_hvpipe_init(void)
 		!rtas_function_implemented(RTAS_FN_IBM_RECEIVE_HVPIPE_MSG))
 		return -ENODEV;
 
-	ret = misc_register(&papr_hvpipe_dev);
-	if (ret) {
-		pr_err("misc-dev registration failed %d\n", ret);
-		return ret;
+	papr_hvpipe_work = kzalloc(sizeof(struct work_struct), GFP_ATOMIC);
+	if (!papr_hvpipe_work)
+		return -ENOMEM;
+
+	INIT_WORK(papr_hvpipe_work, papr_hvpipe_work_fn);
+
+	papr_hvpipe_wq = alloc_ordered_workqueue("papr hvpipe workqueue", 0);
+	if (!papr_hvpipe_wq) {
+		ret = -ENOMEM;
+		goto out;
 	}
 
-	return 0;
+	ret = enable_hvpipe_IRQ();
+	if (!ret)
+		ret = misc_register(&papr_hvpipe_dev);
+
+	if (!ret) {
+		pr_info("hvpipe feature is enabled\n");
+		return 0;
+	} else
+		pr_err("hvpipe feature is not enabled %d\n", ret);
+
+	destroy_workqueue(papr_hvpipe_wq);
+out:
+	kfree(papr_hvpipe_work);
+	papr_hvpipe_work = NULL;
+	return ret;
 }
 machine_device_initcall(pseries, papr_hvpipe_init);
diff --git a/arch/powerpc/platforms/pseries/papr-hvpipe.h b/arch/powerpc/platforms/pseries/papr-hvpipe.h
index 125658e6b596..aab7f77e087d 100644
--- a/arch/powerpc/platforms/pseries/papr-hvpipe.h
+++ b/arch/powerpc/platforms/pseries/papr-hvpipe.h
@@ -19,4 +19,18 @@ struct hvpipe_source_info {
 	struct task_struct *tsk;
 };
 
+/*
+ * Source ID Format 0xCCRRQQQQ
+ * CC = indicating value is source type (ex: 0x02 for HMC)
+ * RR = 0x00 (reserved)
+ * QQQQ = 0x0000 – 0xFFFF indicating the source index indetifier
+ */
+struct hvpipe_event_buf {
+	__be32	srcID;		/* Source ID */
+	u8	event_type;	/* 0x01 for hvpipe message available */
+				/* from specified src ID */
+				/* 0x02 for loss of pipe connection */
+				/* with specified src ID */
+};
+
 #endif /* _PAPR_HVPIPE_H */
-- 
2.50.1

[PATCH v3 8/9] powerpc/pseries: Enable hvpipe with ibm,set-system-parameter RTAS

[Haren Myneni]

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>
Reviewed-by: Mahesh Salgaonkar <mahesh@linux.ibm.com>
Tested-by: Shashank MS <shashank.gowda@in.ibm.com>
---
 arch/powerpc/include/asm/papr-sysparm.h      |  1 +
 arch/powerpc/platforms/pseries/papr-hvpipe.c | 34 ++++++++++++++++++--
 2 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/include/asm/papr-sysparm.h b/arch/powerpc/include/asm/papr-sysparm.h
index c3cd5b131033..a3b5a0d05db6 100644
--- a/arch/powerpc/include/asm/papr-sysparm.h
+++ b/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.
diff --git a/arch/powerpc/platforms/pseries/papr-hvpipe.c b/arch/powerpc/platforms/pseries/papr-hvpipe.c
index 0969efb39d95..504d7f20f0b1 100644
--- a/arch/powerpc/platforms/pseries/papr-hvpipe.c
+++ b/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"
@@ -650,6 +651,32 @@ 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;
@@ -707,8 +734,11 @@ 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");
-- 
2.50.1

[PATCH v3 9/9] powerpc/pseries: HVPIPE changes to support migration

[Haren Myneni]

The hypervisor assigns one pipe per partition for all sources and
assigns new pipe after migration. Also the partition ID that is
used by source as its target ID may be changed after the migration.
So disable hvpipe during SUSPEND event with ‘hvpipe enable’ system
parameter value = 0 and enable it after migration during RESUME
event with  hvpipe enable’ system parameter value = 1.

The user space calls such as ioctl()/ read() / write() / poll()
returns  -ENXIO between SUSPEND and RESUME events. The user space
process can close FD and reestablish connection with new FD after
migration if needed (Example: source IDs are changed).

Signed-off-by: Haren Myneni <haren@linux.ibm.com>
Reviewed-by: Mahesh Salgaonkar <mahesh@linux.ibm.com>
Tested-by: Shashank MS <shashank.gowda@in.ibm.com>
---
 arch/powerpc/platforms/pseries/mobility.c    |  3 +
 arch/powerpc/platforms/pseries/papr-hvpipe.c | 64 ++++++++++++++++++++
 arch/powerpc/platforms/pseries/papr-hvpipe.h |  6 ++
 3 files changed, 73 insertions(+)

diff --git a/arch/powerpc/platforms/pseries/mobility.c b/arch/powerpc/platforms/pseries/mobility.c
index 62bd8e2d5d4c..95fe802ccdfd 100644
--- a/arch/powerpc/platforms/pseries/mobility.c
+++ b/arch/powerpc/platforms/pseries/mobility.c
@@ -28,6 +28,7 @@
 #include <asm/rtas.h>
 #include "pseries.h"
 #include "vas.h"	/* vas_migration_handler() */
+#include "papr-hvpipe.h"	/* hvpipe_migration_handler() */
 #include "../../kernel/cacheinfo.h"
 
 static struct kobject *mobility_kobj;
@@ -744,6 +745,7 @@ static int pseries_migrate_partition(u64 handle)
 	 * by closing VAS windows at the beginning of this function.
 	 */
 	vas_migration_handler(VAS_SUSPEND);
+	hvpipe_migration_handler(HVPIPE_SUSPEND);
 
 	ret = wait_for_vasi_session_suspending(handle);
 	if (ret)
@@ -770,6 +772,7 @@ static int pseries_migrate_partition(u64 handle)
 
 out:
 	vas_migration_handler(VAS_RESUME);
+	hvpipe_migration_handler(HVPIPE_RESUME);
 
 	return ret;
 }
diff --git a/arch/powerpc/platforms/pseries/papr-hvpipe.c b/arch/powerpc/platforms/pseries/papr-hvpipe.c
index 504d7f20f0b1..350b416d2e76 100644
--- a/arch/powerpc/platforms/pseries/papr-hvpipe.c
+++ b/arch/powerpc/platforms/pseries/papr-hvpipe.c
@@ -27,6 +27,7 @@ static unsigned char hvpipe_ras_buf[RTAS_ERROR_LOG_MAX];
 static struct workqueue_struct *papr_hvpipe_wq;
 static struct work_struct *papr_hvpipe_work = NULL;
 static int hvpipe_check_exception_token;
+static bool hvpipe_feature;
 
 /*
  * New PowerPC FW provides support for partitions and various
@@ -233,6 +234,12 @@ static ssize_t papr_hvpipe_handle_write(struct file *file,
 	unsigned long ret, len;
 	char *area_buf;
 
+	/*
+	 * Return -ENXIO during migration
+	 */
+	if (!hvpipe_feature)
+		return -ENXIO;
+
 	if (!src_info)
 		return -EIO;
 
@@ -325,6 +332,12 @@ static ssize_t papr_hvpipe_handle_read(struct file *file,
 	struct papr_hvpipe_hdr hdr;
 	long ret;
 
+	/*
+	 * Return -ENXIO during migration
+	 */
+	if (!hvpipe_feature)
+		return -ENXIO;
+
 	if (!src_info)
 		return -EIO;
 
@@ -401,6 +414,12 @@ static unsigned int papr_hvpipe_handle_poll(struct file *filp,
 {
 	struct hvpipe_source_info *src_info = filp->private_data;
 
+	/*
+	 * Return -ENXIO during migration
+	 */
+	if (!hvpipe_feature)
+		return -ENXIO;
+
 	if (!src_info)
 		return -EIO;
 
@@ -541,6 +560,12 @@ static long papr_hvpipe_dev_ioctl(struct file *filp, unsigned int ioctl,
 	u32 srcID;
 	long ret;
 
+	/*
+	 * Return -ENXIO during migration
+	 */
+	if (!hvpipe_feature)
+		return -ENXIO;
+
 	if (get_user(srcID, argp))
 		return -EFAULT;
 
@@ -699,6 +724,44 @@ static int __init enable_hvpipe_IRQ(void)
 	return 0;
 }
 
+void hvpipe_migration_handler(int action)
+{
+	pr_info("hvpipe migration event %d\n", action);
+
+	/*
+	 * HVPIPE is not used (Failed to create /dev/papr-hvpipe).
+	 * So nothing to do for migration.
+	 */
+	if (!papr_hvpipe_work)
+		return;
+
+	switch (action) {
+	case HVPIPE_SUSPEND:
+		if (hvpipe_feature) {
+			/*
+			 * Disable hvpipe_feature to the user space.
+			 * It will be enabled with RESUME event.
+			 */
+			hvpipe_feature = false;
+			/*
+			 * set system parameter hvpipe 'disable'
+			 */
+			set_hvpipe_sys_param(0);
+		}
+		break;
+	case HVPIPE_RESUME:
+		/*
+		 * set system parameter hvpipe 'enable'
+		 */
+		if (!set_hvpipe_sys_param(1))
+			hvpipe_feature = true;
+		else
+			pr_err("hvpipe is not enabled after migration\n");
+
+		break;
+	}
+}
+
 static const struct file_operations papr_hvpipe_ops = {
 	.unlocked_ioctl	=	papr_hvpipe_dev_ioctl,
 };
@@ -742,6 +805,7 @@ static int __init papr_hvpipe_init(void)
 
 	if (!ret) {
 		pr_info("hvpipe feature is enabled\n");
+		hvpipe_feature = true;
 		return 0;
 	} else
 		pr_err("hvpipe feature is not enabled %d\n", ret);
diff --git a/arch/powerpc/platforms/pseries/papr-hvpipe.h b/arch/powerpc/platforms/pseries/papr-hvpipe.h
index aab7f77e087d..c343f4230865 100644
--- a/arch/powerpc/platforms/pseries/papr-hvpipe.h
+++ b/arch/powerpc/platforms/pseries/papr-hvpipe.h
@@ -11,6 +11,11 @@
 
 #define	HVPIPE_HDR_LEN	sizeof(struct papr_hvpipe_hdr)
 
+enum hvpipe_migrate_action {
+	HVPIPE_SUSPEND,
+	HVPIPE_RESUME,
+};
+
 struct hvpipe_source_info {
 	struct list_head list;	/* list of sources */
 	u32 srcID;
@@ -33,4 +38,5 @@ struct hvpipe_event_buf {
 				/* with specified src ID */
 };
 
+void hvpipe_migration_handler(int action);
 #endif /* _PAPR_HVPIPE_H */
-- 
2.50.1

Re: [PATCH v3 1/9] powerpc/pseries: Define papr-hvpipe ioctl

[Tyrel Datwyler]

On 8/28/25 4:08 PM, Haren Myneni wrote:
> PowerPC FW introduced HVPIPE RTAS calls such as
> ibm,send-hvpipe-msg and ibm,receive-hvpipe-msg for the user space
> to exchange information with different sources such as Hardware
> Management Consoles (HMC).
> 
> HVPIPE_IOC_CREATE_HANDLE is defined to use /dev/papr-hvpipe
> interface for ibm,send-hvpipe-msg and ibm,receive-hvpipe-msg
> RTAS calls.
> 
> Also defined papr_hvpipe_hdr which will added in the payload
> that is passed between the kernel and the user space.
> 
> Signed-off-by: Haren Myneni <haren@linux.ibm.com>
> Reviewed-by: Mahesh Salgaonkar <mahesh@linux.ibm.com>
> Tested-by: Shashank MS <shashank.gowda@in.ibm.com>
> ---

Reviewed-by: Tyrel Datwyler <tyreld@linux.ibm.com>

Re: [PATCH v3 2/9] powerpc/pseries: Define HVPIPE specific macros

[Tyrel Datwyler]

On 8/28/25 4:08 PM, Haren Myneni wrote:
> Define HVPIPE specific macros which are needed to support
> ibm,send-hvpipe-msg and ibm,receive-hvpipe-msg RTAS calls
> and used to handle HVPIPE message events.
> 
> Signed-off-by: Haren Myneni <haren@linux.ibm.com>
> Reviewed-by: Mahesh Salgaonkar <mahesh@linux.ibm.com>
> Tested-by: Shashank MS <shashank.gowda@in.ibm.com>
> ---

Reviewed-by: Tyrel Datwyler <tyreld@linux.ibm.com>

Re: [PATCH v3 3/9] powerpc/pseries: Add papr-hvpipe char driver for HVPIPE interfaces

[Tyrel Datwyler]

On 8/28/25 4:08 PM, Haren Myneni wrote:
> The hypervisor provides ibm,send-hvpipe-msg and
> ibm,receive-hvpipe-msg RTAS calls which can be used by the
> partition to communicate through an inband hypervisor channel with
> different external sources such as Hardware Management Console
> (HMC). The information exchanged, whether it be messages, raw or
> formatted data, etc., is only known to between applications in the
> OS and the source (HMC). This patch adds papr-hvpipe character
> driver and provides the standard interfaces such as open / ioctl/
> read / write to user space for exchanging information with HMC
> using send/recevive HVPIPE RTAS functions.
> 
> PAPR (7.3.32 Hypervisor Pipe Information Exchange) defines the
> HVPIPE usage:
> - The hypervisor has one HVPIPE per partition for all sources.
> - OS can determine this feature’s availability by detecting the
>   “ibm,hypervisor-pipe-capable” property in the /rtas node of the
>   device tree.
> - Each source is represented by the source ID which is used in
>   send / recv HVPIPE RTAS. (Ex: source ID is the target for the
>   payload in send RTAS).
> - Return status of ibm,send-hvpipe-msg can be considered as
>   delivered the payload.
> - Return status of ibm,receive-hvpipe-msg can be considered as
>   ACK to source.
> - The hypervisor generates hvpipe message event interrupt when
>   the partition has the payload to receive.
> 
> Provide the interfaces to the user space with /dev/papr-hvpipe
> character device using the following programming model:
> 
> int devfd = open("/dev/papr-hvpipe")
> int fd = ioctl(devfd, PAPR_HVPIPE_IOC_CREATE_HANDLE, &srcID);
> - Restrict the user space to use the same source ID and do not
>   expect more than one process access with the same source.
> char *buf = malloc(size);
> - SIZE should be 4K and the buffer contains header and the
>   payload.
> length = write(fd, buf, size);
> - OS issues ibm,send-hvpipe-msg RTAS and returns the RTAS status
>   to the user space.
> ret = poll(fd,...)
> - The HVPIPE event message IRQ wakes up for any waiting FDs.
> length = read(fd, buf, size);
> - OS issues ibm,receive-hvpipe-msg to receive payload from the
>   hypervisor.
> release(fd);
> - OS issues ibm,receive-hvpipe-msg if any payload is pending so
>   that pipe is not blocked.
> 
> The actual implementation of these calls are added in the
> next patches.
> 
> Signed-off-by: Haren Myneni <haren@linux.ibm.com>
> Reviewed-by: Mahesh Salgaonkar <mahesh@linux.ibm.com>
> Tested-by: Shashank MS <shashank.gowda@in.ibm.com>
> ---

Reviewed-by: Tyrel Datwyler <tyreld@linux.ibm.com>

Re: [PATCH v3 4/9] powerpc/pseries: Send payload with ibm,send-hvpipe-msg RTAS

[Tyrel Datwyler]

On 8/28/25 4:08 PM, Haren Myneni wrote:
> ibm,send-hvpipe-msg RTAS call is used to send data to the source
> (Ex: Hardware Management Console) over the hypervisor pipe. The
> maximum data length of 4048 bytes is supported with this RTAS call
> right now. The user space uses write() to send this payload which
> invokes this RTAS. Then the write returns the buffer length
> (including papr_hvpipe_hdr length) to the user space for success
> or RTAS failure error.
> 
> ibm,send-hvpipe-msg call takes source ID as target and the buffer
> in the form of buffer list. The buffer list format consists of
> work area of size 4K to hold buffer list and number of 4K work
> areas depends on buffers is as follows:
> 
> Length of Buffer List in bytes
> Address of 4K buffer 1
> Length of 4K buffer 1 used
> ...
> Address of 4K buffer n
> Length of 4K buffer n used
> 
> Only one buffer is used right now because of max payload size is
> 4048 bytes. writev() can be used in future when supported more
> than one buffer.
> 
> Signed-off-by: Haren Myneni <haren@linux.ibm.com>
> Reviewed-by: Mahesh Salgaonkar <mahesh@linux.ibm.com>
> Tested-by: Shashank MS <shashank.gowda@in.ibm.com>
> ---

Reviewed-by: Tyrel Datwyler <tyreld@linux.ibm.com>

Re: [PATCH v3 5/9] powerpc/pseries: Receive payload with ibm,receive-hvpipe-msg RTAS

[Tyrel Datwyler]

On 8/28/25 4:08 PM, Haren Myneni wrote:
> ibm,receive-hvpipe-msg RTAS call is used to receive data from the
> source (Ex: Hardware Management Console) over the hypervisor
> pipe. The hypervisor will signal the OS via a Hypervisor Pipe
> Event external interrupt when data is available to be received
> from the pipe and the event message has the source ID and the
> message type such as payload or closed pipe to the specific
> source. The hypervisor will not generate another interrupt for
> the next payload until the partition reads the previous payload.
> It means the hvpipe is blocked and will not deliver other events
> for any source. The maximum data length of 4048 bytes is
> supported with this RTAS call right now.
> 
> The user space uses read() to receive data from HMC which issues
> ibm,receive-hvpipe-msg RTAS and the kernel returns the buffer
> length (including papr_hvpipe_hdr length) to the user space for
> success or RTAS failure error. If the message is regarding the
> pipe closed, kernel just returns the  papr_hvpipe_hdr with
> flags = HVPIPE_LOST_CONNECTION and expects the user space to
> close FD for the corresponding source.
> 
> bm,receive-hvpipe-msg RTAS call passes the buffer and returns

Missing the "i" in "ibm,receive-hvpipe-msg".

> the source ID from where this payload is received and the
> payload length.
> 
> Signed-off-by: Haren Myneni <haren@linux.ibm.com>
> Reviewed-by: Mahesh Salgaonkar <mahesh@linux.ibm.com>
> Tested-by: Shashank MS <shashank.gowda@in.ibm.com>
> ---

Reviewed-by: Tyrel Datwyler <tyreld@linux.ibm.com>

Re: [PATCH v3 6/9] powerpc/pseries: Wakeup hvpipe FD when the payload is pending

[Tyrel Datwyler]

On 8/28/25 4:08 PM, Haren Myneni wrote:
> The user space polls on the wait_queue for the payload from the
> specific source. The hypervisor interrupts the OS when the pipe
> status for the specific source is changed such as payload is
> available for the partition or pipe to the source is closed. The
> OS retrieves the HVPIPE event message with check-exception RTAS
> and event message contains the source ID and the pipe status.
> Then wakes up all FDs waiting on the wait_queue so that the user
> space can read the payload or close the FD if the pipe to source
> in the hypervisor is closed.
> 
> The hypervisor assigns one pipe per partition for all sources.
> Hence issue  ibm,receive-hvpipe-msg() to read the pending
> payload during release() before closing FD so that pipe to the
> partition will not be blocked.
> 
> Signed-off-by: Haren Myneni <haren@linux.ibm.com>
> Reviewed-by: Mahesh Salgaonkar <mahesh@linux.ibm.com>
> Tested-by: Shashank MS <shashank.gowda@in.ibm.com>
> ---

Reviewed-by: Tyrel Datwyler <tyreld@linux.ibm.com>

Re: [PATCH v3 7/9] powerpc/pseries: Enable HVPIPE event message interrupt

[Tyrel Datwyler]

On 8/28/25 4:08 PM, Haren Myneni wrote:
> The hypervisor signals the OS via a Hypervisor Pipe Event external
> interrupt when data is available to be received from the pipe.
> Then the OS  should call RTAS check-exception and provide the input
> Event Mask as defined for the ‘ibm,hvpipe-msg-events’. In response,
> check-exception will return an event log containing an Pipe Events
> message. This message contains the source ID for which this
> message is intended to and the pipe status such as whether the
> payload is pending in the hypervisor or pipe to source is closed.
> 
> If there is any user space process waiting in the wait_queue for
> the payload from this source ID, wake up that process which can
> issue read() to obtain payload with ibm,receive-hvpipe-msg RTAS
> or close FD if the pipe to source is closed.
> 
> The hypervisor has one pipe per partition for all sources and it
> will not deliver another hvpipe event message until the partition
> reads the payload for the previous hvpipe event. So if the source
> ID is not found in the source list, issue the dummy
> ibm,receive-hvpipe-msg RTAS so that pipe will not blocked.
> 
> Register hvpipe event source interrupt based on entries from
> /proc/device-tree//event-sources/ibm,hvpipe-msg-events property.
> 
> Signed-off-by: Haren Myneni <haren@linux.ibm.com>
> Reviewed-by: Mahesh Salgaonkar <mahesh@linux.ibm.com>
> Tested-by: Shashank MS <shashank.gowda@in.ibm.com>
> ---

Reviewed-by: Tyrel Datwyler <tyreld@linux.ibm.com>

Re: [PATCH v3 8/9] powerpc/pseries: Enable hvpipe with ibm,set-system-parameter RTAS

[Tyrel Datwyler]

On 8/28/25 4:08 PM, Haren Myneni wrote:
> 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>
> Reviewed-by: Mahesh Salgaonkar <mahesh@linux.ibm.com>
> Tested-by: Shashank MS <shashank.gowda@in.ibm.com>
> ---

Reviewed-by: Tyrel Datwyler <tyreld@linux.ibm.com>

Re: [PATCH v3 9/9] powerpc/pseries: HVPIPE changes to support migration

[Tyrel Datwyler]

On 8/28/25 4:08 PM, Haren Myneni wrote:
> The hypervisor assigns one pipe per partition for all sources and
> assigns new pipe after migration. Also the partition ID that is
> used by source as its target ID may be changed after the migration.
> So disable hvpipe during SUSPEND event with ‘hvpipe enable’ system
> parameter value = 0 and enable it after migration during RESUME
> event with  hvpipe enable’ system parameter value = 1.
> 
> The user space calls such as ioctl()/ read() / write() / poll()
> returns  -ENXIO between SUSPEND and RESUME events. The user space
> process can close FD and reestablish connection with new FD after
> migration if needed (Example: source IDs are changed).
> 
> Signed-off-by: Haren Myneni <haren@linux.ibm.com>
> Reviewed-by: Mahesh Salgaonkar <mahesh@linux.ibm.com>
> Tested-by: Shashank MS <shashank.gowda@in.ibm.com>
> ---

Reviewed-by: Tyrel Datwyler <tyreld@linux.ibm.com>