[PATCH v2 00/28] partition suspend updates

[PATCH v2 00/28] partition suspend updates

[Nathan Lynch]

This series aims to improve the pseries-specific partition migration
and hibernation implementation, part of which has been living in
kernel/rtas.c. Most of that code is eliminated or moved to
platforms/pseries, and the following major functional changes are
made:

- Use stop_machine() instead of on_each_cpu() to avoid deadlock in the
  join/suspend sequence.

- Retry the join/suspend sequence on errors that are likely to be
  transient. This is a mitigation for the fact that drivers currently
  have no way to prepare for an impending partition suspension,
  sometimes resulting in a virtual adapter being in a state which
  causes the platform to fail the suspend call.

- Request cancellation of the migration via H_VASI_SIGNAL if Linux is
  going to error out of the suspend attempt. This allows the
  management console and other entities to promptly clean up their
  operations instead of relying on long timeouts to fail the
  migration.

- Little-endian users of ibm,suspend-me, ibm,update-nodes and
  ibm,update-properties via sys_rtas are blocked when
  CONFIG_PPC_RTAS_FILTERS is enabled.

- Legacy user space code (drmgr) historically has driven the migration
  process by using sys_rtas to separately call ibm,suspend-me,
  ibm,activate-firmware, and ibm,update-nodes/properties, in that
  order. With these changes, when sys_rtas() dispatches
  ibm,suspend-me, the kernel performs the device tree update and
  firmware activation before returning. This is more reliable, and
  drmgr does not seem bothered by it.

- If the H_VASI_STATE hcall is absent, the implementation proceeds
  with the suspend instead of erroring out. This allows us to exercise
  these code paths in QEMU.

Changes since v1:
- Drop "powerpc/rtas: move rtas_call_reentrant() out of pseries
  guards". rtas_call_reentrant() actually is pseries-specific and this
  broke builds without CONFIG_PPC_PSERIES set.
- Simplify polling logic in wait_for_vasi_session_suspending().
  ("powerpc/pseries/mobility: extract VASI session polling logic")
- Use direct return instead of goto in pseries_migrate_partition().
  ("powerpc/pseries/mobility: use stop_machine for join/suspend")
- Change dispatch of ibm,suspend-me in rtas syscall path to use
  conventional config symbol guards instead of a weak function.
  ("powerpc/rtas: dispatch partition migration requests to pseries")
- Fix refcount imbalance in add_dt_node() error path.
  ("powerpc/pseries/mobility: refactor node lookup during DT update")

Nathan Lynch (28):
  powerpc/rtas: prevent suspend-related sys_rtas use on LE
  powerpc/rtas: complete ibm,suspend-me status codes
  powerpc/rtas: rtas_ibm_suspend_me -> rtas_ibm_suspend_me_unsafe
  powerpc/rtas: add rtas_ibm_suspend_me()
  powerpc/rtas: add rtas_activate_firmware()
  powerpc/hvcall: add token and codes for H_VASI_SIGNAL
  powerpc/pseries/mobility: don't error on absence of ibm,update-nodes
  powerpc/pseries/mobility: add missing break to default case
  powerpc/pseries/mobility: error message improvements
  powerpc/pseries/mobility: use rtas_activate_firmware() on resume
  powerpc/pseries/mobility: extract VASI session polling logic
  powerpc/pseries/mobility: use stop_machine for join/suspend
  powerpc/pseries/mobility: signal suspend cancellation to platform
  powerpc/pseries/mobility: retry partition suspend after error
  powerpc/rtas: dispatch partition migration requests to pseries
  powerpc/rtas: remove rtas_ibm_suspend_me_unsafe()
  powerpc/pseries/hibernation: drop pseries_suspend_begin() from suspend
    ops
  powerpc/pseries/hibernation: pass stream id via function arguments
  powerpc/pseries/hibernation: remove pseries_suspend_cpu()
  powerpc/machdep: remove suspend_disable_cpu()
  powerpc/rtas: remove rtas_suspend_cpu()
  powerpc/pseries/hibernation: switch to rtas_ibm_suspend_me()
  powerpc/rtas: remove unused rtas_suspend_last_cpu()
  powerpc/pseries/hibernation: remove redundant cacheinfo update
  powerpc/pseries/hibernation: perform post-suspend fixups later
  powerpc/pseries/hibernation: remove prepare_late() callback
  powerpc/rtas: remove unused rtas_suspend_me_data
  powerpc/pseries/mobility: refactor node lookup during DT update

 arch/powerpc/include/asm/hvcall.h         |   9 +
 arch/powerpc/include/asm/machdep.h        |   1 -
 arch/powerpc/include/asm/rtas-types.h     |   8 -
 arch/powerpc/include/asm/rtas.h           |  17 +-
 arch/powerpc/kernel/rtas.c                | 243 ++++++---------
 arch/powerpc/platforms/pseries/mobility.c | 358 ++++++++++++++++++----
 arch/powerpc/platforms/pseries/suspend.c  |  79 +----
 7 files changed, 415 insertions(+), 300 deletions(-)

-- 
2.28.0

[PATCH v2 01/28] powerpc/rtas: prevent suspend-related sys_rtas use on LE

[Nathan Lynch]

While drmgr has had work in some areas to make its RTAS syscall
interactions endian-neutral, its code for performing partition
migration via the syscall has never worked on LE. While it is able to
complete ibm,suspend-me successfully, it crashes when attempting the
subsequent ibm,update-nodes call.

drmgr is the only known (or plausible) user of ibm,suspend-me,
ibm,update-nodes, and ibm,update-properties, so allow them only in
big-endian configurations.

Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
---
 arch/powerpc/kernel/rtas.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c
index 954f41676f69..4ed64aba37d6 100644
--- a/arch/powerpc/kernel/rtas.c
+++ b/arch/powerpc/kernel/rtas.c
@@ -1050,9 +1050,11 @@ static struct rtas_filter rtas_filters[] __ro_after_init = {
 	{ "set-time-for-power-on", -1, -1, -1, -1, -1 },
 	{ "ibm,set-system-parameter", -1, 1, -1, -1, -1 },
 	{ "set-time-of-day", -1, -1, -1, -1, -1 },
+#ifdef CONFIG_CPU_BIG_ENDIAN
 	{ "ibm,suspend-me", -1, -1, -1, -1, -1 },
 	{ "ibm,update-nodes", -1, 0, -1, -1, -1, 4096 },
 	{ "ibm,update-properties", -1, 0, -1, -1, -1, 4096 },
+#endif
 	{ "ibm,physical-attestation", -1, 0, 1, -1, -1 },
 };
 
-- 
2.28.0

[PATCH v2 02/28] powerpc/rtas: complete ibm,suspend-me status codes

[Nathan Lynch]

We don't completely account for the possible return codes for
ibm,suspend-me. Add definitions for these.

Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
---
 arch/powerpc/include/asm/rtas.h | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/rtas.h b/arch/powerpc/include/asm/rtas.h
index 55f9a154c95d..f060181a0d32 100644
--- a/arch/powerpc/include/asm/rtas.h
+++ b/arch/powerpc/include/asm/rtas.h
@@ -23,11 +23,16 @@
 #define RTAS_RMOBUF_MAX (64 * 1024)
 
 /* RTAS return status codes */
-#define RTAS_NOT_SUSPENDABLE	-9004
 #define RTAS_BUSY		-2    /* RTAS Busy */
 #define RTAS_EXTENDED_DELAY_MIN	9900
 #define RTAS_EXTENDED_DELAY_MAX	9905
 
+/* statuses specific to ibm,suspend-me */
+#define RTAS_SUSPEND_ABORTED     9000 /* Suspension aborted */
+#define RTAS_NOT_SUSPENDABLE    -9004 /* Partition not suspendable */
+#define RTAS_THREADS_ACTIVE     -9005 /* Multiple processor threads active */
+#define RTAS_OUTSTANDING_COPROC -9006 /* Outstanding coprocessor operations */
+
 /*
  * In general to call RTAS use rtas_token("string") to lookup
  * an RTAS token for the given string (e.g. "event-scan").
-- 
2.28.0

[PATCH v2 03/28] powerpc/rtas: rtas_ibm_suspend_me -> rtas_ibm_suspend_me_unsafe

[Nathan Lynch]

The pseries partition suspend sequence requires that all active CPUs
call H_JOIN, which suspends all but one of them with interrupts
disabled. The "chosen" CPU is then to call ibm,suspend-me to complete
the suspend. Upon returning from ibm,suspend-me, the chosen CPU is to
use H_PROD to wake the joined CPUs.

Using on_each_cpu() for this, as rtas_ibm_suspend_me() does to
implement partition migration, is susceptible to deadlock with other
users of on_each_cpu() and with users of stop_machine APIs. The
callback passed to on_each_cpu() is not allowed to synchronize with
other CPUs in the way it is used here.

Complicating the fix is the fact that rtas_ibm_suspend_me() also
occupies the function name that should be used to provide a more
conventional wrapper for ibm,suspend-me. Rename rtas_ibm_suspend_me()
to rtas_ibm_suspend_me_unsafe() to free up the name and indicate that
it should not gain users.

Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
---
 arch/powerpc/include/asm/rtas.h           | 2 +-
 arch/powerpc/kernel/rtas.c                | 6 +++---
 arch/powerpc/platforms/pseries/mobility.c | 2 +-
 3 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/include/asm/rtas.h b/arch/powerpc/include/asm/rtas.h
index f060181a0d32..8436ed01567b 100644
--- a/arch/powerpc/include/asm/rtas.h
+++ b/arch/powerpc/include/asm/rtas.h
@@ -257,7 +257,7 @@ extern int rtas_set_indicator_fast(int indicator, int index, int new_value);
 extern void rtas_progress(char *s, unsigned short hex);
 extern int rtas_suspend_cpu(struct rtas_suspend_me_data *data);
 extern int rtas_suspend_last_cpu(struct rtas_suspend_me_data *data);
-extern int rtas_ibm_suspend_me(u64 handle);
+int rtas_ibm_suspend_me_unsafe(u64 handle);
 
 struct rtc_time;
 extern time64_t rtas_get_boot_time(void);
diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c
index 4ed64aba37d6..0a8e5dc2c108 100644
--- a/arch/powerpc/kernel/rtas.c
+++ b/arch/powerpc/kernel/rtas.c
@@ -843,7 +843,7 @@ static void rtas_percpu_suspend_me(void *info)
 	__rtas_suspend_cpu((struct rtas_suspend_me_data *)info, 1);
 }
 
-int rtas_ibm_suspend_me(u64 handle)
+int rtas_ibm_suspend_me_unsafe(u64 handle)
 {
 	long state;
 	long rc;
@@ -949,7 +949,7 @@ int rtas_call_reentrant(int token, int nargs, int nret, int *outputs, ...)
 }
 
 #else /* CONFIG_PPC_PSERIES */
-int rtas_ibm_suspend_me(u64 handle)
+int rtas_ibm_suspend_me_unsafe(u64 handle)
 {
 	return -ENOSYS;
 }
@@ -1185,7 +1185,7 @@ SYSCALL_DEFINE1(rtas, struct rtas_args __user *, uargs)
 		int rc = 0;
 		u64 handle = ((u64)be32_to_cpu(args.args[0]) << 32)
 		              | be32_to_cpu(args.args[1]);
-		rc = rtas_ibm_suspend_me(handle);
+		rc = rtas_ibm_suspend_me_unsafe(handle);
 		if (rc == -EAGAIN)
 			args.rets[0] = cpu_to_be32(RTAS_NOT_SUSPENDABLE);
 		else if (rc == -EIO)
diff --git a/arch/powerpc/platforms/pseries/mobility.c b/arch/powerpc/platforms/pseries/mobility.c
index 2f73cb5bf12d..6ff642e84c6a 100644
--- a/arch/powerpc/platforms/pseries/mobility.c
+++ b/arch/powerpc/platforms/pseries/mobility.c
@@ -370,7 +370,7 @@ static ssize_t migration_store(struct class *class,
 		return rc;
 
 	do {
-		rc = rtas_ibm_suspend_me(streamid);
+		rc = rtas_ibm_suspend_me_unsafe(streamid);
 		if (rc == -EAGAIN)
 			ssleep(1);
 	} while (rc == -EAGAIN);
-- 
2.28.0

[PATCH v2 04/28] powerpc/rtas: add rtas_ibm_suspend_me()

[Nathan Lynch]

Now that the name is available, provide a simple wrapper for
ibm,suspend-me which returns both a Linux errno and optionally the
actual RTAS status to the caller.

Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
---
 arch/powerpc/include/asm/rtas.h |  1 +
 arch/powerpc/kernel/rtas.c      | 57 +++++++++++++++++++++++++++++++++
 2 files changed, 58 insertions(+)

diff --git a/arch/powerpc/include/asm/rtas.h b/arch/powerpc/include/asm/rtas.h
index 8436ed01567b..b43165fc6c2a 100644
--- a/arch/powerpc/include/asm/rtas.h
+++ b/arch/powerpc/include/asm/rtas.h
@@ -258,6 +258,7 @@ extern void rtas_progress(char *s, unsigned short hex);
 extern int rtas_suspend_cpu(struct rtas_suspend_me_data *data);
 extern int rtas_suspend_last_cpu(struct rtas_suspend_me_data *data);
 int rtas_ibm_suspend_me_unsafe(u64 handle);
+int rtas_ibm_suspend_me(int *fw_status);
 
 struct rtc_time;
 extern time64_t rtas_get_boot_time(void);
diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c
index 0a8e5dc2c108..8a618a3c4beb 100644
--- a/arch/powerpc/kernel/rtas.c
+++ b/arch/powerpc/kernel/rtas.c
@@ -684,6 +684,63 @@ int rtas_set_indicator_fast(int indicator, int index, int new_value)
 	return rc;
 }
 
+/**
+ * rtas_ibm_suspend_me() - Call ibm,suspend-me to suspend the LPAR.
+ *
+ * @fw_status: RTAS call status will be placed here if not NULL.
+ *
+ * rtas_ibm_suspend_me() should be called only on a CPU which has
+ * received H_CONTINUE from the H_JOIN hcall. All other active CPUs
+ * should be waiting to return from H_JOIN.
+ *
+ * rtas_ibm_suspend_me() may suspend execution of the OS
+ * indefinitely. Callers should take appropriate measures upon return, such as
+ * resetting watchdog facilities.
+ *
+ * Callers may choose to retry this call if @fw_status is
+ * %RTAS_THREADS_ACTIVE.
+ *
+ * Return:
+ * 0          - The partition has resumed from suspend, possibly after
+ *              migration to a different host.
+ * -ECANCELED - The operation was aborted.
+ * -EAGAIN    - There were other CPUs not in H_JOIN at the time of the call.
+ * -EBUSY     - Some other condition prevented the suspend from succeeding.
+ * -EIO       - Hardware/platform error.
+ */
+int rtas_ibm_suspend_me(int *fw_status)
+{
+	int fwrc;
+	int ret;
+
+	fwrc = rtas_call(rtas_token("ibm,suspend-me"), 0, 1, NULL);
+
+	switch (fwrc) {
+	case 0:
+		ret = 0;
+		break;
+	case RTAS_SUSPEND_ABORTED:
+		ret = -ECANCELED;
+		break;
+	case RTAS_THREADS_ACTIVE:
+		ret = -EAGAIN;
+		break;
+	case RTAS_NOT_SUSPENDABLE:
+	case RTAS_OUTSTANDING_COPROC:
+		ret = -EBUSY;
+		break;
+	case -1:
+	default:
+		ret = -EIO;
+		break;
+	}
+
+	if (fw_status)
+		*fw_status = fwrc;
+
+	return ret;
+}
+
 void __noreturn rtas_restart(char *cmd)
 {
 	if (rtas_flash_term_hook)
-- 
2.28.0

[PATCH v2 05/28] powerpc/rtas: add rtas_activate_firmware()

[Nathan Lynch]

Provide a documented wrapper function for the ibm,activate-firmware
service, which must be called after a partition migration or
hibernation.

If the function is absent or the call fails, the OS will continue to
run normally with the current firmware, so there is no need to perform
any recovery. Just log it and continue.

Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
---
 arch/powerpc/include/asm/rtas.h |  1 +
 arch/powerpc/kernel/rtas.c      | 30 ++++++++++++++++++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/arch/powerpc/include/asm/rtas.h b/arch/powerpc/include/asm/rtas.h
index b43165fc6c2a..fdefe6a974eb 100644
--- a/arch/powerpc/include/asm/rtas.h
+++ b/arch/powerpc/include/asm/rtas.h
@@ -247,6 +247,7 @@ extern void __noreturn rtas_restart(char *cmd);
 extern void rtas_power_off(void);
 extern void __noreturn rtas_halt(void);
 extern void rtas_os_term(char *str);
+void rtas_activate_firmware(void);
 extern int rtas_get_sensor(int sensor, int index, int *state);
 extern int rtas_get_sensor_fast(int sensor, int index, int *state);
 extern int rtas_get_power_level(int powerdomain, int *level);
diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c
index 8a618a3c4beb..3a740ae933f8 100644
--- a/arch/powerpc/kernel/rtas.c
+++ b/arch/powerpc/kernel/rtas.c
@@ -798,6 +798,36 @@ void rtas_os_term(char *str)
 		printk(KERN_EMERG "ibm,os-term call failed %d\n", status);
 }
 
+/**
+ * rtas_activate_firmware() - Activate a new version of firmware.
+ *
+ * Activate a new version of partition firmware. The OS must call this
+ * after resuming from a partition hibernation or migration in order
+ * to maintain the ability to perform live firmware updates. It's not
+ * catastrophic for this method to be absent or to fail; just log the
+ * condition in that case.
+ *
+ * Context: This function may sleep.
+ */
+void rtas_activate_firmware(void)
+{
+	int token;
+	int fwrc;
+
+	token = rtas_token("ibm,activate-firmware");
+	if (token == RTAS_UNKNOWN_SERVICE) {
+		pr_notice("ibm,activate-firmware method unavailable\n");
+		return;
+	}
+
+	do {
+		fwrc = rtas_call(token, 0, 1, NULL);
+	} while (rtas_busy_delay(fwrc));
+
+	if (fwrc)
+		pr_err("ibm,activate-firmware failed (%i)\n", fwrc);
+}
+
 static int ibm_suspend_me_token = RTAS_UNKNOWN_SERVICE;
 #ifdef CONFIG_PPC_PSERIES
 static int __rtas_suspend_last_cpu(struct rtas_suspend_me_data *data, int wake_when_done)
-- 
2.28.0

[PATCH v2 06/28] powerpc/hvcall: add token and codes for H_VASI_SIGNAL

[Nathan Lynch]

H_VASI_SIGNAL can be used by a partition to request cancellation of
its migration. To be used in future changes.

Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
---
 arch/powerpc/include/asm/hvcall.h | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/arch/powerpc/include/asm/hvcall.h b/arch/powerpc/include/asm/hvcall.h
index c1fbccb04390..c98f5141e3fc 100644
--- a/arch/powerpc/include/asm/hvcall.h
+++ b/arch/powerpc/include/asm/hvcall.h
@@ -155,6 +155,14 @@
 #define H_VASI_RESUMED          5
 #define H_VASI_COMPLETED        6
 
+/* VASI signal codes. Only the Cancel code is valid for H_VASI_SIGNAL. */
+#define H_VASI_SIGNAL_CANCEL    1
+#define H_VASI_SIGNAL_ABORT     2
+#define H_VASI_SIGNAL_SUSPEND   3
+#define H_VASI_SIGNAL_COMPLETE  4
+#define H_VASI_SIGNAL_ENABLE    5
+#define H_VASI_SIGNAL_FAILOVER  6
+
 /* Each control block has to be on a 4K boundary */
 #define H_CB_ALIGNMENT          4096
 
@@ -261,6 +269,7 @@
 #define H_ADD_CONN		0x284
 #define H_DEL_CONN		0x288
 #define H_JOIN			0x298
+#define H_VASI_SIGNAL           0x2A0
 #define H_VASI_STATE            0x2A4
 #define H_VIOCTL		0x2A8
 #define H_ENABLE_CRQ		0x2B0
-- 
2.28.0

[PATCH v2 07/28] powerpc/pseries/mobility: don't error on absence of ibm, update-nodes

[Nathan Lynch]

Treat the absence of the ibm,update-nodes function as benign instead
of reporting an error. If the platform does not provide that facility,
it's not a problem for Linux.

Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
---
 arch/powerpc/platforms/pseries/mobility.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/platforms/pseries/mobility.c b/arch/powerpc/platforms/pseries/mobility.c
index 6ff642e84c6a..e66359b00297 100644
--- a/arch/powerpc/platforms/pseries/mobility.c
+++ b/arch/powerpc/platforms/pseries/mobility.c
@@ -261,7 +261,7 @@ int pseries_devicetree_update(s32 scope)
 
 	update_nodes_token = rtas_token("ibm,update-nodes");
 	if (update_nodes_token == RTAS_UNKNOWN_SERVICE)
-		return -EINVAL;
+		return 0;
 
 	rtas_buf = kzalloc(RTAS_DATA_BUF_SIZE, GFP_KERNEL);
 	if (!rtas_buf)
-- 
2.28.0

[PATCH v2 08/28] powerpc/pseries/mobility: add missing break to default case

[Nathan Lynch]

update_dt_node() has a switch statement where the default case lacks a
break statement.

Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
---
 arch/powerpc/platforms/pseries/mobility.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/powerpc/platforms/pseries/mobility.c b/arch/powerpc/platforms/pseries/mobility.c
index e66359b00297..527a64e2d89f 100644
--- a/arch/powerpc/platforms/pseries/mobility.c
+++ b/arch/powerpc/platforms/pseries/mobility.c
@@ -213,6 +213,7 @@ static int update_dt_node(__be32 phandle, s32 scope)
 				}
 
 				prop_data += vd;
+				break;
 			}
 
 			cond_resched();
-- 
2.28.0

[PATCH v2 09/28] powerpc/pseries/mobility: error message improvements

[Nathan Lynch]

- Convert printk(KERN_ERR) to pr_err().
- Include errno in property update failure message.
- Remove reference to "Post-mobility" from device tree update message:
  with pr_err() it will have a "mobility:" prefix.

Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
---
 arch/powerpc/platforms/pseries/mobility.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/mobility.c b/arch/powerpc/platforms/pseries/mobility.c
index 527a64e2d89f..31d81b7da961 100644
--- a/arch/powerpc/platforms/pseries/mobility.c
+++ b/arch/powerpc/platforms/pseries/mobility.c
@@ -208,8 +208,8 @@ static int update_dt_node(__be32 phandle, s32 scope)
 				rc = update_dt_property(dn, &prop, prop_name,
 							vd, prop_data);
 				if (rc) {
-					printk(KERN_ERR "Could not update %s"
-					       " property\n", prop_name);
+					pr_err("updating %s property failed: %d\n",
+					       prop_name, rc);
 				}
 
 				prop_data += vd;
@@ -343,8 +343,7 @@ void post_mobility_fixup(void)
 
 	rc = pseries_devicetree_update(MIGRATION_SCOPE);
 	if (rc)
-		printk(KERN_ERR "Post-mobility device tree update "
-			"failed: %d\n", rc);
+		pr_err("device tree update failed: %d\n", rc);
 
 	cacheinfo_rebuild();
 
-- 
2.28.0

[PATCH v2 10/28] powerpc/pseries/mobility: use rtas_activate_firmware() on resume

[Nathan Lynch]

It's incorrect to abort post-suspend processing if
ibm,activate-firmware isn't available. Use rtas_activate_firmware(),
which logs this condition appropriately and allows us to proceed.

Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
---
 arch/powerpc/platforms/pseries/mobility.c | 15 +--------------
 1 file changed, 1 insertion(+), 14 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/mobility.c b/arch/powerpc/platforms/pseries/mobility.c
index 31d81b7da961..01ac7c03558e 100644
--- a/arch/powerpc/platforms/pseries/mobility.c
+++ b/arch/powerpc/platforms/pseries/mobility.c
@@ -312,21 +312,8 @@ int pseries_devicetree_update(s32 scope)
 void post_mobility_fixup(void)
 {
 	int rc;
-	int activate_fw_token;
 
-	activate_fw_token = rtas_token("ibm,activate-firmware");
-	if (activate_fw_token == RTAS_UNKNOWN_SERVICE) {
-		printk(KERN_ERR "Could not make post-mobility "
-		       "activate-fw call.\n");
-		return;
-	}
-
-	do {
-		rc = rtas_call(activate_fw_token, 0, 1, NULL);
-	} while (rtas_busy_delay(rc));
-
-	if (rc)
-		printk(KERN_ERR "Post-mobility activate-fw failed: %d\n", rc);
+	rtas_activate_firmware();
 
 	/*
 	 * We don't want CPUs to go online/offline while the device
-- 
2.28.0

[PATCH v2 11/28] powerpc/pseries/mobility: extract VASI session polling logic

[Nathan Lynch]

The behavior of rtas_ibm_suspend_me_unsafe() is to return -EAGAIN to
the caller until the specified VASI suspend session state makes the
transition from H_VASI_ENABLED to H_VASI_SUSPENDING. In the interest
of separating concerns to prepare for a new implementation of the
join/suspend sequence, extract VASI session polling logic into a
couple of local functions. Waiting for the session state to reach
H_VASI_SUSPENDING before calling rtas_ibm_suspend_me_unsafe() ensures
that we will never get an EAGAIN result necessitating a retry. No
user-visible change in behavior is intended.

Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
---
 arch/powerpc/platforms/pseries/mobility.c | 69 +++++++++++++++++++++--
 1 file changed, 64 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/mobility.c b/arch/powerpc/platforms/pseries/mobility.c
index 01ac7c03558e..573ed48b43d8 100644
--- a/arch/powerpc/platforms/pseries/mobility.c
+++ b/arch/powerpc/platforms/pseries/mobility.c
@@ -345,6 +345,66 @@ void post_mobility_fixup(void)
 	return;
 }
 
+static int poll_vasi_state(u64 handle, unsigned long *res)
+{
+	unsigned long retbuf[PLPAR_HCALL_BUFSIZE];
+	long hvrc;
+	int ret;
+
+	hvrc = plpar_hcall(H_VASI_STATE, retbuf, handle);
+	switch (hvrc) {
+	case H_SUCCESS:
+		ret = 0;
+		*res = retbuf[0];
+		break;
+	case H_PARAMETER:
+		ret = -EINVAL;
+		break;
+	case H_FUNCTION:
+		ret = -EOPNOTSUPP;
+		break;
+	case H_HARDWARE:
+	default:
+		pr_err("unexpected H_VASI_STATE result %ld\n", hvrc);
+		ret = -EIO;
+		break;
+	}
+	return ret;
+}
+
+static int wait_for_vasi_session_suspending(u64 handle)
+{
+	unsigned long state;
+	int ret;
+
+	/*
+	 * Wait for transition from H_VASI_ENABLED to
+	 * H_VASI_SUSPENDING. Treat anything else as an error.
+	 */
+	while (true) {
+		ret = poll_vasi_state(handle, &state);
+
+		if (ret != 0 || state == H_VASI_SUSPENDING) {
+			break;
+		} else if (state == H_VASI_ENABLED) {
+			ssleep(1);
+		} else {
+			pr_err("unexpected H_VASI_STATE result %lu\n", state);
+			ret = -EIO;
+			break;
+		}
+	}
+
+	/*
+	 * Proceed even if H_VASI_STATE is unavailable. If H_JOIN or
+	 * ibm,suspend-me are also unimplemented, we'll recover then.
+	 */
+	if (ret == -EOPNOTSUPP)
+		ret = 0;
+
+	return ret;
+}
+
 static ssize_t migration_store(struct class *class,
 			       struct class_attribute *attr, const char *buf,
 			       size_t count)
@@ -356,12 +416,11 @@ static ssize_t migration_store(struct class *class,
 	if (rc)
 		return rc;
 
-	do {
-		rc = rtas_ibm_suspend_me_unsafe(streamid);
-		if (rc == -EAGAIN)
-			ssleep(1);
-	} while (rc == -EAGAIN);
+	rc = wait_for_vasi_session_suspending(streamid);
+	if (rc)
+		return rc;
 
+	rc = rtas_ibm_suspend_me_unsafe(streamid);
 	if (rc)
 		return rc;
 
-- 
2.28.0

[PATCH v2 12/28] powerpc/pseries/mobility: use stop_machine for join/suspend

[Nathan Lynch]

The partition suspend sequence as specified in the platform
architecture requires that all active processor threads call
H_JOIN, which:

- suspends the calling thread until it is the target of
  an H_PROD; or
- immediately returns H_CONTINUE, if the calling thread is the last to
  call H_JOIN. This thread is expected to call ibm,suspend-me to
  completely suspend the partition.

Upon returning from ibm,suspend-me the calling thread must wake all
others using H_PROD.

rtas_ibm_suspend_me_unsafe() uses on_each_cpu() to implement this
protocol, but because of its synchronizing nature this is susceptible
to deadlock versus users of stop_machine() or other callers of
on_each_cpu().

Not only is stop_machine() intended for use cases like this, it
handles error propagation and allows us to keep the data shared
between CPUs minimal: a single atomic counter which ensures exactly
one CPU will wake the others from their joined states.

Switch the migration code to use stop_machine() and a less complex
local implementation of the H_JOIN/ibm,suspend-me logic, which
carries additional benefits:

- more informative error reporting, appropriately ratelimited
- resets the lockup detector / watchdog on resume to prevent lockup
  warnings when the OS has been suspended for a time exceeding the
  threshold.

Fixes: 91dc182ca6e2 ("[PATCH] powerpc: special-case ibm,suspend-me RTAS call")
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
---
 arch/powerpc/platforms/pseries/mobility.c | 132 ++++++++++++++++++++--
 1 file changed, 125 insertions(+), 7 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/mobility.c b/arch/powerpc/platforms/pseries/mobility.c
index 573ed48b43d8..5a3951626a96 100644
--- a/arch/powerpc/platforms/pseries/mobility.c
+++ b/arch/powerpc/platforms/pseries/mobility.c
@@ -12,9 +12,11 @@
 #include <linux/cpu.h>
 #include <linux/kernel.h>
 #include <linux/kobject.h>
+#include <linux/nmi.h>
 #include <linux/sched.h>
 #include <linux/smp.h>
 #include <linux/stat.h>
+#include <linux/stop_machine.h>
 #include <linux/completion.h>
 #include <linux/device.h>
 #include <linux/delay.h>
@@ -405,6 +407,128 @@ static int wait_for_vasi_session_suspending(u64 handle)
 	return ret;
 }
 
+static void prod_single(unsigned int target_cpu)
+{
+	long hvrc;
+	int hwid;
+
+	hwid = get_hard_smp_processor_id(target_cpu);
+	hvrc = plpar_hcall_norets(H_PROD, hwid);
+	if (hvrc == H_SUCCESS)
+		return;
+	pr_err_ratelimited("H_PROD of CPU %u (hwid %d) error: %ld\n",
+			   target_cpu, hwid, hvrc);
+}
+
+static void prod_others(void)
+{
+	unsigned int cpu;
+
+	for_each_online_cpu(cpu) {
+		if (cpu != smp_processor_id())
+			prod_single(cpu);
+	}
+}
+
+static u16 clamp_slb_size(void)
+{
+	u16 prev = mmu_slb_size;
+
+	slb_set_size(SLB_MIN_SIZE);
+
+	return prev;
+}
+
+static int do_suspend(void)
+{
+	u16 saved_slb_size;
+	int status;
+	int ret;
+
+	pr_info("calling ibm,suspend-me on CPU %i\n", smp_processor_id());
+
+	/*
+	 * The destination processor model may have fewer SLB entries
+	 * than the source. We reduce mmu_slb_size to a safe minimum
+	 * before suspending in order to minimize the possibility of
+	 * programming non-existent entries on the destination. If
+	 * suspend fails, we restore it before returning. On success
+	 * the OF reconfig path will update it from the new device
+	 * tree after resuming on the destination.
+	 */
+	saved_slb_size = clamp_slb_size();
+
+	ret = rtas_ibm_suspend_me(&status);
+	if (ret != 0) {
+		pr_err("ibm,suspend-me error: %d\n", status);
+		slb_set_size(saved_slb_size);
+	}
+
+	return ret;
+}
+
+static int do_join(void *arg)
+{
+	atomic_t *counter = arg;
+	long hvrc;
+	int ret;
+
+	/* Must ensure MSR.EE off for H_JOIN. */
+	hard_irq_disable();
+	hvrc = plpar_hcall_norets(H_JOIN);
+
+	switch (hvrc) {
+	case H_CONTINUE:
+		/*
+		 * All other CPUs are offline or in H_JOIN. This CPU
+		 * attempts the suspend.
+		 */
+		ret = do_suspend();
+		break;
+	case H_SUCCESS:
+		/*
+		 * The suspend is complete and this cpu has received a
+		 * prod.
+		 */
+		ret = 0;
+		break;
+	case H_BAD_MODE:
+	case H_HARDWARE:
+	default:
+		ret = -EIO;
+		pr_err_ratelimited("H_JOIN error %ld on CPU %i\n",
+				   hvrc, smp_processor_id());
+		break;
+	}
+
+	if (atomic_inc_return(counter) == 1) {
+		pr_info("CPU %u waking all threads\n", smp_processor_id());
+		prod_others();
+	}
+	/*
+	 * Execution may have been suspended for several seconds, so
+	 * reset the watchdog.
+	 */
+	touch_nmi_watchdog();
+	return ret;
+}
+
+static int pseries_migrate_partition(u64 handle)
+{
+	atomic_t counter = ATOMIC_INIT(0);
+	int ret;
+
+	ret = wait_for_vasi_session_suspending(handle);
+	if (ret)
+		return ret;
+
+	ret = stop_machine(do_join, &counter, cpu_online_mask);
+	if (ret == 0)
+		post_mobility_fixup();
+
+	return ret;
+}
+
 static ssize_t migration_store(struct class *class,
 			       struct class_attribute *attr, const char *buf,
 			       size_t count)
@@ -416,16 +540,10 @@ static ssize_t migration_store(struct class *class,
 	if (rc)
 		return rc;
 
-	rc = wait_for_vasi_session_suspending(streamid);
+	rc = pseries_migrate_partition(streamid);
 	if (rc)
 		return rc;
 
-	rc = rtas_ibm_suspend_me_unsafe(streamid);
-	if (rc)
-		return rc;
-
-	post_mobility_fixup();
-
 	return count;
 }
 
-- 
2.28.0

[PATCH v2 13/28] powerpc/pseries/mobility: signal suspend cancellation to platform

[Nathan Lynch]

If we're returning an error to user space, use H_VASI_SIGNAL to send a
cancellation request to the platform. This isn't strictly required but
it communicates that Linux will not attempt to complete the suspend,
which allows the various entities involved to promptly end the
operation in progress.

Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
---
 arch/powerpc/platforms/pseries/mobility.c | 31 +++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/arch/powerpc/platforms/pseries/mobility.c b/arch/powerpc/platforms/pseries/mobility.c
index 5a3951626a96..f234a7ed87aa 100644
--- a/arch/powerpc/platforms/pseries/mobility.c
+++ b/arch/powerpc/platforms/pseries/mobility.c
@@ -513,6 +513,35 @@ static int do_join(void *arg)
 	return ret;
 }
 
+/*
+ * Abort reason code byte 0. We use only the 'Migrating partition' value.
+ */
+enum vasi_aborting_entity {
+	ORCHESTRATOR        = 1,
+	VSP_SOURCE          = 2,
+	PARTITION_FIRMWARE  = 3,
+	PLATFORM_FIRMWARE   = 4,
+	VSP_TARGET          = 5,
+	MIGRATING_PARTITION = 6,
+};
+
+static void pseries_cancel_migration(u64 handle, int err)
+{
+	u32 reason_code;
+	u32 detail;
+	u8 entity;
+	long hvrc;
+
+	entity = MIGRATING_PARTITION;
+	detail = abs(err) & 0xffffff;
+	reason_code = (entity << 24) | detail;
+
+	hvrc = plpar_hcall_norets(H_VASI_SIGNAL, handle,
+				  H_VASI_SIGNAL_CANCEL, reason_code);
+	if (hvrc)
+		pr_err("H_VASI_SIGNAL error: %ld\n", hvrc);
+}
+
 static int pseries_migrate_partition(u64 handle)
 {
 	atomic_t counter = ATOMIC_INIT(0);
@@ -525,6 +554,8 @@ static int pseries_migrate_partition(u64 handle)
 	ret = stop_machine(do_join, &counter, cpu_online_mask);
 	if (ret == 0)
 		post_mobility_fixup();
+	else
+		pseries_cancel_migration(handle, ret);
 
 	return ret;
 }
-- 
2.28.0

[PATCH v2 14/28] powerpc/pseries/mobility: retry partition suspend after error

[Nathan Lynch]

This is a mitigation for the relatively rare occurrence where a
virtual IOA can be in a transient state that prevents the
suspend/migration from succeeding, resulting in an error from
ibm,suspend-me.

If the join/suspend sequence returns an error, it is acceptable to
retry as long as the VASI suspend session state is still
"Suspending" (i.e. the platform is still waiting for the OS to
suspend).

Retry a few times on suspend failure while this condition holds,
progressively increasing the delay between attempts. We don't want to
retry indefinitey because firmware emits an error log event on each
unsuccessful attempt.

Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
---
 arch/powerpc/platforms/pseries/mobility.c | 59 ++++++++++++++++++++++-
 1 file changed, 57 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/mobility.c b/arch/powerpc/platforms/pseries/mobility.c
index f234a7ed87aa..fe7e35cdc9d5 100644
--- a/arch/powerpc/platforms/pseries/mobility.c
+++ b/arch/powerpc/platforms/pseries/mobility.c
@@ -542,16 +542,71 @@ static void pseries_cancel_migration(u64 handle, int err)
 		pr_err("H_VASI_SIGNAL error: %ld\n", hvrc);
 }
 
+static int pseries_suspend(u64 handle)
+{
+	const unsigned int max_attempts = 5;
+	unsigned int retry_interval_ms = 1;
+	unsigned int attempt = 1;
+	int ret;
+
+	while (true) {
+		atomic_t counter = ATOMIC_INIT(0);
+		unsigned long vasi_state;
+		int vasi_err;
+
+		ret = stop_machine(do_join, &counter, cpu_online_mask);
+		if (ret == 0)
+			break;
+		/*
+		 * Encountered an error. If the VASI stream is still
+		 * in Suspending state, it's likely a transient
+		 * condition related to some device in the partition
+		 * and we can retry in the hope that the cause has
+		 * cleared after some delay.
+		 *
+		 * A better design would allow drivers etc to prepare
+		 * for the suspend and avoid conditions which prevent
+		 * the suspend from succeeding. For now, we have this
+		 * mitigation.
+		 */
+		pr_notice("Partition suspend attempt %u of %u error: %d\n",
+			  attempt, max_attempts, ret);
+
+		if (attempt == max_attempts)
+			break;
+
+		vasi_err = poll_vasi_state(handle, &vasi_state);
+		if (vasi_err == 0) {
+			if (vasi_state != H_VASI_SUSPENDING) {
+				pr_notice("VASI state %lu after failed suspend\n",
+					  vasi_state);
+				break;
+			}
+		} else if (vasi_err != -EOPNOTSUPP) {
+			pr_err("VASI state poll error: %d", vasi_err);
+			break;
+		}
+
+		pr_notice("Will retry partition suspend after %u ms\n",
+			  retry_interval_ms);
+
+		msleep(retry_interval_ms);
+		retry_interval_ms *= 10;
+		attempt++;
+	}
+
+	return ret;
+}
+
 static int pseries_migrate_partition(u64 handle)
 {
-	atomic_t counter = ATOMIC_INIT(0);
 	int ret;
 
 	ret = wait_for_vasi_session_suspending(handle);
 	if (ret)
 		return ret;
 
-	ret = stop_machine(do_join, &counter, cpu_online_mask);
+	ret = pseries_suspend(handle);
 	if (ret == 0)
 		post_mobility_fixup();
 	else
-- 
2.28.0

[PATCH v2 15/28] powerpc/rtas: dispatch partition migration requests to pseries

[Nathan Lynch]

sys_rtas() cannot call ibm,suspend-me directly in the same way it
handles other inputs. Instead it must dispatch the request to code
that can first perform the H_JOIN sequence before any call to
ibm,suspend-me can succeed. Over time kernel/rtas.c has accreted a fair
amount of platform-specific code to implement this.

Since a different, more robust implementation of the suspend sequence
is now in the pseries platform code, we want to dispatch the request
there.

Note that invoking ibm,suspend-me via the RTAS syscall is all but
deprecated; this change preserves ABI compatibility for old programs
while providing to them the benefit of the new partition suspend
implementation. This is a behavior change in that the kernel performs
the device tree update and firmware activation before returning, but
experimentation indicates this is tolerated fine by legacy user space.

Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
---
 arch/powerpc/include/asm/rtas.h           | 5 +++++
 arch/powerpc/kernel/rtas.c                | 2 +-
 arch/powerpc/platforms/pseries/mobility.c | 5 +++++
 3 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/include/asm/rtas.h b/arch/powerpc/include/asm/rtas.h
index fdefe6a974eb..3b52d8574fcc 100644
--- a/arch/powerpc/include/asm/rtas.h
+++ b/arch/powerpc/include/asm/rtas.h
@@ -279,8 +279,13 @@ extern time64_t last_rtas_event;
 extern int clobbering_unread_rtas_event(void);
 extern int pseries_devicetree_update(s32 scope);
 extern void post_mobility_fixup(void);
+int rtas_syscall_dispatch_ibm_suspend_me(u64 handle);
 #else
 static inline int clobbering_unread_rtas_event(void) { return 0; }
+static inline int rtas_syscall_dispatch_ibm_suspend_me(u64 handle)
+{
+	return -EINVAL;
+}
 #endif
 
 #ifdef CONFIG_PPC_RTAS_DAEMON
diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c
index 3a740ae933f8..d4b048571728 100644
--- a/arch/powerpc/kernel/rtas.c
+++ b/arch/powerpc/kernel/rtas.c
@@ -1272,7 +1272,7 @@ SYSCALL_DEFINE1(rtas, struct rtas_args __user *, uargs)
 		int rc = 0;
 		u64 handle = ((u64)be32_to_cpu(args.args[0]) << 32)
 		              | be32_to_cpu(args.args[1]);
-		rc = rtas_ibm_suspend_me_unsafe(handle);
+		rc = rtas_syscall_dispatch_ibm_suspend_me(handle);
 		if (rc == -EAGAIN)
 			args.rets[0] = cpu_to_be32(RTAS_NOT_SUSPENDABLE);
 		else if (rc == -EIO)
diff --git a/arch/powerpc/platforms/pseries/mobility.c b/arch/powerpc/platforms/pseries/mobility.c
index fe7e35cdc9d5..e670180f311d 100644
--- a/arch/powerpc/platforms/pseries/mobility.c
+++ b/arch/powerpc/platforms/pseries/mobility.c
@@ -615,6 +615,11 @@ static int pseries_migrate_partition(u64 handle)
 	return ret;
 }
 
+int rtas_syscall_dispatch_ibm_suspend_me(u64 handle)
+{
+	return pseries_migrate_partition(handle);
+}
+
 static ssize_t migration_store(struct class *class,
 			       struct class_attribute *attr, const char *buf,
 			       size_t count)
-- 
2.28.0

[PATCH v2 16/28] powerpc/rtas: remove rtas_ibm_suspend_me_unsafe()

[Nathan Lynch]

rtas_ibm_suspend_me_unsafe() is now unused; remove it and
rtas_percpu_suspend_me() which becomes unused as a result.

Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
---
 arch/powerpc/include/asm/rtas.h |  1 -
 arch/powerpc/kernel/rtas.c      | 67 +--------------------------------
 2 files changed, 1 insertion(+), 67 deletions(-)

diff --git a/arch/powerpc/include/asm/rtas.h b/arch/powerpc/include/asm/rtas.h
index 3b52d8574fcc..9a6107ffe378 100644
--- a/arch/powerpc/include/asm/rtas.h
+++ b/arch/powerpc/include/asm/rtas.h
@@ -258,7 +258,6 @@ extern int rtas_set_indicator_fast(int indicator, int index, int new_value);
 extern void rtas_progress(char *s, unsigned short hex);
 extern int rtas_suspend_cpu(struct rtas_suspend_me_data *data);
 extern int rtas_suspend_last_cpu(struct rtas_suspend_me_data *data);
-int rtas_ibm_suspend_me_unsafe(u64 handle);
 int rtas_ibm_suspend_me(int *fw_status);
 
 struct rtc_time;
diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c
index d4b048571728..7e6024f570da 100644
--- a/arch/powerpc/kernel/rtas.c
+++ b/arch/powerpc/kernel/rtas.c
@@ -925,66 +925,6 @@ int rtas_suspend_cpu(struct rtas_suspend_me_data *data)
 	return __rtas_suspend_cpu(data, 0);
 }
 
-static void rtas_percpu_suspend_me(void *info)
-{
-	__rtas_suspend_cpu((struct rtas_suspend_me_data *)info, 1);
-}
-
-int rtas_ibm_suspend_me_unsafe(u64 handle)
-{
-	long state;
-	long rc;
-	unsigned long retbuf[PLPAR_HCALL_BUFSIZE];
-	struct rtas_suspend_me_data data;
-	DECLARE_COMPLETION_ONSTACK(done);
-
-	if (!rtas_service_present("ibm,suspend-me"))
-		return -ENOSYS;
-
-	/* Make sure the state is valid */
-	rc = plpar_hcall(H_VASI_STATE, retbuf, handle);
-
-	state = retbuf[0];
-
-	if (rc) {
-		printk(KERN_ERR "rtas_ibm_suspend_me: vasi_state returned %ld\n",rc);
-		return rc;
-	} else if (state == H_VASI_ENABLED) {
-		return -EAGAIN;
-	} else if (state != H_VASI_SUSPENDING) {
-		printk(KERN_ERR "rtas_ibm_suspend_me: vasi_state returned state %ld\n",
-		       state);
-		return -EIO;
-	}
-
-	atomic_set(&data.working, 0);
-	atomic_set(&data.done, 0);
-	atomic_set(&data.error, 0);
-	data.token = rtas_token("ibm,suspend-me");
-	data.complete = &done;
-
-	lock_device_hotplug();
-
-	cpu_hotplug_disable();
-
-	/* Call function on all CPUs.  One of us will make the
-	 * rtas call
-	 */
-	on_each_cpu(rtas_percpu_suspend_me, &data, 0);
-
-	wait_for_completion(&done);
-
-	if (atomic_read(&data.error) != 0)
-		printk(KERN_ERR "Error doing global join\n");
-
-
-	cpu_hotplug_enable();
-
-	unlock_device_hotplug();
-
-	return atomic_read(&data.error);
-}
-
 /**
  * rtas_call_reentrant() - Used for reentrant rtas calls
  * @token:	Token for desired reentrant RTAS call
@@ -1035,12 +975,7 @@ int rtas_call_reentrant(int token, int nargs, int nret, int *outputs, ...)
 	return ret;
 }
 
-#else /* CONFIG_PPC_PSERIES */
-int rtas_ibm_suspend_me_unsafe(u64 handle)
-{
-	return -ENOSYS;
-}
-#endif
+#endif /* CONFIG_PPC_PSERIES */
 
 /**
  * Find a specific pseries error log in an RTAS extended event log.
-- 
2.28.0

[PATCH v2 17/28] powerpc/pseries/hibernation: drop pseries_suspend_begin() from suspend ops

[Nathan Lynch]

There are three ways pseries_suspend_begin() can be reached:

1. When "mem" is written to /sys/power/state:

kobj_attr_store()
-> state_store()
  -> pm_suspend()
    -> suspend_devices_and_enter()
      -> pseries_suspend_begin()

This never works because there is no way to supply a valid stream id
using this interface, and H_VASI_STATE is called with a stream id of
zero. So this call path is useless at best.

2. When a stream id is written to /sys/devices/system/power/hibernate.
pseries_suspend_begin() is polled directly from store_hibernate()
until the stream is in the "Suspending" state (i.e. the platform is
ready for the OS to suspend execution):

dev_attr_store()
-> store_hibernate()
  -> pseries_suspend_begin()

3. When a stream id is written to /sys/devices/system/power/hibernate
(continued). After #2, pseries_suspend_begin() is called once again
from the pm core:

dev_attr_store()
-> store_hibernate()
  -> pm_suspend()
    -> suspend_devices_and_enter()
      -> pseries_suspend_begin()

This is redundant because the VASI suspend state is already known to
be Suspending.

The begin() callback of platform_suspend_ops is optional, so we can
simply remove that assignment with no loss of function.

Fixes: 32d8ad4e621d ("powerpc/pseries: Partition hibernation support")
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
---
 arch/powerpc/platforms/pseries/suspend.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/arch/powerpc/platforms/pseries/suspend.c b/arch/powerpc/platforms/pseries/suspend.c
index 81e0ac58d620..3eaa9d59dc7a 100644
--- a/arch/powerpc/platforms/pseries/suspend.c
+++ b/arch/powerpc/platforms/pseries/suspend.c
@@ -187,7 +187,6 @@ static struct bus_type suspend_subsys = {
 
 static const struct platform_suspend_ops pseries_suspend_ops = {
 	.valid		= suspend_valid_only_mem,
-	.begin		= pseries_suspend_begin,
 	.prepare_late	= pseries_prepare_late,
 	.enter		= pseries_suspend_enter,
 };
-- 
2.28.0

[PATCH v2 18/28] powerpc/pseries/hibernation: pass stream id via function arguments

[Nathan Lynch]

There is no need for the stream id to be a file-global variable; pass
it from hibernate_store() to pseries_suspend_begin() for the
H_VASI_STATE call.

Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
---
 arch/powerpc/platforms/pseries/suspend.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/suspend.c b/arch/powerpc/platforms/pseries/suspend.c
index 3eaa9d59dc7a..232621f33510 100644
--- a/arch/powerpc/platforms/pseries/suspend.c
+++ b/arch/powerpc/platforms/pseries/suspend.c
@@ -15,7 +15,6 @@
 #include <asm/topology.h>
 #include "../../kernel/cacheinfo.h"
 
-static u64 stream_id;
 static struct device suspend_dev;
 static DECLARE_COMPLETION(suspend_work);
 static struct rtas_suspend_me_data suspend_data;
@@ -29,7 +28,7 @@ static atomic_t suspending;
  * Return value:
  * 	0 on success / other on failure
  **/
-static int pseries_suspend_begin(suspend_state_t state)
+static int pseries_suspend_begin(u64 stream_id)
 {
 	long vasi_state, rc;
 	unsigned long retbuf[PLPAR_HCALL_BUFSIZE];
@@ -132,6 +131,7 @@ static ssize_t store_hibernate(struct device *dev,
 			       struct device_attribute *attr,
 			       const char *buf, size_t count)
 {
+	u64 stream_id;
 	int rc;
 
 	if (!capable(CAP_SYS_ADMIN))
@@ -140,7 +140,7 @@ static ssize_t store_hibernate(struct device *dev,
 	stream_id = simple_strtoul(buf, NULL, 16);
 
 	do {
-		rc = pseries_suspend_begin(PM_SUSPEND_MEM);
+		rc = pseries_suspend_begin(stream_id);
 		if (rc == -EAGAIN)
 			ssleep(1);
 	} while (rc == -EAGAIN);
@@ -148,8 +148,6 @@ static ssize_t store_hibernate(struct device *dev,
 	if (!rc)
 		rc = pm_suspend(PM_SUSPEND_MEM);
 
-	stream_id = 0;
-
 	if (!rc)
 		rc = count;
 
-- 
2.28.0

[PATCH v2 19/28] powerpc/pseries/hibernation: remove pseries_suspend_cpu()

[Nathan Lynch]

Since commit 48f6e7f6d948 ("powerpc/pseries: remove cede offline state
for CPUs"), ppc_md.suspend_disable_cpu() is no longer used and all
CPUs (save one) are placed into true offline state as opposed to
H_JOIN. So pseries_suspend_cpu() is effectively unused; remove it.

Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
---
 arch/powerpc/platforms/pseries/suspend.c | 15 ---------------
 1 file changed, 15 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/suspend.c b/arch/powerpc/platforms/pseries/suspend.c
index 232621f33510..3315d698d5ab 100644
--- a/arch/powerpc/platforms/pseries/suspend.c
+++ b/arch/powerpc/platforms/pseries/suspend.c
@@ -48,20 +48,6 @@ static int pseries_suspend_begin(u64 stream_id)
 		       vasi_state);
 		return -EIO;
 	}
-
-	return 0;
-}
-
-/**
- * pseries_suspend_cpu - Suspend a single CPU
- *
- * Makes the H_JOIN call to suspend the CPU
- *
- **/
-static int pseries_suspend_cpu(void)
-{
-	if (atomic_read(&suspending))
-		return rtas_suspend_cpu(&suspend_data);
 	return 0;
 }
 
@@ -235,7 +221,6 @@ static int __init pseries_suspend_init(void)
 	if ((rc = pseries_suspend_sysfs_register(&suspend_dev)))
 		return rc;
 
-	ppc_md.suspend_disable_cpu = pseries_suspend_cpu;
 	ppc_md.suspend_enable_irqs = pseries_suspend_enable_irqs;
 	suspend_set_ops(&pseries_suspend_ops);
 	return 0;
-- 
2.28.0

[PATCH v2 20/28] powerpc/machdep: remove suspend_disable_cpu()

[Nathan Lynch]

There are no users left of the suspend_disable_cpu() callback, remove
it.

Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
---
 arch/powerpc/include/asm/machdep.h | 1 -
 1 file changed, 1 deletion(-)

diff --git a/arch/powerpc/include/asm/machdep.h b/arch/powerpc/include/asm/machdep.h
index 475687f24f4a..cf6ebbc16cb4 100644
--- a/arch/powerpc/include/asm/machdep.h
+++ b/arch/powerpc/include/asm/machdep.h
@@ -207,7 +207,6 @@ struct machdep_calls {
 	void (*suspend_disable_irqs)(void);
 	void (*suspend_enable_irqs)(void);
 #endif
-	int (*suspend_disable_cpu)(void);
 
 #ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
 	ssize_t (*cpu_probe)(const char *, size_t);
-- 
2.28.0

[PATCH v2 21/28] powerpc/rtas: remove rtas_suspend_cpu()

[Nathan Lynch]

rtas_suspend_cpu() no longer has users; remove it and
__rtas_suspend_cpu() which now becomes unused as well.

Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
---
 arch/powerpc/include/asm/rtas.h |  1 -
 arch/powerpc/kernel/rtas.c      | 52 ---------------------------------
 2 files changed, 53 deletions(-)

diff --git a/arch/powerpc/include/asm/rtas.h b/arch/powerpc/include/asm/rtas.h
index 9a6107ffe378..97ccb40fb09f 100644
--- a/arch/powerpc/include/asm/rtas.h
+++ b/arch/powerpc/include/asm/rtas.h
@@ -256,7 +256,6 @@ extern bool rtas_indicator_present(int token, int *maxindex);
 extern int rtas_set_indicator(int indicator, int index, int new_value);
 extern int rtas_set_indicator_fast(int indicator, int index, int new_value);
 extern void rtas_progress(char *s, unsigned short hex);
-extern int rtas_suspend_cpu(struct rtas_suspend_me_data *data);
 extern int rtas_suspend_last_cpu(struct rtas_suspend_me_data *data);
 int rtas_ibm_suspend_me(int *fw_status);
 
diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c
index 7e6024f570da..aedd46967b99 100644
--- a/arch/powerpc/kernel/rtas.c
+++ b/arch/powerpc/kernel/rtas.c
@@ -873,58 +873,6 @@ int rtas_suspend_last_cpu(struct rtas_suspend_me_data *data)
 	return __rtas_suspend_last_cpu(data, 0);
 }
 
-static int __rtas_suspend_cpu(struct rtas_suspend_me_data *data, int wake_when_done)
-{
-	long rc = H_SUCCESS;
-	unsigned long msr_save;
-	int cpu;
-
-	atomic_inc(&data->working);
-
-	/* really need to ensure MSR.EE is off for H_JOIN */
-	msr_save = mfmsr();
-	mtmsr(msr_save & ~(MSR_EE));
-
-	while (rc == H_SUCCESS && !atomic_read(&data->done) && !atomic_read(&data->error))
-		rc = plpar_hcall_norets(H_JOIN);
-
-	mtmsr(msr_save);
-
-	if (rc == H_SUCCESS) {
-		/* This cpu was prodded and the suspend is complete. */
-		goto out;
-	} else if (rc == H_CONTINUE) {
-		/* All other cpus are in H_JOIN, this cpu does
-		 * the suspend.
-		 */
-		return __rtas_suspend_last_cpu(data, wake_when_done);
-	} else {
-		printk(KERN_ERR "H_JOIN on cpu %i failed with rc = %ld\n",
-		       smp_processor_id(), rc);
-		atomic_set(&data->error, rc);
-	}
-
-	if (wake_when_done) {
-		atomic_set(&data->done, 1);
-
-		/* This cpu did the suspend or got an error; in either case,
-		 * we need to prod all other other cpus out of join state.
-		 * Extra prods are harmless.
-		 */
-		for_each_online_cpu(cpu)
-			plpar_hcall_norets(H_PROD, get_hard_smp_processor_id(cpu));
-	}
-out:
-	if (atomic_dec_return(&data->working) == 0)
-		complete(data->complete);
-	return rc;
-}
-
-int rtas_suspend_cpu(struct rtas_suspend_me_data *data)
-{
-	return __rtas_suspend_cpu(data, 0);
-}
-
 /**
  * rtas_call_reentrant() - Used for reentrant rtas calls
  * @token:	Token for desired reentrant RTAS call
-- 
2.28.0

[PATCH v2 22/28] powerpc/pseries/hibernation: switch to rtas_ibm_suspend_me()

[Nathan Lynch]

rtas_suspend_last_cpu() and related code perform a lot of work that
isn't relevant to the hibernation workflow. All other CPUs are offline
when called so there is no need to place them in H_JOIN or prod them
on resume, nor is there need for retries or operations on shared
state.

Call the rtas_ibm_suspend_me() wrapper function directly from
pseries_suspend_enter() instead of using rtas_suspend_last_cpu().

Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
---
 arch/powerpc/platforms/pseries/suspend.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/suspend.c b/arch/powerpc/platforms/pseries/suspend.c
index 3315d698d5ab..703728cb95ec 100644
--- a/arch/powerpc/platforms/pseries/suspend.c
+++ b/arch/powerpc/platforms/pseries/suspend.c
@@ -76,11 +76,7 @@ static void pseries_suspend_enable_irqs(void)
  **/
 static int pseries_suspend_enter(suspend_state_t state)
 {
-	int rc = rtas_suspend_last_cpu(&suspend_data);
-
-	atomic_set(&suspending, 0);
-	atomic_set(&suspend_data.done, 1);
-	return rc;
+	return rtas_ibm_suspend_me(NULL);
 }
 
 /**
-- 
2.28.0

[PATCH v2 23/28] powerpc/rtas: remove unused rtas_suspend_last_cpu()

[Nathan Lynch]

rtas_suspend_last_cpu() is now unused, remove it and
__rtas_suspend_last_cpu() which also becomes unused.

Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
---
 arch/powerpc/include/asm/rtas.h |  1 -
 arch/powerpc/kernel/rtas.c      | 43 ---------------------------------
 2 files changed, 44 deletions(-)

diff --git a/arch/powerpc/include/asm/rtas.h b/arch/powerpc/include/asm/rtas.h
index 97ccb40fb09f..332e1000ca0f 100644
--- a/arch/powerpc/include/asm/rtas.h
+++ b/arch/powerpc/include/asm/rtas.h
@@ -256,7 +256,6 @@ extern bool rtas_indicator_present(int token, int *maxindex);
 extern int rtas_set_indicator(int indicator, int index, int new_value);
 extern int rtas_set_indicator_fast(int indicator, int index, int new_value);
 extern void rtas_progress(char *s, unsigned short hex);
-extern int rtas_suspend_last_cpu(struct rtas_suspend_me_data *data);
 int rtas_ibm_suspend_me(int *fw_status);
 
 struct rtc_time;
diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c
index aedd46967b99..9a7d1bba3ef7 100644
--- a/arch/powerpc/kernel/rtas.c
+++ b/arch/powerpc/kernel/rtas.c
@@ -830,49 +830,6 @@ void rtas_activate_firmware(void)
 
 static int ibm_suspend_me_token = RTAS_UNKNOWN_SERVICE;
 #ifdef CONFIG_PPC_PSERIES
-static int __rtas_suspend_last_cpu(struct rtas_suspend_me_data *data, int wake_when_done)
-{
-	u16 slb_size = mmu_slb_size;
-	int rc = H_MULTI_THREADS_ACTIVE;
-	int cpu;
-
-	slb_set_size(SLB_MIN_SIZE);
-	printk(KERN_DEBUG "calling ibm,suspend-me on cpu %i\n", smp_processor_id());
-
-	while (rc == H_MULTI_THREADS_ACTIVE && !atomic_read(&data->done) &&
-	       !atomic_read(&data->error))
-		rc = rtas_call(data->token, 0, 1, NULL);
-
-	if (rc || atomic_read(&data->error)) {
-		printk(KERN_DEBUG "ibm,suspend-me returned %d\n", rc);
-		slb_set_size(slb_size);
-	}
-
-	if (atomic_read(&data->error))
-		rc = atomic_read(&data->error);
-
-	atomic_set(&data->error, rc);
-	pSeries_coalesce_init();
-
-	if (wake_when_done) {
-		atomic_set(&data->done, 1);
-
-		for_each_online_cpu(cpu)
-			plpar_hcall_norets(H_PROD, get_hard_smp_processor_id(cpu));
-	}
-
-	if (atomic_dec_return(&data->working) == 0)
-		complete(data->complete);
-
-	return rc;
-}
-
-int rtas_suspend_last_cpu(struct rtas_suspend_me_data *data)
-{
-	atomic_inc(&data->working);
-	return __rtas_suspend_last_cpu(data, 0);
-}
-
 /**
  * rtas_call_reentrant() - Used for reentrant rtas calls
  * @token:	Token for desired reentrant RTAS call
-- 
2.28.0

[PATCH v2 24/28] powerpc/pseries/hibernation: remove redundant cacheinfo update

[Nathan Lynch]

Partitions with cache nodes in the device tree can encounter the
following warning on resume:

CPU 0 already accounted in PowerPC,POWER9@0(Data)
WARNING: CPU: 0 PID: 3177 at arch/powerpc/kernel/cacheinfo.c:197 cacheinfo_cpu_online+0x640/0x820

These calls to cacheinfo_cpu_offline/online have been redundant since
commit e610a466d16a ("powerpc/pseries/mobility: rebuild cacheinfo
hierarchy post-migration").

Fixes: e610a466d16a ("powerpc/pseries/mobility: rebuild cacheinfo hierarchy post-migration")
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
---
 arch/powerpc/platforms/pseries/suspend.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/suspend.c b/arch/powerpc/platforms/pseries/suspend.c
index 703728cb95ec..6a94cc0deb88 100644
--- a/arch/powerpc/platforms/pseries/suspend.c
+++ b/arch/powerpc/platforms/pseries/suspend.c
@@ -13,7 +13,6 @@
 #include <asm/mmu.h>
 #include <asm/rtas.h>
 #include <asm/topology.h>
-#include "../../kernel/cacheinfo.h"
 
 static struct device suspend_dev;
 static DECLARE_COMPLETION(suspend_work);
@@ -63,9 +62,7 @@ static void pseries_suspend_enable_irqs(void)
 	 * Update configuration which can be modified based on device tree
 	 * changes during resume.
 	 */
-	cacheinfo_cpu_offline(smp_processor_id());
 	post_mobility_fixup();
-	cacheinfo_cpu_online(smp_processor_id());
 }
 
 /**
-- 
2.28.0

[PATCH v2 25/28] powerpc/pseries/hibernation: perform post-suspend fixups later

[Nathan Lynch]

The pseries hibernate code calls post_mobility_fixup() which is sort
of a dumping ground of fixups that need to run after resuming from
suspend regardless of whether suspend was a hibernation or a
migration. Calling post_mobility_fixup() from
pseries_suspend_enable_irqs() runs this code early in resume with
devices suspended and only one CPU up, while the much more commonly
used migration case runs these fixups in a more typical process
context.

Call post_mobility_fixup() after the suspend core returns a success
status to the hibernate sysfs store method and remove
pseries_suspend_enable_irqs().

Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
---
 arch/powerpc/platforms/pseries/suspend.c | 21 ++++-----------------
 1 file changed, 4 insertions(+), 17 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/suspend.c b/arch/powerpc/platforms/pseries/suspend.c
index 6a94cc0deb88..589a91730db8 100644
--- a/arch/powerpc/platforms/pseries/suspend.c
+++ b/arch/powerpc/platforms/pseries/suspend.c
@@ -50,21 +50,6 @@ static int pseries_suspend_begin(u64 stream_id)
 	return 0;
 }
 
-/**
- * pseries_suspend_enable_irqs
- *
- * Post suspend configuration updates
- *
- **/
-static void pseries_suspend_enable_irqs(void)
-{
-	/*
-	 * Update configuration which can be modified based on device tree
-	 * changes during resume.
-	 */
-	post_mobility_fixup();
-}
-
 /**
  * pseries_suspend_enter - Final phase of hibernation
  *
@@ -127,8 +112,11 @@ static ssize_t store_hibernate(struct device *dev,
 	if (!rc)
 		rc = pm_suspend(PM_SUSPEND_MEM);
 
-	if (!rc)
+	if (!rc) {
 		rc = count;
+		post_mobility_fixup();
+	}
+
 
 	return rc;
 }
@@ -214,7 +202,6 @@ static int __init pseries_suspend_init(void)
 	if ((rc = pseries_suspend_sysfs_register(&suspend_dev)))
 		return rc;
 
-	ppc_md.suspend_enable_irqs = pseries_suspend_enable_irqs;
 	suspend_set_ops(&pseries_suspend_ops);
 	return 0;
 }
-- 
2.28.0

[PATCH v2 26/28] powerpc/pseries/hibernation: remove prepare_late() callback

[Nathan Lynch]

The pseries hibernate code no longer calls into the original
join/suspend code in kernel/rtas.c, so pseries_prepare_late() and
related code don't accomplish anything now.

Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
---
 arch/powerpc/platforms/pseries/suspend.c | 25 ------------------------
 1 file changed, 25 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/suspend.c b/arch/powerpc/platforms/pseries/suspend.c
index 589a91730db8..1b902cbf85c5 100644
--- a/arch/powerpc/platforms/pseries/suspend.c
+++ b/arch/powerpc/platforms/pseries/suspend.c
@@ -15,9 +15,6 @@
 #include <asm/topology.h>
 
 static struct device suspend_dev;
-static DECLARE_COMPLETION(suspend_work);
-static struct rtas_suspend_me_data suspend_data;
-static atomic_t suspending;
 
 /**
  * pseries_suspend_begin - First phase of hibernation
@@ -61,23 +58,6 @@ static int pseries_suspend_enter(suspend_state_t state)
 	return rtas_ibm_suspend_me(NULL);
 }
 
-/**
- * pseries_prepare_late - Prepare to suspend all other CPUs
- *
- * Return value:
- * 	0 on success / other on failure
- **/
-static int pseries_prepare_late(void)
-{
-	atomic_set(&suspending, 1);
-	atomic_set(&suspend_data.working, 0);
-	atomic_set(&suspend_data.done, 0);
-	atomic_set(&suspend_data.error, 0);
-	suspend_data.complete = &suspend_work;
-	reinit_completion(&suspend_work);
-	return 0;
-}
-
 /**
  * store_hibernate - Initiate partition hibernation
  * @dev:		subsys root device
@@ -152,7 +132,6 @@ static struct bus_type suspend_subsys = {
 
 static const struct platform_suspend_ops pseries_suspend_ops = {
 	.valid		= suspend_valid_only_mem,
-	.prepare_late	= pseries_prepare_late,
 	.enter		= pseries_suspend_enter,
 };
 
@@ -195,10 +174,6 @@ static int __init pseries_suspend_init(void)
 	if (!firmware_has_feature(FW_FEATURE_LPAR))
 		return 0;
 
-	suspend_data.token = rtas_token("ibm,suspend-me");
-	if (suspend_data.token == RTAS_UNKNOWN_SERVICE)
-		return 0;
-
 	if ((rc = pseries_suspend_sysfs_register(&suspend_dev)))
 		return rc;
 
-- 
2.28.0

[PATCH v2 27/28] powerpc/rtas: remove unused rtas_suspend_me_data

[Nathan Lynch]

All code which used this type has been removed.

Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
---
 arch/powerpc/include/asm/rtas-types.h | 8 --------
 1 file changed, 8 deletions(-)

diff --git a/arch/powerpc/include/asm/rtas-types.h b/arch/powerpc/include/asm/rtas-types.h
index aa420561bc10..8df6235d64d1 100644
--- a/arch/powerpc/include/asm/rtas-types.h
+++ b/arch/powerpc/include/asm/rtas-types.h
@@ -23,14 +23,6 @@ struct rtas_t {
 	struct device_node *dev;	/* virtual address pointer */
 };
 
-struct rtas_suspend_me_data {
-	atomic_t working; /* number of cpus accessing this struct */
-	atomic_t done;
-	int token; /* ibm,suspend-me */
-	atomic_t error;
-	struct completion *complete; /* wait on this until working == 0 */
-};
-
 struct rtas_error_log {
 	/* Byte 0 */
 	u8		byte0;			/* Architectural version */
-- 
2.28.0

[PATCH v2 28/28] powerpc/pseries/mobility: refactor node lookup during DT update

[Nathan Lynch]

In pseries_devicetree_update(), with each call to ibm,update-nodes the
partition firmware communicates the node to be deleted or updated by
placing its phandle in the work buffer. Each of delete_dt_node(),
update_dt_node(), and add_dt_node() have duplicate lookups using the
phandle value and corresponding refcount management.

Move the lookup and of_node_put() into pseries_devicetree_update(),
and emit a warning on any failed lookups.

Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
---
 arch/powerpc/platforms/pseries/mobility.c | 49 ++++++++---------------
 1 file changed, 17 insertions(+), 32 deletions(-)

diff --git a/arch/powerpc/platforms/pseries/mobility.c b/arch/powerpc/platforms/pseries/mobility.c
index e670180f311d..ea4d6a660e0d 100644
--- a/arch/powerpc/platforms/pseries/mobility.c
+++ b/arch/powerpc/platforms/pseries/mobility.c
@@ -61,18 +61,10 @@ static int mobility_rtas_call(int token, char *buf, s32 scope)
 	return rc;
 }
 
-static int delete_dt_node(__be32 phandle)
+static int delete_dt_node(struct device_node *dn)
 {
-	struct device_node *dn;
-
-	dn = of_find_node_by_phandle(be32_to_cpu(phandle));
-	if (!dn)
-		return -ENOENT;
-
 	pr_debug("removing node %pOFfp\n", dn);
-
 	dlpar_detach_node(dn);
-	of_node_put(dn);
 	return 0;
 }
 
@@ -137,10 +129,9 @@ static int update_dt_property(struct device_node *dn, struct property **prop,
 	return 0;
 }
 
-static int update_dt_node(__be32 phandle, s32 scope)
+static int update_dt_node(struct device_node *dn, s32 scope)
 {
 	struct update_props_workarea *upwa;
-	struct device_node *dn;
 	struct property *prop = NULL;
 	int i, rc, rtas_rc;
 	char *prop_data;
@@ -157,14 +148,8 @@ static int update_dt_node(__be32 phandle, s32 scope)
 	if (!rtas_buf)
 		return -ENOMEM;
 
-	dn = of_find_node_by_phandle(be32_to_cpu(phandle));
-	if (!dn) {
-		kfree(rtas_buf);
-		return -ENOENT;
-	}
-
 	upwa = (struct update_props_workarea *)&rtas_buf[0];
-	upwa->phandle = phandle;
+	upwa->phandle = cpu_to_be32(dn->phandle);
 
 	do {
 		rtas_rc = mobility_rtas_call(update_properties_token, rtas_buf,
@@ -224,26 +209,18 @@ static int update_dt_node(__be32 phandle, s32 scope)
 		cond_resched();
 	} while (rtas_rc == 1);
 
-	of_node_put(dn);
 	kfree(rtas_buf);
 	return 0;
 }
 
-static int add_dt_node(__be32 parent_phandle, __be32 drc_index)
+static int add_dt_node(struct device_node *parent_dn, __be32 drc_index)
 {
 	struct device_node *dn;
-	struct device_node *parent_dn;
 	int rc;
 
-	parent_dn = of_find_node_by_phandle(be32_to_cpu(parent_phandle));
-	if (!parent_dn)
-		return -ENOENT;
-
 	dn = dlpar_configure_connector(drc_index, parent_dn);
-	if (!dn) {
-		of_node_put(parent_dn);
+	if (!dn)
 		return -ENOENT;
-	}
 
 	rc = dlpar_attach_node(dn, parent_dn);
 	if (rc)
@@ -251,7 +228,6 @@ static int add_dt_node(__be32 parent_phandle, __be32 drc_index)
 
 	pr_debug("added node %pOFfp\n", dn);
 
-	of_node_put(parent_dn);
 	return rc;
 }
 
@@ -284,22 +260,31 @@ int pseries_devicetree_update(s32 scope)
 			data++;
 
 			for (i = 0; i < node_count; i++) {
+				struct device_node *np;
 				__be32 phandle = *data++;
 				__be32 drc_index;
 
+				np = of_find_node_by_phandle(be32_to_cpu(phandle));
+				if (!np) {
+					pr_warn("Failed lookup: phandle 0x%x for action 0x%x\n",
+						be32_to_cpu(phandle), action);
+					continue;
+				}
+
 				switch (action) {
 				case DELETE_DT_NODE:
-					delete_dt_node(phandle);
+					delete_dt_node(np);
 					break;
 				case UPDATE_DT_NODE:
-					update_dt_node(phandle, scope);
+					update_dt_node(np, scope);
 					break;
 				case ADD_DT_NODE:
 					drc_index = *data++;
-					add_dt_node(phandle, drc_index);
+					add_dt_node(np, drc_index);
 					break;
 				}
 
+				of_node_put(np);
 				cond_resched();
 			}
 		}
-- 
2.28.0

Re: [PATCH v2 00/28] partition suspend updates

[Michael Ellerman]

On Mon, 7 Dec 2020 15:51:32 -0600, Nathan Lynch wrote:
> This series aims to improve the pseries-specific partition migration
> and hibernation implementation, part of which has been living in
> kernel/rtas.c. Most of that code is eliminated or moved to
> platforms/pseries, and the following major functional changes are
> made:
> 
> - Use stop_machine() instead of on_each_cpu() to avoid deadlock in the
>   join/suspend sequence.
> 
> [...]

Applied to powerpc/next.

[01/28] powerpc/rtas: prevent suspend-related sys_rtas use on LE
        https://git.kernel.org/powerpc/c/de0f7349a0dd072e54b5fc04c305907b22d28a5f
[02/28] powerpc/rtas: complete ibm,suspend-me status codes
        https://git.kernel.org/powerpc/c/970e453ea4ecdd7a16a46c229294547148d1c7b6
[03/28] powerpc/rtas: rtas_ibm_suspend_me -> rtas_ibm_suspend_me_unsafe
        https://git.kernel.org/powerpc/c/7049b288ea8c95f270ec8fe643e3c3187938d5af
[04/28] powerpc/rtas: add rtas_ibm_suspend_me()
        https://git.kernel.org/powerpc/c/701ba68342412ae9be99a7c7f3badebf95271403
[05/28] powerpc/rtas: add rtas_activate_firmware()
        https://git.kernel.org/powerpc/c/5f485a66f4d0693a535e4ab38ffc3538716d2c2b
[06/28] powerpc/hvcall: add token and codes for H_VASI_SIGNAL
        https://git.kernel.org/powerpc/c/9bae89f528c041f3117f0a6c21878dda5a55af60
[07/28] powerpc/pseries/mobility: don't error on absence of ibm, update-nodes
        https://git.kernel.org/powerpc/c/b06a6717873560e9dd1c07357781fc2b27545701
[08/28] powerpc/pseries/mobility: add missing break to default case
        https://git.kernel.org/powerpc/c/aa5e5c9b556a2e5f68a915e4b5dfa5c6bda47c64
[09/28] powerpc/pseries/mobility: error message improvements
        https://git.kernel.org/powerpc/c/2d5be6f16c4ba5c27d06704976daf55f3236a236
[10/28] powerpc/pseries/mobility: use rtas_activate_firmware() on resume
        https://git.kernel.org/powerpc/c/c3ae9781d5a64093f161e6cc5dfefb0773106ca9
[11/28] powerpc/pseries/mobility: extract VASI session polling logic
        https://git.kernel.org/powerpc/c/d9213319b84ee8393475c38361c84151d5c33415
[12/28] powerpc/pseries/mobility: use stop_machine for join/suspend
        https://git.kernel.org/powerpc/c/9327dc0aeef36a3cbb9d94f79b79cc4f91ff8a41
[13/28] powerpc/pseries/mobility: signal suspend cancellation to platform
        https://git.kernel.org/powerpc/c/37cddc7d6cf4568a7fb69aeff6f26e4c8a3bc0f7
[14/28] powerpc/pseries/mobility: retry partition suspend after error
        https://git.kernel.org/powerpc/c/aeca35b9a52b0e0d019a5244fbaab699f753b443
[15/28] powerpc/rtas: dispatch partition migration requests to pseries
        https://git.kernel.org/powerpc/c/4d756894ba75f1afe7945ccafe9afebff50484b6
[16/28] powerpc/rtas: remove rtas_ibm_suspend_me_unsafe()
        https://git.kernel.org/powerpc/c/5f6665e400569de479733677e77862542aebb6cc
[17/28] powerpc/pseries/hibernation: drop pseries_suspend_begin() from suspend ops
        https://git.kernel.org/powerpc/c/52719fce3f4c7a8ac9eaa191e8d75a697f9fbcbc
[18/28] powerpc/pseries/hibernation: pass stream id via function arguments
        https://git.kernel.org/powerpc/c/a10a5a17f4ac4f84fcc26162d43b53e2a4e1009a
[19/28] powerpc/pseries/hibernation: remove pseries_suspend_cpu()
        https://git.kernel.org/powerpc/c/ed22bb8d39fa7f3980afc6e16d2a891847367d33
[20/28] powerpc/machdep: remove suspend_disable_cpu()
        https://git.kernel.org/powerpc/c/796f9247b4fa9bec320d6b47ffde2ecf86cc71c0
[21/28] powerpc/rtas: remove rtas_suspend_cpu()
        https://git.kernel.org/powerpc/c/395b2c090907975c627902ba8fda0bdb04c7cad3
[22/28] powerpc/pseries/hibernation: switch to rtas_ibm_suspend_me()
        https://git.kernel.org/powerpc/c/366fb13bf13b029c4d43bf19382f7aea69bfa4b7
[23/28] powerpc/rtas: remove unused rtas_suspend_last_cpu()
        https://git.kernel.org/powerpc/c/1b2488176ea56e299d2b084772daeb5ecbfc16d1
[24/28] powerpc/pseries/hibernation: remove redundant cacheinfo update
        https://git.kernel.org/powerpc/c/b866459489fe8ef0e92cde3cbd6bbb1af6c4e99b
[25/28] powerpc/pseries/hibernation: perform post-suspend fixups later
        https://git.kernel.org/powerpc/c/fa53bcdb7413e7c40170106781f6b5bb9d74db84
[26/28] powerpc/pseries/hibernation: remove prepare_late() callback
        https://git.kernel.org/powerpc/c/d102f8312e1ea5e8bf84fceebf99186f22d16fc6
[27/28] powerpc/rtas: remove unused rtas_suspend_me_data
        https://git.kernel.org/powerpc/c/87b57ea7e109520d3c6dfb01671a0cb134d3ccff
[28/28] powerpc/pseries/mobility: refactor node lookup during DT update
        https://git.kernel.org/powerpc/c/2efd7f6eb9b7107e469837d8452e750d7d080a5d

cheers