linux-stable.git/arch/powerpc/kernel/rtas.c, branch linux-3.16.y Linux kernel stable tree powerpc/rtas: use device model APIs and serialization during LPM 2019-12-10T18:01:13+00:00 Nathan Lynch nathanl@linux.ibm.com 2019-08-02T19:29:24+00:00 6a5a5b347ca18a9ee6f93899f62c8e3725fe8a91 commit a6717c01ddc259f6f73364779df058e2c67309f8 upstream. The LPAR migration implementation and userspace-initiated cpu hotplug can interleave their executions like so: 1. Set cpu 7 offline via sysfs. 2. Begin a partition migration, whose implementation requires the OS to ensure all present cpus are online; cpu 7 is onlined: rtas_ibm_suspend_me -> rtas_online_cpus_mask -> cpu_up This sets cpu 7 online in all respects except for the cpu's corresponding struct device; dev->offline remains true. 3. Set cpu 7 online via sysfs. _cpu_up() determines that cpu 7 is already online and returns success. The driver core (device_online) sets dev->offline = false. 4. The migration completes and restores cpu 7 to offline state: rtas_ibm_suspend_me -> rtas_offline_cpus_mask -> cpu_down This leaves cpu7 in a state where the driver core considers the cpu device online, but in all other respects it is offline and unused. Attempts to online the cpu via sysfs appear to succeed but the driver core actually does not pass the request to the lower-level cpuhp support code. This makes the cpu unusable until the cpu device is manually set offline and then online again via sysfs. Instead of directly calling cpu_up/cpu_down, the migration code should use the higher-level device core APIs to maintain consistent state and serialize operations. Fixes: 120496ac2d2d ("powerpc: Bring all threads online prior to migration/hibernation") Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com> Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20190802192926.19277-2-nathanl@linux.ibm.com Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit a6717c01ddc259f6f73364779df058e2c67309f8 upstream.

The LPAR migration implementation and userspace-initiated cpu hotplug
can interleave their executions like so:

1. Set cpu 7 offline via sysfs.

2. Begin a partition migration, whose implementation requires the OS
   to ensure all present cpus are online; cpu 7 is onlined:

     rtas_ibm_suspend_me -> rtas_online_cpus_mask -> cpu_up

   This sets cpu 7 online in all respects except for the cpu's
   corresponding struct device; dev->offline remains true.

3. Set cpu 7 online via sysfs. _cpu_up() determines that cpu 7 is
   already online and returns success. The driver core (device_online)
   sets dev->offline = false.

4. The migration completes and restores cpu 7 to offline state:

     rtas_ibm_suspend_me -> rtas_offline_cpus_mask -> cpu_down

This leaves cpu7 in a state where the driver core considers the cpu
device online, but in all other respects it is offline and
unused. Attempts to online the cpu via sysfs appear to succeed but the
driver core actually does not pass the request to the lower-level
cpuhp support code. This makes the cpu unusable until the cpu device
is manually set offline and then online again via sysfs.

Instead of directly calling cpu_up/cpu_down, the migration code should
use the higher-level device core APIs to maintain consistent state and
serialize operations.

Fixes: 120496ac2d2d ("powerpc: Bring all threads online prior to migration/hibernation")
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190802192926.19277-2-nathanl@linux.ibm.com
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
powerpc/rtas: Validate rtas.entry before calling enter_rtas() 2015-11-16T11:27:04+00:00 Vasant Hegde hegdevasant@linux.vnet.ibm.com 2015-10-16T10:23:29+00:00 61e709be769c89b445024b668a7c9ef4e3e1c3e1 commit 8832317f662c06f5c06e638f57bfe89a71c9b266 upstream. Currently we do not validate rtas.entry before calling enter_rtas(). This leads to a kernel oops when user space calls rtas system call on a powernv platform (see below). This patch adds code to validate rtas.entry before making enter_rtas() call. Oops: Exception in kernel mode, sig: 4 [#1] SMP NR_CPUS=1024 NUMA PowerNV task: c000000004294b80 ti: c0000007e1a78000 task.ti: c0000007e1a78000 NIP: 0000000000000000 LR: 0000000000009c14 CTR: c000000000423140 REGS: c0000007e1a7b920 TRAP: 0e40 Not tainted (3.18.17-340.el7_1.pkvm3_1_0.2400.1.ppc64le) MSR: 1000000000081000 <HV,ME> CR: 00000000 XER: 00000000 CFAR: c000000000009c0c SOFTE: 0 NIP [0000000000000000] (null) LR [0000000000009c14] 0x9c14 Call Trace: [c0000007e1a7bba0] [c00000000041a7f4] avc_has_perm_noaudit+0x54/0x110 (unreliable) [c0000007e1a7bd80] [c00000000002ddc0] ppc_rtas+0x150/0x2d0 [c0000007e1a7be30] [c000000000009358] syscall_exit+0x0/0x98 Fixes: 55190f88789a ("powerpc: Add skeleton PowerNV platform") Reported-by: NAGESWARA R. SASTRY <nasastry@in.ibm.com> Signed-off-by: Vasant Hegde <hegdevasant@linux.vnet.ibm.com> [mpe: Reword change log, trim oops, and add stable + fixes] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> 
commit 8832317f662c06f5c06e638f57bfe89a71c9b266 upstream.

Currently we do not validate rtas.entry before calling enter_rtas(). This
leads to a kernel oops when user space calls rtas system call on a powernv
platform (see below). This patch adds code to validate rtas.entry before
making enter_rtas() call.

  Oops: Exception in kernel mode, sig: 4 [#1]
  SMP NR_CPUS=1024 NUMA PowerNV
  task: c000000004294b80 ti: c0000007e1a78000 task.ti: c0000007e1a78000
  NIP: 0000000000000000 LR: 0000000000009c14 CTR: c000000000423140
  REGS: c0000007e1a7b920 TRAP: 0e40   Not tainted  (3.18.17-340.el7_1.pkvm3_1_0.2400.1.ppc64le)
  MSR: 1000000000081000 <HV,ME>  CR: 00000000  XER: 00000000
  CFAR: c000000000009c0c SOFTE: 0
  NIP [0000000000000000]           (null)
  LR [0000000000009c14] 0x9c14
  Call Trace:
  [c0000007e1a7bba0] [c00000000041a7f4] avc_has_perm_noaudit+0x54/0x110 (unreliable)
  [c0000007e1a7bd80] [c00000000002ddc0] ppc_rtas+0x150/0x2d0
  [c0000007e1a7be30] [c000000000009358] syscall_exit+0x0/0x98

Fixes: 55190f88789a ("powerpc: Add skeleton PowerNV platform")
Reported-by: NAGESWARA R. SASTRY <nasastry@in.ibm.com>
Signed-off-by: Vasant Hegde <hegdevasant@linux.vnet.ibm.com>
[mpe: Reword change log, trim oops, and add stable + fixes]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
powerpc/rtas: Introduce rtas_get_sensor_fast() for IRQ handlers 2015-09-30T12:20:37+00:00 Thomas Huth thuth@redhat.com 2015-07-17T10:46:58+00:00 5a03b287dad7e8564ab83876356dcea4d4e5e2c9 commit 1c2cb594441d02815d304cccec9742ff5c707495 upstream. The EPOW interrupt handler uses rtas_get_sensor(), which in turn uses rtas_busy_delay() to wait for RTAS becoming ready in case it is necessary. But rtas_busy_delay() is annotated with might_sleep() and thus may not be used by interrupts handlers like the EPOW handler! This leads to the following BUG when CONFIG_DEBUG_ATOMIC_SLEEP is enabled: BUG: sleeping function called from invalid context at arch/powerpc/kernel/rtas.c:496 in_atomic(): 1, irqs_disabled(): 1, pid: 0, name: swapper/1 CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.2.0-rc2-thuth #6 Call Trace: [c00000007ffe7b90] [c000000000807670] dump_stack+0xa0/0xdc (unreliable) [c00000007ffe7bc0] [c0000000000e1f14] ___might_sleep+0x134/0x180 [c00000007ffe7c20] [c00000000002aec0] rtas_busy_delay+0x30/0xd0 [c00000007ffe7c50] [c00000000002bde4] rtas_get_sensor+0x74/0xe0 [c00000007ffe7ce0] [c000000000083264] ras_epow_interrupt+0x44/0x450 [c00000007ffe7d90] [c000000000120260] handle_irq_event_percpu+0xa0/0x300 [c00000007ffe7e70] [c000000000120524] handle_irq_event+0x64/0xc0 [c00000007ffe7eb0] [c000000000124dbc] handle_fasteoi_irq+0xec/0x260 [c00000007ffe7ef0] [c00000000011f4f0] generic_handle_irq+0x50/0x80 [c00000007ffe7f20] [c000000000010f3c] __do_irq+0x8c/0x200 [c00000007ffe7f90] [c0000000000236cc] call_do_irq+0x14/0x24 [c00000007e6f39e0] [c000000000011144] do_IRQ+0x94/0x110 [c00000007e6f3a30] [c000000000002594] hardware_interrupt_common+0x114/0x180 Fix this issue by introducing a new rtas_get_sensor_fast() function that does not use rtas_busy_delay() - and thus can only be used for sensors that do not cause a BUSY condition - known as "fast" sensors. The EPOW sensor is defined to be "fast" in sPAPR - mpe. Fixes: 587f83e8dd50 ("powerpc/pseries: Use rtas_get_sensor in RAS code") Signed-off-by: Thomas Huth <thuth@redhat.com> Reviewed-by: Nathan Fontenot <nfont@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> 
commit 1c2cb594441d02815d304cccec9742ff5c707495 upstream.

The EPOW interrupt handler uses rtas_get_sensor(), which in turn
uses rtas_busy_delay() to wait for RTAS becoming ready in case it
is necessary. But rtas_busy_delay() is annotated with might_sleep()
and thus may not be used by interrupts handlers like the EPOW handler!
This leads to the following BUG when CONFIG_DEBUG_ATOMIC_SLEEP is
enabled:

 BUG: sleeping function called from invalid context at arch/powerpc/kernel/rtas.c:496
 in_atomic(): 1, irqs_disabled(): 1, pid: 0, name: swapper/1
 CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.2.0-rc2-thuth #6
 Call Trace:
 [c00000007ffe7b90] [c000000000807670] dump_stack+0xa0/0xdc (unreliable)
 [c00000007ffe7bc0] [c0000000000e1f14] ___might_sleep+0x134/0x180
 [c00000007ffe7c20] [c00000000002aec0] rtas_busy_delay+0x30/0xd0
 [c00000007ffe7c50] [c00000000002bde4] rtas_get_sensor+0x74/0xe0
 [c00000007ffe7ce0] [c000000000083264] ras_epow_interrupt+0x44/0x450
 [c00000007ffe7d90] [c000000000120260] handle_irq_event_percpu+0xa0/0x300
 [c00000007ffe7e70] [c000000000120524] handle_irq_event+0x64/0xc0
 [c00000007ffe7eb0] [c000000000124dbc] handle_fasteoi_irq+0xec/0x260
 [c00000007ffe7ef0] [c00000000011f4f0] generic_handle_irq+0x50/0x80
 [c00000007ffe7f20] [c000000000010f3c] __do_irq+0x8c/0x200
 [c00000007ffe7f90] [c0000000000236cc] call_do_irq+0x14/0x24
 [c00000007e6f39e0] [c000000000011144] do_IRQ+0x94/0x110
 [c00000007e6f3a30] [c000000000002594] hardware_interrupt_common+0x114/0x180

Fix this issue by introducing a new rtas_get_sensor_fast() function
that does not use rtas_busy_delay() - and thus can only be used for
sensors that do not cause a BUSY condition - known as "fast" sensors.

The EPOW sensor is defined to be "fast" in sPAPR - mpe.

Fixes: 587f83e8dd50 ("powerpc/pseries: Use rtas_get_sensor in RAS code")
Signed-off-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
of/fdt: update of_get_flat_dt_prop in prep for libfdt 2014-04-30T05:59:15+00:00 Rob Herring robh@kernel.org 2014-04-02T04:49:03+00:00 9d0c4dfedd96ee54fc075b16d02f82499c8cc3a6 Make of_get_flat_dt_prop arguments compatible with libfdt fdt_getprop call in preparation to convert FDT code to use libfdt. Make the return value const and the property length ptr type an int. Signed-off-by: Rob Herring <robh@kernel.org> Tested-by: Michal Simek <michal.simek@xilinx.com> Tested-by: Grant Likely <grant.likely@linaro.org> Tested-by: Stephen Chivers <schivers@csc.com> 
Make of_get_flat_dt_prop arguments compatible with libfdt fdt_getprop
call in preparation to convert FDT code to use libfdt. Make the return
value const and the property length ptr type an int.

Signed-off-by: Rob Herring <robh@kernel.org>
Tested-by: Michal Simek <michal.simek@xilinx.com>
Tested-by: Grant Likely <grant.likely@linaro.org>
Tested-by: Stephen Chivers <schivers@csc.com>
powerpc/le: Enable RTAS events support 2014-04-07T00:33:12+00:00 Greg Kurz gkurz@linux.vnet.ibm.com 2014-04-04T07:35:13+00:00 a08a53ea4c97940fe83fea3eab27618ac0fb5ed1 The current kernel code assumes big endian and parses RTAS events all wrong. The most visible effect is that we cannot honor EPOW events, meaning, for example, we cannot shut down a guest properly from the hypervisor. This new patch is largely inspired by Nathan's work: we get rid of all the bit fields in the RTAS event structures (even the unused ones, for consistency). We also introduce endian safe accessors for the fields used by the kernel (trivial rtas_error_type() accessor added for consistency). Cc: Nathan Fontenot <nfont@linux.vnet.ibm.com> Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> 
The current kernel code assumes big endian and parses RTAS events all
wrong. The most visible effect is that we cannot honor EPOW events,
meaning, for example, we cannot shut down a guest properly from the
hypervisor.

This new patch is largely inspired by Nathan's work: we get rid of all
the bit fields in the RTAS event structures (even the unused ones, for
consistency). We also introduce endian safe accessors for the fields used
by the kernel (trivial rtas_error_type() accessor added for consistency).

Cc: Nathan Fontenot <nfont@linux.vnet.ibm.com>
Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
powerpc/le: Big endian arguments for ppc_rtas() 2014-03-23T22:48:36+00:00 Greg Kurz gkurz@linux.vnet.ibm.com 2014-03-19T16:02:51+00:00 599d2870425dcde3bf2a7d969d5977baa57feb8b The ppc_rtas() syscall allows userspace to interact directly with RTAS. For the moment, it assumes every thing is big endian and returns either EINVAL or EFAULT when called in a little endian environment. As suggested by Benjamin, to avoid bugs when userspace wants to pass a non 32 bit value to RTAS, it is far better to stick with a simple rationale: ppc_rtas() should be called with a big endian rtas_args structure. With this patch, it is now up to userspace to forge big endian arguments, as expected by RTAS. Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> 
The ppc_rtas() syscall allows userspace to interact directly with RTAS.
For the moment, it assumes every thing is big endian and returns either
EINVAL or EFAULT when called in a little endian environment.

As suggested by Benjamin, to avoid bugs when userspace wants to pass
a non 32 bit value to RTAS, it is far better to stick with a simple
rationale: ppc_rtas() should be called with a big endian rtas_args
structure.

With this patch, it is now up to userspace to forge big endian arguments,
as expected by RTAS.

Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
powerpc: Make RTAS calls endian safe 2013-08-14T05:33:22+00:00 Anton Blanchard anton@samba.org 2013-08-06T16:01:31+00:00 271282649132f0a84ac8e2f3655cf2b5c192036b RTAS expects arguments in the call buffer to be big endian so we need to byteswap on little endian builds Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> 
RTAS expects arguments in the call buffer to be big endian so we
need to byteswap on little endian builds

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
powerpc: Make RTAS device tree accesses endian safe 2013-08-14T05:33:20+00:00 Anton Blanchard anton@samba.org 2013-08-06T16:01:29+00:00 08bc1dc51ffdaa453990a4cc300f1acf897d7817 Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> 
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
powerpc: Delete __cpuinit usage from all users 2013-07-01T01:10:36+00:00 Paul Gortmaker paul.gortmaker@windriver.com 2013-06-24T19:30:09+00:00 061d19f279f9bebbdb1ee48bef8c25e03de32ae2 The __cpuinit type of throwaway sections might have made sense some time ago when RAM was more constrained, but now the savings do not offset the cost and complications. For example, the fix in commit 5e427ec2d0 ("x86: Fix bit corruption at CPU resume time") is a good example of the nasty type of bugs that can be created with improper use of the various __init prefixes. After a discussion on LKML[1] it was decided that cpuinit should go the way of devinit and be phased out. Once all the users are gone, we can then finally remove the macros themselves from linux/init.h. This removes all the powerpc uses of the __cpuinit macros. There are no __CPUINIT users in assembly files in powerpc. [1] https://lkml.org/lkml/2013/5/20/589 Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Josh Boyer <jwboyer@gmail.com> Cc: Matt Porter <mporter@kernel.crashing.org> Cc: Kumar Gala <galak@kernel.crashing.org> Cc: linuxppc-dev@lists.ozlabs.org Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> 
The __cpuinit type of throwaway sections might have made sense
some time ago when RAM was more constrained, but now the savings
do not offset the cost and complications.  For example, the fix in
commit 5e427ec2d0 ("x86: Fix bit corruption at CPU resume time")
is a good example of the nasty type of bugs that can be created
with improper use of the various __init prefixes.

After a discussion on LKML[1] it was decided that cpuinit should go
the way of devinit and be phased out.  Once all the users are gone,
we can then finally remove the macros themselves from linux/init.h.

This removes all the powerpc uses of the __cpuinit macros.  There
are no __CPUINIT users in assembly files in powerpc.

[1] https://lkml.org/lkml/2013/5/20/589

Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Josh Boyer <jwboyer@gmail.com>
Cc: Matt Porter <mporter@kernel.crashing.org>
Cc: Kumar Gala <galak@kernel.crashing.org>
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
powerpc: Bring all threads online prior to migration/hibernation 2013-05-14T04:36:29+00:00 Robert Jennings rcj@linux.vnet.ibm.com 2013-05-07T04:34:11+00:00 120496ac2d2d60aee68d3123a68169502a85f4b5 This patch brings online all threads which are present but not online prior to migration/hibernation. After migration/hibernation those threads are taken back offline. During migration/hibernation all online CPUs must call H_JOIN, this is required by the hypervisor. Without this patch, threads that are offline (H_CEDE'd) will not be woken to make the H_JOIN call and the OS will be deadlocked (all threads either JOIN'd or CEDE'd). Cc: <stable@kernel.org> Signed-off-by: Robert Jennings <rcj@linux.vnet.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> 
This patch brings online all threads which are present but not online
prior to migration/hibernation.  After migration/hibernation those
threads are taken back offline.

During migration/hibernation all online CPUs must call H_JOIN, this is
required by the hypervisor.  Without this patch, threads that are offline
(H_CEDE'd) will not be woken to make the H_JOIN call and the OS will be
deadlocked (all threads either JOIN'd or CEDE'd).

Cc: <stable@kernel.org>
Signed-off-by: Robert Jennings <rcj@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>