linux-stable.git/arch/powerpc/kernel, branch v3.2.52 Linux kernel stable tree powerpc/pseries/lparcfg: Fix possible overflow are more than 1026 2013-10-26T20:06:11+00:00 Chen Gang gang.chen@asianux.com 2013-04-22T17:12:54+00:00 8f0ce108f5e1c6a443548746b6f01b450f71a407 commit 5676005acf26ab7e924a8438ea4746e47d405762 upstream. need set '\0' for 'local_buffer'. SPLPAR_MAXLENGTH is 1026, RTAS_DATA_BUF_SIZE is 4096. so the contents of rtas_data_buf may truncated in memcpy. if contents are really truncated. the splpar_strlen is more than 1026. the next while loop checking will not find the end of buffer. that will cause memory access violation. Signed-off-by: Chen Gang <gang.chen@asianux.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 5676005acf26ab7e924a8438ea4746e47d405762 upstream.

need set '\0' for 'local_buffer'.

SPLPAR_MAXLENGTH is 1026, RTAS_DATA_BUF_SIZE is 4096. so the contents of
rtas_data_buf may truncated in memcpy.

if contents are really truncated.
  the splpar_strlen is more than 1026. the next while loop checking will
  not find the end of buffer. that will cause memory access violation.

Signed-off-by: Chen Gang <gang.chen@asianux.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
powerpc/iommu: Use GFP_KERNEL instead of GFP_ATOMIC in iommu_init_table() 2013-10-26T20:06:08+00:00 Nishanth Aravamudan nacc@linux.vnet.ibm.com 2013-10-01T21:04:53+00:00 21958b854649fcd3a7b50db4f00573d488da1edb commit 1cf389df090194a0976dc867b7fffe99d9d490cb upstream. Under heavy (DLPAR?) stress, we tripped this panic() in arch/powerpc/kernel/iommu.c::iommu_init_table(): page = alloc_pages_node(nid, GFP_ATOMIC, get_order(sz)); if (!page) panic("iommu_init_table: Can't allocate %ld bytes\n", sz); Before the panic() we got a page allocation failure for an order-2 allocation. There appears to be memory free, but perhaps not in the ATOMIC context. I looked through all the call-sites of iommu_init_table() and didn't see any obvious reason to need an ATOMIC allocation. Most call-sites in fact have an explicit GFP_KERNEL allocation shortly before the call to iommu_init_table(), indicating we are not in an atomic context. There is some indirection for some paths, but I didn't see any locks indicating that GFP_KERNEL is inappropriate. With this change under the same conditions, we have not been able to reproduce the panic. Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 1cf389df090194a0976dc867b7fffe99d9d490cb upstream.

Under heavy (DLPAR?) stress, we tripped this panic() in
arch/powerpc/kernel/iommu.c::iommu_init_table():

	page = alloc_pages_node(nid, GFP_ATOMIC, get_order(sz));
	if (!page)
		panic("iommu_init_table: Can't allocate %ld bytes\n", sz);

Before the panic() we got a page allocation failure for an order-2
allocation. There appears to be memory free, but perhaps not in the
ATOMIC context. I looked through all the call-sites of
iommu_init_table() and didn't see any obvious reason to need an ATOMIC
allocation. Most call-sites in fact have an explicit GFP_KERNEL
allocation shortly before the call to iommu_init_table(), indicating we
are not in an atomic context. There is some indirection for some paths,
but I didn't see any locks indicating that GFP_KERNEL is inappropriate.

With this change under the same conditions, we have not been able to
reproduce the panic.

Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
powerpc/sysfs: Disable writing to PURR in guest mode 2013-10-26T20:06:07+00:00 Madhavan Srinivasan maddy@linux.vnet.ibm.com 2013-10-01T19:04:10+00:00 28cfcc851d5c8a7075ea8bb9b8695bb376f6872d commit d1211af3049f4c9c1d8d4eb8f8098cc4f4f0d0c7 upstream. arch/powerpc/kernel/sysfs.c exports PURR with write permission. This may be valid for kernel in phyp mode. But writing to the file in guest mode causes crash due to a priviledge violation Signed-off-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> [bwh: Backported to 3.2: - Adjust context - CPUs are sysdev and we must use the sysdev API] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit d1211af3049f4c9c1d8d4eb8f8098cc4f4f0d0c7 upstream.

arch/powerpc/kernel/sysfs.c exports PURR with write permission.
This may be valid for kernel in phyp mode. But writing to
the file in guest mode causes crash due to a priviledge violation

Signed-off-by: Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
[bwh: Backported to 3.2:
 - Adjust context
 - CPUs are sysdev and we must use the sysdev API]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
powerpc: Handle unaligned ldbrx/stdbrx 2013-10-26T20:05:58+00:00 Anton Blanchard anton@samba.org 2013-08-06T16:01:19+00:00 ef9ba15dbf44cf0d84131f72f7e72e6af3d0a232 commit 230aef7a6a23b6166bd4003bfff5af23c9bd381f upstream. Normally when we haven't implemented an alignment handler for a load or store instruction the process will be terminated. The alignment handler uses the DSISR (or a pseudo one) to locate the right handler. Unfortunately ldbrx and stdbrx overlap lfs and stfs so we incorrectly think ldbrx is an lfs and stdbrx is an stfs. This bug is particularly nasty - instead of terminating the process we apply an incorrect fixup and continue on. With more and more overlapping instructions we should stop creating a pseudo DSISR and index using the instruction directly, but for now add a special case to catch ldbrx/stdbrx. Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 230aef7a6a23b6166bd4003bfff5af23c9bd381f upstream.

Normally when we haven't implemented an alignment handler for
a load or store instruction the process will be terminated.

The alignment handler uses the DSISR (or a pseudo one) to locate
the right handler. Unfortunately ldbrx and stdbrx overlap lfs and
stfs so we incorrectly think ldbrx is an lfs and stdbrx is an
stfs.

This bug is particularly nasty - instead of terminating the
process we apply an incorrect fixup and continue on.

With more and more overlapping instructions we should stop
creating a pseudo DSISR and index using the instruction directly,
but for now add a special case to catch ldbrx/stdbrx.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
powerpc: Don't Oops when accessing /proc/powerpc/lparcfg without hypervisor 2013-09-10T00:57:33+00:00 Benjamin Herrenschmidt benh@kernel.crashing.org 2013-08-27T06:38:33+00:00 c349bf07d6c05e89c967327af0f334604826d0e4 commit f5f6cbb61610b7bf9d9d96db9c3979d62a424bab upstream. /proc/powerpc/lparcfg is an ancient facility (though still actively used) which allows access to some informations relative to the partition when running underneath a PAPR compliant hypervisor. It makes no sense on non-pseries machines. However, currently, not only can it be created on these if the kernel has pseries support, but accessing it on such a machine will crash due to trying to do hypervisor calls. In fact, it should also not do HV calls on older pseries that didn't have an hypervisor either. Finally, it has the plumbing to be a module but is a "bool" Kconfig option. This fixes the whole lot by turning it into a machine_device_initcall that is only created on pseries, and adding the necessary hypervisor check before calling the H_GET_EM_PARMS hypercall Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> [bwh: Backported to 3.2: lparcfg_cleanup() was a bit different] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit f5f6cbb61610b7bf9d9d96db9c3979d62a424bab upstream.

/proc/powerpc/lparcfg is an ancient facility (though still actively used)
which allows access to some informations relative to the partition when
running underneath a PAPR compliant hypervisor.

It makes no sense on non-pseries machines. However, currently, not only
can it be created on these if the kernel has pseries support, but accessing
it on such a machine will crash due to trying to do hypervisor calls.

In fact, it should also not do HV calls on older pseries that didn't have
an hypervisor either.

Finally, it has the plumbing to be a module but is a "bool" Kconfig option.

This fixes the whole lot by turning it into a machine_device_initcall
that is only created on pseries, and adding the necessary hypervisor
check before calling the H_GET_EM_PARMS hypercall

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
[bwh: Backported to 3.2: lparcfg_cleanup() was a bit different]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
powerpc/modules: Module CRC relocation fix causes perf issues 2013-08-02T20:15:07+00:00 Anton Blanchard anton@samba.org 2013-07-15T04:04:50+00:00 bbacf54234dd47e0f976918a4b88a839025461a2 commit 0e0ed6406e61434d3f38fb58aa8464ec4722b77e upstream. Module CRCs are implemented as absolute symbols that get resolved by a linker script. We build an intermediate .o that contains an unresolved symbol for each CRC. genksysms parses this .o, calculates the CRCs and writes a linker script that "resolves" the symbols to the calculated CRC. Unfortunately the ppc64 relocatable kernel sees these CRCs as symbols that need relocating and relocates them at boot. Commit d4703aef (module: handle ppc64 relocating kcrctabs when CONFIG_RELOCATABLE=y) added a hook to reverse the bogus relocations. Part of this patch created a symbol at 0x0: # head -2 /proc/kallsyms 0000000000000000 T reloc_start c000000000000000 T .__start This reloc_start symbol is causing lots of confusion to perf. It thinks reloc_start is a massive function that stretches from 0x0 to 0xc000000000000000 and we get various cryptic errors out of perf, including: problem incrementing symbol count, skipping event This patch removes the reloc_start linker script label and instead defines it as PHYSICAL_START. We also need to wrap it with CONFIG_PPC64 because the ppc32 kernel can set a non zero PHYSICAL_START at compile time and we wouldn't want to subtract it from the CRCs in that case. Signed-off-by: Anton Blanchard <anton@samba.org> Acked-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 0e0ed6406e61434d3f38fb58aa8464ec4722b77e upstream.

Module CRCs are implemented as absolute symbols that get resolved by
a linker script. We build an intermediate .o that contains an
unresolved symbol for each CRC. genksysms parses this .o, calculates
the CRCs and writes a linker script that "resolves" the symbols to
the calculated CRC.

Unfortunately the ppc64 relocatable kernel sees these CRCs as symbols
that need relocating and relocates them at boot. Commit d4703aef
(module: handle ppc64 relocating kcrctabs when CONFIG_RELOCATABLE=y)
added a hook to reverse the bogus relocations. Part of this patch
created a symbol at 0x0:

# head -2 /proc/kallsyms
0000000000000000 T reloc_start
c000000000000000 T .__start

This reloc_start symbol is causing lots of confusion to perf. It
thinks reloc_start is a massive function that stretches from 0x0 to
0xc000000000000000 and we get various cryptic errors out of perf,
including:

problem incrementing symbol count, skipping event

This patch removes the  reloc_start linker script label and instead
defines it as PHYSICAL_START. We also need to wrap it with
CONFIG_PPC64 because the ppc32 kernel can set a non zero
PHYSICAL_START at compile time and we wouldn't want to subtract
it from the CRCs in that case.

Signed-off-by: Anton Blanchard <anton@samba.org>
Acked-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
powerpc/smp: Section mismatch from smp_release_cpus to __initdata spinning_secondaries 2013-07-27T04:34:24+00:00 Chen Gang gang.chen@asianux.com 2013-03-20T06:30:12+00:00 1aa33199c5969b6a062727438ba0795864dd3fbe commit 8246aca7058f3f2c2ae503081777965cd8df7b90 upstream. the smp_release_cpus is a normal funciton and called in normal environments, but it calls the __initdata spinning_secondaries. need modify spinning_secondaries to match smp_release_cpus. the related warning: (the linker report boot_paca.33377, but it should be spinning_secondaries) ----------------------------------------------------------------------------- WARNING: arch/powerpc/kernel/built-in.o(.text+0x23176): Section mismatch in reference from the function .smp_release_cpus() to the variable .init.data:boot_paca.33377 The function .smp_release_cpus() references the variable __initdata boot_paca.33377. This is often because .smp_release_cpus lacks a __initdata annotation or the annotation of boot_paca.33377 is wrong. WARNING: arch/powerpc/kernel/built-in.o(.text+0x231fe): Section mismatch in reference from the function .smp_release_cpus() to the variable .init.data:boot_paca.33377 The function .smp_release_cpus() references the variable __initdata boot_paca.33377. This is often because .smp_release_cpus lacks a __initdata annotation or the annotation of boot_paca.33377 is wrong. ----------------------------------------------------------------------------- Signed-off-by: Chen Gang <gang.chen@asianux.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 8246aca7058f3f2c2ae503081777965cd8df7b90 upstream.

the smp_release_cpus is a normal funciton and called in normal environments,
  but it calls the __initdata spinning_secondaries.
  need modify spinning_secondaries to match smp_release_cpus.

the related warning:
  (the linker report boot_paca.33377, but it should be spinning_secondaries)

-----------------------------------------------------------------------------

WARNING: arch/powerpc/kernel/built-in.o(.text+0x23176): Section mismatch in reference from the function .smp_release_cpus() to the variable .init.data:boot_paca.33377
The function .smp_release_cpus() references
the variable __initdata boot_paca.33377.
This is often because .smp_release_cpus lacks a __initdata
annotation or the annotation of boot_paca.33377 is wrong.

WARNING: arch/powerpc/kernel/built-in.o(.text+0x231fe): Section mismatch in reference from the function .smp_release_cpus() to the variable .init.data:boot_paca.33377
The function .smp_release_cpus() references
the variable __initdata boot_paca.33377.
This is often because .smp_release_cpus lacks a __initdata
annotation or the annotation of boot_paca.33377 is wrong.

-----------------------------------------------------------------------------

Signed-off-by: Chen Gang <gang.chen@asianux.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
powerpc: Fix emulation of illegal instructions on PowerNV platform 2013-06-19T01:17:02+00:00 Paul Mackerras paulus@samba.org 2013-06-14T10:07:41+00:00 e4f37de094d8c0a55af0fe63d7f715457b2de3e6 commit bf593907f7236e95698a76b7c7a2bbf8b1165327 upstream. Normally, the kernel emulates a few instructions that are unimplemented on some processors (e.g. the old dcba instruction), or privileged (e.g. mfpvr). The emulation of unimplemented instructions is currently not working on the PowerNV platform. The reason is that on these machines, unimplemented and illegal instructions cause a hypervisor emulation assist interrupt, rather than a program interrupt as on older CPUs. Our vector for the emulation assist interrupt just calls program_check_exception() directly, without setting the bit in SRR1 that indicates an illegal instruction interrupt. This fixes it by making the emulation assist interrupt set that bit before calling program_check_interrupt(). With this, old programs that use no-longer implemented instructions such as dcba now work again. Signed-off-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit bf593907f7236e95698a76b7c7a2bbf8b1165327 upstream.

Normally, the kernel emulates a few instructions that are unimplemented
on some processors (e.g. the old dcba instruction), or privileged (e.g.
mfpvr).  The emulation of unimplemented instructions is currently not
working on the PowerNV platform.  The reason is that on these machines,
unimplemented and illegal instructions cause a hypervisor emulation
assist interrupt, rather than a program interrupt as on older CPUs.
Our vector for the emulation assist interrupt just calls
program_check_exception() directly, without setting the bit in SRR1
that indicates an illegal instruction interrupt.  This fixes it by
making the emulation assist interrupt set that bit before calling
program_check_interrupt().  With this, old programs that use no-longer
implemented instructions such as dcba now work again.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
powerpc: Bring all threads online prior to migration/hibernation 2013-05-30T13:34:59+00:00 Robert Jennings rcj@linux.vnet.ibm.com 2013-05-07T04:34:11+00:00 97bc4b97d4908d5c76592b740e88df0ca6362e59 commit 120496ac2d2d60aee68d3123a68169502a85f4b5 upstream. 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). Signed-off-by: Robert Jennings <rcj@linux.vnet.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 120496ac2d2d60aee68d3123a68169502a85f4b5 upstream.

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).

Signed-off-by: Robert Jennings <rcj@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
powerpc/pseries: Fix partition migration hang in stop_topology_update 2013-05-30T13:34:58+00:00 Brian King brking@linux.vnet.ibm.com 2012-01-11T06:56:04+00:00 37dda1cc714d2af30ab5a537907b4317c6bb62e6 commit 444080d13d05dc38d07dd3bf751d38bce7ab7c72 upstream. This fixes a hang that was observed during live partition migration. Since stop_topology_update must not be called from an interrupt context, call it earlier in the migration process. The hang observed can be seen below: WARNING: at kernel/timer.c:1011 Modules linked in: ip6t_LOG xt_tcpudp xt_pkttype ipt_LOG xt_limit ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 ip6table_raw xt_NOTRACK ipt_REJECT xt_state iptable_raw iptable_filter ip6table_mangle nf_conntrack_netbios_ns nf_conntrack_broadcast nf_conntrack_ipv4 nf_conntrack nf_defrag_ipv4 ip_tables ip6table_filter ip6_tables x_tables ipv6 fuse loop ibmveth sg ext3 jbd mbcache raid456 async_raid6_recov async_pq raid6_pq async_xor xor async_memcpy async_tx raid10 raid1 raid0 scsi_dh_alua scsi_dh_rdac scsi_dh_hp_sw scsi_dh_emc dm_round_robin dm_multipath scsi_dh sd_mod crc_t10dif ibmvfc scsi_transport_fc scsi_tgt scsi_mod dm_snapshot dm_mod NIP: c0000000000c52d8 LR: c00000000004be28 CTR: 0000000000000000 REGS: c00000005ffd77d0 TRAP: 0700 Not tainted (3.2.0-git-00001-g07d106d) MSR: 8000000000021032 <ME,CE,IR,DR> CR: 48000084 XER: 00000001 CFAR: c00000000004be20 TASK = c00000005ec78860[0] 'swapper/3' THREAD: c00000005ec98000 CPU: 3 GPR00: 0000000000000001 c00000005ffd7a50 c000000000fbbc98 c000000000ec8340 GPR04: 00000000282a0020 0000000000000000 0000000000004000 0000000000000101 GPR08: 0000000000000012 c00000005ffd4000 0000000000000020 c000000000f3ba88 GPR12: 0000000000000000 c000000007f40900 0000000000000001 0000000000000004 GPR16: 0000000000000001 0000000000000000 0000000000000000 c000000001022310 GPR20: 0000000000000001 0000000000000000 0000000000200200 c000000001029e14 GPR24: 0000000000000000 0000000000000001 0000000000000040 c00000003f74bc80 GPR28: c00000003f74bc84 c000000000f38038 c000000000f16b58 c000000000ec8340 NIP [c0000000000c52d8] .del_timer_sync+0x28/0x60 LR [c00000000004be28] .stop_topology_update+0x20/0x38 Call Trace: [c00000005ffd7a50] [c00000005ec78860] 0xc00000005ec78860 (unreliable) [c00000005ffd7ad0] [c00000000004be28] .stop_topology_update+0x20/0x38 [c00000005ffd7b40] [c000000000028378] .__rtas_suspend_last_cpu+0x58/0x260 [c00000005ffd7bf0] [c0000000000fa230] .generic_smp_call_function_interrupt+0x160/0x358 [c00000005ffd7cf0] [c000000000036ec8] .smp_ipi_demux+0x88/0x100 [c00000005ffd7d80] [c00000000005c154] .icp_hv_ipi_action+0x5c/0x80 [c00000005ffd7e00] [c00000000012a088] .handle_irq_event_percpu+0x100/0x318 [c00000005ffd7f00] [c00000000012e774] .handle_percpu_irq+0x84/0xd0 [c00000005ffd7f90] [c000000000022ba8] .call_handle_irq+0x1c/0x2c [c00000005ec9ba20] [c00000000001157c] .do_IRQ+0x22c/0x2a8 [c00000005ec9bae0] [c0000000000054bc] hardware_interrupt_entry+0x18/0x1c Exception: 501 at .cpu_idle+0x194/0x2f8 LR = .cpu_idle+0x194/0x2f8 [c00000005ec9bdd0] [c000000000017e58] .cpu_idle+0x188/0x2f8 (unreliable) [c00000005ec9be90] [c00000000067ec18] .start_secondary+0x3e4/0x524 [c00000005ec9bf90] [c0000000000093e8] .start_secondary_prolog+0x10/0x14 Instruction dump: ebe1fff8 4e800020 fbe1fff8 7c0802a6 f8010010 7c7f1b78 f821ff81 78290464 80090014 5400019e 7c0000d0 78000fe0 <0b000000> 4800000c 7c210b78 7c421378 Signed-off-by: Brian King <brking@linux.vnet.ibm.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> 
commit 444080d13d05dc38d07dd3bf751d38bce7ab7c72 upstream.

This fixes a hang that was observed during live partition migration.
Since stop_topology_update must not be called from an interrupt
context, call it earlier in the migration process. The hang observed
can be seen below:

WARNING: at kernel/timer.c:1011
Modules linked in: ip6t_LOG xt_tcpudp xt_pkttype ipt_LOG xt_limit ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 ip6table_raw xt_NOTRACK ipt_REJECT xt_state iptable_raw iptable_filter ip6table_mangle nf_conntrack_netbios_ns nf_conntrack_broadcast nf_conntrack_ipv4 nf_conntrack nf_defrag_ipv4 ip_tables ip6table_filter ip6_tables x_tables ipv6 fuse loop ibmveth sg ext3 jbd mbcache raid456 async_raid6_recov async_pq raid6_pq async_xor xor async_memcpy async_tx raid10 raid1 raid0 scsi_dh_alua scsi_dh_rdac scsi_dh_hp_sw scsi_dh_emc dm_round_robin dm_multipath scsi_dh sd_mod crc_t10dif ibmvfc scsi_transport_fc scsi_tgt scsi_mod dm_snapshot dm_mod
NIP: c0000000000c52d8 LR: c00000000004be28 CTR: 0000000000000000
REGS: c00000005ffd77d0 TRAP: 0700   Not tainted  (3.2.0-git-00001-g07d106d)
MSR: 8000000000021032 <ME,CE,IR,DR>  CR: 48000084  XER: 00000001
CFAR: c00000000004be20
TASK = c00000005ec78860[0] 'swapper/3' THREAD: c00000005ec98000 CPU: 3
GPR00: 0000000000000001 c00000005ffd7a50 c000000000fbbc98 c000000000ec8340
GPR04: 00000000282a0020 0000000000000000 0000000000004000 0000000000000101
GPR08: 0000000000000012 c00000005ffd4000 0000000000000020 c000000000f3ba88
GPR12: 0000000000000000 c000000007f40900 0000000000000001 0000000000000004
GPR16: 0000000000000001 0000000000000000 0000000000000000 c000000001022310
GPR20: 0000000000000001 0000000000000000 0000000000200200 c000000001029e14
GPR24: 0000000000000000 0000000000000001 0000000000000040 c00000003f74bc80
GPR28: c00000003f74bc84 c000000000f38038 c000000000f16b58 c000000000ec8340
NIP [c0000000000c52d8] .del_timer_sync+0x28/0x60
LR [c00000000004be28] .stop_topology_update+0x20/0x38
Call Trace:
[c00000005ffd7a50] [c00000005ec78860] 0xc00000005ec78860 (unreliable)
[c00000005ffd7ad0] [c00000000004be28] .stop_topology_update+0x20/0x38
[c00000005ffd7b40] [c000000000028378] .__rtas_suspend_last_cpu+0x58/0x260
[c00000005ffd7bf0] [c0000000000fa230] .generic_smp_call_function_interrupt+0x160/0x358
[c00000005ffd7cf0] [c000000000036ec8] .smp_ipi_demux+0x88/0x100
[c00000005ffd7d80] [c00000000005c154] .icp_hv_ipi_action+0x5c/0x80
[c00000005ffd7e00] [c00000000012a088] .handle_irq_event_percpu+0x100/0x318
[c00000005ffd7f00] [c00000000012e774] .handle_percpu_irq+0x84/0xd0
[c00000005ffd7f90] [c000000000022ba8] .call_handle_irq+0x1c/0x2c
[c00000005ec9ba20] [c00000000001157c] .do_IRQ+0x22c/0x2a8
[c00000005ec9bae0] [c0000000000054bc] hardware_interrupt_entry+0x18/0x1c
Exception: 501 at .cpu_idle+0x194/0x2f8
    LR = .cpu_idle+0x194/0x2f8
[c00000005ec9bdd0] [c000000000017e58] .cpu_idle+0x188/0x2f8 (unreliable)
[c00000005ec9be90] [c00000000067ec18] .start_secondary+0x3e4/0x524
[c00000005ec9bf90] [c0000000000093e8] .start_secondary_prolog+0x10/0x14
Instruction dump:
ebe1fff8 4e800020 fbe1fff8 7c0802a6 f8010010 7c7f1b78 f821ff81 78290464
80090014 5400019e 7c0000d0 78000fe0 <0b000000> 4800000c 7c210b78 7c421378

Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>