linux-stable.git/arch/powerpc/kernel, branch v4.8

powerpc/powernv: Fix restore of SPRs upon wake up from hypervisor state loss

2016-09-12T02:45:50+00:00

pnv_wakeup_tb_loss() currently expects cr4 to be "eq" if the CPU is
waking up from a complete hypervisor state loss. Hence, it currently
restores the SPR contents only if cr4 is "eq".

However, after commit bcef83a00dc4 ("powerpc/powernv: Add platform
support for stop instruction"), on ISA v3.0 CPUs, the function
pnv_restore_hyp_resource() sets cr4 to contain the result of the
comparison between the state the CPU has woken up from and the first
deep stop state before calling pnv_wakeup_tb_loss().

Thus if the CPU woke up from a state that is deeper than the first
deep stop state, cr4 will have "gt" set and hence, pnv_wakeup_tb_loss()
will fail to restore the SPRs on waking up from such a state.

Fix the code in pnv_wakeup_tb_loss() to restore the SPR states when cr4
is "eq" or "gt".

Fixes: bcef83a00dc4 ("powerpc/powernv: Add platform support for stop instruction")
Signed-off-by: Gautham R. Shenoy 
Reviewed-by: Shreyas B. Prabhu 
Signed-off-by: Michael Ellerman

powerpc: signals: Discard transaction state from signal frames

2016-08-29T02:48:40+00:00

Userspace can begin and suspend a transaction within the signal
handler which means they might enter sys_rt_sigreturn() with the
processor in suspended state.

sys_rt_sigreturn() wants to restore process context (which may have
been in a transaction before signal delivery). To do this it must
restore TM SPRS. To achieve this, any transaction initiated within the
signal frame must be discarded in order to be able to restore TM SPRs
as TM SPRs can only be manipulated non-transactionally..
>From the PowerPC ISA:
  TM Bad Thing Exception [Category: Transactional Memory]
   An attempt is made to execute a mtspr targeting a TM register in
   other than Non-transactional state.

Not doing so results in a TM Bad Thing:
[12045.221359] Kernel BUG at c000000000050a40 [verbose debug info unavailable]
[12045.221470] Unexpected TM Bad Thing exception at c000000000050a40 (msr 0x201033)
[12045.221540] Oops: Unrecoverable exception, sig: 6 [#1]
[12045.221586] SMP NR_CPUS=2048 NUMA PowerNV
[12045.221634] Modules linked in: xt_CHECKSUM iptable_mangle ipt_MASQUERADE
 nf_nat_masquerade_ipv4 iptable_nat nf_nat_ipv4 nf_nat nf_conntrack_ipv4 nf_defrag_ipv4
 xt_conntrack nf_conntrack ipt_REJECT nf_reject_ipv4 xt_tcpudp bridge stp llc ebtable_filter
 ebtables ip6table_filter ip6_tables iptable_filter ip_tables x_tables kvm_hv kvm
 uio_pdrv_genirq ipmi_powernv uio powernv_rng ipmi_msghandler autofs4 ses enclosure
 scsi_transport_sas bnx2x ipr mdio libcrc32c
[12045.222167] CPU: 68 PID: 6178 Comm: sigreturnpanic Not tainted 4.7.0 #34
[12045.222224] task: c0000000fce38600 ti: c0000000fceb4000 task.ti: c0000000fceb4000
[12045.222293] NIP: c000000000050a40 LR: c0000000000163bc CTR: 0000000000000000
[12045.222361] REGS: c0000000fceb7ac0 TRAP: 0700   Not tainted (4.7.0)
[12045.222418] MSR: 9000000300201033  CR: 28444280  XER: 20000000
[12045.222625] CFAR: c0000000000163b8 SOFTE: 0 PACATMSCRATCH: 900000014280f033
GPR00: 01100000b8000001 c0000000fceb7d40 c00000000139c100 c0000000fce390d0
GPR04: 900000034280f033 0000000000000000 0000000000000000 0000000000000000
GPR08: 0000000000000000 b000000000001033 0000000000000001 0000000000000000
GPR12: 0000000000000000 c000000002926400 0000000000000000 0000000000000000
GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
GPR20: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
GPR24: 0000000000000000 00003ffff98cadd0 00003ffff98cb470 0000000000000000
GPR28: 900000034280f033 c0000000fceb7ea0 0000000000000001 c0000000fce390d0
[12045.223535] NIP [c000000000050a40] tm_restore_sprs+0xc/0x1c
[12045.223584] LR [c0000000000163bc] tm_recheckpoint+0x5c/0xa0
[12045.223630] Call Trace:
[12045.223655] [c0000000fceb7d80] [c000000000026e74] sys_rt_sigreturn+0x494/0x6c0
[12045.223738] [c0000000fceb7e30] [c0000000000092e0] system_call+0x38/0x108
[12045.223806] Instruction dump:
[12045.223841] 7c800164 4e800020 7c0022a6 f80304a8 7c0222a6 f80304b0 7c0122a6 f80304b8
[12045.223955] 4e800020 e80304a8 7c0023a6 e80304b0 <7c0223a6> e80304b8 7c0123a6 4e800020
[12045.224074] ---[ end trace cb8002ee240bae76 ]---

It isn't clear exactly if there is really a use case for userspace
returning with a suspended transaction, however, doing so doesn't (on
its own) constitute a bad frame. As such, this patch simply discards
the transactional state of the context calling the sigreturn and
continues.

Reported-by: Laurent Dufour 
Signed-off-by: Cyril Bur 
Tested-by: Laurent Dufour 
Reviewed-by: Laurent Dufour 
Acked-by: Simon Guo 
Signed-off-by: Benjamin Herrenschmidt

powerpc/tm: do not use r13 for tabort_syscall

2016-08-29T02:47:56+00:00

tabort_syscall runs with RI=1, so a nested recoverable machine
check will load the paca into r13 and overwrite what we loaded
it with, because exceptions returning to privileged mode do not
restore r13.

Fixes: b4b56f9ecab4 (powerpc/tm: Abort syscalls in active transactions)
Cc: stable@vger.kernel.org
Signed-off-by: Nick Piggin 
Signed-off-by: Benjamin Herrenschmidt

powerpc: move hmi.c to arch/powerpc/kvm/

2016-08-22T01:09:33+00:00

hmi.c functions are unused unless sibling_subcore_state is nonzero, and
that in turn happens only if KVM is in use.  So move the code to
arch/powerpc/kvm/, putting it under CONFIG_KVM_BOOK3S_HV_POSSIBLE
rather than CONFIG_PPC_BOOK3S_64.  The sibling_subcore_state is also
included in struct paca_struct only if KVM is supported by the kernel.

Cc: Daniel Axtens 
Cc: Michael Ellerman 
Cc: Mahesh Salgaonkar 
Cc: Paul Mackerras 
Cc: linuxppc-dev@lists.ozlabs.org
Cc: kvm-ppc@vger.kernel.org
Cc: kvm@vger.kernel.org
Signed-off-by: Paolo Bonzini 
Signed-off-by: Benjamin Herrenschmidt

powerpc/pseries: PACA save area fix for MCE vs MCE

2016-08-22T01:09:33+00:00

MCE must not enable MSR_RI until PACA_EXMC is no longer being used.

Signed-off-by: Benjamin Herrenschmidt

powerpc/pseries: PACA save area fix for general exception vs MCE

2016-08-22T01:09:33+00:00

MCE must not use PACA_EXGEN. When a general exception enables MSR_RI,
that means SPRN_SRR[01] and SPRN_SPRG are no longer used. However the
PACA save area is still in use.
Acked-by: Mahesh Salgaonkar 

Signed-off-by: Benjamin Herrenschmidt

powerpc/prom: Fix sub-processor option passed to ibm, client-architecture-support

2016-08-22T01:09:33+00:00

When booting from an OpenFirmware which supports it, we use the
"ibm,client-architecture-support" firmware call to communicate
our capabilities to firmware.

The format of the structure we pass to firmware is specified in
PAPR (Power Architecture Platform Requirements), or the public version
LoPAPR (Linux on Power Architecture Platform Reference).

Referring to table 244 in LoPAPR v1.1, option vector 5 contains a 4 byte
field at bytes 17-20 for the "Platform Facilities Enable". This is
followed by a 1 byte field at byte 21 for "Sub-Processor Represenation
Level".

Comparing to the code, there we have the Platform Facilities
options (OV5_PFO_*) at byte 17, but we fail to pad that field out to its
full width of 4 bytes. This means the OV5_SUB_PROCESSORS option is
incorrectly placed at byte 18.

Fix it by adding zero bytes for bytes 18, 19, 20, and comment the bytes
to hopefully make it clearer in future.

As far as I'm aware nothing actually consumes this value at this time,
so the effect of this bug is nil in practice.

It does mean we've been incorrectly setting bit 15 of the "Platform
Facilities Enable" option for the past ~3 1/2 years, so we should avoid
allocating that bit to anything else in future.

Fixes: df77c7992029 ("powerpc/pseries: Update ibm,architecture.vec for PAPR 2.7/POWER8")
Signed-off-by: Michael Ellerman 
Signed-off-by: Benjamin Herrenschmidt

powerpc, hotplug: Avoid to touch non-existent cpumasks.

2016-08-22T01:09:33+00:00

We observed a kernel oops when running a PPC guest with config NR_CPUS=4
and qemu option "-smp cores=1,threads=8":

[   30.634781] Unable to handle kernel paging request for data at
address 0xc00000014192eb17
[   30.636173] Faulting instruction address: 0xc00000000003e5cc
[   30.637069] Oops: Kernel access of bad area, sig: 11 [#1]
[   30.637877] SMP NR_CPUS=4 NUMA pSeries
[   30.638471] Modules linked in:
[   30.638949] CPU: 3 PID: 27 Comm: migration/3 Not tainted
4.7.0-07963-g9714b26 #1
[   30.640059] task: c00000001e29c600 task.stack: c00000001e2a8000
[   30.640956] NIP: c00000000003e5cc LR: c00000000003e550 CTR:
0000000000000000
[   30.642001] REGS: c00000001e2ab8e0 TRAP: 0300   Not tainted
(4.7.0-07963-g9714b26)
[   30.643139] MSR: 8000000102803033   CR: 22004084  XER: 00000000
[   30.644583] CFAR: c000000000009e98 DAR: c00000014192eb17 DSISR: 40000000 SOFTE: 0
GPR00: c00000000140a6b8 c00000001e2abb60 c0000000016dd300 0000000000000003
GPR04: 0000000000000000 0000000000000004 c0000000016e5920 0000000000000008
GPR08: 0000000000000004 c00000014192eb17 0000000000000000 0000000000000020
GPR12: c00000000140a6c0 c00000000ffffc00 c0000000000d3ea8 c00000001e005680
GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
GPR20: 0000000000000000 c00000001e6b3a00 0000000000000000 0000000000000001
GPR24: c00000001ff85138 c00000001ff85130 000000001eb6f000 0000000000000001
GPR28: 0000000000000000 c0000000017014e0 0000000000000000 0000000000000018
[   30.653882] NIP [c00000000003e5cc] __cpu_disable+0xcc/0x190
[   30.654713] LR [c00000000003e550] __cpu_disable+0x50/0x190
[   30.655528] Call Trace:
[   30.655893] [c00000001e2abb60] [c00000000003e550] __cpu_disable+0x50/0x190 (unreliable)
[   30.657280] [c00000001e2abbb0] [c0000000000aca0c] take_cpu_down+0x5c/0x100
[   30.658365] [c00000001e2abc10] [c000000000163918] multi_cpu_stop+0x1a8/0x1e0
[   30.659617] [c00000001e2abc60] [c000000000163cc0] cpu_stopper_thread+0xf0/0x1d0
[   30.660737] [c00000001e2abd20] [c0000000000d8d70] smpboot_thread_fn+0x290/0x2a0
[   30.661879] [c00000001e2abd80] [c0000000000d3fa8] kthread+0x108/0x130
[   30.662876] [c00000001e2abe30] [c000000000009968] ret_from_kernel_thread+0x5c/0x74
[   30.664017] Instruction dump:
[   30.664477] 7bde1f24 38a00000 787f1f24 3b600001 39890008 7d204b78 7d05e214 7d0b07b4
[   30.665642] 796b1f24 7d26582a 7d204a14 7d29f214 <7d4048a8> 7d4a3878 7d4049ad 40c2fff4
[   30.666854] ---[ end trace 32643b7195717741 ]---

The reason of this is that in __cpu_disable(), when we try to set the
cpu_sibling_mask or cpu_core_mask of the sibling CPUs of the disabled
one, we don't check whether the current configuration employs those
sibling CPUs(hw threads). And if a CPU is not employed by a
configuration, the percpu structures cpu_{sibling,core}_mask are not
allocated, therefore accessing those cpumasks will result in problems as
above.

This patch fixes this problem by adding an addition check on whether the
id is no less than nr_cpu_ids in the sibling CPU iteration code.

Signed-off-by: Boqun Feng 
Signed-off-by: Benjamin Herrenschmidt

powerpc: migrate exception table users off module.h and onto extable.h

2016-08-22T01:09:33+00:00

These files were only including module.h for exception table
related functions.  We've now separated that content out into its
own file "extable.h" so now move over to that and avoid all the
extra header content in module.h that we don't really need to compile
these files.

Cc: Benjamin Herrenschmidt 
Cc: Paul Mackerras 
Cc: Michael Ellerman 
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Paul Gortmaker 
Signed-off-by: Benjamin Herrenschmidt

powerpc/pseries: use pci_host_bridge.release_fn() to kfree(phb)

2016-08-22T01:09:33+00:00

This patch leverages 'struct pci_host_bridge' from the PCI subsystem
in order to free the pci_controller only after the last reference to
its devices is dropped (avoiding an oops in pcibios_release_device()
if the last reference is dropped after pcibios_free_controller()).

The patch relies on pci_host_bridge.release_fn() (and .release_data),
which is called automatically by the PCI subsystem when the root bus
is released (i.e., the last reference is dropped).  Those fields are
set via pci_set_host_bridge_release() (e.g. in the platform-specific
implementation of pcibios_root_bridge_prepare()).

It introduces the 'pcibios_free_controller_deferred()' .release_fn()
and it expects .release_data to hold a pointer to the pci_controller.

The function implictly calls 'pcibios_free_controller()', so an user
must *NOT* explicitly call it if using the new _deferred() callback.

The functionality is enabled for pseries (although it isn't platform
specific, and may be used by cxl).

Details on not-so-elegant design choices:

 - Use 'pci_host_bridge.release_data' field as pointer to associated
   'struct pci_controller' so *not* to 'pci_bus_to_host(bridge->bus)'
   in pcibios_free_controller_deferred().

   That's because pci_remove_root_bus() sets 'host_bridge->bus = NULL'
   (so, if the last reference is released after pci_remove_root_bus()
   runs, which eventually reaches pcibios_free_controller_deferred(),
   that would hit a null pointer dereference).

   The cxl/vphb.c code calls pci_remove_root_bus(), and the cxl folks
   are interested in this fix.

Test-case #1 (hold references)

  # ls -ld /sys/block/sd* | grep -m1 0021:01:00.0
  <...> /sys/block/sdaa -> ../devices/pci0021:01/0021:01:00.0/<...>

  # ls -ld /sys/block/sd* | grep -m1 0021:01:00.1
  <...> /sys/block/sdab -> ../devices/pci0021:01/0021:01:00.1/<...>

  # cat >/dev/sdaa & pid1=$!
  # cat >/dev/sdab & pid2=$!

  # drmgr -w 5 -d 1 -c phb -s 'PHB 33' -r
  Validating PHB DLPAR capability...yes.
  [  594.306719] pci_hp_remove_devices: PCI: Removing devices on bus 0021:01
  [  594.306738] pci_hp_remove_devices:    Removing 0021:01:00.0...
  ...
  [  598.236381] pci_hp_remove_devices:    Removing 0021:01:00.1...
  ...
  [  611.972077] pci_bus 0021:01: busn_res: [bus 01-ff] is released
  [  611.972140] rpadlpar_io: slot PHB 33 removed

  # kill -9 $pid1
  # kill -9 $pid2
  [  632.918088] pcibios_free_controller_deferred: domain 33, dynamic 1

Test-case #2 (don't hold references)

  # drmgr -w 5 -d 1 -c phb -s 'PHB 33' -r
  Validating PHB DLPAR capability...yes.
  [  916.357363] pci_hp_remove_devices: PCI: Removing devices on bus 0021:01
  [  916.357386] pci_hp_remove_devices:    Removing 0021:01:00.0...
  ...
  [  920.566527] pci_hp_remove_devices:    Removing 0021:01:00.1...
  ...
  [  933.955873] pci_bus 0021:01: busn_res: [bus 01-ff] is released
  [  933.955977] pcibios_free_controller_deferred: domain 33, dynamic 1
  [  933.955999] rpadlpar_io: slot PHB 33 removed

Suggested-By: Gavin Shan 
Signed-off-by: Mauricio Faria de Oliveira 
Reviewed-by: Gavin Shan 
Reviewed-by: Andrew Donnellan 
Tested-by: Andrew Donnellan  # cxl
Signed-off-by: Benjamin Herrenschmidt