There are quite a few machine check exceptions that can be caused by
kernel bugs. To make debugging easier, use the kernel crash path in
cases of synchronous machine checks that occur in kernel mode, if that
would not result in the machine going straight to panic or crash dump.

There is a downside here that die()ing the process in kernel mode can
still leave the system unstable. panic_on_oops will always force the
system to fail-stop, so systems where that behaviour is important will
still do the right thing.

As a test, when triggering an i-side 0111b error (ifetch from foreign
address) in kernel mode process context on POWER9, the kernel currently
dies quickly like this:

  Severe Machine check interrupt [Not recovered]
    NIP [ffff000000000000]: 0xffff000000000000
    Initiator: CPU
    Error type: Real address [Instruction fetch (foreign)]
  [  127.426651616,0] OPAL: Reboot requested due to Platform error.
      Effective[  127.426693712,3] OPAL: Reboot requested due to Platform error. address: ffff000000000000
  opal: Reboot type 1 not supported
  Kernel panic - not syncing: PowerNV Unrecovered Machine Check
  CPU: 56 PID: 4425 Comm: syscall Tainted: G   M            4.12.0-rc1-13857-ga4700a26-dirty #35
  Call Trace:
  [  128.017988928,4] IPMI: BUG: Dropping ESEL on the floor due to
    buggy/mising code in OPAL for this BMC
    Rebooting in 10 seconds..
  Trying to free IRQ 496 from IRQ context!

After this patch, the process is killed and the kernel continues with
this message, which gives enough information to identify the offending
branch (i.e., with CFAR):

  Severe Machine check interrupt [Not recovered]
    NIP [ffff000000000000]: 0xffff000000000000
    Initiator: CPU
    Error type: Real address [Instruction fetch (foreign)]
      Effective address: ffff000000000000
  Oops: Machine check, sig: 7 [#1]
  SMP NR_CPUS=2048
  NUMA
  PowerNV
  Modules linked in: iptable_mangle ipt_MASQUERADE nf_nat_masquerade_ipv4 ...
  CPU: 22 PID: 4436 Comm: syscall Tainted: G   M            4.12.0-rc1-13857-ga4700a26-dirty #36
  task: c000000932300000 task.stack: c000000932380000
  NIP: ffff000000000000 LR: 00000000217706a4 CTR: ffff000000000000
  REGS: c00000000fc8fd80 TRAP: 0200   Tainted: G   M             (4.12.0-rc1-13857-ga4700a26-dirty)
  MSR: 90000000001c1003 <SF,HV,ME,RI,LE>
    CR: 24000484  XER: 20000000
  CFAR: c000000000004c80 DAR: 0000000021770a90 DSISR: 0a000000 SOFTE: 1
  GPR00: 0000000000001ebe 00007fffce4818b0 0000000021797f00 0000000000000000
  GPR04: 00007fff8007ac24 0000000044000484 0000000000004000 00007fff801405e8
  GPR08: 900000000280f033 0000000024000484 0000000000000000 0000000000000030
  GPR12: 9000000000001003 00007fff801bc370 0000000000000000 0000000000000000
  GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
  GPR20: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
  GPR24: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
  GPR28: 00007fff801b0000 0000000000000000 00000000217707a0 00007fffce481918
  NIP [ffff000000000000] 0xffff000000000000
  LR [00000000217706a4] 0x217706a4
  Call Trace:
  Instruction dump:
  XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX
  XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX XXXXXXXX
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Unrecovered MCE and HMI errors are sent through a special restart OPAL
call to log the platform error. The downside is that they don't go
through normal Linux crash paths, so they don't give much information
to the Linux console.

Change this by providing a special crash function which does some of
the console flushing from the panic() path before calling firmware to
reboot.

The downside of this is a little more code to execute before reaching
the firmware reboot. However in practice, it's critical to get the
Linux console messages output in order to debug a problem. So this is
a desirable tradeoff.

Note on the implementation: It is difficult to plumb a custom reboot
handler into the panic path, because panic does a little bit too much
work. For example, it will try to delay with the timebase, but that
may be corrupted in some cases resulting in a hang without reaching
the platform reboot. Another problem is that panic can invoke the
crash dump code which is not what we want in the case of a hardware
platform error. Long-term the best solution will be to rework the
panic path so it can be suitable for this kind of panic, but for now
we just duplicate a bit of the code.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

A system reset is a request to crash / debug the system rather than
necessarily caused by encountering a BUG. So there is no need to
serialize all CPUs behind the die lock, adding taints to all
subsequent traces beyond the first, breaking console locks, etc.

The system reset is NMI context which has its own printk buffers to
prevent output being interleaved. Then it's better to have all
secondaries print out their debug as quickly as possible and the
primary will flush out all printk buffers during panic().

So remove the 0x100 path from die, and move it into system_reset. Name
the crash/dump reasons "System Reset".

This gives "not tained" traces when crashing an untainted kernel. It
also gives the panic reason as "System Reset" as opposed to "Fatal
exception in interrupt" (or "die oops" for fadump).
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Some PowerVM firmware when delivering a system reset interrupt to a
little endian OS will mess up SRR registers. They are byteswapped, and
SRR1 is incorrect. An example from a crash:

  NIP: 14dd0900000000c0
  MSR: 1000000200000080

It's possible to detect this pattern in SRR1 (that would never happen
in normal operation), and at least fix the NIP. After this patch, the
same interrupt reports NIP properly:

  NIP [c00000000009dd14] plpar_hcall_norets+0x1c/0x28
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

If fadump is not registered, and no other crash or debug handlers are
registered, the powerpc panic handler stops the guest before the
generic panic code can push out debug information to the console.

Currently, system reset injection causes the guest to silently stop.

Stop calling ppc_md.panic in the panic notifier. crash_fadump already
does rtas_os_term() to terminate the guest if fadump is registered.

Remove ppc_md.panic. Move fadump panic notifier into fadump code.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

This fixes a couple more bits of fallout from the new hard lockup watchdog
patch.

It restores the required hw_nmi_get_sample_period() function for the
perf watchdog, and removes some function declarations on 64e that are only
defined for 64s. This fixes the 64e build when the hardlockup detector is
enabled.

It restores the default behaviour of disabling the perf watchdog, and also
fixes disabling the 64s watchdog when running as a guest.

Fixes: 2104180a ("powerpc/64s: implement arch-specific hardlockup watchdog")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

These are unused in radix mode.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Radix MMU does not take SLB or TLB interrupts when accessing kernel
linear address. Remove this restriction for radix mode.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Remove incorrect comment about real mode address restrictions on
powernv (bare metal), and unnecessary clamping to ppc64_rma_size.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

The hardware can execute stop in any context, and KVM does not
require real mode because siblings do not share MMU state. This
saves a switch to real-mode when going idle.
Acked-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

There are no longer any callers of IDLE_STATE_ENTER_SEQ, all callers
use IDLE_STATE_ENTER_SEQ_NORET. So drop the former.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Split out of larger patch, write change log]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

We don't need to use IDLE_STATE_ENTER_SEQ_NORET on Power9.
Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Split out of larger patch]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

This macro is only used in idle_book3s.S, move it in there and add a
more descriptive comment.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Split out of larger patch and write change log]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Merge Nicks commit to rework the KVM thread management, shared with the
KVM tree via the ppc-kvm topic branch.

POWER9 CPUs have independent MMU contexts per thread, so KVM does not
need to quiesce secondary threads, so the hwthread_req/hwthread_state
protocol does not have to be used. So patch it away on POWER9, and patch
away the branch from the Linux idle wakeup to kvm_start_guest that is
never used.

Add a warning and error out of kvmppc_grab_hwthread in case it is ever
called on POWER9.

This avoids a hwsync in the idle wakeup path on POWER9.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Acked-by: Paul Mackerras <paulus@ozlabs.org>
[mpe: Use WARN(...) instead of WARN_ON()/pr_err(...)]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

In commit a335aaf3 ("usb: misc: remove outdated USB LED driver")
CONFIG_USB_LED was removed, so drop it from our defconfigs.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Since commit 76c4969f ("Bluetooth: hci_uart: fix kconfig
dependency") we can no longer select CONFIG_BT_HCIUART_LL.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

In commit 835ea93e ("char/genrtc: remove powerpc support"),
CONFIG_GEN_RTC switch from tristate to bool, update the defconfig to
match.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

In commit ca07e1c1 ("drivers:usb:fsl:Make fsl ehci drv an
independent driver module"), CONFIG_USB_EHCI_FSL was switched from
built-in to modular. Update the defconfig.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Since commit 943cc592 ("Bluetooth: bpa10x: Use h4_recv_buf helper
for frame reassembly") we no longer need to set CONFIG_BT_HCIUART_H4
in our defconfigs.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Since commit 8db4c5be ("netfilter: move socket lookup
infrastructure to nf_socket_ipv{4,6}.c") we no longer need to set
CONFIG_NETFILTER_XT_MATCH_SOCKET in our defconfigs.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

In commit 1aefc75b ("cpufreq: stats: Make the stats code
non-modular"), the CPU_FREQ_STAT code was made non-modular. Our
defconfig still said =m though, which meant we no longer got the
code at all. Switch the defconfig to =y.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Since commit adf05168 ("netfilter: remove ip_conntrack* sysctl
compat code") we no longer need to set CONFIG_NF_CONNTRACK_PROC_COMPAT
in our defconfigs.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

In commit 8e14be53 ("remove the obsolete hd driver") the
CONFIG_BLK_DEV_HD symbol was removed, so drop it from the defconfig.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

We had two values for CONFIG_EXT4, =m and =y, just use =y.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Since commit dfb4357d ("time: Remove CONFIG_TIMER_STATS") we no
longer need to set CONFIG_TIMER_STATS in our defconfigs.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

In commit d92d9c3a ("drm: hide legacy drivers with CONFIG_DRM_LEGACY")
CONFIG_DRM_RADEON was moved behind CONFIG_DRM_LEGACY meaning it
stopped being enabled by ppc6xx_defconfig. Although no one has
noticed, given this is basically a legacy platform, it seems anyone
who is using it probably still wants this driver. So turn it back on
for now.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Since commit a03fdcb1 ("drm: Add top level Kconfig option for DRM
fbdev emulation") we no longer need to set CONFIG_FB in our
defconfigs.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

In commit 73d8ef76 ("Input: mousedev - stop offering PS/2 to
userspace by default") the symbol INPUT_MOUSEDEV went from being
'default y' to 'default n' (implied).

That means we no longer need to explicitly disable it in our
defconfigs.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

In commit 1d0fd57a ("logfs: remove from tree"), logfs was removed
from the tree, so we can drop it from our defconfigs.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

In commit d92d9c3a ("drm: hide legacy drivers with
CONFIG_DRM_LEGACY") CONFIG_R128 was moved behind CONFIG_DRM_LEGACY
meaning it stopped being enabled by pmac32_defconfig. Although no one
has noticed, given this is basically a legacy platform, it seems
anyone who is using it probably still wants this driver. So turn it
back on for now.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Since commit 300ae149 ("netfilter: select LIBCRC32C together with
SCTP conntrack") we no longer need to set CONFIG_LIBCRC32C in our
defconfigs.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

There are no EDAC drivers for ppc64e.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Since commit 67f6d665 ("powerpc: convert amigaone_defconfig to use
libata PATA drivers") we no longer need to set CONFIG_SCSI in our
defconfigs.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Since commit de551f2e ("net: Build IPv6 into kernel by default")
we no longer need to set CONFIG_IPV6 in our defconfigs.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

In commit e3c4ff6d ("EDAC: Remove EDAC_MM_EDAC") CONFIG_EDAC grew
a dependency on CONFIG_RAS. Some of our defconfigs don't have the
latter, which means we lose CONFIG_EDAC, so add CONFIG_RAS to fix
that.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Since commit cb74ed27 ("audit: always enable syscall auditing when
supported and audit is enabled") we no longer need to set
CONFIG_AUDITSYSCALL in our defconfigs.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

In commit bf4981a0 ("powerpc: Remove the celleb support") we
dropped the celleb support, which made these symbols unselectable
because we no longer select HAS_TX99_SERIAL. So drop them from the
defconfigs.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

xxxx

In commit 577ec789 ("powerpc/cell: Drop select of MEMORY_HOTPLUG")
we removed the last traces of any dependency between
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

In commit 43a1dd9b ("powerpc/powernv: Add driver for operator
panel on FSP machines") we added CONFIG_POWERNV_OP_PANEL=m to the
powernv defconfig, but it's default m so that's no necessary.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>