powerpc/mce: Avoid using irq_work_queue() in realmode

In realmode mce handler we use irq_work_queue() to defer
the processing of mce events, irq_work_queue() can only
be called when translation is enabled because it touches
memory outside RMA, hence we enable translation before
calling irq_work_queue and disable on return, though it
is not safe to do in realmode.

To avoid this, program the decrementer and call the event
processing functions from timer handler.

Signed-off-by: Ganesh Goudar <ganeshgr@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220120121931.517974-1-ganeshgr@linux.ibm.com

powerpc/mce: Remove per cpu variables from MCE handlers

Access to per-cpu variables requires translation to be enabled on
pseries machine running in hash mmu mode, Since part of MCE handler
runs in realmode and part of MCE handling code is shared between ppc
architectures pseries and powernv, it becomes difficult to manage
these variables differently on different architectures, So have
these variables in paca instead of having them as per-cpu variables
to avoid complications.

Signed-off-by: Ganesh Goudar <ganeshgr@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210128104143.70668-2-ganeshgr@linux.ibm.com

powerpc/mce: Reduce the size of event arrays

Maximum recursive depth of MCE is 4, Considering the maximum depth
allowed reduce the size of event to 10 from 100. This saves us ~19kB
of memory and has no fatal consequences.

Signed-off-by: Ganesh Goudar <ganeshgr@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210128104143.70668-1-ganeshgr@linux.ibm.com

powerpc/64s/pseries: Add ERAT specific machine check handler

Don't treat ERAT MCEs as SLB, don't save the SLB and use a specific
ERAT flush to recover it.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201128070728.825934-7-npiggin@gmail.com

powerpc/kernel: Cleanup machine check function declarations

__machine_check_early_realmode_p*() are currently declared as extern
in cputable.c and because of this when compiled with "C=1" (which
enables semantic checker) produces these warnings.

CHECK arch/powerpc/kernel/mce_power.c
arch/powerpc/kernel/mce_power.c:709:6: warning: symbol '__machine_check_early_realmode_p7' was not declared. Should it be static?
arch/powerpc/kernel/mce_power.c:717:6: warning: symbol '__machine_check_early_realmode_p8' was not declared. Should it be static?
arch/powerpc/kernel/mce_power.c:722:6: warning: symbol '__machine_check_early_realmode_p9' was not declared. Should it be static?
arch/powerpc/kernel/mce_power.c:740:6: warning: symbol '__machine_check_early_realmode_p10' was not declared. Should it be static?

Patch here moves the declaration to asm/mce.h and includes the same in
cputable.c

Fixes: ae744f3432d3 ("powerpc/book3s: Flush SLB/TLBs if we get SLB/TLB machine check errors on power8")
Fixes: 7b9f71f974a1 ("powerpc/64s: POWER9 machine check handler")
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200817005618.3305028-1-maddy@linux.ibm.com

powerpc/powernv: Machine check handler for POWER10

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200702233343.1128026-1-npiggin@gmail.com

powerpc/mce: Add MCE notification chain

Introduce notification chain which lets us know about uncorrected memory
errors(UE). This would help prospective users in pmem or nvdimm subsystem
to track bad blocks for better handling of persistent memory allocations.

Signed-off-by: Santosh Sivaraj <santosh@fossix.org>
Signed-off-by: Ganesh Goudar <ganeshgr@linux.ibm.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200709135142.721504-1-santosh@fossix.org

powerpc/pseries: Handle UE event for memcpy_mcsafe

memcpy_mcsafe has been implemented for power machines which is used
by pmem infrastructure, so that an UE encountered during memcpy from
pmem devices would not result in panic instead a right error code
is returned. The implementation expects machine check handler to ignore
the event and set nip to continue the execution from fixup code.

Appropriate changes are already made to powernv machine check handler,
make similar changes to pseries machine check handler to ignore the
the event and set nip to continue execution at the fixup entry if we
hit UE at an instruction with a fixup entry.

while we are at it, have a common function which searches the exception
table entry and updates nip with fixup address, and any future common
changes can be made in this function that are valid for both architectures.

powernv changes are made by
commit 895e3dceeb97 ("powerpc/mce: Handle UE event for memcpy_mcsafe")

Reviewed-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Reviewed-by: Santosh S <santosh@fossix.org>
Signed-off-by: Ganesh Goudar <ganeshgr@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200326184916.31172-1-ganeshgr@linux.ibm.com

powerpc/64s/pseries: machine check convert to use common event code

The common machine_check_event data structures and queues are mostly
platform independent, with powernv decoding SRR1/DSISR/etc., into
machine_check_event objects.

This patch converts pseries to use this infrastructure by decoding
fwnmi/rtas data into machine_check_event objects.

This allows queueing to be used by a subsequent change to delay the
virtual mode handling of machine checks that occur in kernel space
where it is unsafe to switch immediately to virtual mode, similarly
to powernv.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Fix implicit fallthrough warnings in mce_handle_error()]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190802105709.27696-10-npiggin@gmail.com

powerpc/mce: Handle UE event for memcpy_mcsafe

If we take a UE on one of the instructions with a fixup entry, set nip
to continue execution at the fixup entry. Stop processing the event
further or print it.

Co-developed-by: Reza Arbab <arbab@linux.ibm.com>
Signed-off-by: Reza Arbab <arbab@linux.ibm.com>
Signed-off-by: Balbir Singh <bsingharora@gmail.com>
Reviewed-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Santosh Sivaraj <santosh@fossix.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190820081352.8641-6-santosh@fossix.org

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 156

Based on 1 normalized pattern(s):

this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version this program is distributed in the
hope that it will be useful but without any warranty without even
the implied warranty of merchantability or fitness for a particular
purpose see the gnu general public license for more details you
should have received a copy of the gnu general public license along
with this program if not write to the free software foundation inc
59 temple place suite 330 boston ma 02111 1307 usa

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 1334 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Richard Fontana <rfontana@redhat.com>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070033.113240726@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

powerpc/powernv/mce: Print additional information about MCE error.

Print more information about MCE error whether it is an hardware or
software error.

Some of the MCE errors can be easily categorized as hardware or
software errors e.g. UEs are due to hardware error, where as error
triggered due to invalid usage of tlbie is a pure software bug. But
not all the MCE errors can be easily categorize into either software
or hardware. There are errors like multihit errors which are usually
result of a software bug, but in some rare cases a hardware failure
can cause a multihit error. In past, we have seen case where after
replacing faulty chip, multihit errors stopped occurring. Same with
parity errors, which are usually due to faulty hardware but there are
chances where multihit can also cause an parity error. Such errors are
difficult to determine what really caused it. Hence this patch
classifies MCE errors into following four categorize:

1. Hardware error:
UE and Link timeout failure errors.
2. Probable hardware error (some chance of software cause)
SLB/ERAT/TLB Parity errors.
3. Software error
Invalid tlbie form.
4. Probable software error (some chance of hardware cause)
SLB/ERAT/TLB Multihit errors.

Sample output:

MCE: CPU80: machine check (Warning) Guest SLB Multihit DAR: 000001001b6e0320 [Recovered]
MCE: CPU80: PID: 24765 Comm: qemu-system-ppc Guest NIP: [00007fffa309dc60]
MCE: CPU80: Probable Software error (some chance of hardware cause)

Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc/powernv/mce: Print correct severity for MCE error.

Currently all machine check errors are printed as severe errors which
isn't correct. Print soft errors as warning instead of severe errors.

Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc/powernv/mce: Reduce MCE console logs to lesser lines.

Also add cpu number while displaying MCE log. This will help cleaner
logs when MCE hits on multiple cpus simultaneously.

Before the changes the MCE output was:

Severe Machine check interrupt [Recovered]
NIP [d00000000ba80280]: insert_slb_entry.constprop.0+0x278/0x2c0 [mcetest_slb]
Initiator: CPU
Error type: SLB [Multihit]
Effective address: d00000000ba80280

After this patch series changes the MCE output will be:

MCE: CPU80: machine check (Warning) Host SLB Multihit [Recovered]
MCE: CPU80: NIP: [d00000000b550280] insert_slb_entry.constprop.0+0x278/0x2c0 [mcetest_slb]
MCE: CPU80: Probable software error (some chance of hardware cause)

UE in host application:

MCE: CPU48: machine check (Severe) Host UE Load/Store DAR: 00007fffc6079a80 paddr: 0000000f8e260000 [Not recovered]
MCE: CPU48: PID: 4584 Comm: find NIP: [0000000010023368]
MCE: CPU48: Hardware error

and for MCE in Guest:

MCE: CPU80: machine check (Warning) Guest SLB Multihit DAR: 000001001b6e0320 [Recovered]
MCE: CPU80: PID: 24765 Comm: qemu-system-ppc Guest NIP: [00007fffa309dc60]
MCE: CPU80: Probable software error (some chance of hardware cause)

Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc/pseries: hwpoison the pages upon hitting UE

Add support to hwpoison the pages upon hitting machine check
exception.

This patch queues the address where UE is hit to percpu array
and schedules work to plumb it into memory poison infrastructure.

Reviewed-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Ganesh Goudar <ganeshgr@linux.ibm.com>
[mpe: Combine #ifdefs, drop PPC_BIT8(), and empty inline stub]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc/64s: Better printing of machine check info for guest MCEs

This adds an "in_guest" parameter to machine_check_print_event_info()
so that we can avoid trying to translate guest NIP values into
symbolic form using the host kernel's symbol table.

Reviewed-by: Aravinda Prasad <aravinda@linux.vnet.ibm.com>
Reviewed-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc/pseries: Flush SLB contents on SLB MCE errors.

On pseries, as of today system crashes if we get a machine check
exceptions due to SLB errors. These are soft errors and can be fixed
by flushing the SLBs so the kernel can continue to function instead of
system crash. We do this in real mode before turning on MMU. Otherwise
we would run into nested machine checks. This patch now fetches the
rtas error log in real mode and flushes the SLBs on SLB/ERAT errors.

Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Michal Suchanek <msuchanek@suse.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc/mce: Hookup derror (load/store) UE errors

Extract physical_address for UE errors by walking the page
tables for the mm and address at the NIP, to extract the
instruction. Then use the instruction to find the effective
address via analyse_instr().

We might have page table walking races, but we expect them to
be rare, the physical address extraction is best effort. The idea
is to then hook up this infrastructure to memory failure eventually.

Signed-off-by: Balbir Singh <bsingharora@gmail.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc/mce: Remove unused function get_mce_fault_addr()

There are no users of get_mce_fault_addr() since commit
1363875bdb63 ("powerpc/64s: fix handling of non-synchronous machine
checks") removed the last usage.

Signed-off-by: Balbir Singh <bsingharora@gmail.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc/64s: Machine check handle ifetch from foreign real address for POWER9

The i-side 0111b machine check, which is "Instruction Fetch to foreign
address space", was missed by 7b9f71f974 ("powerpc/64s: POWER9 machine
check handler").

The POWER9 processor core considers host real addresses with a
nonzero value in RA(8:12) as foreign address space, accessible only
by the copy and paste instructions. The copy and paste instruction
pair can be used to invoke the Nest accelerators via the Virtual
Accelerator Switchboard (VAS).

It is an error for any regular load/store or ifetch to go to a foreign
addresses. When relocation is on, this causes an MMU exception. When
relocation is off, a machine check exception. It is possible to trigger
this machine check by branching to a foreign address with MSR[IR]=0.

Fixes: 7b9f71f974a1 ("powerpc/64s: POWER9 machine check handler")
Reported-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc/book3s: Print task info if we take a machine check in user mode

For an MCE (Machine Check Exception) that hits while in user mode
MSR(PR=1), print the task info to the console MCE error log. This may
help to identify an application that triggered the MCE.

After this patch the MCE console looks like:

Severe Machine check interrupt [Recovered]
NIP: [0000000010039778] PID: 762 Comm: ebizzy
Initiator: CPU
Error type: SLB [Multihit]
Effective address: 0000000010039778

Severe Machine check interrupt [Not recovered]
NIP: [0000000010039778] PID: 763 Comm: ebizzy
Initiator: CPU
Error type: UE [Page table walk ifetch]
Effective address: 0000000010039778
ebizzy[763]: unhandled signal 7 at 0000000010039778 nip 0000000010039778 lr 0000000010001b44 code 30004

Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc/64s: Move POWER machine check defines into mce_power.c

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc/64s: POWER9 machine check handler

Add POWER9 machine check handler. There are several new types of errors
added, so logging messages for those are also added.

This doesn't attempt to reuse any of the P7/8 defines or functions,
because that becomes too complex. The better option in future is to use
a table driven approach.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc/64s: allow machine check handler to set severity and initiator

Currently severity and initiator are always set to MCE_SEV_ERROR_SYNC and
MCE_INITIATOR_CPU in the core mce code. Allow them to be set by the
machine specific mce handlers.

No functional change for existing handlers.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

powerpc/book3s: Recover from MC in sapphire on SCOM read via MMIO.

Detect and recover from machine check when inside opal on a special
scom load instructions. On specific SCOM read via MMIO we may get a machine
check exception with SRR0 pointing inside opal. To recover from MC
in this scenario, get a recovery instruction address and return to it from
MC.

OPAL will export the machine check recoverable ranges through
device tree node mcheck-recoverable-ranges under ibm,opal:

# hexdump /proc/device-tree/ibm,opal/mcheck-recoverable-ranges
0000000 0000 0000 3000 2804 0000 000c 0000 0000
0000010 3000 2814 0000 0000 3000 27f0 0000 000c
0000020 0000 0000 3000 2814 xxxx xxxx xxxx xxxx
0000030 llll llll yyyy yyyy yyyy yyyy
...
...
#

where:
xxxx xxxx xxxx xxxx = Starting instruction address
llll llll = Length of the address range.
yyyy yyyy yyyy yyyy = recovery address

Each recoverable address range entry is (start address, len,
recovery address), 2 cells each for start and recovery address, 1 cell for
len, totalling 5 cells per entry. During kernel boot time, build up the
recovery table with the list of recovery ranges from device-tree node which
will be used during machine check exception to recover from MMIO SCOM UE.

Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

Move precessing of MCE queued event out from syscall exit path.

Huge Dickins reported an issue that b5ff4211a829
"powerpc/book3s: Queue up and process delayed MCE events" breaks the
PowerMac G5 boot. This patch fixes it by moving the mce even processing
away from syscall exit, which was wrong to do that in first place, and
using irq work framework to delay processing of mce event.

Reported-by: Hugh Dickins <hughd@google.com
Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

powerpc/powernv: Machine check exception handling.

Add basic error handling in machine check exception handler.

- If MSR_RI isn't set, we can not recover.
- Check if disposition set to OpalMCE_DISPOSITION_RECOVERED.
- Check if address at fault is inside kernel address space, if not then send
SIGBUS to process if we hit exception when in userspace.
- If address at fault is not provided then and if we get a synchronous machine
check while in userspace then kill the task.

Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

powerpc/book3s: Queue up and process delayed MCE events.

When machine check real mode handler can not continue into host kernel
in V mode, it returns from the interrupt and we loose MCE event which
never gets logged. In such a situation queue up the MCE event so that
we can log it later when we get back into host kernel with r1 pointing to
kernel stack e.g. during syscall exit.

Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

powerpc/book3s: Decode and save machine check event.

Now that we handle machine check in linux, the MCE decoding should also
take place in linux host. This info is crucial to log before we go down
in case we can not handle the machine check errors. This patch decodes
and populates a machine check event which contain high level meaning full
MCE information.

We do this in real mode C code with ME bit on. The MCE information is still
available on emergency stack (in pt_regs structure format). Even if we take
another exception at this point the MCE early handler will allocate a new
stack frame on top of current one. So when we return back here we still have
our MCE information safe on current stack.

We use per cpu buffer to save high level MCE information. Each per cpu buffer
is an array of machine check event structure indexed by per cpu counter
mce_nest_count. The mce_nest_count is incremented every time we enter
machine check early handler in real mode to get the current free slot
(index = mce_nest_count - 1). The mce_nest_count is decremented once the
MCE info is consumed by virtual mode machine exception handler.

This patch provides save_mce_event(), get_mce_event() and release_mce_event()
generic routines that can be used by machine check handlers to populate and
retrieve the event. The routine release_mce_event() will free the event slot so
that it can be reused. Caller can invoke get_mce_event() with a release flag
either to release the event slot immediately OR keep it so that it can be
fetched again. The event slot can be also released anytime by invoking
release_mce_event().

This patch also updates kvm code to invoke get_mce_event to retrieve generic
mce event rather than paca->opal_mce_evt.

The KVM code always calls get_mce_event() with release flags set to false so
that event is available for linus host machine

If machine check occurs while we are in guest, KVM tries to handle the error.
If KVM is able to handle MC error successfully, it enters the guest and
delivers the machine check to guest. If KVM is not able to handle MC error, it
exists the guest and passes the control to linux host machine check handler
which then logs MC event and decides how to handle it in linux host. In failure
case, KVM needs to make sure that the MC event is available for linux host to
consume. Hence KVM always calls get_mce_event() with release flags set to false
and later it invokes release_mce_event() only if it succeeds to handle error.

Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

powerpc/book3s: Flush SLB/TLBs if we get SLB/TLB machine check errors on power8.

This patch handles the memory errors on power8. If we get a machine check
exception due to SLB or TLB errors, then flush SLBs/TLBs and reload SLBs to
recover.

Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Acked-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

powerpc/book3s: Flush SLB/TLBs if we get SLB/TLB machine check errors on power7.

If we get a machine check exception due to SLB or TLB errors, then flush
SLBs/TLBs and reload SLBs to recover. We do this in real mode before turning
on MMU. Otherwise we would run into nested machine checks.

If we get a machine check when we are in guest, then just flush the
SLBs and continue. This patch handles errors for power7. The next
patch will handle errors for power8

Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>