When we take an SLB multi-hit on bare metal, we see both the multi-hit
and parity error bits set in DSISR. The user manuals indicates this is
expected to always happen on Power8, whereas on Power9 it says a
multi-hit will "usually" also cause a parity error.
We decide what to do based on the various error tables in mce_power.c,
and because we process them in order and only report the first, we
currently always report a parity error but not the multi-hit, eg:
Severe Machine check interrupt [Recovered]
Initiator: CPU
Error type: SLB [Parity]
Effective address: c000000ffffd4300
Although this is correct, it leaves the user wondering why they got a
parity error. It would be clearer instead if we reported the
multi-hit because that is more likely to be simply a software bug,
whereas a true parity error is possibly an indication of a bad core.
We can do that simply by reordering the error tables so that multi-hit
appears before parity. That doesn't affect the error recovery at all,
because we flush the SLB either way.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
The current code extracts the physical address for UE errors and then
hooks it up into memory failure infrastructure. On successful
extraction of physical address it wrongly sets "handled = 1" which
means this UE error has been recovered. Since MCE handler gets return
value as handled = 1, it assumes that error has been recovered and
goes back to same NIP. This causes MCE interrupt again and again in a
loop leading to hard lockup.
Also, initialize phys_addr to ULONG_MAX so that we don't end up
queuing undesired page to hwpoison.
Without this patch we see:
Severe Machine check interrupt [Recovered]
NIP: [000000001002588c] PID: 7109 Comm: find
Initiator: CPU
Error type: UE [Load/Store]
Effective address: 00007fffd2755940
Physical address: 000020181a080000
...
Severe Machine check interrupt [Recovered]
NIP: [000000001002588c] PID: 7109 Comm: find
Initiator: CPU
Error type: UE [Load/Store]
Effective address: 00007fffd2755940
Physical address: 000020181a080000
Severe Machine check interrupt [Recovered]
NIP: [000000001002588c] PID: 7109 Comm: find
Initiator: CPU
Error type: UE [Load/Store]
Effective address: 00007fffd2755940
Physical address: 000020181a080000
Memory failure: 0x20181a08: recovery action for dirty LRU page: Recovered
Memory failure: 0x20181a08: already hardware poisoned
Memory failure: 0x20181a08: already hardware poisoned
Memory failure: 0x20181a08: already hardware poisoned
Memory failure: 0x20181a08: already hardware poisoned
Memory failure: 0x20181a08: already hardware poisoned
Memory failure: 0x20181a08: already hardware poisoned
...
Watchdog CPU:38 Hard LOCKUP
After this patch we see:
Severe Machine check interrupt [Not recovered]
NIP: [00007fffaae585f4] PID: 7168 Comm: find
Initiator: CPU
Error type: UE [Load/Store]
Effective address: 00007fffaafe28ac
Physical address: 00002017c0bd0000
find[7168]: unhandled signal 7 at 00007fffaae585f4 nip 00007fffaae585f4 lr 00007fffaae585e0 code 4
Memory failure: 0x2017c0bd: recovery action for dirty LRU page: Recovered
Fixes: 01eaac2b05 ("powerpc/mce: Hookup ierror (instruction) UE errors")
Fixes: ba41e1e1cc ("powerpc/mce: Hookup derror (load/store) UE errors")
Cc: stable@vger.kernel.org # v4.15+
Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Balbir Singh <bsingharora@gmail.com>
Reviewed-by: Balbir Singh <bsingharora@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
There are several cases outside the normal address space management
where a CPU's entire local TLB is to be flushed:
1. Booting the kernel, in case something has left stale entries in
the TLB (e.g., kexec).
2. Machine check, to clean corrupted TLB entries.
One other place where the TLB is flushed, is waking from deep idle
states. The flush is a side-effect of calling ->cpu_restore with the
intention of re-setting various SPRs. The flush itself is unnecessary
because in the first case, the TLB should not acquire new corrupted
TLB entries as part of sleep/wake (though they may be lost).
This type of TLB flush is coded inflexibly, several times for each CPU
type, and they have a number of problems with ISA v3.0B:
- The current radix mode of the MMU is not taken into account, it is
always done as a hash flushn For IS=2 (LPID-matching flush from host)
and IS=3 with HV=0 (guest kernel flush), tlbie(l) is undefined if
the R field does not match the current radix mode.
- ISA v3.0B hash must flush the partition and process table caches as
well.
- ISA v3.0B radix must flush partition and process scoped translations,
partition and process table caches, and also the page walk cache.
So consolidate the flushing code and implement it in C and inline asm
under the mm/ directory with the rest of the flush code. Add ISA v3.0B
cases for radix and hash, and use the radix flush in radix environment.
Provide a way for IS=2 (LPID flush) to specify the radix mode of the
partition. Have KVM pass in the radix mode of the guest.
Take out the flushes from early cputable/dt_cpu_ftrs detection hooks,
and move it later in the boot process after, the MMU registers are set
up and before relocation is first turned on.
The TLB flush is no longer called when restoring from deep idle states.
This was not be done as a separate step because booting secondaries
uses the same cpu_restore as idle restore, which needs the TLB flush.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
We have some dependencies & conflicts between patches in fixes and
things to go in next, both in the radix TLB flush code and the IMC PMU
driver. So merge fixes into next.
CONFIG_PPC_STD_MMU_64 indicates support for the "standard" powerpc MMU
on 64-bit CPUs. The "standard" MMU refers to the hash page table MMU
found in "server" processors, from IBM mainly.
Currently CONFIG_PPC_STD_MMU_64 is == CONFIG_PPC_BOOK3S_64. While it's
annoying to have two symbols that always have the same value, it's not
quite annoying enough to bother removing one.
However with the arrival of Power9, we now have the situation where
CONFIG_PPC_STD_MMU_64 is enabled, but the kernel is running using the
Radix MMU - *not* the "standard" MMU. So it is now actively confusing
to use it, because it implies that code is disabled or inactive when
the Radix MMU is in use, however that is not necessarily true.
So s/CONFIG_PPC_STD_MMU_64/CONFIG_PPC_BOOK3S_64/, and do some minor
formatting updates of some of the affected lines.
This will be a pain for backports, but c'est la vie.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Hookup instruction errors (UE) for memory offling via memory_failure()
in a manner similar to load/store errors (derror). Since we have access
to the NIP, the conversion is a one step process in this case.
Signed-off-by: Balbir Singh <bsingharora@gmail.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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>
This code is used at boot and machine checks, so it should be using
early_radix_enabled() (which is usable any time).
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
In the recent commit d8bd9f3f09 ("powerpc: Handle MCE on POWER9 with
only DSISR bit 30 set") I screwed up the bit number. It should be bit
25 (IBM bit 38).
Fixes: d8bd9f3f09 ("powerpc: Handle MCE on POWER9 with only DSISR bit 30 set")
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
On POWER9 DD2.1 and below, it's possible for a paste instruction to
cause a Machine Check Exception (MCE) where only DSISR bit 30 (IBM 33)
is set. This will result in the MCE handler seeing an unknown event,
which triggers linux to crash.
We change this by detecting unknown events caused by load/stores in
the MCE handler and marking them as handled so that we no longer
crash.
An MCE that occurs like this is spurious, so we don't need to do
anything in terms of servicing it. If there is something that needs to
be serviced, the CPU will raise the MCE again with the correct DSISR
so that it can be serviced properly.
Signed-off-by: Michael Neuling <mikey@neuling.org>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com
Acked-by: Balbir Singh <bsingharora@gmail.com>
[mpe: Expand comment with details from change log, use normal bit #s]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
There are two cases outside the normal address space management
where a CPU's local TLB is to be flushed:
1. Host boot; in case something has left stale entries in the
TLB (e.g., kexec).
2. Machine check; to clean corrupted TLB entries.
CPU state restore from deep idle states also flushes the TLB.
However this seems to be a side effect of reusing the boot code to set
CPU state, rather than a requirement itself.
The current flushing has a number of problems with ISA v3.0B:
- The current radix mode of the MMU is not taken into account. tlbiel
is undefined if the R field does not match the current radix mode.
- ISA v3.0B hash must flush the partition and process table caches.
- ISA v3.0B radix must flush partition and process scoped translations,
partition and process table caches, and also the page walk cache.
Add POWER9 cases to handle these, with radix vs hash determined by the
host MMU mode.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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: 7b9f71f974 ("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>
The TLB flush for radix first flushes TLB for radix configuration,
then flushes for hash configuration. The second flush is unnecessary
but does not affect correctness.
Fixes: 1a472c9dba ("powerpc/mm/radix: Add tlbflush routines")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
POWER8 uses bit 36 in SRR1 like POWER9 for i-side machine checks, and
contains several conditions for link timeouts that are not currently
handled.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Move the handling (corrective action) of machine checks to the table
based evaluation.
This changes P7 and P8 ERAT flushing from using SLB flush to using ERAT
flush.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Have machine types define i-side and d-side tables to describe their
machine check encodings, and match entries to evaluate (for reporting)
machine checks.
Functionality is mostly unchanged (tested with a userspace harness), but
it does make a change in that it no longer records DAR as the effective
address for those errors where it is specified to be invalid (which is a
reporting change only).
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Use the flush function introduced with the POWER9 machine check handler
for POWER7 and 8, rather than open coding it multiple times in callers.
There is a specific ERAT flush type introduced for POWER9, but the
POWER7-8 ERAT errors continue to do SLB flushing (which also flushes
ERAT), so as not to introduce functional changes with this cleanup
patch.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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>
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>
We also use MMU_FTR_RADIX to branch out from code path specific to
hash.
No functionality change.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Core kernel doesn't track the page size of the VA range that we are
invalidating. Hence we end up flushing TLB for the entire mm here. Later
patches will improve this.
We also don't flush page walk cache separetly instead use RIC=2 when
flushing TLB, because we do a MMU gather flush after freeing page table.
MMU_NO_CONTEXT is updated for hash.
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Add a cputable entry for POWER9. More code is required to actually
boot and run on a POWER9 but this gets the base piece in which we can
start building on.
Copies over from POWER8 except for:
- Adds a new CPU_FTR_ARCH_300 bit to start hanging new architecture
features from (in subsequent patches).
- Advertises new user features bits PPC_FEATURE2_ARCH_3_00 &
HAS_IEEE128 when on POWER9.
- Drops CPU_FTR_SUBCORE.
- Drops PMU code and machine check.
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
The flush_tlb hook in cpu_spec was introduced as a generic function hook
to invalidate TLBs. But the current implementation of flush_tlb hook
takes IS (invalidation selector) as an argument which is architecture
dependent. Hence, It is not right to have a generic routine where caller
has to pass non-generic argument.
This patch fixes this and makes flush_tlb hook as high level API.
Reported-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
The existing MCE code calls flush_tlb hook with IS=0 (single page) resulting
in partial invalidation of TLBs which is not right. This patch fixes
that by passing IS=0xc00 to invalidate whole TLB for successful recovery
from TLB and ERAT errors.
Cc: stable@vger.kernel.org
Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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>
The SLB save area is shared with the hypervisor and is defined
as big endian, so we need to byte swap on little endian builds.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
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>
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>
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>
