If we are in user space and hit a UE error, we now have the
basic infrastructure to walk the page tables and find out
the effective address that was accessed, since the DAR
is not valid.
We use a work_queue content to hookup the bad pfn, any
other context causes problems, since memory_failure itself
can call into schedule() via lru_drain_ bits.
We could probably poison the struct page to avoid a race
between detection and taking corrective action.
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>
Use the same alignment as Effective address.
Signed-off-by: Balbir Singh <bsingharora@gmail.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
There are no users of get_mce_fault_addr() since commit
1363875bdb ("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>
POWER9 DD2.1 and earlier has an issue where some cache inhibited
vector load will return bad data. The workaround is two part, one
firmware/microcode part triggers HMI interrupts when hitting such
loads, the other part is this patch which then emulates the
instructions in Linux.
The affected instructions are limited to lxvd2x, lxvw4x, lxvb16x and
lxvh8x.
When an instruction triggers the HMI, all threads in the core will be
sent to the HMI handler, not just the one running the vector load.
In general, these spurious HMIs are detected by the emulation code and
we just return back to the running process. Unfortunately, if a
spurious interrupt occurs on a vector load that's to normal memory we
have no way to detect that it's spurious (unless we walk the page
tables, which is very expensive). In this case we emulate the load but
we need do so using a vector load itself to ensure 128bit atomicity is
preserved.
Some additional debugfs emulated instruction counters are added also.
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
[mpe: Switch CONFIG_PPC_BOOK3S_64 to CONFIG_VSX to unbreak the build]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
We already have mce.c which is built for 64bit and contains other parts
of the machine check code, so move these bits in there too.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Highlights include:
- Support for STRICT_KERNEL_RWX on 64-bit server CPUs.
- Platform support for FSP2 (476fpe) board
- Enable ZONE_DEVICE on 64-bit server CPUs.
- Generic & powerpc spin loop primitives to optimise busy waiting
- Convert VDSO update function to use new update_vsyscall() interface
- Optimisations to hypercall/syscall/context-switch paths
- Improvements to the CPU idle code on Power8 and Power9.
As well as many other fixes and improvements.
Thanks to:
Akshay Adiga, Andrew Donnellan, Andrew Jeffery, Anshuman Khandual, Anton
Blanchard, Balbir Singh, Benjamin Herrenschmidt, Christophe Leroy, Christophe
Lombard, Colin Ian King, Dan Carpenter, Gautham R. Shenoy, Hari Bathini, Ian
Munsie, Ivan Mikhaylov, Javier Martinez Canillas, Madhavan Srinivasan,
Masahiro Yamada, Matt Brown, Michael Neuling, Michal Suchanek, Murilo
Opsfelder Araujo, Naveen N. Rao, Nicholas Piggin, Oliver O'Halloran, Paul
Mackerras, Pavel Machek, Russell Currey, Santosh Sivaraj, Stephen Rothwell,
Thiago Jung Bauermann, Yang Li.
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Merge tag 'powerpc-4.13-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux
Pull powerpc updates from Michael Ellerman:
"Highlights include:
- Support for STRICT_KERNEL_RWX on 64-bit server CPUs.
- Platform support for FSP2 (476fpe) board
- Enable ZONE_DEVICE on 64-bit server CPUs.
- Generic & powerpc spin loop primitives to optimise busy waiting
- Convert VDSO update function to use new update_vsyscall() interface
- Optimisations to hypercall/syscall/context-switch paths
- Improvements to the CPU idle code on Power8 and Power9.
As well as many other fixes and improvements.
Thanks to: Akshay Adiga, Andrew Donnellan, Andrew Jeffery, Anshuman
Khandual, Anton Blanchard, Balbir Singh, Benjamin Herrenschmidt,
Christophe Leroy, Christophe Lombard, Colin Ian King, Dan Carpenter,
Gautham R. Shenoy, Hari Bathini, Ian Munsie, Ivan Mikhaylov, Javier
Martinez Canillas, Madhavan Srinivasan, Masahiro Yamada, Matt Brown,
Michael Neuling, Michal Suchanek, Murilo Opsfelder Araujo, Naveen N.
Rao, Nicholas Piggin, Oliver O'Halloran, Paul Mackerras, Pavel Machek,
Russell Currey, Santosh Sivaraj, Stephen Rothwell, Thiago Jung
Bauermann, Yang Li"
* tag 'powerpc-4.13-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (158 commits)
powerpc/Kconfig: Enable STRICT_KERNEL_RWX for some configs
powerpc/mm/radix: Implement STRICT_RWX/mark_rodata_ro() for Radix
powerpc/mm/hash: Implement mark_rodata_ro() for hash
powerpc/vmlinux.lds: Align __init_begin to 16M
powerpc/lib/code-patching: Use alternate map for patch_instruction()
powerpc/xmon: Add patch_instruction() support for xmon
powerpc/kprobes/optprobes: Use patch_instruction()
powerpc/kprobes: Move kprobes over to patch_instruction()
powerpc/mm/radix: Fix execute permissions for interrupt_vectors
powerpc/pseries: Fix passing of pp0 in updatepp() and updateboltedpp()
powerpc/64s: Blacklist rtas entry/exit from kprobes
powerpc/64s: Blacklist functions invoked on a trap
powerpc/64s: Un-blacklist system_call() from kprobes
powerpc/64s: Move system_call() symbol to just after setting MSR_EE
powerpc/64s: Blacklist system_call() and system_call_common() from kprobes
powerpc/64s: Convert .L__replay_interrupt_return to a local label
powerpc64/elfv1: Only dereference function descriptor for non-text symbols
cxl: Export library to support IBM XSL
powerpc/dts: Use #include "..." to include local DT
powerpc/perf/hv-24x7: Aggregate result elements on POWER9 SMT8
...
It will be used in arch/powerpc/kvm/book3s_hv.c KVM module.
Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
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>
machine_check_early() gets called in real mode. The very first time when
add_taint() is called, it prints a warning which ends up calling opal
call (that uses OPAL_CALL wrapper) for writing it to console. If we get a
very first machine check while we are in opal we are doomed. OPAL_CALL
overwrites the PACASAVEDMSR in r13 and in this case when we are done with
MCE handling the original opal call will use this new MSR on it's way
back to opal_return. This usually leads to unexpected behaviour or the
kernel to panic. Instead move the add_taint() call later in the virtual
mode where it is safe to call.
This is broken with current FW level. We got lucky so far for not getting
very first MCE hit while in OPAL. But easily reproducible on Mambo.
Fixes: 27ea2c420c ("powerpc: Set the correct kernel taint on machine check errors.")
Cc: stable@vger.kernel.org # v4.2+
Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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>
For D-side errors we print the load/store address that caused the
machine check as 'Effective address'. But the instruction that may have
caused the machine check can also be helpful, so in addition to printing
the NIP, also print the kernel function name as well.
After this patch the MCE console log would look like:
Severe Machine check interrupt [Recovered]
NIP [d00000001bc70194]: init_module+0x194/0x2b0 [bork_kernel]
Initiator: CPU
Error type: SLB [Parity]
Effective address: d000000026de0000
Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Print the faulting address of the machine check that may help with
debugging. The effective address reported can be a target memory address
rather than the faulting instruction address.
Fix up a dangling bracket while here.
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>
Remove the unused but set variable srr1 in save_mce_event() to
fix the following GCC warning when building with 'W=1':
arch/powerpc/kernel/mce.c:75:11: warning: variable 'srr1' set but not used
It has never been used.
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
When machine check occurs with MSR(RI=0), it means MC interrupt is
unrecoverable and kernel goes down to panic path. But the console
message still shows it as recovered. This patch fixes the MCE console
messages.
Fixes: 36df96f8ac ("powerpc/book3s: Decode and save machine check event.")
Signed-off-by: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Highlights:
- Support for Power ISA 3.0 (Power9) Radix Tree MMU from Aneesh Kumar K.V
- Live patching support for ppc64le (also merged via livepatching.git)
Various cleanups & minor fixes from:
- Aaro Koskinen, Alexey Kardashevskiy, Andrew Donnellan, Aneesh Kumar K.V,
Chris Smart, Daniel Axtens, Frederic Barrat, Gavin Shan, Ian Munsie, Lennart
Sorensen, Madhavan Srinivasan, Mahesh Salgaonkar, Markus Elfring, Michael
Ellerman, Oliver O'Halloran, Paul Gortmaker, Paul Mackerras, Rashmica Gupta,
Russell Currey, Suraj Jitindar Singh, Thiago Jung Bauermann, Valentin
Rothberg, Vipin K Parashar.
General:
- Update LMB associativity index during DLPAR add/remove from Nathan Fontenot
- Fix branching to OOL handlers in relocatable kernel from Hari Bathini
- Add support for userspace Power9 copy/paste from Chris Smart
- Always use STRICT_MM_TYPECHECKS from Michael Ellerman
- Add mask of possible MMU features from Michael Ellerman
PCI:
- Enable pass through of NVLink to guests from Alexey Kardashevskiy
- Cleanups in preparation for powernv PCI hotplug from Gavin Shan
- Don't report error in eeh_pe_reset_and_recover() from Gavin Shan
- Restore initial state in eeh_pe_reset_and_recover() from Gavin Shan
- Revert "powerpc/eeh: Fix crash in eeh_add_device_early() on Cell" from Guilherme G. Piccoli
- Remove the dependency on EEH struct in DDW mechanism from Guilherme G. Piccoli
selftests:
- Test cp_abort during context switch from Chris Smart
- Add several tests for transactional memory support from Rashmica Gupta
perf:
- Add support for sampling interrupt register state from Anju T
- Add support for unwinding perf-stackdump from Chandan Kumar
cxl:
- Configure the PSL for two CAPI ports on POWER8NVL from Philippe Bergheaud
- Allow initialization on timebase sync failures from Frederic Barrat
- Increase timeout for detection of AFU mmio hang from Frederic Barrat
- Handle num_of_processes larger than can fit in the SPA from Ian Munsie
- Ensure PSL interrupt is configured for contexts with no AFU IRQs from Ian Munsie
- Add kernel API to allow a context to operate with relocate disabled from Ian Munsie
- Check periodically the coherent platform function's state from Christophe Lombard
Freescale:
- Updates from Scott: "Contains 86xx fixes, minor device tree fixes, an erratum
workaround, and a kconfig dependency fix."
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Merge tag 'powerpc-4.7-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux
Pull powerpc updates from Michael Ellerman:
"Highlights:
- Support for Power ISA 3.0 (Power9) Radix Tree MMU from Aneesh Kumar K.V
- Live patching support for ppc64le (also merged via livepatching.git)
Various cleanups & minor fixes from:
- Aaro Koskinen, Alexey Kardashevskiy, Andrew Donnellan, Aneesh Kumar K.V,
Chris Smart, Daniel Axtens, Frederic Barrat, Gavin Shan, Ian Munsie,
Lennart Sorensen, Madhavan Srinivasan, Mahesh Salgaonkar, Markus Elfring,
Michael Ellerman, Oliver O'Halloran, Paul Gortmaker, Paul Mackerras,
Rashmica Gupta, Russell Currey, Suraj Jitindar Singh, Thiago Jung
Bauermann, Valentin Rothberg, Vipin K Parashar.
General:
- Update LMB associativity index during DLPAR add/remove from Nathan
Fontenot
- Fix branching to OOL handlers in relocatable kernel from Hari Bathini
- Add support for userspace Power9 copy/paste from Chris Smart
- Always use STRICT_MM_TYPECHECKS from Michael Ellerman
- Add mask of possible MMU features from Michael Ellerman
PCI:
- Enable pass through of NVLink to guests from Alexey Kardashevskiy
- Cleanups in preparation for powernv PCI hotplug from Gavin Shan
- Don't report error in eeh_pe_reset_and_recover() from Gavin Shan
- Restore initial state in eeh_pe_reset_and_recover() from Gavin Shan
- Revert "powerpc/eeh: Fix crash in eeh_add_device_early() on Cell"
from Guilherme G Piccoli
- Remove the dependency on EEH struct in DDW mechanism from Guilherme
G Piccoli
selftests:
- Test cp_abort during context switch from Chris Smart
- Add several tests for transactional memory support from Rashmica
Gupta
perf:
- Add support for sampling interrupt register state from Anju T
- Add support for unwinding perf-stackdump from Chandan Kumar
cxl:
- Configure the PSL for two CAPI ports on POWER8NVL from Philippe
Bergheaud
- Allow initialization on timebase sync failures from Frederic Barrat
- Increase timeout for detection of AFU mmio hang from Frederic
Barrat
- Handle num_of_processes larger than can fit in the SPA from Ian
Munsie
- Ensure PSL interrupt is configured for contexts with no AFU IRQs
from Ian Munsie
- Add kernel API to allow a context to operate with relocate disabled
from Ian Munsie
- Check periodically the coherent platform function's state from
Christophe Lombard
Freescale:
- Updates from Scott: "Contains 86xx fixes, minor device tree fixes,
an erratum workaround, and a kconfig dependency fix."
* tag 'powerpc-4.7-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (192 commits)
powerpc/86xx: Fix PCI interrupt map definition
powerpc/86xx: Move pci1 definition to the include file
powerpc/fsl: Fix build of the dtb embedded kernel images
powerpc/fsl: Fix rcpm compatible string
powerpc/fsl: Remove FSL_SOC dependency from FSL_LBC
powerpc/fsl-pci: Add a workaround for PCI 5 errata
powerpc/fsl: Fix SPI compatible on t208xrdb and t1040rdb
powerpc/powernv/npu: Add PE to PHB's list
powerpc/powernv: Fix insufficient memory allocation
powerpc/iommu: Remove the dependency on EEH struct in DDW mechanism
Revert "powerpc/eeh: Fix crash in eeh_add_device_early() on Cell"
powerpc/eeh: Drop unnecessary label in eeh_pe_change_owner()
powerpc/eeh: Ignore handlers in eeh_pe_reset_and_recover()
powerpc/eeh: Restore initial state in eeh_pe_reset_and_recover()
powerpc/eeh: Don't report error in eeh_pe_reset_and_recover()
Revert "powerpc/powernv: Exclude root bus in pnv_pci_reset_secondary_bus()"
powerpc/powernv/npu: Enable NVLink pass through
powerpc/powernv/npu: Rework TCE Kill handling
powerpc/powernv/npu: Add set/unset window helpers
powerpc/powernv/ioda2: Export debug helper pe_level_printk()
...
This patch fix spelling typos in printk from various part
of the codes.
Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
As sparse suggests, these should be made static.
Signed-off-by: Daniel Axtens <dja@axtens.net>
Reviewed-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Reviewed-by: Stewart Smith <stewart@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Before 69111bac42 ("powerpc: Replace __get_cpu_var uses"), in
save_mce_event, index got the value of mce_nest_count, and
mce_nest_count was incremented *after* index was set.
However, that patch changed the behaviour so that mce_nest count was
incremented *before* setting index.
This causes an off-by-one error, as get_mce_event sets index as
mce_nest_count - 1 before reading mce_event. Thus get_mce_event reads
bogus data, causing warnings like
"Machine Check Exception, Unknown event version 0 !"
and breaking MCEs handling.
Restore the old behaviour and unbreak MCE handling by subtracting one
from the newly incremented value.
The same broken change occured in machine_check_queue_event (which set
a queue read by machine_check_process_queued_event). Fix that too,
unbreaking printing of MCE information.
Fixes: 69111bac42 ("powerpc: Replace __get_cpu_var uses")
CC: stable@vger.kernel.org
CC: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
CC: Christoph Lameter <cl@linux.com>
Signed-off-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This still has not been merged and now powerpc is the only arch that does
not have this change. Sorry about missing linuxppc-dev before.
V2->V2
- Fix up to work against 3.18-rc1
__get_cpu_var() is used for multiple purposes in the kernel source. One of
them is address calculation via the form &__get_cpu_var(x). This calculates
the address for the instance of the percpu variable of the current processor
based on an offset.
Other use cases are for storing and retrieving data from the current
processors percpu area. __get_cpu_var() can be used as an lvalue when
writing data or on the right side of an assignment.
__get_cpu_var() is defined as :
__get_cpu_var() always only does an address determination. However, store
and retrieve operations could use a segment prefix (or global register on
other platforms) to avoid the address calculation.
this_cpu_write() and this_cpu_read() can directly take an offset into a
percpu area and use optimized assembly code to read and write per cpu
variables.
This patch converts __get_cpu_var into either an explicit address
calculation using this_cpu_ptr() or into a use of this_cpu operations that
use the offset. Thereby address calculations are avoided and less registers
are used when code is generated.
At the end of the patch set all uses of __get_cpu_var have been removed so
the macro is removed too.
The patch set includes passes over all arches as well. Once these operations
are used throughout then specialized macros can be defined in non -x86
arches as well in order to optimize per cpu access by f.e. using a global
register that may be set to the per cpu base.
Transformations done to __get_cpu_var()
1. Determine the address of the percpu instance of the current processor.
DEFINE_PER_CPU(int, y);
int *x = &__get_cpu_var(y);
Converts to
int *x = this_cpu_ptr(&y);
2. Same as #1 but this time an array structure is involved.
DEFINE_PER_CPU(int, y[20]);
int *x = __get_cpu_var(y);
Converts to
int *x = this_cpu_ptr(y);
3. Retrieve the content of the current processors instance of a per cpu
variable.
DEFINE_PER_CPU(int, y);
int x = __get_cpu_var(y)
Converts to
int x = __this_cpu_read(y);
4. Retrieve the content of a percpu struct
DEFINE_PER_CPU(struct mystruct, y);
struct mystruct x = __get_cpu_var(y);
Converts to
memcpy(&x, this_cpu_ptr(&y), sizeof(x));
5. Assignment to a per cpu variable
DEFINE_PER_CPU(int, y)
__get_cpu_var(y) = x;
Converts to
__this_cpu_write(y, x);
6. Increment/Decrement etc of a per cpu variable
DEFINE_PER_CPU(int, y);
__get_cpu_var(y)++
Converts to
__this_cpu_inc(y)
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
CC: Paul Mackerras <paulus@samba.org>
Signed-off-by: Christoph Lameter <cl@linux.com>
[mpe: Fix build errors caused by set/or_softirq_pending(), and rework
assignment in __set_breakpoint() to use memcpy().]
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>
Huge Dickins reported an issue that b5ff4211a8
"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>
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>
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>
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>
