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The kernel thread function ps3_probe_thread() invokes the try_to_freeze()
in its loop. But all the kernel threads are non-freezable by default.
So if we want to make a kernel thread to be freezable, we have to invoke
set_freezable() explicitly.
Signed-off-by: Kevin Hao <haokexin@gmail.com>
Acked-by: Geoff Levand <geoff@infradead.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231221044510.1802429-4-haokexin@gmail.com
A freezable kernel thread can enter frozen state during freezing by
either calling try_to_freeze() or using wait_event_freezable() and its
variants. So for the following snippet of code in a kernel thread loop:
wait_event_interruptible();
try_to_freeze();
We can change it to a simple wait_event_freezable() and then eliminate
a function call.
Signed-off-by: Kevin Hao <haokexin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231221044510.1802429-3-haokexin@gmail.com
The kernel thread function agent_thread_fn() invokes the try_to_freeze()
in its loop. But all the kernel threads are non-freezable by default.
So if we want to make a kernel thread to be freezable, we have to invoke
set_freezable() explicitly.
Signed-off-by: Kevin Hao <haokexin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231221044510.1802429-2-haokexin@gmail.com
Then when specifying '-d' for kexec_file_load interface, loaded locations
of kernel/initrd/cmdline etc can be printed out to help debug.
Here replace pr_debug() with the newly added kexec_dprintk() in kexec_file
loading related codes.
Link: https://lkml.kernel.org/r/20231213055747.61826-7-bhe@redhat.com
Signed-off-by: Baoquan He <bhe@redhat.com>
Cc: Conor Dooley <conor@kernel.org>
Cc: Joe Perches <joe@perches.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The cleanup for the CONFIG_KEXEC Kconfig logic accidentally changed the
'depends on CRYPTO=y' dependency to a plain 'depends on CRYPTO', which
causes a link failure when all the crypto support is in a loadable module
and kexec_file support is built-in:
x86_64-linux-ld: vmlinux.o: in function `__x64_sys_kexec_file_load':
(.text+0x32e30a): undefined reference to `crypto_alloc_shash'
x86_64-linux-ld: (.text+0x32e58e): undefined reference to `crypto_shash_update'
x86_64-linux-ld: (.text+0x32e6ee): undefined reference to `crypto_shash_final'
Both s390 and x86 have this problem, while ppc64 and riscv have the
correct dependency already. On riscv, the dependency is only used for the
purgatory, not for the kexec_file code itself, which may be a bit
surprising as it means that with CONFIG_CRYPTO=m, it is possible to enable
KEXEC_FILE but then the purgatory code is silently left out.
Move this into the common Kconfig.kexec file in a way that is correct
everywhere, using the dependency on CRYPTO_SHA256=y only when the
purgatory code is available. This requires reversing the dependency
between ARCH_SUPPORTS_KEXEC_PURGATORY and KEXEC_FILE, but the effect
remains the same, other than making riscv behave like the other ones.
On s390, there is an additional dependency on CRYPTO_SHA256_S390, which
should technically not be required but gives better performance. Remove
this dependency here, noting that it was not present in the initial
Kconfig code but was brought in without an explanation in commit
71406883fd357 ("s390/kexec_file: Add kexec_file_load system call").
[arnd@arndb.de: fix riscv build]
Link: https://lkml.kernel.org/r/67ddd260-d424-4229-a815-e3fcfb864a77@app.fastmail.com
Link: https://lkml.kernel.org/r/20231023110308.1202042-1-arnd@kernel.org
Fixes: 6af5138083005 ("x86/kexec: refactor for kernel/Kconfig.kexec")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Eric DeVolder <eric_devolder@yahoo.com>
Tested-by: Eric DeVolder <eric_devolder@yahoo.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Conor Dooley <conor@kernel.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
fsl,tmu-calibration is defined as a u32 matrix in
Documentation/devicetree/bindings/thermal/qoriq-thermal.yaml.
Use matching property syntax. No functional changes.
Signed-off-by: David Heidelberg <david@ixit.cz>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231212184515.82886-2-david@ixit.cz
- Fix a bug where heavy VAS (accelerator) usage could race with partition
migration and prevent the migration from completing.
- Update MAINTAINERS to add Aneesh & Naveen.
Thanks to: Haren Myneni
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Merge tag 'powerpc-6.7-5' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux
Pull powerpc fixes from Michael Ellerman:
- Fix a bug where heavy VAS (accelerator) usage could race with
partition migration and prevent the migration from completing.
- Update MAINTAINERS to add Aneesh & Naveen.
Thanks to Haren Myneni.
* tag 'powerpc-6.7-5' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
MAINTAINERS: powerpc: Add Aneesh & Naveen
powerpc/pseries/vas: Migration suspend waits for no in-progress open windows
This code is rarely (never?) enabled by distros, and it hasn't caught
anything in decades. Let's kill off this legacy debug code.
Suggested-by: Linus Torvalds <torvalds@linuxfoundation.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Merge a branch containing SMP topology updates from Srikar, purely so we can
include the cover letter which has a lot of good detail here:
PowerVM systems configured in shared processors mode have some unique
challenges. Some device-tree properties will be missing on a shared
processor. Hence some sched domains may not make sense for shared processor
systems.
Most shared processor systems are over-provisioned. Underlying PowerVM
Hypervisor would schedule at a Big Core (SMT8) granularity. The most recent
power processors support two almost independent cores. In a lightly loaded
condition, it helps the overall system performance if we pack to lesser number
of Big Cores.
Since each thread-group is independent, running threads on both the
thread-groups of a SMT8 core, should have a minimal adverse impact in
non over provisioned scenarios. These changes in this patchset will not
affect in the over provisioned scenario. If there are more threads than
SMT domains, then asym_packing will not kick-in.
System Configuration
type=Shared mode=Uncapped smt=8 lcpu=96 mem=1066409344 kB cpus=96 ent=64.00
So *64 Entitled cores/ 96 Virtual processor* Scenario
lscpu
Architecture: ppc64le
Byte Order: Little Endian
CPU(s): 768
On-line CPU(s) list: 0-767
Model name: POWER10 (architected), altivec supported
Model: 2.0 (pvr 0080 0200)
Thread(s) per core: 8
Core(s) per socket: 16
Socket(s): 6
Hypervisor vendor: pHyp
Virtualization type: para
L1d cache: 6 MiB (192 instances)
L1i cache: 9 MiB (192 instances)
NUMA node(s): 6
NUMA node0 CPU(s): 0-7,32-39,80-87,128-135,176-183,224-231,272-279,320-327,368-375,416-423,464-471,512-519,560-567,608-615,656-663,704-711,752-759
NUMA node1 CPU(s): 8-15,40-47,88-95,136-143,184-191,232-239,280-287,328-335,376-383,424-431,472-479,520-527,568-575,616-623,664-671,712-719,760-767
NUMA node4 CPU(s): 64-71,112-119,160-167,208-215,256-263,304-311,352-359,400-407,448-455,496-503,544-551,592-599,640-647,688-695,736-743
NUMA node5 CPU(s): 16-23,48-55,96-103,144-151,192-199,240-247,288-295,336-343,384-391,432-439,480-487,528-535,576-583,624-631,672-679,720-727
NUMA node6 CPU(s): 72-79,120-127,168-175,216-223,264-271,312-319,360-367,408-415,456-463,504-511,552-559,600-607,648-655,696-703,744-751
NUMA node7 CPU(s): 24-31,56-63,104-111,152-159,200-207,248-255,296-303,344-351,392-399,440-447,488-495,536-543,584-591,632-639,680-687,728-735
ebizzy -t 32 -S 200 (5 iterations) Records per second. (Higher is better)
Kernel N Min Max Median Avg Stddev %Change
6.6.0-rc3 5 3840178 4059268 3978042 3973936.6 84264.456
+patch 5 3768393 3927901 3874994 3854046 71532.926 -3.01692
>From lparstat (when the workload stabilized)
Kernel %user %sys %wait %idle physc %entc lbusy app vcsw phint
6.6.0-rc3 4.16 0.00 0.00 95.84 26.06 40.72 4.16 69.88 276906989 578
+patch 4.16 0.00 0.00 95.83 17.70 27.66 4.17 78.26 70436663 119
ebizzy -t 128 -S 200 (5 iterations) Records per second. (Higher is better)
Kernel N Min Max Median Avg Stddev %Change
6.6.0-rc3 5 5520692 5981856 5717709 5727053.2 176093.2
+patch 5 5305888 6259610 5854590 5843311 375917.03 2.02998
>From lparstat (when the workload stabilized)
Kernel %user %sys %wait %idle physc %entc lbusy app vcsw phint
6.6.0-rc3 16.66 0.00 0.00 83.33 45.49 71.08 16.67 50.50 288778533 581
+patch 16.65 0.00 0.00 83.35 30.15 47.11 16.65 65.76 85196150 133
ebizzy -t 512 -S 200 (5 iterations) Records per second. (Higher is better)
Kernel N Min Max Median Avg Stddev %Change
6.6.0-rc3 5 19563921 20049955 19701510 19728733 198295.18
+patch 5 19455992 20176445 19718427 19832017 304094.05 0.523521
>From lparstat (when the workload stabilized)
%Kernel user %sys %wait %idle physc %entc lbusy app vcsw phint
66.6.0-rc3 6.44 0.01 0.00 33.55 94.14 147.09 66.45 1.33 313345175 621
6+patch 6.44 0.01 0.00 33.55 94.15 147.11 66.45 1.33 109193889 309
System Configuration
type=Shared mode=Uncapped smt=8 lcpu=40 mem=1067539392 kB cpus=96 ent=40.00
So *40 Entitled cores/ 40 Virtual processor* Scenario
lscpu
Architecture: ppc64le
Byte Order: Little Endian
CPU(s): 320
On-line CPU(s) list: 0-319
Model name: POWER10 (architected), altivec supported
Model: 2.0 (pvr 0080 0200)
Thread(s) per core: 8
Core(s) per socket: 10
Socket(s): 4
Hypervisor vendor: pHyp
Virtualization type: para
L1d cache: 2.5 MiB (80 instances)
L1i cache: 3.8 MiB (80 instances)
NUMA node(s): 4
NUMA node0 CPU(s): 0-7,32-39,64-71,96-103,128-135,160-167,192-199,224-231,256-263,288-295
NUMA node1 CPU(s): 8-15,40-47,72-79,104-111,136-143,168-175,200-207,232-239,264-271,296-303
NUMA node4 CPU(s): 16-23,48-55,80-87,112-119,144-151,176-183,208-215,240-247,272-279,304-311
NUMA node5 CPU(s): 24-31,56-63,88-95,120-127,152-159,184-191,216-223,248-255,280-287,312-319
ebizzy -t 32 -S 200 (5 iterations) Records per second. (Higher is better)
Kernel N Min Max Median Avg Stddev %Change
6.6.0-rc3 5 3535518 3864532 3745967 3704233.2 130216.76
+patch 5 3608385 3708026 3649379 3651596.6 37862.163 -1.42099
%Kernel user %sys %wait %idle physc %entc lbusy app vcsw phint
6.6.0-rc3 10.00 0.01 0.00 89.99 22.98 57.45 10.01 41.01 1135139 262
+patch 10.00 0.00 0.00 90.00 16.95 42.37 10.00 47.05 925561 19
ebizzy -t 64 -S 200 (5 iterations) Records per second. (Higher is better)
Kernel N Min Max Median Avg Stddev %Change
6.6.0-rc3 5 4434984 4957281 4548786 4591298.2 211770.2
+patch 5 4461115 4835167 4544716 4607795.8 151474.85 0.359323
%Kernel user %sys %wait %idle physc %entc lbusy app vcsw phint
6.6.0-rc3 20.01 0.00 0.00 79.99 38.22 95.55 20.01 25.77 1287553 265
+patch 19.99 0.00 0.00 80.01 25.55 63.88 19.99 38.44 1077341 20
ebizzy -t 256 -S 200 (5 iterations) Records per second. (Higher is better)
Kernel N Min Max Median Avg Stddev %Change
6.6.0-rc3 5 8850648 8982659 8951911 8936869.2 52278.031
+patch 5 8751038 9060510 8981409 8942268.4 117070.6 0.0604149
%Kernel user %sys %wait %idle physc %entc lbusy app vcsw phint
6.6.0-rc3 80.02 0.01 0.01 19.96 40.00 100.00 80.03 24.00 1597665 276
+patch 80.02 0.01 0.01 19.96 40.00 100.00 80.03 23.99 1383921 63
Observation:
We are able to see Improvement in ebizzy throughput even with lesser
core utilization (almost half the core utilization) in low utilization
scenarios while still retaining throughput in mid and higher utilization
scenarios.
Note: The numbers are with Uncapped + no-noise case. In the Capped and/or
noise case, due to contention on the Cores, the numbers are expected to
further improve.
Note: The numbers included (sched/fair: Enable group_asym_packing in find_idlest_group)
https://lore.kernel.org/all/20231018155036.2314342-1-srikar@linux.vnet.ibm.com/
Currently there are four Powerpc specific sched topologies. These are
all statically defined. However not all these topologies are used by
all Powerpc systems.
To avoid unnecessary degenerations by the scheduler, masks and flags
are compared. However if the sched topologies are build dynamically then
the code is simpler and there are greater chances of avoiding
degenerations.
Note:
Even X86 builds its sched topologies dynamically and proposed changes
are very similar to the way X86 is building its topologies.
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231214180720.310852-6-srikar@linux.vnet.ibm.com
PowerVM Hypervisor will schedule at a core granularity. However each
core can have more than one thread_groups. For better utilization in
case of a shared processor, its preferable for the scheduler to pack to
the lowest core. However there is no benefit of moving a thread between
two thread groups of the same core.
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231214180720.310852-5-srikar@linux.vnet.ibm.com
There are some variables that are only updated at boot time.
So add __ro_after_init attribute to such variables
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231214180720.310852-4-srikar@linux.vnet.ibm.com
Like L2-cache info, coregroup information which is used to determine MC
sched domains is only present on dedicated LPARs. i.e PowerVM doesn't
export coregroup information for shared processor LPARs. Hence disable
creating MC domains on shared LPAR Systems.
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231214180720.310852-3-srikar@linux.vnet.ibm.com
If there are shared processor LPARs, underlying Hypervisor can have more
virtual cores to handle than actual physical cores.
Starting with Power 9, a big core (aka SMT8 core) has 2 nearly
independent thread groups. On a shared processors LPARs, it helps to
pack threads to lesser number of cores so that the overall system
performance and utilization improves. PowerVM schedules at a big core
level. Hence packing to fewer cores helps.
Since each thread-group is independent, running threads on both the
thread-groups of a SMT8 core, should have a minimal adverse impact in
non over provisioned scenarios. These changes in this patchset will not
affect in the over provisioned scenario. If there are more threads than
SMT domains, then asym_packing will not kick-in
For example: Lets says there are two 8-core Shared LPARs that are
actually sharing a 8 Core shared physical pool, each running 8 threads
each. Then Consolidating 8 threads to 4 cores on each LPAR would help
them to perform better. This is because each of the LPAR will get
100% time to run applications and there will no switching required by
the Hypervisor.
To achieve this, enable SD_ASYM_PACKING flag at CACHE, MC and DIE level
when the system is running in shared processor mode and has big cores.
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231214180720.310852-2-srikar@linux.vnet.ibm.com
No functional change in this patch. A helper is added to find if
vcpu is dispatched by hypervisor. Use that instead of opencoding.
Also clarify some of the comments.
Signed-off-by: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231114071219.198222-1-aneesh.kumar@linux.ibm.com
CPU features can be determined in makedumpfile, using
'cur_cpu_spec.cpu_features'.
This provides more data to makedumpfile about the crashed system, and
can help in filtering the vmcore accordingly.
Signed-off-by: Aditya Gupta <adityag@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20230920105706.853626-2-adityag@linux.ibm.com
kasprintf() returns a pointer to dynamically allocated memory
which can be NULL upon failure.
Fixes: 885dcd709ba9 ("powerpc/perf: Add nest IMC PMU support")
Signed-off-by: Kunwu Chan <chentao@kylinos.cn>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231126093719.1440305-1-chentao@kylinos.cn
kasprintf() returns a pointer to dynamically allocated memory
which can be NULL upon failure.
Fixes: b9ef7b4b867f ("powerpc: Convert to using %pOFn instead of device_node.name")
Signed-off-by: Kunwu Chan <chentao@kylinos.cn>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231126095739.1501990-1-chentao@kylinos.cn
kasprintf() returns a pointer to dynamically allocated memory
which can be NULL upon failure.
Fixes: 2717a33d6074 ("powerpc/opal-irqchip: Use interrupt names if present")
Signed-off-by: Kunwu Chan <chentao@kylinos.cn>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231127030755.1546750-1-chentao@kylinos.cn
kasprintf() returns a pointer to dynamically allocated memory
which can be NULL upon failure.
Add a null pointer check, and release 'ent' to avoid memory leaks.
Fixes: bfd2f0d49aef ("powerpc/powernv: Get rid of old scom_controller abstraction")
Signed-off-by: Kunwu Chan <chentao@kylinos.cn>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231208085937.107210-1-chentao@kylinos.cn
kasprintf() returns a pointer to dynamically allocated memory
which can be NULL upon failure. Ensure the allocation was successful
by checking the pointer validity.
Suggested-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Suggested-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Kunwu Chan <chentao@kylinos.cn>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231204023223.2447523-1-chentao@kylinos.cn
The hypervisor returns migration failure if all VAS windows are not
closed. During pre-migration stage, vas_migration_handler() sets
migration_in_progress flag and closes all windows from the list.
The allocate VAS window routine checks the migration flag, setup
the window and then add it to the list. So there is possibility of
the migration handler missing the window that is still in the
process of setup.
t1: Allocate and open VAS t2: Migration event
window
lock vas_pseries_mutex
If migration_in_progress set
unlock vas_pseries_mutex
return
open window HCALL
unlock vas_pseries_mutex
Modify window HCALL lock vas_pseries_mutex
setup window migration_in_progress=true
Closes all windows from the list
// May miss windows that are
// not in the list
unlock vas_pseries_mutex
lock vas_pseries_mutex return
if nr_closed_windows == 0
// No DLPAR CPU or migration
add window to the list
// Window will be added to the
// list after the setup is completed
unlock vas_pseries_mutex
return
unlock vas_pseries_mutex
Close VAS window
// due to DLPAR CPU or migration
return -EBUSY
This patch resolves the issue with the following steps:
- Set the migration_in_progress flag without holding mutex.
- Introduce nr_open_wins_progress counter in VAS capabilities
struct
- This counter tracks the number of open windows are still in
progress
- The allocate setup window thread closes windows if the migration
is set and decrements nr_open_window_progress counter
- The migration handler waits for no in-progress open windows.
The code flow with the fix is as follows:
t1: Allocate and open VAS t2: Migration event
window
lock vas_pseries_mutex
If migration_in_progress set
unlock vas_pseries_mutex
return
open window HCALL
nr_open_wins_progress++
// Window opened, but not
// added to the list yet
unlock vas_pseries_mutex
Modify window HCALL migration_in_progress=true
setup window lock vas_pseries_mutex
Closes all windows from the list
While nr_open_wins_progress {
unlock vas_pseries_mutex
lock vas_pseries_mutex sleep
if nr_closed_windows == 0 // Wait if any open window in
or migration is not started // progress. The open window
// No DLPAR CPU or migration // thread closes the window without
add window to the list // adding to the list and return if
nr_open_wins_progress-- // the migration is in progress.
unlock vas_pseries_mutex
return
Close VAS window
nr_open_wins_progress--
unlock vas_pseries_mutex
return -EBUSY lock vas_pseries_mutex
}
unlock vas_pseries_mutex
return
Fixes: 37e6764895ef ("powerpc/pseries/vas: Add VAS migration handler")
Signed-off-by: Haren Myneni <haren@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231125235104.3405008-1-haren@linux.ibm.com
Commit d49a0626216b95 ("arch: Introduce CONFIG_FUNCTION_ALIGNMENT")
introduced a generic function-alignment infrastructure. Move to using
FUNCTION_ALIGNMENT_4B on powerpc, to use the same alignment as that of
the existing _GLOBAL macro.
Signed-off-by: Sathvika Vasireddy <sv@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/21892186ec44abe24df0daf64f577dac0e78783f.1702045299.git.naveen@kernel.org
Until now the papr_sysparm APIs have been kernel-internal. But user
space needs access to PAPR system parameters too. The only method
available to user space today to get or set system parameters is using
sys_rtas() and /dev/mem to pass RTAS-addressable buffers between user
space and firmware. This is incompatible with lockdown and should be
deprecated.
So provide an alternative ABI to user space in the form of a
/dev/papr-sysparm character device with just two ioctl commands (get
and set). The data payloads involved are small enough to fit in the
ioctl argument buffer, making the code relatively simple.
Exposing the system parameters through sysfs has been considered but
it would be too awkward:
* The kernel currently does not have to contain an exhaustive list of
defined system parameters. This is a convenient property to maintain
because we don't have to update the kernel whenever a new parameter
is added to PAPR. Exporting a named attribute in sysfs for each
parameter would negate this.
* Some system parameters are text-based and some are not.
* Retrieval of at least one system parameter requires input data,
which a simple read-oriented interface can't support.
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231212-papr-sys_rtas-vs-lockdown-v6-11-e9eafd0c8c6c@linux.ibm.com
The ability to get and set system parameters will be exposed to user
space, so let's get a little more strict about malformed
papr_sysparm_buf objects.
* Create accessors for the length field of struct papr_sysparm_buf.
The length is always stored in MSB order and this is better than
spreading the necessary conversions all over.
* Reject attempts to submit invalid buffers to RTAS.
* Warn if RTAS returns a buffer with an invalid length, clamping the
returned length to a safe value that won't overrun the buffer.
These are meant as precautionary measures to mitigate both firmware
and kernel bugs in this area, should they arise, but I am not aware of
any.
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231212-papr-sys_rtas-vs-lockdown-v6-10-e9eafd0c8c6c@linux.ibm.com
PowerVM LPARs may retrieve Vital Product Data (VPD) for system
components using the ibm,get-vpd RTAS function.
We can expose this to user space with a /dev/papr-vpd character
device, where the programming model is:
struct papr_location_code plc = { .str = "", }; /* obtain all VPD */
int devfd = open("/dev/papr-vpd", O_RDONLY);
int vpdfd = ioctl(devfd, PAPR_VPD_CREATE_HANDLE, &plc);
size_t size = lseek(vpdfd, 0, SEEK_END);
char *buf = malloc(size);
pread(devfd, buf, size, 0);
When a file descriptor is obtained from ioctl(PAPR_VPD_CREATE_HANDLE),
the file contains the result of a complete ibm,get-vpd sequence. The
file contents are immutable from the POV of user space. To get a new
view of the VPD, the client must create a new handle.
This design choice insulates user space from most of the complexities
that ibm,get-vpd brings:
* ibm,get-vpd must be called more than once to obtain complete
results.
* Only one ibm,get-vpd call sequence should be in progress at a time;
interleaved sequences will disrupt each other. Callers must have a
protocol for serializing their use of the function.
* A call sequence in progress may receive a "VPD changed, try again"
status, requiring the client to abandon the sequence and start
over.
The memory required for the VPD buffers seems acceptable, around 20KB
for all VPD on one of my systems. And the value of the
/rtas/ibm,vpd-size DT property (the estimated maximum size of VPD) is
consistently 300KB across various systems I've checked.
I've implemented support for this new ABI in the rtas_get_vpd()
function in librtas, which the vpdupdate command currently uses to
populate its VPD database. I've verified that an unmodified vpdupdate
binary generates an identical database when using a librtas.so that
prefers the new ABI.
Along with the papr-vpd.h header exposed to user space, this
introduces a common papr-miscdev.h uapi header to share a base ioctl
ID with similar drivers to come.
Tested-by: Michal Suchánek <msuchanek@suse.de>
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231212-papr-sys_rtas-vs-lockdown-v6-9-e9eafd0c8c6c@linux.ibm.com
If the function descriptor has a populated lock member, then callers
are required to hold it across calls. Now that the firmware activation
sequence is appropriately guarded, we can warn when the requirement
isn't satisfied.
__do_enter_rtas_trace() gets reorganized a bit as a result of
performing the function descriptor lookup unconditionally now.
Reviewed-by: "Aneesh Kumar K.V (IBM)" <aneesh.kumar@kernel.org>
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231212-papr-sys_rtas-vs-lockdown-v6-8-e9eafd0c8c6c@linux.ibm.com
Use rtas_ibm_activate_firmware_lock to prevent interleaving call
sequences of the ibm,activate-firmware RTAS function, which typically
requires multiple calls to complete the update. While the spec does
not specifically prohibit interleaved sequences, there's almost
certainly no advantage to allowing them.
Reviewed-by: "Aneesh Kumar K.V (IBM)" <aneesh.kumar@kernel.org>
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231212-papr-sys_rtas-vs-lockdown-v6-7-e9eafd0c8c6c@linux.ibm.com
On RTAS platforms there is a general restriction that the OS must not
enter RTAS on more than one CPU at a time. This low-level
serialization requirement is satisfied by holding a spin
lock (rtas_lock) across most RTAS function invocations.
However, some pseries RTAS functions require multiple successive calls
to complete a logical operation. Beginning a new call sequence for such a
function may disrupt any other sequences of that function already in
progress. Safe and reliable use of these functions effectively
requires higher-level serialization beyond what is already done at the
level of RTAS entry and exit.
Where a sequence-based RTAS function is invoked only through
sys_rtas(), with no in-kernel users, there is no issue as far as the
kernel is concerned. User space is responsible for appropriately
serializing its call sequences. (Whether user space code actually
takes measures to prevent sequence interleaving is another matter.)
Examples of such functions currently include ibm,platform-dump and
ibm,get-vpd.
But where a sequence-based RTAS function has both user space and
in-kernel uesrs, there is a hazard. Even if the in-kernel call sites
of such a function serialize their sequences correctly, a user of
sys_rtas() can invoke the same function at any time, potentially
disrupting a sequence in progress.
So in order to prevent disruption of kernel-based RTAS call sequences,
they must serialize not only with themselves but also with sys_rtas()
users, somehow. Preferably without adding more function-specific hacks
to sys_rtas(). This is a prerequisite for adding an in-kernel call
sequence of ibm,get-vpd, which is in a change to follow.
Note that it has never been feasible for the kernel to prevent
sys_rtas()-based sequences from being disrupted because control
returns to user space on every call. sys_rtas()-based users of these
functions have always been, and continue to be, responsible for
coordinating their call sequences with other users, even those which
may invoke the RTAS functions through less direct means than
sys_rtas(). This is an unavoidable consequence of exposing
sequence-based RTAS functions through sys_rtas().
* Add an optional mutex member to struct rtas_function.
* Statically define a mutex for each RTAS function with known call
sequence serialization requirements, and assign its address to the
.lock member of the corresponding function table entry, along with
justifying commentary.
* In sys_rtas(), if the table entry for the RTAS function being
called has a populated lock member, acquire it before taking
rtas_lock and entering RTAS.
* Kernel-based RTAS call sequences are expected to access the
appropriate mutex explicitly by name. For example, a user of the
ibm,activate-firmware RTAS function would do:
int token = rtas_function_token(RTAS_FN_IBM_ACTIVATE_FIRMWARE);
int fwrc;
mutex_lock(&rtas_ibm_activate_firmware_lock);
do {
fwrc = rtas_call(token, 0, 1, NULL);
} while (rtas_busy_delay(fwrc));
mutex_unlock(&rtas_ibm_activate_firmware_lock);
There should be no perceivable change introduced here except that
concurrent callers of the same RTAS function via sys_rtas() may block
on a mutex instead of spinning on rtas_lock.
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231212-papr-sys_rtas-vs-lockdown-v6-6-e9eafd0c8c6c@linux.ibm.com
The rtas system call handler sys_rtas() delegates certain input
validation steps to a helper function: block_rtas_call(). One of these
steps ensures that the user-supplied token value maps to a known RTAS
function. This is done by performing a "reverse" token-to-function
lookup via rtas_token_to_function_untrusted() to obtain an
rtas_function object.
In changes to come, sys_rtas() itself will need the function
descriptor for the token. To prepare:
* Move the lookup and validation up into sys_rtas() and pass the
resulting rtas_function pointer to block_rtas_call(), which is
otherwise unconcerned with the token value.
* Change block_rtas_call() to report the RTAS function name instead of
the token value on validation failures, since it can now rely on
having a valid function descriptor.
One behavior change is that sys_rtas() now silently errors out when
passed a bad token, before calling block_rtas_call(). So we will no
longer log "RTAS call blocked - exploit attempt?" on invalid
tokens. This is consistent with how sys_rtas() currently handles other
"metadata" (nargs and nret), while block_rtas_call() is primarily
concerned with validating the arguments to be passed to specific RTAS
functions.
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231212-papr-sys_rtas-vs-lockdown-v6-5-e9eafd0c8c6c@linux.ibm.com
Not all of the generic RTAS function statuses specified in PAPR have
symbolic constants and descriptions in rtas.h. Fix this, providing a
little more background, slightly updating the existing wording, and
improving the formatting.
Reviewed-by: "Aneesh Kumar K.V (IBM)" <aneesh.kumar@kernel.org>
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231212-papr-sys_rtas-vs-lockdown-v6-4-e9eafd0c8c6c@linux.ibm.com
Enabling any of the powerpc:rtas_* tracepoints at boot is likely to
result in an oops on RTAS platforms. For example, booting a QEMU
pseries model with 'trace_event=powerpc:rtas_input' in the command
line leads to:
BUG: Kernel NULL pointer dereference on read at 0x00000008
Oops: Kernel access of bad area, sig: 7 [#1]
NIP [c00000000004231c] do_enter_rtas+0x1bc/0x460
LR [c00000000004231c] do_enter_rtas+0x1bc/0x460
Call Trace:
do_enter_rtas+0x1bc/0x460 (unreliable)
rtas_call+0x22c/0x4a0
rtas_get_boot_time+0x80/0x14c
read_persistent_clock64+0x124/0x150
read_persistent_wall_and_boot_offset+0x28/0x58
timekeeping_init+0x70/0x348
start_kernel+0xa0c/0xc1c
start_here_common+0x1c/0x20
(This is preceded by a warning for the failed lookup in
rtas_token_to_function().)
This happens when __do_enter_rtas_trace() attempts a token to function
descriptor lookup before the xarray containing the mappings has been
set up.
Fall back to linear scan of the table if rtas_token_to_function_xarray
is empty.
Fixes: 24098f580e2b ("powerpc/rtas: add tracepoints around RTAS entry")
Reviewed-by: "Aneesh Kumar K.V (IBM)" <aneesh.kumar@kernel.org>
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231212-papr-sys_rtas-vs-lockdown-v6-3-e9eafd0c8c6c@linux.ibm.com
Add a convenience macro for iterating over every element of the
internal function table and convert the one site that can use it. An
additional user of the macro is anticipated in changes to follow.
Reviewed-by: "Aneesh Kumar K.V (IBM)" <aneesh.kumar@kernel.org>
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231212-papr-sys_rtas-vs-lockdown-v6-2-e9eafd0c8c6c@linux.ibm.com
rtas_token_to_function() WARNs when passed an invalid token; it's
meant to catch bugs in kernel-based users of RTAS functions. However,
user space controls the token value passed to rtas_token_to_function()
by block_rtas_call(), so user space with sufficient privilege to use
sys_rtas() can trigger the warnings at will:
unexpected failed lookup for token 2048
WARNING: CPU: 20 PID: 2247 at arch/powerpc/kernel/rtas.c:556
rtas_token_to_function+0xfc/0x110
...
NIP rtas_token_to_function+0xfc/0x110
LR rtas_token_to_function+0xf8/0x110
Call Trace:
rtas_token_to_function+0xf8/0x110 (unreliable)
sys_rtas+0x188/0x880
system_call_exception+0x268/0x530
system_call_common+0x160/0x2c4
It's desirable to continue warning on bogus tokens in
rtas_token_to_function(). Currently it is used to look up RTAS
function descriptors when tracing, where we know there has to have
been a successful descriptor lookup by different means already, and it
would be a serious inconsistency for the reverse lookup to fail.
So instead of weakening rtas_token_to_function()'s contract by
removing the warnings, introduce rtas_token_to_function_untrusted(),
which has no opinion on failed lookups. Convert block_rtas_call() and
rtas_token_to_function() to use it.
Fixes: 8252b88294d2 ("powerpc/rtas: improve function information lookups")
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231212-papr-sys_rtas-vs-lockdown-v6-1-e9eafd0c8c6c@linux.ibm.com
To access hv-gpci kernel interface files data, the
"Enable Performance Information Collection" option has to be set
in hmc. Incase that option is not set and user try to read
the interface files, it should give error message as
operation not permitted.
Result of accessing added interface files with disabled
performance collection option:
[command]# cat processor_bus_topology
cat: processor_bus_topology: Operation not permitted
[command]# cat processor_config
cat: processor_config: Operation not permitted
[command]# cat affinity_domain_via_domain
cat: affinity_domain_via_domain: Operation not permitted
[command]# cat affinity_domain_via_virtual_processor
cat: affinity_domain_via_virtual_processor: Operation not permitted
[command]# cat affinity_domain_via_partition
Based on above result there is no error message when reading
affinity_domain_via_partition file because of missing
check for failed hcall. Fix this issue by adding
a check in the start of affinity_domain_via_partition_show
function, to return error incase hcall fails, with error type
other then H_PARAMETER.
Fixes: a15e0d6a6929 ("powerpc/hv_gpci: Add sysfs file inside hv_gpci device to show affinity domain via partition information")
Reported-by: Disha Goel <disgoel@linux.vnet.ibm.com>
Signed-off-by: Kajol Jain <kjain@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231116122033.160964-1-kjain@linux.ibm.com
This is required for the later patch "Makefile.extrawarn: turn on
missing-prototypes globally".
Link: https://lkml.kernel.org/r/20231127132809.45c2b398@canb.auug.org.au
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
IA-64 was the only architecture which selected ARCH_TASK_STRUCT_ON_STACK.
IA-64 was removed with commit cf8e8658100d ("arch: Remove Itanium (IA-64)
architecture"). Therefore remove support for ARCH_TASK_STRUCT_ON_STACK
as well.
Note: this also reveals a potential bug in powerpc code, which makes use of
__init_task_data without selecting ARCH_TASK_STRUCT_ON_STACK which makes
__init_task_data a no-op. This is broken since commit d11ed3ab3166 ("Expand
INIT_TASK() in init/init_task.c and remove") from 2018 and needs to be
addressed separately.
Link: https://lkml.kernel.org/r/20231116133638.1636277-4-hca@linux.ibm.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
All platforms with a kernel irqchip have support for irqfd. Unify the
two configuration items so that userspace can expect to use irqfd to
inject interrupts into the irqchip.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
virt/kvm/eventfd.c is compiled unconditionally, meaning that the ioeventfds
member of struct kvm is accessed unconditionally. CONFIG_HAVE_KVM_EVENTFD
therefore must be defined for KVM common code to compile successfully,
remove it.
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Switch character types to u8 and sizes to size_t. To conform to
characters/sizes in the rest of the tty layer.
Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Amit Shah <amit@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: virtualization@lists.linux.dev
Cc: linux-riscv@lists.infradead.org
Link: https://lore.kernel.org/r/20231206073712.17776-13-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
If no cross compiler is specified, try to auto detect one.
Look for various combinations, matching:
powerpc(64(le)?)?(-unknown)?-linux(-gnu)?-
There are more possibilities, but the above is known to find a compiler
on Fedora and Ubuntu (which use linux-gnu-), and also detects the
kernel.org cross compilers (which use linux-).
This allows cross compiling with simply:
# Ubuntu
$ sudo apt install gcc-powerpc-linux-gnu
# Fedora
$ sudo dnf install gcc-powerpc64-linux-gnu
$ make ARCH=powerpc defconfig
$ make ARCH=powerpc -j 4
Inspired by arch/parisc/Makefile.
Acked-by: Segher Boessenkool <segher@kernel.crashing.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231206115548.1466874-4-mpe@ellerman.id.au
If the kernel is being cross compiled, there is no information from
uname on which defconfig is most appropriate, so the Makefile defaults
to ppc64.
However these days almost all distros that support powerpc are little
endian, so it's more likely that defaulting to ppc64le_defconfig will
produce something useful for a user.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231206115548.1466874-3-mpe@ellerman.id.au
The vdso Makefile adds -U$(ARCH) to CPPFLAGS for the vdso64.lds linker
script. ARCH is always powerpc, so it becomes -Upowerpc, which means
undefine the "powerpc" symbol.
But the 64-bit compiler doesn't define powerpc in the first place,
compare:
$ gcc-5.1.0-nolibc/powerpc64-linux/bin/powerpc64-linux-gcc -m32 -E -dM - </dev/null | grep -w powerpc
#define powerpc 1
$ gcc-5.1.0-nolibc/powerpc64-linux/bin/powerpc64-linux-gcc -m64 -E -dM - </dev/null | grep -w powerpc
$
So there's no need to undefine it for the 64-bit linker script.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231206115548.1466874-2-mpe@ellerman.id.au
This reverts commit 1abce0580b89 ("powerpc/64s: Fix __pte_needs_flush()
false positive warning")
The previous patch dropped the usage of _PAGE_PRIVILEGED with PAGE_NONE.
Hence this check can be dropped.
Signed-off-by: "Aneesh Kumar K.V (IBM)" <aneesh.kumar@kernel.org>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231204093638.71503-2-aneesh.kumar@kernel.org
There used to be a dependency on _PAGE_PRIVILEGED with pte_savedwrite.
But that got dropped by
commit 6a56ccbcf6c6 ("mm/autonuma: use can_change_(pte|pmd)_writable() to replace savedwrite")
With the change in this patch numa fault pte (pte_protnone()) gets mapped as regular user pte
with RWX cleared (no-access) whereas earlier it used to be mapped _PAGE_PRIVILEGED.
Hash fault handling code gets some WARN_ON added in this patch because
those functions are not expected to get called with _PAGE_READ cleared.
commit 18061c17c8ec ("powerpc/mm: Update PROTFAULT handling in the page
fault path") explains the details.
Signed-off-by: "Aneesh Kumar K.V (IBM)" <aneesh.kumar@kernel.org>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/20231204093638.71503-1-aneesh.kumar@kernel.org
