Since the assembly soft-masking code was moved to 64e specific, there
are some 64s specific interrupt types still there. Remove them.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200915114650.3980244-4-npiggin@gmail.com
Replayed interrupts get an "artificial" struct pt_regs constructed to
pass to interrupt handler functions. This did not get the softe field
set correctly, it's as though the interrupt has hit while irqs are
disabled. It should be IRQS_ENABLED.
This is possibly harmless, asynchronous handlers should not be testing
if irqs were disabled, but it might be possible for example some code
is shared with synchronous or NMI handlers, and it makes more sense if
debug output looks at this.
Fixes: 3282a3da25 ("powerpc/64: Implement soft interrupt replay in C")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200915114650.3980244-2-npiggin@gmail.com
Prior to commit 3282a3da25 ("powerpc/64: Implement soft interrupt
replay in C"), replayed interrupts returned by the regular interrupt
exit code, which performs preemption in case an interrupt had set
need_resched.
This logic was missed by the conversion. Adding preempt_disable/enable
around the interrupt replay and final irq enable will reschedule if
needed.
Fixes: 3282a3da25 ("powerpc/64: Implement soft interrupt replay in C")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200915114650.3980244-1-npiggin@gmail.com
The hypervisor interface has defined branch prediction security bits for
handling the link stack. Wire them up.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200825075612.224656-1-npiggin@gmail.com
The copy buffer is implemented as a real address in the nest which is
translated from EA by copy, and used for memory access by paste. This
requires that it be invalidated by TLB invalidation.
TLBIE does invalidate the copy buffer, but TLBIEL does not. Add
cp_abort to the tlbiel sequence.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Fixup whitespace and comment formatting]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200916030234.4110379-2-npiggin@gmail.com
Having cputable.h include mce.h means it pulls in a bunch of low level
headers (e.g., synch.h) which then can't use CPU_FTR_ definitions.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200916030234.4110379-1-npiggin@gmail.com
Every error log reported by OPAL is exported to userspace through a
sysfs interface and notified using kobject_uevent(). The userspace
daemon (opal_errd) then reads the error log and acknowledges the error
log is saved safely to disk. Once acknowledged the kernel removes the
respective sysfs file entry causing respective resources to be
released including kobject.
However it's possible the userspace daemon may already be scanning
elog entries when a new sysfs elog entry is created by the kernel.
User daemon may read this new entry and ack it even before kernel can
notify userspace about it through kobject_uevent() call. If that
happens then we have a potential race between
elog_ack_store->kobject_put() and kobject_uevent which can lead to
use-after-free of a kernfs object resulting in a kernel crash. eg:
BUG: Unable to handle kernel data access on read at 0x6b6b6b6b6b6b6bfb
Faulting instruction address: 0xc0000000008ff2a0
Oops: Kernel access of bad area, sig: 11 [#1]
LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA PowerNV
CPU: 27 PID: 805 Comm: irq/29-opal-elo Not tainted 5.9.0-rc2-gcc-8.2.0-00214-g6f56a67bcbb5-dirty #363
...
NIP kobject_uevent_env+0xa0/0x910
LR elog_event+0x1f4/0x2d0
Call Trace:
0x5deadbeef0000122 (unreliable)
elog_event+0x1f4/0x2d0
irq_thread_fn+0x4c/0xc0
irq_thread+0x1c0/0x2b0
kthread+0x1c4/0x1d0
ret_from_kernel_thread+0x5c/0x6c
This patch fixes this race by protecting the sysfs file
creation/notification by holding a reference count on kobject until we
safely send kobject_uevent().
The function create_elog_obj() returns the elog object which if used
by caller function will end up in use-after-free problem again.
However, the return value of create_elog_obj() function isn't being
used today and there is no need as well. Hence change it to return
void to make this fix complete.
Fixes: 774fea1a38 ("powerpc/powernv: Read OPAL error log and export it through sysfs")
Cc: stable@vger.kernel.org # v3.15+
Reported-by: Oliver O'Halloran <oohall@gmail.com>
Signed-off-by: Mahesh Salgaonkar <mahesh@linux.ibm.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Reviewed-by: Oliver O'Halloran <oohall@gmail.com>
Reviewed-by: Vasant Hegde <hegdevasant@linux.vnet.ibm.com>
[mpe: Rework the logic to use a single return, reword comments, add oops]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201006122051.190176-1-mpe@ellerman.id.au
This fixes a compile error with W=1.
CC arch/powerpc/kernel/traps.o
../arch/powerpc/kernel/traps.c:1663:6: error: no previous prototype for ‘stack_overflow_exception’ [-Werror=missing-prototypes]
void stack_overflow_exception(struct pt_regs *regs)
^~~~~~~~~~~~~~~~~~~~~~~~
Fixes: 3978eb7851 ("powerpc/32: Add early stack overflow detection with VMAP stack.")
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200914211007.2285999-8-clg@kaod.org
The check should be performed by the caller. This fixes a compile
error with W=1.
../arch/powerpc/lib/sstep.c: In function ‘mlsd_8lsd_ea’:
../arch/powerpc/lib/sstep.c:225:3: error: suggest braces around empty body in an ‘if’ statement [-Werror=empty-body]
; /* Invalid form. Should already be checked for by caller! */
^
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200914211007.2285999-4-clg@kaod.org
This fixes a compile error with W=1.
arch/powerpc/kernel/sysfs.c: In function ‘sysfs_create_dscr_default’:
arch/powerpc/kernel/sysfs.c:228:7: error: variable ‘err’ set but not used [-Werror=unused-but-set-variable]
int err = 0;
^~~
cc1: all warnings being treated as errors
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200914211007.2285999-2-clg@kaod.org
It's possible to enable CONFIG_PPC_EARLY_DEBUG_BOOTX for a pseries
kernel (maybe it shouldn't be), which is then booted with qemu/slof.
But if you do that the kernel crashes in draw_byte(), with a DAR
pointing somewhere near INT_MAX.
Adding some debug to prom_init we see that we're not able to read the
"address" property from OF, so we're just using whatever junk value
was on the stack.
So check the properties can be read properly from OF, if not we bail
out before initialising btext, which avoids the crash.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Link: https://lore.kernel.org/r/20200821103407.3362149-1-mpe@ellerman.id.au
We have smp_ops->cpu_die() and ppc_md.cpu_die(). One of them offlines
the current CPU and one offlines another CPU, can you guess which is
which? Also one is in smp_ops and one is in ppc_md?
So rename ppc_md.cpu_die(), to cpu_offline_self(), because that's what
it does. And move it into smp_ops where it belongs.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200819015634.1974478-3-mpe@ellerman.id.au
arch_cpu_idle_dead() is in idle.c, which makes sense, but it's inside
a CONFIG_HOTPLUG_CPU block.
It would be more at home in smp.c, inside the existing
CONFIG_HOTPLUG_CPU block. Note that CONFIG_HOTPLUG_CPU depends on
CONFIG_SMP so even though smp.c is not built for SMP=n builds, that's
fine.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200819015634.1974478-1-mpe@ellerman.id.au
Sparse warns about all the init functions:
symbol init_ppc970_pmu was not declared. Should it be static?
symbol init_power5p_pmu was not declared. Should it be static?
symbol init_power5_pmu was not declared. Should it be static?
symbol init_power6_pmu was not declared. Should it be static?
symbol init_power7_pmu was not declared. Should it be static?
symbol init_power9_pmu was not declared. Should it be static?
symbol init_power8_pmu was not declared. Should it be static?
symbol init_generic_compat_pmu was not declared. Should it be static?
They're already declared in internal.h, so just make sure all the C
files include that directly or indirectly.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://lore.kernel.org/r/20200916115637.3100484-2-mpe@ellerman.id.au
Fix link error when CONFIG_PPC_RADIX_MMU is disabled:
powerpc64-linux-gnu-ld: arch/powerpc/platforms/pseries/lpar.o:(.toc+0x0): undefined reference to `mmu_pid_bits'
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200917020643.90375-1-yangyingliang@huawei.com
Clang, and GCC with -Wmaybe-uninitialized, can't see that val is
unused in get_fpexec_mode():
arch/powerpc/kernel/process.c:1940:7: error: variable 'val' is used
uninitialized whenever 'if' condition is true
if (cpu_has_feature(CPU_FTR_SPE)) {
^~~~~~~~~~~~~~~~~~~~~~~~~~~~
We know that CPU_FTR_SPE will only be true iff CONFIG_SPE is also
true, but the compiler doesn't.
Avoid it by initialising val to zero.
Reported-by: kernel test robot <lkp@intel.com>
Fixes: 532ed1900d ("powerpc/process: Remove useless #ifdef CONFIG_SPE")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
Link: https://lore.kernel.org/r/20200917024509.3253837-1-mpe@ellerman.id.au
Lookup the coregroup id from the associativity array.
If unable to detect the coregroup id, fallback on the core id.
This way, ensure sched_domain degenerates and an extra sched domain is
not created.
Ideally this function should have been implemented in
arch/powerpc/kernel/smp.c. However if its implemented in mm/numa.c, we
don't need to find the primary domain again.
If the device-tree mentions more than one coregroup, then kernel
implements only the last or the smallest coregroup, which currently
corresponds to the penultimate domain in the device-tree.
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200810071834.92514-11-srikar@linux.vnet.ibm.com
Add percpu coregroup maps and masks to create coregroup domain.
If a coregroup doesn't exist, the coregroup domain will be degenerated
in favour of SMT/CACHE domain. Do note this patch is only creating stubs
for cpu_to_coregroup_id. The actual cpu_to_coregroup_id implementation
would be in a subsequent patch.
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200810071834.92514-10-srikar@linux.vnet.ibm.com
If allocated earlier and the search fails, then cpu_l1_cache_map cpumask
is unnecessarily cleared. However cpu_l1_cache_map can be allocated /
cleared after we search thread group.
Please note CONFIG_CPUMASK_OFFSTACK is not set on Powerpc. Hence cpumask
allocated by zalloc_cpumask_var_node is never freed.
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200810071834.92514-9-srikar@linux.vnet.ibm.com
Add support for grouping cores based on the device-tree classification.
- The last domain in the associativity domains always refers to the
core.
- If primary reference domain happens to be the penultimate domain in
the associativity domains device-tree property, then there are no
coregroups. However if its not a penultimate domain, then there are
coregroups. There can be more than one coregroup. For now we would be
interested in the last or the smallest coregroups, i.e one sub-group
per DIE.
Currently there are no firmwares that are exposing this grouping. Hence
allow the basis for grouping to be abstract. Once the firmware starts
using this grouping, code would be added to detect the type of grouping
and adjust the sd domain flags accordingly.
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200810071834.92514-8-srikar@linux.vnet.ibm.com
In start_secondary, even if shared_cache was already set, system does a
redundant match for cpumask. This redundant check can be removed by
checking if shared_cache is already set.
While here, localize the sibling_mask variable to within the if
condition.
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200810071834.92514-7-srikar@linux.vnet.ibm.com
Current code assumes that cpumask of cpus sharing a l2-cache mask will
always be a superset of cpu_sibling_mask.
Lets stop that assumption. cpu_l2_cache_mask is a superset of
cpu_sibling_mask if and only if shared_caches is set.
Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200913171038.GB11808@linux.vnet.ibm.com
Move topology fixup based on the platform attributes into its own
function which is called just before set_sched_topology.
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200810071834.92514-5-srikar@linux.vnet.ibm.com
Just moving the powerpc_topology description above.
This will help in using functions in this file and avoid declarations.
No other functional changes
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200810071834.92514-4-srikar@linux.vnet.ibm.com
A new sched_domain_topology_level was added just for Power9. However the
same can be achieved by merging powerpc_topology with power9_topology
and makes the code more simpler especially when adding a new sched
domain.
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200810071834.92514-3-srikar@linux.vnet.ibm.com
Fix a build warning in a non CONFIG_NEED_MULTIPLE_NODES
"error: _numa_cpu_lookup_table_ undeclared"
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Reviewed-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200810071834.92514-2-srikar@linux.vnet.ibm.com
Currently Linux kernel with CONFIG_NUMA on a system with multiple
possible nodes, marks node 0 as online at boot. However in practice,
there are systems which have node 0 as memoryless and cpuless.
This can cause numa_balancing to be enabled on systems with only one node
with memory and CPUs. The existence of this dummy node which is cpuless and
memoryless node can confuse users/scripts looking at output of lscpu /
numactl.
By marking, node 0 as offline, lets stop assuming that node 0 is
always online. If node 0 has CPU or memory that are online, node 0 will
again be set as online.
v5.8
available: 2 nodes (0,2)
node 0 cpus:
node 0 size: 0 MB
node 0 free: 0 MB
node 2 cpus: 0 1 2 3 4 5 6 7
node 2 size: 32625 MB
node 2 free: 31490 MB
node distances:
node 0 2
0: 10 20
2: 20 10
proc and sys files
------------------
/sys/devices/system/node/online: 0,2
/proc/sys/kernel/numa_balancing: 1
/sys/devices/system/node/has_cpu: 2
/sys/devices/system/node/has_memory: 2
/sys/devices/system/node/has_normal_memory: 2
/sys/devices/system/node/possible: 0-31
v5.8 + patch
------------------
available: 1 nodes (2)
node 2 cpus: 0 1 2 3 4 5 6 7
node 2 size: 32625 MB
node 2 free: 31487 MB
node distances:
node 2
2: 10
proc and sys files
------------------
/sys/devices/system/node/online: 2
/proc/sys/kernel/numa_balancing: 0
/sys/devices/system/node/has_cpu: 2
/sys/devices/system/node/has_memory: 2
/sys/devices/system/node/has_normal_memory: 2
/sys/devices/system/node/possible: 0-31
Example of a node with online CPUs/memory on node 0.
(Same o/p with and without patch)
numactl -H
available: 4 nodes (0-3)
node 0 cpus: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47
node 0 size: 32482 MB
node 0 free: 22994 MB
node 1 cpus: 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95
node 1 size: 0 MB
node 1 free: 0 MB
node 2 cpus: 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143
node 2 size: 0 MB
node 2 free: 0 MB
node 3 cpus: 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 node 3 size: 0 MB
node 3 free: 0 MB
node distances:
node 0 1 2 3
0: 10 20 40 40
1: 20 10 40 40
2: 40 40 10 20
3: 40 40 20 10
Note: On Powerpc, cpu_to_node of possible but not present cpus would
previously return 0. Hence this commit depends on commit ("powerpc/numa: Set
numa_node for all possible cpus") and commit ("powerpc/numa: Prefer node id
queried from vphn"). Without the 2 commits, Powerpc system might crash.
1. User space applications like Numactl, lscpu, that parse the sysfs tend to
believe there is an extra online node. This tends to confuse users and
applications. Other user space applications start believing that system was
not able to use all the resources (i.e missing resources) or the system was
not setup correctly.
2. Also existence of dummy node also leads to inconsistent information. The
number of online nodes is inconsistent with the information in the
device-tree and resource-dump
3. When the dummy node is present, single node non-Numa systems end up showing
up as NUMA systems and numa_balancing gets enabled. This will mean we take
the hit from the unnecessary numa hinting faults.
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200818081104.57888-4-srikar@linux.vnet.ibm.com
Node id queried from the static device tree may not
be correct. For example: it may always show 0 on a shared processor.
Hence prefer the node id queried from vphn and fallback on the device tree
based node id if vphn query fails.
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200818081104.57888-3-srikar@linux.vnet.ibm.com
A Powerpc system with multiple possible nodes and with CONFIG_NUMA
enabled always used to have a node 0, even if node 0 does not any cpus
or memory attached to it. As per PAPR, node affinity of a cpu is only
available once its present / online. For all cpus that are possible but
not present, cpu_to_node() would point to node 0.
To ensure a cpuless, memoryless dummy node is not online, powerpc need
to make sure all possible but not present cpu_to_node are set to a
proper node.
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200818081104.57888-2-srikar@linux.vnet.ibm.com
As per draft LoPAPR (Revision 2.9_pre7), section B.5.3 "Run Time
Abstraction Services (RTAS) Node" available at:
https://openpowerfoundation.org/wp-content/uploads/2020/07/LoPAR-20200611.pdf
... there are 2 device tree properties:
"ibm,max-associativity-domains"
which defines the maximum number of domains that the firmware i.e
PowerVM can support.
and:
"ibm,current-associativity-domains"
which defines the maximum number of domains that the current
platform can support.
The value of "ibm,max-associativity-domains" is always greater than or
equal to "ibm,current-associativity-domains" property. If the latter
property is not available, use "ibm,max-associativity-domain" as a
fallback. In this yet to be released LoPAPR, "ibm,current-associativity-domains"
is mentioned in page 833 / B.5.3 which is covered under under
"Appendix B. System Binding" section
Currently powerpc uses the "ibm,max-associativity-domains" property
while setting the possible number of nodes. This is currently set at
32. However the possible number of nodes for a platform may be
significantly less. Hence set the possible number of nodes based on
"ibm,current-associativity-domains" property.
Nathan Lynch had raised a valid concern that post LPM (Live Partition
Migration), a user could DLPAR add processors and memory after LPM
with "new" associativity properties:
https://lore.kernel.org/linuxppc-dev/871rljfet9.fsf@linux.ibm.com/t/#u
He also pointed out that "ibm,max-associativity-domains" has the same
contents on all currently available PowerVM systems, unlike
"ibm,current-associativity-domains" and hence may be better able to
handle the new NUMA associativity properties.
However with the recent commit dbce456280 ("powerpc/numa: Limit
possible nodes to within num_possible_nodes"), all new NUMA
associativity properties are capped to initially set nr_node_ids.
Hence this commit should be safe with any new DLPAR add post LPM.
$ lsprop /proc/device-tree/rtas/ibm,*associ*-domains
/proc/device-tree/rtas/ibm,current-associativity-domains
00000005 00000001 00000002 00000002 00000002 00000010
/proc/device-tree/rtas/ibm,max-associativity-domains
00000005 00000001 00000008 00000020 00000020 00000100
$ cat /sys/devices/system/node/possible ##Before patch
0-31
$ cat /sys/devices/system/node/possible ##After patch
0-1
Note the maximum nodes this platform can support is only 2 but the
possible nodes is set to 32.
This is important because lot of kernel and user space code allocate
structures for all possible nodes leading to a lot of memory that is
allocated but not used.
I ran a simple experiment to create and destroy 100 memory cgroups on
boot on a 8 node machine (Power8 Alpine).
Before patch:
free -k at boot
total used free shared buff/cache available
Mem: 523498176 4106816 518820608 22272 570752 516606720
Swap: 4194240 0 4194240
free -k after creating 100 memory cgroups
total used free shared buff/cache available
Mem: 523498176 4628416 518246464 22336 623296 516058688
Swap: 4194240 0 4194240
free -k after destroying 100 memory cgroups
total used free shared buff/cache available
Mem: 523498176 4697408 518173760 22400 627008 515987904
Swap: 4194240 0 4194240
After patch:
free -k at boot
total used free shared buff/cache available
Mem: 523498176 3969472 518933888 22272 594816 516731776
Swap: 4194240 0 4194240
free -k after creating 100 memory cgroups
total used free shared buff/cache available
Mem: 523498176 4181888 518676096 22208 640192 516496448
Swap: 4194240 0 4194240
free -k after destroying 100 memory cgroups
total used free shared buff/cache available
Mem: 523498176 4232320 518619904 22272 645952 516443264
Swap: 4194240 0 4194240
Observations:
Fixed kernel takes 137344 kb (4106816-3969472) less to boot.
Fixed kernel takes 309184 kb (4628416-4181888-137344) less to create 100 memcgs.
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
[mpe: Reformat change log a bit for readability]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200817055257.110873-1-srikar@linux.vnet.ibm.com
cpu_smt_mask tracks topology_sibling_cpumask. This would be good for
most architectures. One of the users of cpu_smt_mask(), would be to
identify idle-cores. On Power9, a pair of SMT4 cores can be presented
by the firmware as a SMT8 core for backward compatibility reasons.
powerpc allows LPARs to be live migrated from Power8 to Power9. Do
note Power8 had only SMT8 cores. Existing software which has been
developed/configured for Power8 would expect to see SMT8 core.
Maintaining the illusion of SMT8 core is a requirement to make that
work.
In order to maintain above userspace backward compatibility with
previous versions of processor, Power9 onwards there is option to the
firmware to advertise a pair of SMT4 cores as a fused cores aka SMT8
core. On Power9 this pair shares the L2 cache as well. However, from
the scheduler's point of view, a core should be determined by SMT4,
since its a completely independent unit of compute. Hence allow
powerpc architecture to override the default cpu_smt_mask() to point
to the SMT4 cores in a SMT8 mode.
This will ensure the scheduler is always given the right information.
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200807074517.27957-1-srikar@linux.vnet.ibm.com
Make kernel with `C=2`:
drivers/macintosh/smu.c:1018:30: warning: symbol
'__smu_get_sdb_partition' was not declared. Should it be static?
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Wang Wensheng <wangwensheng4@huawei.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200914122615.65669-1-wangwensheng4@huawei.com
A warning is reported by the kernel in case perf_stats_show() returns
an error code. The warning is of the form below:
papr_scm ibm,persistent-memory:ibm,pmemory@44100001:
Failed to query performance stats, Err:-10
dev_attr_show: perf_stats_show+0x0/0x1c0 [papr_scm] returned bad count
fill_read_buffer: dev_attr_show+0x0/0xb0 returned bad count
On investigation it looks like that the compiler is silently
truncating the return value of drc_pmem_query_stats() from 'long' to
'int', since the variable used to store the return code 'rc' is an
'int'. This truncated value is then returned back as a 'ssize_t' back
from perf_stats_show() to 'dev_attr_show()' which thinks of it as a
large unsigned number and triggers this warning..
To fix this we update the type of variable 'rc' from 'int' to
'ssize_t' that prevents the compiler from truncating the return value
of drc_pmem_query_stats() and returning correct signed value back from
perf_stats_show().
Fixes: 2d02bf835e ("powerpc/papr_scm: Fetch nvdimm performance stats from PHYP")
Signed-off-by: Vaibhav Jain <vaibhav@linux.ibm.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200912081451.66225-1-vaibhav@linux.ibm.com
Commit 0cef77c779 ("powerpc/64s/radix: flush remote CPUs out of
single-threaded mm_cpumask") added a mechanism to trim the mm_cpumask of
a process under certain conditions. One of the assumptions is that
mm_users would not be incremented via a reference outside the process
context with mmget_not_zero() then go on to kthread_use_mm() via that
reference.
That invariant was broken by io_uring code (see previous sparc64 fix),
but I'll point Fixes: to the original powerpc commit because we are
changing that assumption going forward, so this will make backports
match up.
Fix this by no longer relying on that assumption, but by having each CPU
check the mm is not being used, and clearing their own bit from the mask
only if it hasn't been switched-to by the time the IPI is processed.
This relies on commit 38cf307c1f ("mm: fix kthread_use_mm() vs TLB
invalidate") and ARCH_WANT_IRQS_OFF_ACTIVATE_MM to disable irqs over mm
switch sequences.
Fixes: 0cef77c779 ("powerpc/64s/radix: flush remote CPUs out of single-threaded mm_cpumask")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Michael Ellerman <mpe@ellerman.id.au>
Depends-on: 38cf307c1f ("mm: fix kthread_use_mm() vs TLB invalidate")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200914045219.3736466-5-npiggin@gmail.com
The de facto (and apparently uncommented) standard for using an mm had,
thanks to this code in sparc if nothing else, been that you must have a
reference on mm_users *and that reference must have been obtained with
mmget()*, i.e., from a thread with a reference to mm_users that had used
the mm.
The introduction of mmget_not_zero() in commit d2005e3f41
("userfaultfd: don't pin the user memory in userfaultfd_file_create()")
allowed mm_count holders to aoperate on user mappings asynchronously
from the actual threads using the mm, but they were not to load those
mappings into their TLB (i.e., walking vmas and page tables is okay,
kthread_use_mm() is not).
io_uring 2b188cc1bb ("Add io_uring IO interface") added code which
does a kthread_use_mm() from a mmget_not_zero() refcount.
The problem with this is code which previously assumed mm == current->mm
and mm->mm_users == 1 implies the mm will remain single-threaded at
least until this thread creates another mm_users reference, has now
broken.
arch/sparc/kernel/smp_64.c:
if (atomic_read(&mm->mm_users) == 1) {
cpumask_copy(mm_cpumask(mm), cpumask_of(cpu));
goto local_flush_and_out;
}
vs fs/io_uring.c
if (unlikely(!(ctx->flags & IORING_SETUP_SQPOLL) ||
!mmget_not_zero(ctx->sqo_mm)))
return -EFAULT;
kthread_use_mm(ctx->sqo_mm);
mmget_not_zero() could come in right after the mm_users == 1 test, then
kthread_use_mm() which sets its CPU in the mm_cpumask. That update could
be lost if cpumask_copy() occurs afterward.
I propose we fix this by allowing mmget_not_zero() to be a first-class
reference, and not have this obscure undocumented and unchecked
restriction.
The basic fix for sparc64 is to remove its mm_cpumask clearing code. The
optimisation could be effectively restored by sending IPIs to mm_cpumask
members and having them remove themselves from mm_cpumask. This is more
tricky so I leave it as an exercise for someone with a sparc64 SMP.
powerpc has a (currently similarly broken) example.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200914045219.3736466-4-npiggin@gmail.com
powerpc uses IPIs in some situations to switch a kernel thread away
from a lazy tlb mm, which is subject to the TLB flushing race
described in the changelog introducing ARCH_WANT_IRQS_OFF_ACTIVATE_MM.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200914045219.3736466-3-npiggin@gmail.com
Reading and modifying current->mm and current->active_mm and switching
mm should be done with irqs off, to prevent races seeing an intermediate
state.
This is similar to commit 38cf307c1f ("mm: fix kthread_use_mm() vs TLB
invalidate"). At exec-time when the new mm is activated, the old one
should usually be single-threaded and no longer used, unless something
else is holding an mm_users reference (which may be possible).
Absent other mm_users, there is also a race with preemption and lazy tlb
switching. Consider the kernel_execve case where the current thread is
using a lazy tlb active mm:
call_usermodehelper()
kernel_execve()
old_mm = current->mm;
active_mm = current->active_mm;
*** preempt *** --------------------> schedule()
prev->active_mm = NULL;
mmdrop(prev active_mm);
...
<-------------------- schedule()
current->mm = mm;
current->active_mm = mm;
if (!old_mm)
mmdrop(active_mm);
If we switch back to the kernel thread from a different mm, there is a
double free of the old active_mm, and a missing free of the new one.
Closing this race only requires interrupts to be disabled while ->mm
and ->active_mm are being switched, but the TLB problem requires also
holding interrupts off over activate_mm. Unfortunately not all archs
can do that yet, e.g., arm defers the switch if irqs are disabled and
expects finish_arch_post_lock_switch() to be called to complete the
flush; um takes a blocking lock in activate_mm().
So as a first step, disable interrupts across the mm/active_mm updates
to close the lazy tlb preempt race, and provide an arch option to
extend that to activate_mm which allows architectures doing IPI based
TLB shootdowns to close the second race.
This is a bit ugly, but in the interest of fixing the bug and backporting
before all architectures are converted this is a compromise.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200914045219.3736466-2-npiggin@gmail.com
