Use flag output macros in inline asm to allow for better code generation if
the compiler has support for the flag output constraint.
Reviewed-by: Juergen Christ <jchrist@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Use flag output macros in inline asm to allow for better code generation if
the compiler has support for the flag output constraint.
Reviewed-by: Juergen Christ <jchrist@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Use flag output macros in inline asm to allow for better code generation if
the compiler has support for the flag output constraint.
Reviewed-by: Juergen Christ <jchrist@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Use flag output macros in inline asm to allow for better code generation if
the compiler has support for the flag output constraint.
Reviewed-by: Juergen Christ <jchrist@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Use flag output macros in inline asm to allow for better code generation if
the compiler has support for the flag output constraint.
Reviewed-by: Juergen Christ <jchrist@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Use flag output macros in inline asm to allow for better code generation if
the compiler has support for the flag output constraint.
Reviewed-by: Juergen Christ <jchrist@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Use flag output macros in inline asm to allow for better code generation if
the compiler has support for the flag output constraint.
Reviewed-by: Juergen Christ <jchrist@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Use flag output macros in inline asm to allow for better code generation if
the compiler has support for the flag output constraint.
Reviewed-by: Juergen Christ <jchrist@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Use flag output macros in inline asm to allow for better code generation if
the compiler has support for the flag output constraint.
Reviewed-by: Juergen Christ <jchrist@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Use flag output macros in inline asm to allow for better code generation if
the compiler has support for the flag output constraint.
Reviewed-by: Juergen Christ <jchrist@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Use flag output macros in inline asm to allow for better code generation if
the compiler has support for the flag output constraint.
Reviewed-by: Juergen Christ <jchrist@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Use flag output macros in inline asm to allow for better code generation if
the compiler has support for the flag output constraint.
Reviewed-by: Juergen Christ <jchrist@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Use flag output macros in inline asm to allow for better code generation if
the compiler has support for the flag output constraint.
Reviewed-by: Juergen Christ <jchrist@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Use flag output macros in inline asm to allow for better code generation if
the compiler has support for the flag output constraint.
Reviewed-by: Juergen Christ <jchrist@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Since gcc supports flag out operands for inline assemblies there is always
the question when this feature should be used and if it is worth all the
ifdefs that come with that.
In order to avoid that provide similar macros like x86 which can be used
for all inline assemblies which extract the condition code. Depending on
compiler features the generated code will either always contain an ipm+srl
instruction pair, which extracts the condition code, or alternatively let
the compiler handle this completely.
Suggested-by: Juergen Christ <jchrist@linux.ibm.com>
Reviewed-by: Juergen Christ <jchrist@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
The current "measurement_chars" CHPID sysfs attribute exposes only a
limited, validity-filtered portion of data from the associated Channel-
Measurements Characteristics Block (CMCB). New machine models add data
that is relevant for userspace tooling to the "header"-portion of the
CMCB. This data that is not currently accessible to userspace.
To prevent having to add new sysfs attributes whenever a new bit of data
is added to the CMCB "header", add a new sysfs attribute named
"measurement_chars_full" that exposes the full, unfiltered CMCB.
Signed-off-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Reviewed-by: Vineeth Vijayan <vneethv@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
The filechk macro always executes the syscalltbl script (and discards
the output if there are no changes).
Using if_changed is more efficient because it avoids running the script
when the target is up-to-date and the command remains unchanged.
All other architectures use if_changed for generating syscall headers.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Link: https://lore.kernel.org/r/20241111134603.2063226-3-masahiroy@kernel.org
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Building the kernel with ARCH=s390 creates a weird arch/arch/ directory.
$ find arch/arch
arch/arch
arch/arch/s390
arch/arch/s390/include
arch/arch/s390/include/generated
arch/arch/s390/include/generated/asm
arch/arch/s390/include/generated/uapi
arch/arch/s390/include/generated/uapi/asm
The root cause is 'targets' in arch/s390/kernel/syscalls/Makefile,
where the relative path is incorrect.
Strictly speaking, 'targets' was not necessary in the first place
because this Makefile uses 'filechk' instead of 'if_changed'.
However, this commit keeps it, as it will be useful when converting
'filechk' to 'if_changed' later.
Fixes: 5c75824d91 ("s390/syscalls: add Makefile to generate system call header files")
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Link: https://lore.kernel.org/r/20241111134603.2063226-1-masahiroy@kernel.org
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Convert local64_cmpxchg() usages to local64_try_cmpxchg() in
order to generate slightly better code.
Reviewed-by: Juergen Christ <jchrist@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Convert cmpxchg128() usages to try_cmpxchg128() in order to generate
slightly better code.
Reviewed-by: Juergen Christ <jchrist@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
With users converted to the standard arch_cmpxchg() variants, remove
the now unused __atomic_cmpxchg() and __atomic_cmpxchg_bool() variants.
Reviewed-by: Juergen Christ <jchrist@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Use arch_try_cmpxchg() instead of __atomic_cmpxchg_bool() everywhere.
This generates the same code like before, but uses the standard
cmpxchg() implementation instead of a custom __atomic_cmpxchg_bool().
Reviewed-by: Juergen Christ <jchrist@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Use arch_try_cmpxchg() instead of __atomic_cmpxchg() in
preempt_count_set() to generate similar or better code,
depending in compiler features.
Reviewed-by: Juergen Christ <jchrist@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Since gcc 14 flag output operands are supported also for s390.
Provide an arch_atomic try_cmpxchg() implementation so that all
existing atomic_try_cmpxchg() usages generate slightly better code,
if compiled with gcc 14 or newer.
Reviewed-by: Juergen Christ <jchrist@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Use arch_cmpxchg() instead of __atomic_cmpxchg() for the
arch_atomic_cmpxchg() implementations. arch_cmpxchg() generates
the same code and doesn't need a cast like it is required for
arch_atomic64_cmpxchg().
Reviewed-by: Juergen Christ <jchrist@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Convert the arch_atomic_xchg define to a C function so that proper
type checking is provided.
Reviewed-by: Juergen Christ <jchrist@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Since gcc 14 flag output operands are supported also for s390.
Provide an arch_try_cmpxchg128() implementation so that all existing
try_cmpxchg128() variants provide slightly better code, if compiled
with gcc 14 or newer.
Reviewed-by: Juergen Christ <jchrist@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Just like x86 and arm64 provide a trivial arch_cmpxchg128_local()
implementation by mapping it to arch_cmpxchg128().
Reviewed-by: Juergen Christ <jchrist@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Get rid of the arch_xchg() inline assemblies by converting the inline
assemblies to C functions which make use of arch_try_cmpxchg().
With flag output operand support the generated code is at least as good as
the previous version. Without it is slightly worse, however getting rid of
all the inline assembly code is worth it.
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Since gcc 14 flag output operands are supported also for s390.
Provide an arch_try_cmpxchg() implementation so that all existing
try_cmpxchg() variants provide slightly better code, if compiled
with gcc 14 or newer.
Reviewed-by: Juergen Christ <jchrist@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Rewrite __cmpxchg() in order to get rid of the large inline
assemblies. Convert the one and two byte inline assemblies to
C functions.
The generated code of the new implementation is nearly as good or bad as
the old variant, but easier to read.
Note that the new variants are quite close to the generic cmpxchg_emu_u8()
implementation, however a conversion to the generic variant will not follow
since with mm/vmstat.c there is heavy user of one byte cmpxchg(). A not
inlined variant would have a negative performance impact.
Also note that the calls within __arch_cmpxchg() come with rather pointless
"& 0xff..." operations. They exist only to avoid false positive sparse
warnings like "warning: cast truncates bits from constant value ...".
Reviewed-by: Juergen Christ <jchrist@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Dump tools from s390-tools such as zipl need to know the correct dump area
size of the machine they run on in order to be able to create valid
standalone dumper images. Therefore, allow it to be obtained through
the new sysfs read-only attribute /sys/firmware/dump/dump_area_size.
Suggested-by: Heiko Carstens <hca@linux.ibm.com>
Suggested-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Alexander Egorenkov <egorenar@linux.ibm.com>
Reviewed-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Get rid of sparse warnings:
CHECK drivers/s390/char/con3270.c
drivers/s390/char/con3270.c:531:15: warning: Using plain integer as NULL pointer
drivers/s390/char/con3270.c:749:15: warning: Using plain integer as NULL pointer
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
While pci_iov.h has include guards it doesn't include the necessary
header for struct zpci_dev, pci_bus.h on the other hand lacks even basic
include guards. This isn't only fragile and breaks convention but also
confuses tooling such as clang-analyzer. Add both include guards and the
necessary includes.
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Reviewed-by: Gerd Bayer <gbayer@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Enable the list IOCTL to provide lists longer than one page (85 entries).
The list IOCTL now accepts any argument length in page granularity.
It fills the argument up to this length with entries until the list
ends. User space unaware of this enhancement will still receive one page
of data and an uv_rc 0x0100.
Signed-off-by: Steffen Eiden <seiden@linux.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Link: https://lore.kernel.org/r/20241104153609.1361388-1-seiden@linux.ibm.com
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Message-ID: <20241104153609.1361388-1-seiden@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Add a trival phys_to_target_node() implementation which always returns 0 if
CONFIG_NUMA is enabled, since the s390 NUMA implementation only supports
node 0.
This is similar to memory_add_physaddr_to_nid() in order to avoid runtime
warnings.
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
David Hildenbrand says:
====================
virtio-mem: s390 support
Let's finally add s390 support for virtio-mem; my last RFC was sent
4 years ago, and a lot changed in the meantime.
The latest QEMU series is available at [1], which contains some more
details and a usage example on s390 (last patch).
There is not too much in here: The biggest part is querying a new diag(500)
STORAGE_LIMIT hypercall to obtain the proper "max_physmem_end".
The last three patches are not strictly required but certainly nice-to-have.
Note that -- in contrast to standby memory -- virtio-mem memory must be
configured to be automatically onlined as soon as hotplugged. The easiest
approach is using the "memhp_default_state=" kernel parameter or by using
proper udev rules. More details can be found at [2].
I have reviving+upstreaming a systemd service to handle configuring
that on my todo list, but for some reason I keep getting distracted ...
I tested various things, including:
* Various memory hotplug/hotunplug combinations
* Device hotplug/hotunplug
* /proc/iomem output
* reboot
* kexec
* kdump: make sure we properly enter the "kdump mode" in the virtio-mem
driver
kdump support for virtio-mem memory on s390 will be sent out separately.
v2 -> v3
* "s390/kdump: make is_kdump_kernel() consistently return "true" in kdump
environments only"
-> Sent out separately [3]
* "s390/physmem_info: query diag500(STORAGE LIMIT) to support QEMU/KVM memory
devices"
-> No query function for diag500 for now.
-> Update comment above setup_ident_map_size().
-> Optimize/rewrite diag500_storage_limit() [Heiko]
-> Change handling in detect_physmem_online_ranges [Alexander]
-> Improve documentation.
* "s390/sparsemem: provide memory_add_physaddr_to_nid() with CONFIG_NUMA"
-> Added after testing on systems with CONFIG_NUMA=y
v1 -> v2:
* Document the new diag500 subfunction
* Use "s390" instead of "s390x" consistently
[1] https://lkml.kernel.org/r/20241008105455.2302628-1-david@redhat.com
[2] https://virtio-mem.gitlab.io/user-guide/user-guide-linux.html
[3] https://lkml.kernel.org/r/20241023090651.1115507-1-david@redhat.com
====================
Link: https://lore.kernel.org/r/20241025141453.1210600-1-david@redhat.com/
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
virtio-mem uses memory_add_physaddr_to_nid() to determine the NID to use
for memory it adds.
We currently fallback to the dummy implementation in mm/numa.c with
CONFIG_NUMA, which will end up triggering an undesired pr_info_once():
Unknown online node for memory at 0x100000000, assuming node 0
On s390, we map all cpus and memory to node 0, so let's add a simple
memory_add_physaddr_to_nid() implementation that does exactly that,
but without complaining.
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Tested-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Link: https://lore.kernel.org/r/20241025141453.1210600-8-david@redhat.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Ever since commit 421c175c4d ("[S390] Add support for memory hot-add.")
we've been using a section size of 256 MiB on s390 and 32 MiB on s390.
Before that, we were using a section size of 32 MiB on both
architectures.
Now that we have a new mechanism to expose additional memory to a VM --
virtio-mem -- reduce the section size to 128 MiB to allow for more
flexibility and reduce the metadata overhead when dealing with hot(un)plug
granularity smaller than 256 MiB.
128 MiB has been used by x86-64 since the very beginning. arm64 with 4k
base pages switched to 128 MiB as well: it's just big enough on these
architectures to allows for using a huge page (2 MiB) in the vmemmap in
sane setups with sizeof(struct page) == 64 bytes and a huge page mapping
in the direct mapping, while still allowing for small hot(un)plug
granularity.
For s390, we could even switch to a 64 MiB section size, as our huge page
size is 1 MiB: but the smaller the section size, the more sections we'll
have to manage especially on bigger machines. Making it consistent with
x86-64 and arm64 feels like the right thing for now.
Note that the smallest memory hot(un)plug granularity is also limited by
the memory block size, determined by extracting the memory increment
size from SCLP. Under QEMU/KVM, implementing virtio-mem, we expose 0;
therefore, we'll end up with a memory block size of 128 MiB with a
128 MiB section size.
Tested-by: Mario Casquero <mcasquer@redhat.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Tested-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Link: https://lore.kernel.org/r/20241025141453.1210600-7-david@redhat.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
virtio-mem currently depends on !DEVMEM | STRICT_DEVMEM. Let's default
STRICT_DEVMEM to "y" just like we do for arm64 and x86.
There could be ways in the future to filter access to virtio-mem device
memory even without STRICT_DEVMEM, but for now let's just keep it
simple.
Tested-by: Mario Casquero <mcasquer@redhat.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Tested-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Link: https://lore.kernel.org/r/20241025141453.1210600-6-david@redhat.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Now that s390 code is prepared for memory devices that reside above the
maximum storage increment exposed through SCLP, everything is in place
to unlock virtio-mem support.
As virtio-mem in Linux currently supports logically onlining/offlining
memory in pageblock granularity, we have an effective hot(un)plug
granularity of 1 MiB on s390.
As virito-mem adds/removes individual Linux memory blocks (256MB), we
will currently never use gigantic pages in the identity mapping.
It is worth noting that neither storage keys nor storage attributes (e.g.,
data / nodat) are touched when onlining memory blocks, which is good
because we are not supposed to touch these parts for unplugged device
blocks that are logically offline in Linux.
We will currently never initialize storage keys for virtio-mem
memory -- IOW, storage_key_init_range() is never called. It could be added
in the future when plugging device blocks. But as that function
essentially does nothing without modifying the code (changing
PAGE_DEFAULT_ACC), that's just fine for now.
kexec should work as intended and just like on other architectures that
support virtio-mem: we will never place kexec binaries on virtio-mem
memory, and never indicate virtio-mem memory to the 2nd kernel. The
device driver in the 2nd kernel can simply reset the device --
turning all memory unplugged, to then start plugging memory and adding
them to Linux, without causing trouble because the memory is already
used elsewhere.
The special s390 kdump mode, whereby the 2nd kernel creates the ELF
core header, won't currently dump virtio-mem memory. The virtio-mem
driver has a special kdump mode, from where we can detect memory ranges
to dump. Based on this, support for dumping virtio-mem memory can be
added in the future fairly easily.
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Mario Casquero <mcasquer@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Tested-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Link: https://lore.kernel.org/r/20241025141453.1210600-5-david@redhat.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
To support memory devices under QEMU/KVM, such as virtio-mem,
we have to prepare our kernel virtual address space accordingly and
have to know the highest possible physical memory address we might see
later: the storage limit. The good old SCLP interface is not suitable for
this use case.
In particular, memory owned by memory devices has no relationship to
storage increments, it is always detected using the device driver, and
unaware OSes (no driver) must never try making use of that memory.
Consequently this memory is located outside of the "maximum storage
increment"-indicated memory range.
Let's use our new diag500 STORAGE_LIMIT subcode to query this storage
limit that can exceed the "maximum storage increment", and use the
existing interfaces (i.e., SCLP) to obtain information about the initial
memory that is not owned+managed by memory devices.
If a hypervisor does not support such memory devices, the address exposed
through diag500 STORAGE_LIMIT will correspond to the maximum storage
increment exposed through SCLP.
To teach kdump on s390 to include memory owned by memory devices, there
will be ways to query the relevant memory ranges from the device via a
driver running in special kdump mode (like virtio-mem already implements
to filter /proc/vmcore access so we don't end up reading from unplugged
device blocks).
Update setup_ident_map_size(), to clarify that there can be more than
just online and standby memory.
Tested-by: Mario Casquero <mcasquer@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Heiko Carstens <hca@linux.ibm.com>
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Tested-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Link: https://lore.kernel.org/r/20241025141453.1210600-4-david@redhat.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Let's document our new diag500 subfunction that can be implemented by
userspace.
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Reviewed-by: Eric Farman <farman@linux.ibm.com>
Tested-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Link: https://lore.kernel.org/r/20241025141453.1210600-3-david@redhat.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Let's make it a generic KVM hypercall, allowing other subfunctions to
be more independent of virtio.
While at it, document that unsupported/unimplemented subfunctions result
in a SPECIFICATION exception.
This is a preparation for documenting a new subfunction.
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Reviewed-by: Eric Farman <farman@linux.ibm.com>
Tested-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Link: https://lore.kernel.org/r/20241025141453.1210600-2-david@redhat.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
The program interrupt code has some extra bits that are sometimes set
by hardware for various reasons; those bits should be ignored when the
program interrupt number is needed for interrupt handling.
Fixes: 05066cafa9 ("s390/mm/fault: Handle guest-related program interrupts in KVM")
Reported-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Tested-by: Christian Borntraeger <borntraeger@linux.ibm.com>
Link: https://lore.kernel.org/r/20241031120316.25462-1-imbrenda@linux.ibm.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
The flags variable was being used uninitialized.
Initialize it to 0 as expected.
For some reason neither gcc nor clang reported a warning.
Fixes: 05066cafa9 ("s390/mm/fault: Handle guest-related program interrupts in KVM")
Reported-by: Janosch Frank <frankja@linux.ibm.com>
Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Link: https://lore.kernel.org/r/20241030161906.85476-1-imbrenda@linux.ibm.com
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Reservation of the PMU hardware is done at first event creation
and is protected by a pair of mutex_lock() and mutex_unlock().
After reservation of the PMU hardware the memory
required for the PMUs the event is to be installed on is
allocated by allocate_buffers() and alloc_sampling_buffer().
This done outside of the mutex protection.
Without mutex protection two or more concurrent invocations of
perf_event_init() may run in parallel.
This can lead to allocation of Sample Data Blocks (SDBs)
multiple times for the same PMU.
Prevent this and protect memory allocation of SDBs by
mutex.
Fixes: 8a6fe8f21e ("s390/cpum_sf: Use refcount_t instead of atomic_t")
Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Reviewed-by: Sumanth Korikkar <sumanthk@linux.ibm.com>
Reviewed-by: Hendrik Brueckner <brueckner@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
