Merge tag 'v6.6.29' into dev-6.6

This is the 6.6.29 stable release

sched: Add missing memory barrier in switch_mm_cid

commit fe90f3967bdb3e13f133e5f44025e15f943a99c5 upstream.

Many architectures' switch_mm() (e.g. arm64) do not have an smp_mb()
which the core sche

sched: Add missing memory barrier in switch_mm_cid

commit fe90f3967bdb3e13f133e5f44025e15f943a99c5 upstream.

Many architectures' switch_mm() (e.g. arm64) do not have an smp_mb()
which the core scheduler code has depended upon since commit:

commit 223baf9d17f25 ("sched: Fix performance regression introduced by mm_cid")

If switch_mm() doesn't call smp_mb(), sched_mm_cid_remote_clear() can
unset the actively used cid when it fails to observe active task after it
sets lazy_put.

There *is* a memory barrier between storing to rq->curr and _return to
userspace_ (as required by membarrier), but the rseq mm_cid has stricter
requirements: the barrier needs to be issued between store to rq->curr
and switch_mm_cid(), which happens earlier than:

- spin_unlock(),
- switch_to().

So it's fine when the architecture switch_mm() happens to have that
barrier already, but less so when the architecture only provides the
full barrier in switch_to() or spin_unlock().

It is a bug in the rseq switch_mm_cid() implementation. All architectures
that don't have memory barriers in switch_mm(), but rather have the full
barrier either in finish_lock_switch() or switch_to() have them too late
for the needs of switch_mm_cid().

Introduce a new smp_mb__after_switch_mm(), defined as smp_mb() in the
generic barrier.h header, and use it in switch_mm_cid() for scheduler
transitions where switch_mm() is expected to provide a memory barrier.

Architectures can override smp_mb__after_switch_mm() if their
switch_mm() implementation provides an implicit memory barrier.
Override it with a no-op on x86 which implicitly provide this memory
barrier by writing to CR3.

Fixes: 223baf9d17f2 ("sched: Fix performance regression introduced by mm_cid")
Reported-by: levi.yun <yeoreum.yun@arm.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> # for arm64
Acked-by: Dave Hansen <dave.hansen@linux.intel.com> # for x86
Cc: <stable@vger.kernel.org> # 6.4.x
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20240415152114.59122-2-mathieu.desnoyers@efficios.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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Merge tag 'v6.6.18' into dev-6.6

This is the 6.6.18 stable release

x86/barrier: Do not serialize MSR accesses on AMD

commit 04c3024560d3a14acd18d0a51a1d0a89d29b7eb5 upstream.

AMD does not have the requirement for a synchronization barrier when
acccessing a certain

x86/barrier: Do not serialize MSR accesses on AMD

commit 04c3024560d3a14acd18d0a51a1d0a89d29b7eb5 upstream.

AMD does not have the requirement for a synchronization barrier when
acccessing a certain group of MSRs. Do not incur that unnecessary
penalty there.

There will be a CPUID bit which explicitly states that a MFENCE is not
needed. Once that bit is added to the APM, this will be extended with
it.

While at it, move to processor.h to avoid include hell. Untangling that
file properly is a matter for another day.

Some notes on the performance aspect of why this is relevant, courtesy
of Kishon VijayAbraham <Kishon.VijayAbraham@amd.com>:

On a AMD Zen4 system with 96 cores, a modified ipi-bench[1] on a VM
shows x2AVIC IPI rate is 3% to 4% lower than AVIC IPI rate. The
ipi-bench is modified so that the IPIs are sent between two vCPUs in the
same CCX. This also requires to pin the vCPU to a physical core to
prevent any latencies. This simulates the use case of pinning vCPUs to
the thread of a single CCX to avoid interrupt IPI latency.

In order to avoid run-to-run variance (for both x2AVIC and AVIC), the
below configurations are done:

1) Disable Power States in BIOS (to prevent the system from going to
lower power state)

2) Run the system at fixed frequency 2500MHz (to prevent the system
from increasing the frequency when the load is more)

With the above configuration:

*) Performance measured using ipi-bench for AVIC:
Average Latency: 1124.98ns [Time to send IPI from one vCPU to another vCPU]

Cumulative throughput: 42.6759M/s [Total number of IPIs sent in a second from
48 vCPUs simultaneously]

*) Performance measured using ipi-bench for x2AVIC:
Average Latency: 1172.42ns [Time to send IPI from one vCPU to another vCPU]

Cumulative throughput: 40.9432M/s [Total number of IPIs sent in a second from
48 vCPUs simultaneously]

From above, x2AVIC latency is ~4% more than AVIC. However, the expectation is
x2AVIC performance to be better or equivalent to AVIC. Upon analyzing
the perf captures, it is observed significant time is spent in
weak_wrmsr_fence() invoked by x2apic_send_IPI().

With the fix to skip weak_wrmsr_fence()

*) Performance measured using ipi-bench for x2AVIC:
Average Latency: 1117.44ns [Time to send IPI from one vCPU to another vCPU]

Cumulative throughput: 42.9608M/s [Total number of IPIs sent in a second from
48 vCPUs simultaneously]

Comparing the performance of x2AVIC with and without the fix, it can be seen
the performance improves by ~4%.

Performance captured using an unmodified ipi-bench using the 'mesh-ipi' option
with and without weak_wrmsr_fence() on a Zen4 system also showed significant
performance improvement without weak_wrmsr_fence(). The 'mesh-ipi' option ignores
CCX or CCD and just picks random vCPU.

Average throughput (10 iterations) with weak_wrmsr_fence(),
Cumulative throughput: 4933374 IPI/s

Average throughput (10 iterations) without weak_wrmsr_fence(),
Cumulative throughput: 6355156 IPI/s

[1] https://github.com/bytedance/kvm-utils/tree/master/microbenchmark/ipi-bench

Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20230622095212.20940-1-bp@alien8.de
Signed-off-by: Kishon Vijay Abraham I <kvijayab@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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Merge tag 'v5.18'

Linux 5.18

Merge branches 'fixes' and 'misc' into for-linus

Merge tag 'v5.17-rc4' into for-linus

Merge with mainline to get the Intel ASoC generic helpers header and
other changes.

Merge tag 'v5.17-rc4' into next

Sync up with mainline to get the latest changes in HID subsystem.

Merge remote-tracking branch 'drm/drm-next' into drm-misc-next

First backmerge into drm-misc-next. Required for more helpers backmerged,
and to pull in 5.17 (rc2).

Signed-off-by: Maarten Lankhorst

Merge remote-tracking branch 'drm/drm-next' into drm-misc-next

First backmerge into drm-misc-next. Required for more helpers backmerged,
and to pull in 5.17 (rc2).

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>

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Merge tag 'kvmarm-fixes-5.17-2' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD

KVM/arm64 fixes for 5.17, take #2

- A couple of fixes when handling an exception while a SEr

Merge tag 'kvmarm-fixes-5.17-2' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD

KVM/arm64 fixes for 5.17, take #2

- A couple of fixes when handling an exception while a SError has been
delivered

- Workaround for Cortex-A510's single-step[ erratum

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Merge drm/drm-next into drm-intel-gt-next

Backmerge to bring in 5.17-rc2 to introduce a common baseline
to merge i915_regs changes from drm-intel-next.

Signed-off-by: Joonas Lahtinen <joonas.lahtin

Merge drm/drm-next into drm-intel-gt-next

Backmerge to bring in 5.17-rc2 to introduce a common baseline
to merge i915_regs changes from drm-intel-next.

Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>

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Merge drm/drm-next into drm-intel-next

Catch-up with 5.17-rc2 and trying to align with drm-intel-gt-next
for a possible topic branch for merging the split of i915_regs...

Signed-off-by: Rodrigo Viv

Merge drm/drm-next into drm-intel-next

Catch-up with 5.17-rc2 and trying to align with drm-intel-gt-next
for a possible topic branch for merging the split of i915_regs...

Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

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Merge drm/drm-fixes into drm-misc-fixes

Backmerging drm/drm-fixes into drm-misc-fixes for v5.17-rc1.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>

Merge branch 'next' into for-linus

Prepare input updates for 5.17 merge window.

Merge remote-tracking branch 'torvalds/master' into perf/core

To pick up fixes and get in line with other trees, powerpc kernel
mostly this time, but BPF as well.

Signed-off-by: Arnaldo Carvalho de

Merge remote-tracking branch 'torvalds/master' into perf/core

To pick up fixes and get in line with other trees, powerpc kernel
mostly this time, but BPF as well.

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

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Merge tag 'kcsan.2022.01.09a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu

Pull KCSAN updates from Paul McKenney:
"This provides KCSAN fixes and also the ability to take memor

Merge tag 'kcsan.2022.01.09a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu

Pull KCSAN updates from Paul McKenney:
"This provides KCSAN fixes and also the ability to take memory barriers
into account for weakly-ordered systems. This last can increase the
probability of detecting certain types of data races"

* tag 'kcsan.2022.01.09a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu: (29 commits)
kcsan: Only test clear_bit_unlock_is_negative_byte if arch defines it
kcsan: Avoid nested contexts reading inconsistent reorder_access
kcsan: Turn barrier instrumentation into macros
kcsan: Make barrier tests compatible with lockdep
kcsan: Support WEAK_MEMORY with Clang where no objtool support exists
compiler_attributes.h: Add __disable_sanitizer_instrumentation
objtool, kcsan: Remove memory barrier instrumentation from noinstr
objtool, kcsan: Add memory barrier instrumentation to whitelist
sched, kcsan: Enable memory barrier instrumentation
mm, kcsan: Enable barrier instrumentation
x86/qspinlock, kcsan: Instrument barrier of pv_queued_spin_unlock()
x86/barriers, kcsan: Use generic instrumentation for non-smp barriers
asm-generic/bitops, kcsan: Add instrumentation for barriers
locking/atomics, kcsan: Add instrumentation for barriers
locking/barriers, kcsan: Support generic instrumentation
locking/barriers, kcsan: Add instrumentation for barriers
kcsan: selftest: Add test case to check memory barrier instrumentation
kcsan: Ignore GCC 11+ warnings about TSan runtime support
kcsan: test: Add test cases for memory barrier instrumentation
kcsan: test: Match reordered or normal accesses
...

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x86/barriers, kcsan: Use generic instrumentation for non-smp barriers

Prefix all barriers with __, now that asm-generic/barriers.h supports
defining the final instrumented version of these barriers.

x86/barriers, kcsan: Use generic instrumentation for non-smp barriers

Prefix all barriers with __, now that asm-generic/barriers.h supports
defining the final instrumented version of these barriers. The change is
limited to barriers used by x86-64.

Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

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Merge tag 'v5.15' into next

Sync up with the mainline to get the latest APIs and DT bindings.

Merge branch 'perf/urgent' into perf/core, to pick up fixes

Signed-off-by: Ingo Molnar <mingo@kernel.org>

Merge tag 'v5.14-rc6' into locking/core, to pick up fixes

Signed-off-by: Ingo Molnar <mingo@kernel.org>

Backmerge remote-tracking branch 'drm/drm-next' into drm-misc-next

Required bump from v5.13-rc3 to v5.14-rc3, and to pick up sysfb compilation fixes.

Signed-off-by: Maarten Lankhorst <maarten.lankh

Backmerge remote-tracking branch 'drm/drm-next' into drm-misc-next

Required bump from v5.13-rc3 to v5.14-rc3, and to pick up sysfb compilation fixes.

Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>

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Merge branch 'fixes-v5.14' into fixes

Merge drm/drm-next into drm-intel-gt-next

Catching up with 5.14-rc1 and also preparing for a
needed common topic branch for the "Minor revid/stepping
and workaround cleanup"

Reference: https://patc

Merge drm/drm-next into drm-intel-gt-next

Catching up with 5.14-rc1 and also preparing for a
needed common topic branch for the "Minor revid/stepping
and workaround cleanup"

Reference: https://patchwork.freedesktop.org/series/92299/
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

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Merge drm/drm-next into drm-intel-next

Catching up with 5.14-rc1

Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

Merge branch 'cpufreq/cppc-fie' into cpufreq/arm/linux-next