KVM/arm64 fixes for 7.1, take #5

- Correctly drop the ITS translation cache reference when it actually
  gets invalidated

- Take the SRCU lock for SW page table walks

- Restore POR_EL0 access to host EL0, avoiding POR_EL0 becoming
  inaccessible from EL0 after running a guest

- Reassign nested_mmus array behind mmu_lock, ensuring that vcpu init
  and MMU notifiers are mutually exclusive

- Correctly handle FEAT_XNX at stage-2

XN has already been extracted from its bitfield position so using
FIELD_PREP() on the mask that clears XN[0] is completely broken, having
the effect of unconditionally granting execute permissions...

Fix the obvious mistake by manipulating the right bit.

Cc: stable@vger.kernel.org
Fixes: d93febe2ed2e ("KVM: arm64: nv: Forward FEAT_XNX permissions to the shadow stage-2")
Reviewed-by: Wei-Lin Chang <weilin.chang@arm.com>
Signed-off-by: Oliver Upton <oupton@kernel.org>
Link: https://patch.msgid.link/20260602165901.52800-2-oupton@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>

KVM/arm64 fixes for 7.1, take #4

- Restore CONFIG_PKVM_DISABLE_STAGE2_ON_PANIC to its former glory by
  making sure the config symbol is correctly spelled out in the code

- Don't reset the AArch32 view of the PMU counters to zero when the
  guest is writing to them

- Fix an assorted collection of memory leaks in the newly added tracing
  code

- Fix the capping of ZCR_EL2 which could be used in an unsanitised way
  by an L2 guest

ZCR_EL2 can be updated by a VHE guest hypervisor either using ZCR_EL2
(which traps) or ZCR_EL1 (which does not trap). KVM handles both in
different way:

- on ZCR_EL2 trap, ZCR_EL2.LEN is immediately capped at the VM's own
  VL limit. This has the potential to break existing SW that relies
  on the full LEN field to be stateful.

- on ZCR_EL1 access, we do absolutely nothing.

On restoring the SVE context for an L2 guest, we directly restore the
guest hypervisor's view of ZCR_EL2 into the physical ZCR_EL2. If the
guest's view of the register was updated using the ZCR_EL2 accessor,
the value has already been sanitised (with the caveat mentioned above).

But if the guest used ZCR_EL1, the raw value is written into the HW,
and the L2 guest can now access VLs that it shouldn't.

Fix all the above by moving the VL capping to the restore points,
ensuring that:

- the HW is always programmed with a capped value, irrespective of
  the accessor being used,

- the ZCR_EL2.LEN field is always completely stateful, irrespective
  of the accessor being used.

Additionally, move ZCR_EL2 to be a sanitised register, ensuring that
only the LEN field is actually stateful. This requires some creative
construction of the RES0 mask, as the sysreg generation script does
not yet generate RAZ/WI fields.

Fixes: b3d29a823099 ("KVM: arm64: nv: Handle ZCR_EL2 traps")
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260529-kvm-arm64-fix-zcr-len-nv-v2-1-86cad51992bd@kernel.org
[maz: rewrote commit message, tidy up access_zcr_el2()]
Signed-off-by: Marc Zyngier <maz@kernel.org>

Pull arm64 fixes from Catalin Marinas:

 - Handle probe on hinted conditional branch instructions.

   BC.cond instructions can be simulated in the same way as B.cond
   instructions, so extend the decode mask for B.cond to cover BC.cond

 - Flush the walk cache when unsharing PMD tables. Recent changes to
   huge_pmd_unshare() introduced mmu_gather::unshared_tables but the
   arm64 code was still treating the TLB flushing as only targeting leaf
   entries (TLBI VALE1IS).

   Fix it by using non-leaf-only instructions (TLBI VAE1IS) when
   tlb->unshared_tables is set

* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
  arm64: tlb: Flush walk cache when unsharing PMD tables
  arm64: probes: Handle probes on hinted conditional branch instructions

When huge_pmd_unshare() is called to unshare a PMD table, the
tlb_unshare_pmd_ptdesc() function sets tlb->unshared_tables=true
but the aarch64 tlb_flush() only checked tlb->freed_tables to
determine whether to use TLBF_NONE (vae1is, invalidates walk
cache) or TLBF_NOWALKCACHE (vale1is, leaf-only).

This caused the stale PMD page table entry to remain in the walk cache
after unshare, potentially leading to incorrect page table walks.

Fix by including unshared_tables in the check, so that when
unsharing tables, TLBF_NONE is used and the walk cache is properly
invalidated.

Here is the detailed distinction between vae1is and vale1is:

| Instruction Combination  | Actual Invalidation Scope                         |
| ------------------------ | --------------------------------------------------|
| `VAE1IS`  + TTL=`0`      | All entries at all levels (full invalidation)     |
| `VAE1IS`  + TTL=`2` (L2) | Non-leaf at Level 0/1 + leaf at Level 2           |
| `VALE1IS` + TTL=`0`      | Leaf entries at all levels (non-leaf not cleared) |
| `VALE1IS` + TTL=`2` (L2) | Leaf entry at Level 2 only                        |

Signed-off-by: Zeng Heng <zengheng4@huawei.com>
Fixes: 8ce720d5bd91 ("mm/hugetlb: fix excessive IPI broadcasts when unsharing PMD tables using mmu_gather")
Cc: <stable@vger.kernel.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

Pull ring-buffer fixes from Steven Rostedt:

 - Fix reporting MISSED EVENTS in trace iterator

   When the "trace" file is read with tracing enabled, if the writer
   were to pass the iterator reader, it resets, sets a "missed_events"
   flag and continues. The tracing output checks for missed events and
   if there are some, it prints out "[LOST EVENTS]" to let the user know
   events were dropped.

   But the clearing of the missed_events happened when the tracing
   system queried the ring buffer iterator about missed events. This was
   premature as the ring buffer is per CPU, and the tracing code reads
   all the CPU buffers and checks for missed events when it is read. If
   the CPU iterator that had missed events isn't printed next, the
   output for the LOST EVENTS is lost.

   Clear the missed_events flag when the iterator moves to the next
   event and not when the missed_events flag is queried. Also clear it
   on reset.

 - Flush and stop the persistent ring buffer on panic

   On panic the persistent ring buffer is used to debug what caused the
   panic. But on some architectures, it requires flushing the memory
   from cache, otherwise, the ring buffer persistent memory may not have
   the last events and this could also cause the ring buffer to be
   corrupted on the next boot.

 - Fix nr_subbufs initialization in simple_ring_buffer_init_mm

   The remote simple ring buffer meta data nr_subbufs is initialized too
   early and gets cleared later on, making it zero and not reflect the
   actual number of sub-buffers.

 - Fix unload_page for simple_ring_buffer init rollback

   On error, the pages loaded need to be unloaded. To unload a page it
   is expected that: page = load_page(va); -> unload_page(page). But the
   code was doing: unload_page(va) and not unload_page(page).

 - Create output file from cmd_check_undefined

   The check for undefined symbols checks if the file *.o.checked exists
   and if so it skips doing the work. But the *.o.checked file never was
   created making every build do the work even when it was already done
   previously.

* tag 'trace-ringbuffer-v7.1-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  tracing: Create output file from cmd_check_undefined
  tracing: Fix unload_page for simple_ring_buffer init rollback
  tracing: Fix nr_subbufs initialization in simple_ring_buffer_init_mm()
  ring-buffer: Flush and stop persistent ring buffer on panic
  ring-buffer: Fix reporting of missed events in iterator

On real hardware, panic and machine reboot may not flush hardware cache
to memory. This means the persistent ring buffer, which relies on a
coherent state of memory, may not have its events written to the buffer
and they may be lost. Moreover, there may be inconsistency with the
counters which are used for validation of the integrity of the
persistent ring buffer which may cause all data to be discarded.

To avoid this issue, stop recording of the ring buffer on panic and
flush the cache of the ring buffer's memory.

Fixes: e645535a954a ("tracing: Add option to use memmapped memory for trace boot instance")
Cc: stable@vger.kernel.org
Cc: Will Deacon <will@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Ian Rogers <irogers@google.com>
Link: https://patch.msgid.link/177751969602.2136606.12031934362587643488.stgit@mhiramat.tok.corp.google.com
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

Pull misc fixes from Andrew Morton:
 "14 hotfixes. 9 are for MM. 10 are cc:stable and the remainder are for
  post-7.1 issues or aren't deemed suitable for backporting.

  There's a two-patch MAINTAINERS series from Mike Rapoport which
  updates us for the new KEXEC/KDUMP/crash/LUO/etc arrangements. And
  another two-patch series from Muchun Song to fix a couple of
  memory-hotplug issues. Otherwise singletons, please see the changelogs
  for details"

* tag 'mm-hotfixes-stable-2026-05-18-21-07' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm:
  mm/memory: fix spurious warning when unmapping device-private/exclusive pages
  mm: fix __vm_normal_page() to handle missing support for pmd_special()/pud_special()
  drivers/base/memory: fix memory block reference leak in poison accounting
  mm/memory_hotplug: fix memory block reference leak on remove
  lib: kunit_iov_iter: fix test fail on powerpc
  mm/page_alloc: fix initialization of tags of the huge zero folio with init_on_free
  MAINTAINERS: add kexec@ list to LIVE UPDATE ENTRY
  MAINTAINERS: add tree for KDUMP and KEXEC
  selftests/mm: run_vmtests.sh: fix destructive tests invocation
  scripts/gdb: slab: update field names of struct kmem_cache
  scripts/gdb: mm: cast untyped symbols in x86_page_ops
  mm/damon: fix damos_stat tracepoint format for sz_applied
  mm/damon/sysfs-schemes: call missing mem_cgroup_iter_break()
  mm/migrate_device: fix spinlock leak in migrate_vma_insert_huge_pmd_page

BC.cond instructions introduced by FEAT_HBC cannot be executed
out-of-line, like other branch instructions. However, they can be
simulated in the same way as B.cond instructions.

Extend the B.cond decoder mask to match BC.cond instructions as well,
and handle them using the existing B.cond simulation path.

Fixes: 7f86d128e437 ("arm64: add HWCAP for FEAT_HBC (hinted conditional branches)")
Cc: <stable@vger.kernel.org>
Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>