<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/arch/arm64/mm/fault.c, branch master</title>
<subtitle>Linux kernel source tree.</subtitle>
<id>https://git.ilvokhin.com/linux.git/atom/arch/arm64/mm/fault.c?h=master</id>
<link rel='self' href='https://git.ilvokhin.com/linux.git/atom/arch/arm64/mm/fault.c?h=master'/>
<link rel='alternate' type='text/html' href='https://git.ilvokhin.com/linux.git/'/>
<updated>2026-07-16T15:11:13Z</updated>
<entry>
<title>arm64: mm: When logging data aborts only decode Xs when ISV=1</title>
<updated>2026-07-16T15:11:13Z</updated>
<author>
<name>Mark Brown</name>
<email>broonie@kernel.org</email>
</author>
<published>2026-07-02T19:13:35Z</published>
<link rel='alternate' type='text/html' href='https://git.ilvokhin.com/linux.git/commit/?id=f797f51a185ffdc1e3f915afed55f308b376842f'/>
<id>urn:sha1:f797f51a185ffdc1e3f915afed55f308b376842f</id>
<content type='text'>
When logging the decode of a data abort we currently unconditionally decode
and display Xs. Currently the only defined non-RES0 values for this field
are for cases where ISV=1, move the decode of Xs into our existing check
for ISV=1. This avoids potential confusion if some other use is assigned to
these bits for ISV=0 cases in future, or misleading someone into thinking
there is a meaningful value there with currently defined architecture.

Signed-off-by: Mark Brown &lt;broonie@kernel.org&gt;
Signed-off-by: Will Deacon &lt;will@kernel.org&gt;
</content>
</entry>
<entry>
<title>Merge branch 'arena_direct_access'</title>
<updated>2026-05-25T15:35:48Z</updated>
<author>
<name>Alexei Starovoitov</name>
<email>ast@kernel.org</email>
</author>
<published>2026-05-25T15:35:07Z</published>
<link rel='alternate' type='text/html' href='https://git.ilvokhin.com/linux.git/commit/?id=8496d9020ff37a33c2a7b2fc84350fd03ffbde78'/>
<id>urn:sha1:8496d9020ff37a33c2a7b2fc84350fd03ffbde78</id>
<content type='text'>
Tejun Heo says:

====================
This makes BPF arena memory directly dereferenceable from kernel code
(struct_ops callbacks, kfuncs). Each arena gets a per-arena scratch page
that an arch fault hook installs into empty PTEs on kernel-side faults,
after KFENCE. The faulting instruction retries and the violation is reported
through the program's BPF stream.

v4:
- Patch 1: note that the strict-zero cmpxchg is narrower than pte_none() in
  inline comments on both x86 and arm64. (Andrea)
- Patch 2: stub bpf_arena_handle_page_fault() for !CONFIG_BPF_SYSCALL via a
  new include/linux/bpf_defs.h. (lkp)
- Patch 7: scx_arena_alloc() retries via a loop instead of a single retry on
  pool growth. (Andrea)
- Picked up Reviewed-by tags from Emil and Andrea.

v3: https://lore.kernel.org/r/20260520235052.4180316-1-tj@kernel.org
v2: https://lore.kernel.org/r/20260517211232.1670594-1-tj@kernel.org
v1 (RFC): https://lore.kernel.org/r/20260427105109.2554518-1-tj@kernel.org

Motivation
----------

sched_ext's ops_cid.set_cmask() hands the BPF scheduler a struct scx_cmask
*. The kernel translates a kernel cpumask to a cmask, but it had no way to
write into the arena, so the cmask lived in kernel memory and was passed as
a trusted pointer. BPF cmask helpers all operate on arena cmasks though, so
the BPF side had to word-by-word probe-read the kernel cmask into an arena
cmask via cmask_copy_from_kernel() before any helper could touch it. It
works, but is clumsy.

The shape isn't unique to set_cmask. Sub-scheduler support is on the way and
more sched_ext callbacks will want to pass structured data to BPF. Anywhere
a kfunc or struct_ops callback wants to hand a struct to a BPF program,
arena residence is the natural answer.

Approach
--------

Each arena gets a per-arena scratch page. Arenas stay sparsely mapped as
today - PTEs are populated only for allocated pages. A new arch fault hook
(bpf_arena_handle_page_fault) is wired into x86 page_fault_oops() and arm64
__do_kernel_fault(), after KFENCE. When a kernel-side access faults inside
an arena's kern_vm range, the helper walks the stack to find the BPF program
responsible, range-checks the fault address against prog-&gt;aux-&gt;arena, and
atomically installs the scratch page into the empty PTE via the new
ptep_try_set() wrapper. The kernel instruction retries and reads/writes the
scratch page. Free paths and map destruction treat scratch as non-owned.
Real allocation refuses to overwrite scratch (apply_range_set_cb returns
-EBUSY). A scratched address stays dead until map destroy, since its
presence means the BPF program has already malfunctioned.

The mechanism is default behavior - no UAPI flag.

What this preserves
-------------------

All the debugging properties of today's sparse-PTE design are preserved:

* BPF programs still fault on unmapped arena accesses. The fault semantics
  (instruction retry with rdst = 0) and the violation report through
  bpf_streams are unchanged for prog-side accesses.

* The first kernel-side touch of an unmapped address is reported via
  bpf_streams the same way as a prog-side fault, with the stack walk
  attributing it to the originating prog.

* User-side fault on a never-scratched address still lazy-allocates a real
  page (or returns SIGSEGV under BPF_F_SEGV_ON_FAULT). User-side fault on a
  scratched address SIGSEGVs.

What changes for the kernel-side caller is just that an unmapped deref no
longer oopses - it retries through the scratch page and emits a violation
report. The same shape today's BPF instruction faults have.

Patches 1-2 (atomic PTE install + arena scratch-page recovery)
--------------------------------------------------------------

  mm: Add ptep_try_set() for lockless empty-slot installs
  bpf: Recover arena kernel faults with scratch page

Patches 3-5 (helpers used by struct_ops registration)
-----------------------------------------------------

  bpf: Add sleepable variant of bpf_arena_alloc_pages for kernel callers
  bpf: Add bpf_struct_ops_for_each_prog()
  bpf/arena: Add bpf_arena_map_kern_vm_start() and bpf_prog_arena()
====================

Link: https://lore.kernel.org/bpf/20260522172219.1423324-1-tj@kernel.org/
Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;
</content>
</entry>
<entry>
<title>bpf: Recover arena kernel faults with scratch page</title>
<updated>2026-05-23T08:50:33Z</updated>
<author>
<name>Kumar Kartikeya Dwivedi</name>
<email>memxor@gmail.com</email>
</author>
<published>2026-05-22T17:22:13Z</published>
<link rel='alternate' type='text/html' href='https://git.ilvokhin.com/linux.git/commit/?id=dc11a4dba2464e5144c318ffaf7fb16b1a5c74d6'/>
<id>urn:sha1:dc11a4dba2464e5144c318ffaf7fb16b1a5c74d6</id>
<content type='text'>
BPF arena usage is becoming more prevalent, but kernel &lt;-&gt; BPF communication
over arena memory is awkward today. Data has to be staged through a trusted
kernel pointer with extra code and copying on the BPF side. While reads
through arena pointers can use a fault-safe helper, writes don't have a good
solution. The in-line alternative would need instruction emulation or asm
fixup labels.

Enable direct kernel-side reads and writes within GUARD_SZ / 2 of any
handed-in arena pointer, without bounds checking. A per-arena scratch page
is installed by the arch fault path into empty arena kernel PTEs - x86 from
page_fault_oops() for not-present faults, arm64 from __do_kernel_fault() for
translation faults, both after the existing exception-table and KFENCE
handling. The faulting instruction retries and the access is also reported
through the program's BPF stream, preserving error reporting.

bpf_prog_find_from_stack() resolves the current BPF program (and its arena)
from the kernel stack - no new bpf_run_ctx state is added. Recovery covers
the 4 GiB arena plus the upper half-guard (GUARD_SZ / 2). The lower
half-guard is excluded because well-behaved kfuncs only access forward from
arena pointers. The kfunc-author contract - access at most GUARD_SZ / 2 past
a handed-in pointer - is documented in Documentation/bpf/kfuncs.rst.

The install is lock-free via ptep_try_set(). On race-loss the winning
installer's PTE is already valid, so the access retry succeeds. The arena
clear path uses ptep_get_and_clear() so installer and clearer race through
atomic accessors. No flush_tlb_kernel_range() afterwards. Stale "not mapped"
entries just cause one extra re-fault, cheaper than a global IPI on every
install.

Scratch exists only to keep the kernel from oopsing on an in-line arena
access. Its presence at a PTE means the BPF program has already
malfunctioned, and the violation is reported through the program's BPF
stream. The only requirement for behavior on a scratched PTE is that the
kernel doesn't crash. In particular, any user-side access through such a PTE
may segfault. The shared scratch page is freed once during map destruction.

BPF instruction faults continue to use the existing JIT exception-table
path. This patch changes only the kernel-text fault path. No UAPI flag is
added. The new behavior is the default.

v2: Use ptep_get_and_clear() in apply_range_clear_cb(). (David)
v3: Stub bpf_arena_handle_page_fault() for !CONFIG_BPF_SYSCALL. (lkp)

Suggested-by: Alexei Starovoitov &lt;ast@kernel.org&gt;
Signed-off-by: Kumar Kartikeya Dwivedi &lt;memxor@gmail.com&gt;
Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
Reviewed-by: Emil Tsalapatis &lt;emil@etsalapatis.com&gt;
Cc: David Hildenbrand &lt;david@kernel.org&gt;
Link: https://lore.kernel.org/r/20260522172219.1423324-3-tj@kernel.org
Signed-off-by: Alexei Starovoitov &lt;ast@kernel.org&gt;
</content>
</entry>
<entry>
<title>mm/page_alloc: fix initialization of tags of the huge zero folio with init_on_free</title>
<updated>2026-05-14T00:40:02Z</updated>
<author>
<name>David Hildenbrand (Arm)</name>
<email>david@kernel.org</email>
</author>
<published>2026-04-21T15:39:07Z</published>
<link rel='alternate' type='text/html' href='https://git.ilvokhin.com/linux.git/commit/?id=6a288a4ddb4a994490505ab5f41c445f8e6b6467'/>
<id>urn:sha1:6a288a4ddb4a994490505ab5f41c445f8e6b6467</id>
<content type='text'>
__GFP_ZEROTAGS semantics are currently a bit weird, but effectively this
flag is only ever set alongside __GFP_ZERO and __GFP_SKIP_KASAN.

If we run with init_on_free, we will zero out pages during
__free_pages_prepare(), to skip zeroing on the allocation path.

However, when allocating with __GFP_ZEROTAG set, post_alloc_hook() will
consequently not only skip clearing page content, but also skip clearing
tag memory.

Not clearing tags through __GFP_ZEROTAGS is irrelevant for most pages that
will get mapped to user space through set_pte_at() later: set_pte_at() and
friends will detect that the tags have not been initialized yet
(PG_mte_tagged not set), and initialize them.

However, for the huge zero folio, which will be mapped through a PMD
marked as special, this initialization will not be performed, ending up
exposing whatever tags were still set for the pages.

The docs (Documentation/arch/arm64/memory-tagging-extension.rst) state
that allocation tags are set to 0 when a page is first mapped to user
space.  That no longer holds with the huge zero folio when init_on_free is
enabled.

Fix it by decoupling __GFP_ZEROTAGS from __GFP_ZERO, passing to
tag_clear_highpages() whether we want to also clear page content.

Invert the meaning of the tag_clear_highpages() return value to have
clearer semantics.

Reproduced with the huge zero folio by modifying the check_buffer_fill
arm64/mte selftest to use a 2 MiB area, after making sure that pages have
a non-0 tag set when freeing (note that, during boot, we will not actually
initialize tags, but only set KASAN_TAG_KERNEL in the page flags).

	$ ./check_buffer_fill
	1..20
	...
	not ok 17 Check initial tags with private mapping, sync error mode and mmap memory
	not ok 18 Check initial tags with private mapping, sync error mode and mmap/mprotect memory
	...

This code needs more cleanups; we'll tackle that next, like
decoupling __GFP_ZEROTAGS from __GFP_SKIP_KASAN.

[akpm@linux-foundation.org: s/__GPF_ZERO/__GFP_ZERO/, per David]
Link: https://lore.kernel.org/20260421-zerotags-v2-1-05cb1035482e@kernel.org
Fixes: adfb6609c680 ("mm/huge_memory: initialise the tags of the huge zero folio")
Signed-off-by: David Hildenbrand (Arm) &lt;david@kernel.org&gt;
Reviewed-by: Catalin Marinas &lt;catalin.marinas@arm.com&gt;
Tested-by: Lance Yang &lt;lance.yang@linux.dev&gt;
Cc: Brendan Jackman &lt;jackmanb@google.com&gt;
Cc: Dev Jain &lt;dev.jain@arm.com&gt;
Cc: Johannes Weiner &lt;hannes@cmpxchg.org&gt;
Cc: Liam Howlett &lt;liam@infradead.org&gt;
Cc: Lorenzo Stoakes (Oracle) &lt;ljs@kernel.org&gt;
Cc: Mark Brown &lt;broonie@kernel.org&gt;
Cc: Michal Hocko &lt;mhocko@suse.com&gt;
Cc: Mike Rapoport &lt;rppt@kernel.org&gt;
Cc: Ryan Roberts &lt;ryan.roberts@arm.com&gt;
Cc: Suren Baghdasaryan &lt;surenb@google.com&gt;
Cc: Will Deacon &lt;will@kernel.org&gt;
Cc: Zi Yan &lt;ziy@nvidia.com&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm</title>
<updated>2026-04-17T14:18:03Z</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2026-04-17T14:18:03Z</published>
<link rel='alternate' type='text/html' href='https://git.ilvokhin.com/linux.git/commit/?id=01f492e1817e858d1712f2489d0afbaa552f417b'/>
<id>urn:sha1:01f492e1817e858d1712f2489d0afbaa552f417b</id>
<content type='text'>
Pull kvm updates from Paolo Bonzini:
 "Arm:

   - Add support for tracing in the standalone EL2 hypervisor code,
     which should help both debugging and performance analysis. This
     uses the new infrastructure for 'remote' trace buffers that can be
     exposed by non-kernel entities such as firmware, and which came
     through the tracing tree

   - Add support for GICv5 Per Processor Interrupts (PPIs), as the
     starting point for supporting the new GIC architecture in KVM

   - Finally add support for pKVM protected guests, where pages are
     unmapped from the host as they are faulted into the guest and can
     be shared back from the guest using pKVM hypercalls. Protected
     guests are created using a new machine type identifier. As the
     elusive guestmem has not yet delivered on its promises, anonymous
     memory is also supported

     This is only a first step towards full isolation from the host; for
     example, the CPU register state and DMA accesses are not yet
     isolated. Because this does not really yet bring fully what it
     promises, it is hidden behind CONFIG_ARM_PKVM_GUEST +
     'kvm-arm.mode=protected', and also triggers TAINT_USER when a VM is
     created. Caveat emptor

   - Rework the dreaded user_mem_abort() function to make it more
     maintainable, reducing the amount of state being exposed to the
     various helpers and rendering a substantial amount of state
     immutable

   - Expand the Stage-2 page table dumper to support NV shadow page
     tables on a per-VM basis

   - Tidy up the pKVM PSCI proxy code to be slightly less hard to
     follow

   - Fix both SPE and TRBE in non-VHE configurations so that they do not
     generate spurious, out of context table walks that ultimately lead
     to very bad HW lockups

   - A small set of patches fixing the Stage-2 MMU freeing in error
     cases

   - Tighten-up accepted SMC immediate value to be only #0 for host
     SMCCC calls

   - The usual cleanups and other selftest churn

  LoongArch:

   - Use CSR_CRMD_PLV for kvm_arch_vcpu_in_kernel()

   - Add DMSINTC irqchip in kernel support

  RISC-V:

   - Fix steal time shared memory alignment checks

   - Fix vector context allocation leak

   - Fix array out-of-bounds in pmu_ctr_read() and pmu_fw_ctr_read_hi()

   - Fix double-free of sdata in kvm_pmu_clear_snapshot_area()

   - Fix integer overflow in kvm_pmu_validate_counter_mask()

   - Fix shift-out-of-bounds in make_xfence_request()

   - Fix lost write protection on huge pages during dirty logging

   - Split huge pages during fault handling for dirty logging

   - Skip CSR restore if VCPU is reloaded on the same core

   - Implement kvm_arch_has_default_irqchip() for KVM selftests

   - Factored-out ISA checks into separate sources

   - Added hideleg to struct kvm_vcpu_config

   - Factored-out VCPU config into separate sources

   - Support configuration of per-VM HGATP mode from KVM user space

  s390:

   - Support for ESA (31-bit) guests inside nested hypervisors

   - Remove restriction on memslot alignment, which is not needed
     anymore with the new gmap code

   - Fix LPSW/E to update the bear (which of course is the breaking
     event address register)

  x86:

   - Shut up various UBSAN warnings on reading module parameter before
     they were initialized

   - Don't zero-allocate page tables that are used for splitting
     hugepages in the TDP MMU, as KVM is guaranteed to set all SPTEs in
     the page table and thus write all bytes

   - As an optimization, bail early when trying to unsync 4KiB mappings
     if the target gfn can just be mapped with a 2MiB hugepage

  x86 generic:

   - Copy single-chunk MMIO write values into struct kvm_vcpu (more
     precisely struct kvm_mmio_fragment) to fix use-after-free stack
     bugs where KVM would dereference stack pointer after an exit to
     userspace

   - Clean up and comment the emulated MMIO code to try to make it
     easier to maintain (not necessarily "easy", but "easier")

   - Move VMXON+VMXOFF and EFER.SVME toggling out of KVM (not *all* of
     VMX and SVM enabling) as it is needed for trusted I/O

   - Advertise support for AVX512 Bit Matrix Multiply (BMM) instructions

   - Immediately fail the build if a required #define is missing in one
     of KVM's headers that is included multiple times

   - Reject SET_GUEST_DEBUG with -EBUSY if there's an already injected
     exception, mostly to prevent syzkaller from abusing the uAPI to
     trigger WARNs, but also because it can help prevent userspace from
     unintentionally crashing the VM

   - Exempt SMM from CPUID faulting on Intel, as per the spec

   - Misc hardening and cleanup changes

  x86 (AMD):

   - Fix and optimize IRQ window inhibit handling for AVIC; make it
     per-vCPU so that KVM doesn't prematurely re-enable AVIC if multiple
     vCPUs have to-be-injected IRQs

   - Clean up and optimize the OSVW handling, avoiding a bug in which
     KVM would overwrite state when enabling virtualization on multiple
     CPUs in parallel. This should not be a problem because OSVW should
     usually be the same for all CPUs

   - Drop a WARN in KVM_MEMORY_ENCRYPT_REG_REGION where KVM complains
     about a "too large" size based purely on user input

   - Clean up and harden the pinning code for KVM_MEMORY_ENCRYPT_REG_REGION

   - Disallow synchronizing a VMSA of an already-launched/encrypted
     vCPU, as doing so for an SNP guest will crash the host due to an
     RMP violation page fault

   - Overhaul KVM's APIs for detecting SEV+ guests so that VM-scoped
     queries are required to hold kvm-&gt;lock, and enforce it by lockdep.
     Fix various bugs where sev_guest() was not ensured to be stable for
     the whole duration of a function or ioctl

   - Convert a pile of kvm-&gt;lock SEV code to guard()

   - Play nicer with userspace that does not enable
     KVM_CAP_EXCEPTION_PAYLOAD, for which KVM needs to set CR2 and DR6
     as a response to ioctls such as KVM_GET_VCPU_EVENTS (even if the
     payload would end up in EXITINFO2 rather than CR2, for example).
     Only set CR2 and DR6 when consumption of the payload is imminent,
     but on the other hand force delivery of the payload in all paths
     where userspace retrieves CR2 or DR6

   - Use vcpu-&gt;arch.cr2 when updating vmcb12's CR2 on nested #VMEXIT
     instead of vmcb02-&gt;save.cr2. The value is out of sync after a
     save/restore or after a #PF is injected into L2

   - Fix a class of nSVM bugs where some fields written by the CPU are
     not synchronized from vmcb02 to cached vmcb12 after VMRUN, and so
     are not up-to-date when saved by KVM_GET_NESTED_STATE

   - Fix a class of bugs where the ordering between KVM_SET_NESTED_STATE
     and KVM_SET_{S}REGS could cause vmcb02 to be incorrectly
     initialized after save+restore

   - Add a variety of missing nSVM consistency checks

   - Fix several bugs where KVM failed to correctly update VMCB fields
     on nested #VMEXIT

   - Fix several bugs where KVM failed to correctly synthesize #UD or
     #GP for SVM-related instructions

   - Add support for save+restore of virtualized LBRs (on SVM)

   - Refactor various helpers and macros to improve clarity and
     (hopefully) make the code easier to maintain

   - Aggressively sanitize fields when copying from vmcb12, to guard
     against unintentionally allowing L1 to utilize yet-to-be-defined
     features

   - Fix several bugs where KVM botched rAX legality checks when
     emulating SVM instructions. There are remaining issues in that KVM
     doesn't handle size prefix overrides for 64-bit guests

   - Fail emulation of VMRUN/VMLOAD/VMSAVE if mapping vmcb12 fails
     instead of somewhat arbitrarily synthesizing #GP (i.e. don't double
     down on AMD's architectural but sketchy behavior of generating #GP
     for "unsupported" addresses)

   - Cache all used vmcb12 fields to further harden against TOCTOU bugs

  x86 (Intel):

   - Drop obsolete branch hint prefixes from the VMX instruction macros

   - Use ASM_INPUT_RM() in __vmcs_writel() to coerce clang into using a
     register input when appropriate

   - Code cleanups

  guest_memfd:

   - Don't mark guest_memfd folios as accessed, as guest_memfd doesn't
     support reclaim, the memory is unevictable, and there is no storage
     to write back to

  LoongArch selftests:

   - Add KVM PMU test cases

  s390 selftests:

   - Enable more memory selftests

  x86 selftests:

   - Add support for Hygon CPUs in KVM selftests

   - Fix a bug in the MSR test where it would get false failures on
     AMD/Hygon CPUs with exactly one of RDPID or RDTSCP

   - Add an MADV_COLLAPSE testcase for guest_memfd as a regression test
     for a bug where the kernel would attempt to collapse guest_memfd
     folios against KVM's will"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (373 commits)
  KVM: x86: use inlines instead of macros for is_sev_*guest
  x86/virt: Treat SVM as unsupported when running as an SEV+ guest
  KVM: SEV: Goto an existing error label if charging misc_cg for an ASID fails
  KVM: SVM: Move lock-protected allocation of SEV ASID into a separate helper
  KVM: SEV: use mutex guard in snp_handle_guest_req()
  KVM: SEV: use mutex guard in sev_mem_enc_unregister_region()
  KVM: SEV: use mutex guard in sev_mem_enc_ioctl()
  KVM: SEV: use mutex guard in snp_launch_update()
  KVM: SEV: Assert that kvm-&gt;lock is held when querying SEV+ support
  KVM: SEV: Document that checking for SEV+ guests when reclaiming memory is "safe"
  KVM: SEV: Hide "struct kvm_sev_info" behind CONFIG_KVM_AMD_SEV=y
  KVM: SEV: WARN on unhandled VM type when initializing VM
  KVM: LoongArch: selftests: Add PMU overflow interrupt test
  KVM: LoongArch: selftests: Add basic PMU event counting test
  KVM: LoongArch: selftests: Add cpucfg read/write helpers
  LoongArch: KVM: Add DMSINTC inject msi to vCPU
  LoongArch: KVM: Add DMSINTC device support
  LoongArch: KVM: Make vcpu_is_preempted() as a macro rather than function
  LoongArch: KVM: Move host CSR_GSTAT save and restore in context switch
  LoongArch: KVM: Move host CSR_EENTRY save and restore in context switch
  ...
</content>
</entry>
<entry>
<title>KVM: arm64: Reclaim faulting page from pKVM in spurious fault handler</title>
<updated>2026-03-30T15:58:09Z</updated>
<author>
<name>Will Deacon</name>
<email>will@kernel.org</email>
</author>
<published>2026-03-30T14:48:27Z</published>
<link rel='alternate' type='text/html' href='https://git.ilvokhin.com/linux.git/commit/?id=281a38ad2920b5ccfbbc2a0ca0caeee110ad5d6b'/>
<id>urn:sha1:281a38ad2920b5ccfbbc2a0ca0caeee110ad5d6b</id>
<content type='text'>
Host kernel accesses to pages that are inaccessible at stage-2 result in
the injection of a translation fault, which is fatal unless an exception
table fixup is registered for the faulting PC (e.g. for user access
routines). This is undesirable, since a get_user_pages() call could be
used to obtain a reference to a donated page and then a subsequent
access via a kernel mapping would lead to a panic().

Rework the spurious fault handler so that stage-2 faults injected back
into the host result in the target page being forcefully reclaimed when
no exception table fixup handler is registered.

Tested-by: Fuad Tabba &lt;tabba@google.com&gt;
Tested-by: Mostafa Saleh &lt;smostafa@google.com&gt;
Signed-off-by: Will Deacon &lt;will@kernel.org&gt;
Link: https://patch.msgid.link/20260330144841.26181-27-will@kernel.org
Signed-off-by: Marc Zyngier &lt;maz@kernel.org&gt;
</content>
</entry>
<entry>
<title>KVM: arm64: Inject SIGSEGV on illegal accesses</title>
<updated>2026-03-30T15:58:08Z</updated>
<author>
<name>Quentin Perret</name>
<email>qperret@google.com</email>
</author>
<published>2026-03-30T14:48:20Z</published>
<link rel='alternate' type='text/html' href='https://git.ilvokhin.com/linux.git/commit/?id=9ff714a09222128da16900fc7c15dea65692fc26'/>
<id>urn:sha1:9ff714a09222128da16900fc7c15dea65692fc26</id>
<content type='text'>
The pKVM hypervisor will currently panic if the host tries to access
memory that it doesn't own (e.g. protected guest memory). Sadly, as
guest memory can still be mapped into the VMM's address space, userspace
can trivially crash the kernel/hypervisor by poking into guest memory.

To prevent this, inject the abort back in the host with S1PTW set in the
ESR, hence allowing the host to differentiate this abort from normal
userspace faults and inject a SIGSEGV cleanly.

Reviewed-by: Fuad Tabba &lt;tabba@google.com&gt;
Tested-by: Fuad Tabba &lt;tabba@google.com&gt;
Tested-by: Mostafa Saleh &lt;smostafa@google.com&gt;
Signed-off-by: Quentin Perret &lt;qperret@google.com&gt;
Signed-off-by: Will Deacon &lt;will@kernel.org&gt;
Link: https://patch.msgid.link/20260330144841.26181-20-will@kernel.org
Signed-off-by: Marc Zyngier &lt;maz@kernel.org&gt;
</content>
</entry>
<entry>
<title>arm64: mm: __ptep_set_access_flags must hint correct TTL</title>
<updated>2026-03-25T18:08:13Z</updated>
<author>
<name>Ryan Roberts</name>
<email>ryan.roberts@arm.com</email>
</author>
<published>2026-03-23T16:39:16Z</published>
<link rel='alternate' type='text/html' href='https://git.ilvokhin.com/linux.git/commit/?id=b7d9d2e3a8ab535ff3bc8e9156a917bb8934f856'/>
<id>urn:sha1:b7d9d2e3a8ab535ff3bc8e9156a917bb8934f856</id>
<content type='text'>
It has been reported that since commit 752a0d1d483e9 ("arm64: mm:
Provide level hint for flush_tlb_page()"), the arm64
check_hugetlb_options selftest has been locking up while running "Check
child hugetlb memory with private mapping, sync error mode and mmap
memory".

This is due to hugetlb (and THP) helpers casting their PMD/PUD entries
to PTE and calling __ptep_set_access_flags(), which issues a
__flush_tlb_page(). Now that this is hinted for level 3, in this case,
the TLB entry does not get evicted and we end up in a spurious fault
loop.

Fix this by creating a __ptep_set_access_flags_anysz() function which
takes the pgsize of the entry. It can then add the appropriate hint. The
"_anysz" approach is the established pattern for problems of this class.

Reported-by: Aishwarya TCV &lt;Aishwarya.TCV@arm.com&gt;
Fixes: 752a0d1d483e ("arm64: mm: Provide level hint for flush_tlb_page()")
Signed-off-by: Ryan Roberts &lt;ryan.roberts@arm.com&gt;
Signed-off-by: Catalin Marinas &lt;catalin.marinas@arm.com&gt;
</content>
</entry>
<entry>
<title>arm64: mm: Wrap flush_tlb_page() around __do_flush_tlb_range()</title>
<updated>2026-03-13T17:26:26Z</updated>
<author>
<name>Ryan Roberts</name>
<email>ryan.roberts@arm.com</email>
</author>
<published>2026-03-02T13:55:59Z</published>
<link rel='alternate' type='text/html' href='https://git.ilvokhin.com/linux.git/commit/?id=15397e3c3850d447b7167614cbb24a98192c3693'/>
<id>urn:sha1:15397e3c3850d447b7167614cbb24a98192c3693</id>
<content type='text'>
Flushing a page from the tlb is just a special case of flushing a range.
So let's rework flush_tlb_page() so that it simply wraps
__do_flush_tlb_range(). While at it, let's also update the API to take
the same flags that we use when flushing a range. This allows us to
delete all the ugly "_nosync", "_local" and "_nonotify" variants.

Thanks to constant folding, all of the complex looping and tlbi-by-range
options get eliminated so that the generated code for flush_tlb_page()
looks very similar to the previous version.

Reviewed-by: Linu Cherian &lt;linu.cherian@arm.com&gt;
Signed-off-by: Ryan Roberts &lt;ryan.roberts@arm.com&gt;
Reviewed-by: Jonathan Cameron &lt;jonathan.cameron@huawei.com&gt;
Signed-off-by: Catalin Marinas &lt;catalin.marinas@arm.com&gt;
</content>
</entry>
<entry>
<title>Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux</title>
<updated>2025-12-03T01:03:55Z</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2025-12-03T01:03:55Z</published>
<link rel='alternate' type='text/html' href='https://git.ilvokhin.com/linux.git/commit/?id=44fc84337b6eae580a51cf6f7ca6a22ef1349556'/>
<id>urn:sha1:44fc84337b6eae580a51cf6f7ca6a22ef1349556</id>
<content type='text'>
Pull arm64 updates from Catalin Marinas:
 "These are the arm64 updates for 6.19.

  The biggest part is the Arm MPAM driver under drivers/resctrl/.
  There's a patch touching mm/ to handle spurious faults for huge pmd
  (similar to the pte version). The corresponding arm64 part allows us
  to avoid the TLB maintenance if a (huge) page is reused after a write
  fault. There's EFI refactoring to allow runtime services with
  preemption enabled and the rest is the usual perf/PMU updates and
  several cleanups/typos.

  Summary:

  Core features:

   - Basic Arm MPAM (Memory system resource Partitioning And Monitoring)
     driver under drivers/resctrl/ which makes use of the fs/rectrl/ API

  Perf and PMU:

   - Avoid cycle counter on multi-threaded CPUs

   - Extend CSPMU device probing and add additional filtering support
     for NVIDIA implementations

   - Add support for the PMUs on the NoC S3 interconnect

   - Add additional compatible strings for new Cortex and C1 CPUs

   - Add support for data source filtering to the SPE driver

   - Add support for i.MX8QM and "DB" PMU in the imx PMU driver

  Memory managemennt:

   - Avoid broadcast TLBI if page reused in write fault

   - Elide TLB invalidation if the old PTE was not valid

   - Drop redundant cpu_set_*_tcr_t0sz() macros

   - Propagate pgtable_alloc() errors outside of __create_pgd_mapping()

   - Propagate return value from __change_memory_common()

  ACPI and EFI:

   - Call EFI runtime services without disabling preemption

   - Remove unused ACPI function

  Miscellaneous:

   - ptrace support to disable streaming on SME-only systems

   - Improve sysreg generation to include a 'Prefix' descriptor

   - Replace __ASSEMBLY__ with __ASSEMBLER__

   - Align register dumps in the kselftest zt-test

   - Remove some no longer used macros/functions

   - Various spelling corrections"

* tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (94 commits)
  arm64/mm: Document why linear map split failure upon vm_reset_perms is not problematic
  arm64/pageattr: Propagate return value from __change_memory_common
  arm64/sysreg: Remove unused define ARM64_FEATURE_FIELD_BITS
  KVM: arm64: selftests: Consider all 7 possible levels of cache
  KVM: arm64: selftests: Remove ARM64_FEATURE_FIELD_BITS and its last user
  arm64: atomics: lse: Remove unused parameters from ATOMIC_FETCH_OP_AND macros
  Documentation/arm64: Fix the typo of register names
  ACPI: GTDT: Get rid of acpi_arch_timer_mem_init()
  perf: arm_spe: Add support for filtering on data source
  perf: Add perf_event_attr::config4
  perf/imx_ddr: Add support for PMU in DB (system interconnects)
  perf/imx_ddr: Get and enable optional clks
  perf/imx_ddr: Move ida_alloc() from ddr_perf_init() to ddr_perf_probe()
  dt-bindings: perf: fsl-imx-ddr: Add compatible string for i.MX8QM, i.MX8QXP and i.MX8DXL
  arm64: remove duplicate ARCH_HAS_MEM_ENCRYPT
  arm64: mm: use untagged address to calculate page index
  MAINTAINERS: new entry for MPAM Driver
  arm_mpam: Add kunit tests for props_mismatch()
  arm_mpam: Add kunit test for bitmap reset
  arm_mpam: Add helper to reset saved mbwu state
  ...
</content>
</entry>
</feed>
