kernel/linux.git/arch/s390/include, branch v7.1.12

s390/mm: Fix handling of _PAGE_UNUSED pte bit

2026-07-24T14:20:29+00:00

[ Upstream commit d4bb00704a66024502261fa7a523c07420249fea ] The _PAGE_UNUSED softbit should not really be lying around. Its sole purpose is to signal to try_to_unmap_one() and try_to_migrate_one() that the page can be discarded instead of being moved / swapped. KVM has no way to know why a page is being unmapped, so it sets the bit on userspace ptes corresponding to unused guest pages every time they get unmapped. KVM has no reasonable way to clear the bit once the page is in use again. While set_ptes() checks and clears the bit, other paths that set new ptes did not. This led to used pages being thrown out as if they were unused, causing guest corruption. Fix the issue by clearing the _PAGE_UNUSED bit for present ptes in set_pte(), i.e. whenever a present pte is getting set. The check in set_ptes() is then redundant and can be removed. Also fix gmap_helper_try_set_pte_unused() to only set the bit if the pte is present; the _PAGE_UNUSED bit is only defined for present ptes and thus should not be set for non-present ptes. Fixes: c98175b7917f ("KVM: s390: Add gmap_helper_set_unused()") Acked-by: Heiko Carstens Signed-off-by: Claudio Imbrenda Message-ID: <20260623153331.233784-2-imbrenda@linux.ibm.com> Signed-off-by: Sasha Levin

uaccess: unify inline vs outline copy_{from,to}_user() selection

2026-07-24T14:19:23+00:00

[ Upstream commit c02be2ad2b88c67c5d7c06b6aa7083b5b40e1077 ] The kernel allows arches to select between inline and outline implementations of the copy_{from,to}_user() by defining individual INLINE_COPY_FROM_USER and INLINE_COPY_TO_USER, correspondingly. However, all arches enable or disable them always together. Without the real use-case for one helper being inlined while the other outlined, having independent controls is excessive and error prone. Switch the codebase to the single unified INLINE_COPY_USER control. Link: https://lore.kernel.org/20260425020857.356850-3-ynorov@nvidia.com Signed-off-by: Yury Norov Tested-by: Alice Ryhl Cc: Arnd Bergmann Cc: Christophe Leroy (CS GROUP) Cc: Mathieu Desnoyers Cc: Peter Zijlstra Cc: Randy Dunlap Cc: Viktor Malik Signed-off-by: Andrew Morton Stable-dep-of: bd99fcfc6219 ("uaccess: minimize INLINE_COPY_USER-related ifdefery") Signed-off-by: Sasha Levin

s390: Revert support for DCACHE_WORD_ACCESS

2026-07-18T14:55:33+00:00

commit 37540b8c287fc817bdbd0c62bb75ad6eab0e5d03 upstream. load_unaligned_zeropad() reads eight bytes from unaligned addresses and may cross page boundaries. It handles exceptions which may happen if reading from the second page results in an exception. For pages which are donated to the Ultravisor for secure execution purposes the do_secure_storage_access() exception handler however does not handle such exceptions correctly. Such an exception may result in an endless exception loop which will never be resolved. An attempt to fix this [1] turned out to be not sufficient. For now revert load_unaligned_zeropad() until this problem has been resolved in a proper way. Note that the implementation of load_unaligned_zeropad() itself is correct. The revert is just a temporary workaround until there is complete fix for secure storage access exceptions. [1] commit b00be77302d7 ("s390/mm: Add missing secure storage access fixups for donated memory") Fixes: 802ba53eefc5 ("s390: add support for DCACHE_WORD_ACCESS") Cc: stable@vger.kernel.org Acked-by: Christian Borntraeger Signed-off-by: Heiko Carstens Signed-off-by: Alexander Gordeev Signed-off-by: Greg Kroah-Hartman

Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

2026-06-05T17:38:45+00:00

Pull kvm fixes from Paolo Bonzini: "arm64: - 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 s390: - More fixes for the new page table management and nested virtualization x86: - More fixes for GHCB issues: - Read start/end indices of page size change requests exactly once per vmexit - Unmap and unpin the GHCB as needed on vCPU free" * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (23 commits) KVM: arm64: Correctly identify executable PTEs at stage-2 KVM: arm64: nv: Fix handling of XN[0] when !FEAT_XNX KVM: arm64: Reassign nested_mmus array behind mmu_lock KVM: arm64: Restore POR_EL0 access to host EL0 KVM: arm64: Take the SRCU lock for page table walks in fault injection and AT emulation KVM: arm64: vgic-its: Drop the translation cache reference only for the erased entry KVM: SEV: Unmap and unpin the GHCB as needed on vCPU free KVM: SEV: Decouple the need to sync the GHCB SA from the need to free the SA KVM: SEV: Move sev_free_vcpu() down below sev_es_unmap_ghcb() KVM: Don't WARN if memory is dirtied without a vCPU when the VM is dying KVM: SEV: Read start/end indices of PSC requests exactly once per #VMGEXIT KVM: SEV: Add an anonymous "psc" struct to track current PSC metadata KVM: SEV: Make it more obvious when KVM is writing back the current PSC index KVM: s390: Remove ptep_zap_softleaf_entry() KVM: s390: Fix possible reference leak in fault-in code KVM: s390: Prevent memslots outside the ASCE range KVM: s390: Lock pte when making page secure KVM: s390: Fix fault-in code KVM: s390: vsie: Fix rmap handling in _do_shadow_crste() KVM: s390: Fix guest / virtual address confusion in _essa_clear_cbrl() ...

Merge tag 's390-7.1-4' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux

2026-06-04T19:31:20+00:00

Pull s390 fixes from Alexander Gordeev: - Enable IOMMUFD and VFIO cdev such that PCI pass-through to QEMU/KVM can optionally utilize native IOMMUFD - With HAVE_ARCH_BUG_FORMAT enabled the BUG infrastructure might misinterpret flags or fault. Fix this by moving the "format" field emission into __BUG_ENTRY() - The generic version of _THIS_IP_ is known to be brittle and may break with current and future GCC and Clang optimizations. Fix it by overriding _THIS_IP_ * tag 's390-7.1-4' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: s390: Implement _THIS_IP_ using inline asm s390/bug: Always emit format word in __BUG_ENTRY s390/configs: Enable IOMMUFD and VFIO cdev in defconfigs

KVM: s390: Avoid potentially sleeping while atomic when zapping pages

2026-06-02T14:46:41+00:00

Factor out try_get_locked_pte(), which behaves similarly to get_locked_pte(), but does not attempt to allocate missing tables and performs a spin_trylock() instead of blocking. The new function is also exported, since it will be used in other patches. If intermediate entries are missing, there can be no pte swap entry to free, so it's safe to ignore them. This avoids potentially sleeping while atomic. Fixes: e38c884df921 ("KVM: s390: Switch to new gmap") Signed-off-by: Claudio Imbrenda Message-ID: <20260602142356.169458-4-imbrenda@linux.ibm.com>

s390: Implement _THIS_IP_ using inline asm

2026-05-30T09:33:32+00:00

Both GCC [1] and Clang [2] consider the generic version of _THIS_IP_ to be broken: #define _THIS_IP_ ({ __label__ __here; __here: (unsigned long)&&__here; }) In particular, the address of a label is only expected to be used with a computed goto. While the generic version more or less works today, it is known to be brittle and may break with current and future optimizations. For example, Clang -O2 always returns 1 when this function is inlined: static inline unsigned long get_ip(void) { return ({ __label__ __here; __here: (unsigned long)&&__here; }); } Fix it by overriding _THIS_IP_ in (which is included by ) using an architecture-specific inline asm version. Additionally, avoiding taking the address of a label prevents compilers from emitting spurious indirect branch targets (e.g. ENDBR or BTI) under control-flow integrity schemes. Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=120071 [1] Link: https://github.com/llvm/llvm-project/issues/138272 [2] Signed-off-by: Marco Elver Reviewed-by: Heiko Carstens Signed-off-by: Alexander Gordeev

s390/bug: Always emit format word in __BUG_ENTRY

2026-05-28T10:08:27+00:00

When CONFIG_DEBUG_BUGVERBOSE is disabled, the s390 __BUG_ENTRY() macro omits the format string pointer, so the generated __bug_table entry no longer matches struct bug_entry. With HAVE_ARCH_BUG_FORMAT enabled, the generic BUG infrastructure reads bug_entry::format via bug_get_format(). If the format word is missing, subsequent fields are read from the wrong offset, which may: - Misinterpret flags (BUG vs WARN classification errors) - Fault when dereferencing a misread format pointer The root cause is that __BUG_ENTRY() delegates format word emission to __BUG_ENTRY_VERBOSE(), which is conditional on CONFIG_DEBUG_BUGVERBOSE. Fix this by moving the format field emission directly into __BUG_ENTRY() so it is always emitted unconditionally. Remove the format parameter from __BUG_ENTRY_VERBOSE() and keep only file/line emission conditional on CONFIG_DEBUG_BUGVERBOSE. Fixes: 2b71b8ab9718 ("s390/bug: Use BUG_FORMAT for DEBUG_BUGVERBOSE_DETAILED") Signed-off-by: Jan Polensky Reviewed-by: Heiko Carstens Signed-off-by: Alexander Gordeev

ring-buffer: Flush and stop persistent ring buffer on panic

2026-05-21T12:20:58+00:00

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 Cc: Mathieu Desnoyers Cc: Ian Rogers Link: https://patch.msgid.link/177751969602.2136606.12031934362587643488.stgit@mhiramat.tok.corp.google.com Signed-off-by: Masami Hiramatsu (Google) Acked-by: Catalin Marinas Acked-by: Geert Uytterhoeven Signed-off-by: Steven Rostedt

Merge tag 's390-7.1-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux

2026-04-22T18:13:45+00:00

Pull s390 updates from Vasily Gorbik: - Add support for CONFIG_PAGE_TABLE_CHECK and enable it in debug_defconfig. s390 can only tell user from kernel PTEs via the mm, so mm_struct is now passed into pxx_user_accessible_page() callbacks - Expose the PCI function UID as an arch-specific slot attribute in sysfs so a function can be identified by its user-defined id while still in standby. Introduces a generic ARCH_PCI_SLOT_GROUPS hook in drivers/pci/slot.c - Refresh s390 PCI documentation to reflect current behavior and cover previously undocumented sysfs attributes - zcrypt device driver cleanup series: consistent field types, clearer variable naming, a kernel-doc warning fix, and a comment explaining the intentional synchronize_rcu() in pkey_handler_register() - Provide an s390 arch_raw_cpu_ptr() that avoids the detour via get_lowcore() using alternatives, shrinking defconfig by ~27 kB - Guard identity-base randomization with kaslr_enabled() so nokaslr keeps the identity mapping at 0 even with RANDOMIZE_IDENTITY_BASE=y - Build S390_MODULES_SANITY_TEST as a module only by requiring KUNIT && m, since built-in would not exercise module loading - Remove the permanently commented-out HMCDRV_DEV_CLASS create_class() code in the hmcdrv driver - Drop stale ident_map_size extern conflicting with asm/page.h * tag 's390-7.1-1' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: s390/zcrypt: Fix warning about wrong kernel doc comment PCI: s390: Expose the UID as an arch specific PCI slot attribute docs: s390/pci: Improve and update PCI documentation s390/pkey: Add comment about synchronize_rcu() to pkey base s390/hmcdrv: Remove commented out code s390/zcrypt: Slight rework on the agent_id field s390/zcrypt: Explicitly use a card variable in _zcrypt_send_cprb s390/zcrypt: Rework MKVP fields and handling s390/zcrypt: Make apfs a real unsigned int field s390/zcrypt: Rework domain processing within zcrypt device driver s390/zcrypt: Move inline function rng_type6cprb_msgx from header to code s390/percpu: Provide arch_raw_cpu_ptr() s390: Enable page table check for debug_defconfig s390/pgtable: Add s390 support for page table check s390/pgtable: Use set_pmd_bit() to invalidate PMD entry mm/page_table_check: Pass mm_struct to pxx_user_accessible_page() s390/boot: Respect kaslr_enabled() for identity randomization s390/Kconfig: Make modules sanity test a module-only option s390/setup: Drop stale ident_map_size declaration