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7 daysmm/ptdump: take the memory hotplug lock inside ptdump_walk_pgd()Anshuman Khandual1-2/+0
commit 59305202c67fea50378dcad0cc199dbc13a0e99a upstream. Memory hot remove unmaps and tears down various kernel page table regions as required. The ptdump code can race with concurrent modifications of the kernel page tables. When leaf entries are modified concurrently, the dump code may log stale or inconsistent information for a VA range, but this is otherwise not harmful. But when intermediate levels of kernel page table are freed, the dump code will continue to use memory that has been freed and potentially reallocated for another purpose. In such cases, the ptdump code may dereference bogus addresses, leading to a number of potential problems. To avoid the above mentioned race condition, platforms such as arm64, riscv and s390 take memory hotplug lock, while dumping kernel page table via the sysfs interface /sys/kernel/debug/kernel_page_tables. Similar race condition exists while checking for pages that might have been marked W+X via /sys/kernel/debug/kernel_page_tables/check_wx_pages which in turn calls ptdump_check_wx(). Instead of solving this race condition again, let's just move the memory hotplug lock inside generic ptdump_check_wx() which will benefit both the scenarios. Drop get_online_mems() and put_online_mems() combination from all existing platform ptdump code paths. Link: https://lkml.kernel.org/r/20250620052427.2092093-1-anshuman.khandual@arm.com Fixes: bbd6ec605c0f ("arm64/mm: Enable memory hot remove") Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> Acked-by: David Hildenbrand <david@redhat.com> Reviewed-by: Dev Jain <dev.jain@arm.com> Acked-by: Alexander Gordeev <agordeev@linux.ibm.com> [s390] Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will@kernel.org> Cc: Ryan Roberts <ryan.roberts@arm.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Alexander Gordeev <agordeev@linux.ibm.com> Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com> Cc: Heiko Carstens <hca@linux.ibm.com> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Christian Borntraeger <borntraeger@linux.ibm.com> Cc: Sven Schnelle <svens@linux.ibm.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
7 dayss390/early: Copy last breaking event address to pt_regsHeiko Carstens1-0/+1
[ Upstream commit 7cf636c99b257c1b4b12066ab34fd5f06e8d892f ] In case of an early crash the early program check handler also prints the last breaking event address which is contained within the pt_regs structure. However it is not initialized, and therefore a more or less random value is printed in case of a crash. Copy the last breaking event address from lowcore to pt_regs in case of an early program check to address this. This also makes it easier to analyze early crashes. Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
7 dayss390/stp: Remove udelay from stp_sync_clock()Sven Schnelle1-1/+1
[ Upstream commit b367017cdac21781a74eff4e208d3d38e1f38d3f ] When an stp sync check is handled on a system with multiple cpus each cpu gets a machine check but only the first one actually handles the sync operation. All other CPUs spin waiting for the first one to finish with a short udelay(). But udelay can't be used here as the first CPU modifies tod_clock_base before performing the sync op. During this timeframe get_tod_clock_monotonic() might return a non-monotonic time. The time spent waiting should be very short and udelay is a busy loop anyways, therefore simply remove the udelay. Reviewed-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Sven Schnelle <svens@linux.ibm.com> Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
7 dayss390/time: Use monotonic clock in get_cycles()Sven Schnelle1-7/+6
[ Upstream commit 09e7e29d2b49ba84bcefb3dc1657726d2de5bb24 ] Otherwise the code might not work correctly when the clock is changed. Signed-off-by: Sven Schnelle <svens@linux.ibm.com> Reviewed-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
12 dayss390/mm: Remove possible false-positive warning in pte_free_defer()Gerald Schaefer1-5/+0
commit 5647f61ad9171e8f025558ed6dc5702c56a33ba3 upstream. Commit 8211dad627981 ("s390: add pte_free_defer() for pgtables sharing page") added a warning to pte_free_defer(), on our request. It was meant to warn if this would ever be reached for KVM guest mappings, because the page table would be freed w/o a gmap_unlink(). THP mappings are not allowed for KVM guests on s390, so this should never happen. However, it is possible that the warning is triggered in a valid case as false-positive. s390_enable_sie() takes the mmap_lock, marks all VMAs as VM_NOHUGEPAGE and splits possibly existing THP guest mappings. mm->context.has_pgste is set to 1 before that, to prevent races with the mm_has_pgste() check in MADV_HUGEPAGE. khugepaged drops the mmap_lock for file mappings and might run in parallel, before a vma is marked VM_NOHUGEPAGE, but after mm->context.has_pgste was set to 1. If it finds file mappings to collapse, it will eventually call pte_free_defer(). This will trigger the warning, but it is a valid case because gmap is not yet set up, and the THP mappings will be split again. Therefore, remove the warning and the comment. Fixes: 8211dad627981 ("s390: add pte_free_defer() for pgtables sharing page") Cc: <stable@vger.kernel.org> # 6.6+ Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com> Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com> Signed-off-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com> Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
12 dayss390/boot: Fix startup debugging logMikhail Zaslonko1-1/+1
[ Upstream commit e29409faec87ffd2de2ed20b6109f303f129281b ] Fix 'kernel image' end address for kaslr case. Fixes: ec6f9f7e5bbf ("s390/boot: Add startup debugging support") Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com> Signed-off-by: Mikhail Zaslonko <zaslonko@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
12 dayss390/mm: Allocate page table with PAGE_SIZE granularitySumanth Korikkar1-3/+2
[ Upstream commit daa8af80d283ee9a7d42dd6f164a65036665b9d4 ] Make vmem_pte_alloc() consistent by always allocating page table of PAGE_SIZE granularity, regardless of whether page_table_alloc() (with slab) or memblock_alloc() is used. This ensures page table can be fully freed when the corresponding page table entries are removed. Fixes: d08d4e7cd6bf ("s390/mm: use full 4KB page for 2KB PTE") Reviewed-by: Heiko Carstens <hca@linux.ibm.com> Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com> Signed-off-by: Sumanth Korikkar <sumanthk@linux.ibm.com> Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
12 dayss390/mm: Set high_memory at the end of the identity mappingAlexander Gordeev1-0/+6
[ Upstream commit 56f4cfab1c93b14da422cdcd23898eb008033696 ] The value of high_memory variable is set by set_high_memory() function to a value returned by memblock_end_of_DRAM(). The latter function returns by default the upper bound of the last online memory block, not the upper bound of the directly mapped memory region. As result, in case the end of memory happens to be offline, high_memory variable is set to a value that is short on the last offline memory blocks size: RANGE SIZE STATE REMOVABLE BLOCK 0x0000000000000000-0x000000ffffffffff 1T online yes 0-511 0x0000010000000000-0x0000011fffffffff 128G offline 512-575 Memory block size: 2G Total online memory: 1T Total offline memory: 128G crash> p/x vm_layout $1 = { kaslr_offset = 0x3453e918000, kaslr_offset_phys = 0xa534218000, identity_base = 0x0, identity_size = 0x12000000000 } crash> p/x high_memory $2 = 0x10000000000 In the past the value of high_memory was derived from max_low_pfn, which in turn was derived from the identity_size. Since identity_size accommodates the whole memory size - including tailing offline blocks, the offlined blocks did not impose any problem. But since commit e120d1bc12da ("arch, mm: set high_memory in free_area_init()") the value of high_memory is derived from the last memblock online region, and that is where the problem comes from. The value of high_memory is used by several drivers and by external tools (e.g. crash tool aborts while loading a dump). Similarily to ARM, use the override path provided by set_high_memory() function and set the value of high_memory at the end of the identity mapping early. That forces set_high_memory() to leave in high_memory the correct value, even when the end of available memory is offline. Fixes: e120d1bc12da ("arch, mm: set high_memory in free_area_init()") Tested-by: Mikhail Zaslonko <zaslonko@linux.ibm.com> Reviewed-by: Heiko Carstens <hca@linux.ibm.com> Reviewed-by: Gerald Schaefer <gerald.schaefer@linux.ibm.com> Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
12 dayss390/ap: Unmask SLCF bit in card and queue ap functions sysfsHarald Freudenberger1-1/+1
[ Upstream commit 123b7c7c2ba725daf3bfa5ce421d65b92cb5c075 ] The SLCF bit ("stateless command filtering") introduced with CEX8 cards was because of the function mask's default value suppressed when user space read the ap function for an AP card or queue. Unmask this bit so that user space applications like lszcrypt can evaluate and list this feature. Fixes: d4c53ae8e494 ("s390/ap: store TAPQ hwinfo in struct ap_card") Signed-off-by: Harald Freudenberger <freude@linux.ibm.com> Reviewed-by: Holger Dengler <dengler@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
2025-07-24s390/bpf: Fix bpf_arch_text_poke() with new_addr == NULL againIlya Leoshkevich1-1/+9
commit 6a5abf8cf182f577c7ae6c62f14debc9754ec986 upstream. Commit 7ded842b356d ("s390/bpf: Fix bpf_plt pointer arithmetic") has accidentally removed the critical piece of commit c730fce7c70c ("s390/bpf: Fix bpf_arch_text_poke() with new_addr == NULL"), causing intermittent kernel panics in e.g. perf's on_switch() prog to reappear. Restore the fix and add a comment. Fixes: 7ded842b356d ("s390/bpf: Fix bpf_plt pointer arithmetic") Cc: stable@vger.kernel.org Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com> Link: https://lore.kernel.org/r/20250716194524.48109-2-iii@linux.ibm.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-07-17crypto: s390/sha - Fix uninitialized variable in SHA-1 and SHA-2Eric Biggers3-0/+8
commit 68279380266a5fa70e664de754503338e2ec3f43 upstream. Commit 88c02b3f79a6 ("s390/sha3: Support sha3 performance enhancements") added the field s390_sha_ctx::first_message_part and made it be used by s390_sha_update() (now s390_sha_update_blocks()). At the time, s390_sha_update() was used by all the s390 SHA-1, SHA-2, and SHA-3 algorithms. However, only the initialization functions for SHA-3 were updated, leaving SHA-1 and SHA-2 using first_message_part uninitialized. This could cause e.g. the function code CPACF_KIMD_SHA_512 | CPACF_KIMD_NIP to be used instead of just CPACF_KIMD_SHA_512. This apparently was harmless, as the SHA-1 and SHA-2 function codes ignore CPACF_KIMD_NIP; it is recognized only by the SHA-3 function codes (https://lore.kernel.org/r/73477fe9-a1dc-4e38-98a6-eba9921e8afa@linux.ibm.com/). Therefore, this bug was found only when first_message_part was later converted to a boolean and UBSAN detected its uninitialized use. Regardless, let's fix this by just initializing to zero. Note: in 6.16, we need to patch SHA-1, SHA-384, and SHA-512. In 6.15 and earlier, we'll also need to patch SHA-224 and SHA-256, as they hadn't yet been librarified (which incidentally fixed this bug). Fixes: 88c02b3f79a6 ("s390/sha3: Support sha3 performance enhancements") Cc: stable@vger.kernel.org Reported-by: Ingo Franzki <ifranzki@linux.ibm.com> Closes: https://lore.kernel.org/r/12740696-595c-4604-873e-aefe8b405fbf@linux.ibm.com Acked-by: Heiko Carstens <hca@linux.ibm.com> Link: https://lore.kernel.org/r/20250703172316.7914-1-ebiggers@kernel.org Signed-off-by: Eric Biggers <ebiggers@kernel.org> Signed-off-by: Eric Biggers <ebiggers@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-07-10s390/pci: Do not try re-enabling load/store if device is disabledNiklas Schnelle1-0/+4
commit b97a7972b1f4f81417840b9a2ab0c19722b577d5 upstream. If a device is disabled unblocking load/store on its own is not useful as a full re-enable of the function is necessary anyway. Note that SCLP Write Event Data Action Qualifier 0 (Reset) leaves the device disabled and triggers this case unless the driver already requests a reset. Cc: stable@vger.kernel.org Fixes: 4cdf2f4e24ff ("s390/pci: implement minimal PCI error recovery") Reviewed-by: Farhan Ali <alifm@linux.ibm.com> Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com> Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-07-10s390/pci: Fix stale function handles in error handlingNiklas Schnelle1-0/+11
commit 45537926dd2aaa9190ac0fac5a0fbeefcadfea95 upstream. The error event information for PCI error events contains a function handle for the respective function. This handle is generally captured at the time the error event was recorded. Due to delays in processing or cascading issues, it may happen that during firmware recovery multiple events are generated. When processing these events in order Linux may already have recovered an affected function making the event information stale. Fix this by doing an unconditional CLP List PCI function retrieving the current function handle with the zdev->state_lock held and ignoring the event if its function handle is stale. Cc: stable@vger.kernel.org Fixes: 4cdf2f4e24ff ("s390/pci: implement minimal PCI error recovery") Reviewed-by: Julian Ruess <julianr@linux.ibm.com> Reviewed-by: Gerd Bayer <gbayer@linux.ibm.com> Reviewed-by: Farhan Ali <alifm@linux.ibm.com> Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com> Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-07-06s390/ptrace: Fix pointer dereferencing in regs_get_kernel_stack_nth()Heiko Carstens1-1/+1
commit 7f8073cfb04a97842fe891ca50dad60afd1e3121 upstream. The recent change which added READ_ONCE_NOCHECK() to read the nth entry from the kernel stack incorrectly dropped dereferencing of the stack pointer in order to read the requested entry. In result the address of the entry is returned instead of its content. Dereference the pointer again to fix this. Reported-by: Will Deacon <will@kernel.org> Closes: https://lore.kernel.org/r/20250612163331.GA13384@willie-the-truck Fixes: d93a855c31b7 ("s390/ptrace: Avoid KASAN false positives in regs_get_kernel_stack_nth()") Cc: stable@vger.kernel.org Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-07-06s390/mm: Fix in_atomic() handling in do_secure_storage_access()Heiko Carstens1-0/+2
[ Upstream commit 11709abccf93b08adde95ef313c300b0d4bc28f1 ] Kernel user spaces accesses to not exported pages in atomic context incorrectly try to resolve the page fault. With debug options enabled call traces like this can be seen: BUG: sleeping function called from invalid context at kernel/locking/rwsem.c:1523 in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 419074, name: qemu-system-s39 preempt_count: 1, expected: 0 RCU nest depth: 0, expected: 0 INFO: lockdep is turned off. Preemption disabled at: [<00000383ea47cfa2>] copy_page_from_iter_atomic+0xa2/0x8a0 CPU: 12 UID: 0 PID: 419074 Comm: qemu-system-s39 Tainted: G W 6.16.0-20250531.rc0.git0.69b3a602feac.63.fc42.s390x+debug #1 PREEMPT Tainted: [W]=WARN Hardware name: IBM 3931 A01 703 (LPAR) Call Trace: [<00000383e990d282>] dump_stack_lvl+0xa2/0xe8 [<00000383e99bf152>] __might_resched+0x292/0x2d0 [<00000383eaa7c374>] down_read+0x34/0x2d0 [<00000383e99432f8>] do_secure_storage_access+0x108/0x360 [<00000383eaa724b0>] __do_pgm_check+0x130/0x220 [<00000383eaa842e4>] pgm_check_handler+0x114/0x160 [<00000383ea47d028>] copy_page_from_iter_atomic+0x128/0x8a0 ([<00000383ea47d016>] copy_page_from_iter_atomic+0x116/0x8a0) [<00000383e9c45eae>] generic_perform_write+0x16e/0x310 [<00000383e9eb87f4>] ext4_buffered_write_iter+0x84/0x160 [<00000383e9da0de4>] vfs_write+0x1c4/0x460 [<00000383e9da123c>] ksys_write+0x7c/0x100 [<00000383eaa7284e>] __do_syscall+0x15e/0x280 [<00000383eaa8417e>] system_call+0x6e/0x90 INFO: lockdep is turned off. It is not allowed to take the mmap_lock while in atomic context. Therefore handle such a secure storage access fault as if the accessed page is not mapped: the uaccess function will return -EFAULT, and the caller has to deal with this. Usually this means that the access is retried in process context, which allows to resolve the page fault (or in this case export the page). Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com> Acked-by: Alexander Gordeev <agordeev@linux.ibm.com> Acked-by: Christian Borntraeger <borntraeger@linux.ibm.com> Link: https://lore.kernel.org/r/20250603134936.1314139-1-hca@linux.ibm.com Signed-off-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
2025-06-27KVM: s390: rename PROT_NONE to PROT_TYPE_DUMMYLorenzo Stoakes1-4/+4
commit 15ac613f124e51a6623975efad9657b1f3ee47e7 upstream. The enum type prot_type declared in arch/s390/kvm/gaccess.c declares an unfortunate identifier within it - PROT_NONE. This clashes with the protection bit define from the uapi for mmap() declared in include/uapi/asm-generic/mman-common.h, which is indeed what those casually reading this code would assume this to refer to. This means that any changes which subsequently alter headers in any way which results in the uapi header being imported here will cause build errors. Resolve the issue by renaming PROT_NONE to PROT_TYPE_DUMMY. Link: https://lkml.kernel.org/r/20250519145657.178365-1-lorenzo.stoakes@oracle.com Fixes: b3cefd6bf16e ("KVM: s390: Pass initialized arg even if unused") Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> Suggested-by: Ignacio Moreno Gonzalez <Ignacio.MorenoGonzalez@kuka.com> Reported-by: kernel test robot <lkp@intel.com> Closes: https://lore.kernel.org/oe-kbuild-all/202505140943.IgHDa9s7-lkp@intel.com/ Acked-by: Christian Borntraeger <borntraeger@linux.ibm.com> Acked-by: Ignacio Moreno Gonzalez <Ignacio.MorenoGonzalez@kuka.com> Acked-by: Yang Shi <yang@os.amperecomputing.com> Reviewed-by: David Hildenbrand <david@redhat.com> Acked-by: Liam R. Howlett <Liam.Howlett@oracle.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com> Cc: <stable@vger.kernel.org> Cc: Alexander Gordeev <agordeev@linux.ibm.com> Cc: Heiko Carstens <hca@linux.ibm.com> Cc: James Houghton <jthoughton@google.com> Cc: Janosch Frank <frankja@linux.ibm.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Sven Schnelle <svens@linux.ibm.com> Cc: Vasily Gorbik <gor@linux.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-06-27s390/pci: Serialize device addition and removalNiklas Schnelle1-0/+7
commit 774a1fa880bc949d88b5ddec9494a13be733dfa8 upstream. Prior changes ensured that when zpci_release_device() is called and it removed the zdev from the zpci_list this instance can not be found via the zpci_list anymore even while allowing re-add of reserved devices. This only accounts for the overall lifetime and zpci_list addition and removal, it does not yet prevent concurrent add of a new instance for the same underlying device. Such concurrent add would subsequently cause issues such as attempted re-use of the same IOMMU sysfs directory and is generally undesired. Introduce a new zpci_add_remove_lock mutex to serialize adding a new device with removal. Together this ensures that if a struct zpci_dev is not found in the zpci_list it was either already removed and torn down, or its removal and tear down is in progress with the zpci_add_remove_lock held. Cc: stable@vger.kernel.org Fixes: a46044a92add ("s390/pci: fix zpci_zdev_put() on reserve") Reviewed-by: Gerd Bayer <gbayer@linux.ibm.com> Tested-by: Gerd Bayer <gbayer@linux.ibm.com> Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-06-27s390/pci: Allow re-add of a reserved but not yet removed deviceNiklas Schnelle3-16/+45
commit 4b1815a52d7eb03b3e0e6742c6728bc16a4b2d1d upstream. The architecture assumes that PCI functions can be removed synchronously as PCI events are processed. This however clashes with the reference counting of struct pci_dev which allows device drivers to hold on to a struct pci_dev reference even as the underlying device is removed. To bridge this gap commit 2a671f77ee49 ("s390/pci: fix use after free of zpci_dev") keeps the struct zpci_dev in ZPCI_FN_STATE_RESERVED state until common code releases the struct pci_dev. Only when all references are dropped, the struct zpci_dev can be removed and freed. Later commit a46044a92add ("s390/pci: fix zpci_zdev_put() on reserve") moved the deletion of the struct zpci_dev from the zpci_list in zpci_release_device() to the point where the device is reserved. This was done to prevent handling events for a device that is already being removed, e.g. when the platform generates both PCI event codes 0x304 and 0x308. In retrospect, deletion from the zpci_list in the release function without holding the zpci_list_lock was also racy. A side effect of this handling is that if the underlying device re-appears while the struct zpci_dev is in the ZPCI_FN_STATE_RESERVED state, the new and old instances of the struct zpci_dev and/or struct pci_dev may clash. For example when trying to create the IOMMU sysfs files for the new instance. In this case, re-adding the new instance is aborted. The old instance is removed, and the device will remain absent until the platform issues another event. Fix this by allowing the struct zpci_dev to be brought back up right until it is finally removed. To this end also keep the struct zpci_dev in the zpci_list until it is finally released when all references have been dropped. Deletion from the zpci_list from within the release function is made safe by using kref_put_lock() with the zpci_list_lock. This ensures that the releasing code holds the last reference. Cc: stable@vger.kernel.org Fixes: a46044a92add ("s390/pci: fix zpci_zdev_put() on reserve") Reviewed-by: Gerd Bayer <gbayer@linux.ibm.com> Tested-by: Gerd Bayer <gbayer@linux.ibm.com> Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-06-27s390/pci: Remove redundant bus removal and disable from zpci_release_device()Niklas Schnelle1-6/+0
commit d76f9633296785343d45f85199f4138cb724b6d2 upstream. Remove zpci_bus_remove_device() and zpci_disable_device() calls from zpci_release_device(). These calls were done when the device transitioned into the ZPCI_FN_STATE_STANDBY state which is guaranteed to happen before it enters the ZPCI_FN_STATE_RESERVED state. When zpci_release_device() is called the device is known to be in the ZPCI_FN_STATE_RESERVED state which is also checked by a WARN_ON(). Cc: stable@vger.kernel.org Fixes: a46044a92add ("s390/pci: fix zpci_zdev_put() on reserve") Reviewed-by: Gerd Bayer <gbayer@linux.ibm.com> Reviewed-by: Julian Ruess <julianr@linux.ibm.com> Tested-by: Gerd Bayer <gbayer@linux.ibm.com> Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-06-27s390/pci: Fix __pcilg_mio_inuser() inline assemblyHeiko Carstens1-1/+1
commit c4abe6234246c75cdc43326415d9cff88b7cf06c upstream. Use "a" constraint for the shift operand of the __pcilg_mio_inuser() inline assembly. The used "d" constraint allows the compiler to use any general purpose register for the shift operand, including register zero. If register zero is used this my result in incorrect code generation: 8f6: a7 0a ff f8 ahi %r0,-8 8fa: eb 32 00 00 00 0c srlg %r3,%r2,0 <---- If register zero is selected to contain the shift value, the srlg instruction ignores the contents of the register and always shifts zero bits. Therefore use the "a" constraint which does not permit to select register zero. Fixes: f058599e22d5 ("s390/pci: Fix s390_mmio_read/write with MIO") Cc: stable@vger.kernel.org Reported-by: Niklas Schnelle <schnelle@linux.ibm.com> Reviewed-by: Niklas Schnelle <schnelle@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-06-19s390/uv: Improve splitting of large folios that cannot be split while dirtyDavid Hildenbrand1-6/+60
[ Upstream commit ab73b29efd36f8916c6cc9954e912c4723c9a1b0 ] Currently, starting a PV VM on an iomap-based filesystem with large folio support, such as XFS, will not work. We'll be stuck in unpack_one()->gmap_make_secure(), because we can't seem to make progress splitting the large folio. The problem is that we require a writable PTE but a writable PTE under such filesystems will imply a dirty folio. So whenever we have a writable PTE, we'll have a dirty folio, and dirty iomap folios cannot currently get split, because split_folio()->split_huge_page_to_list_to_order()->filemap_release_folio() will fail in iomap_release_folio(). So we will not make any progress splitting such large folios. Until dirty folios can be split more reliably, let's manually trigger writeback of the problematic folio using filemap_write_and_wait_range(), and retry the split immediately afterwards exactly once, before looking up the folio again. Should this logic be part of split_folio()? Likely not; most split users don't have to split so eagerly to make any progress. For now, this seems to affect xfs, zonefs and erofs, and this patch makes it work again (tested on xfs only). While this could be considered a fix for commit 6795801366da ("xfs: Support large folios"), commit df2f9708ff1f ("zonefs: enable support for large folios") and commit ce529cc25b18 ("erofs: enable large folios for iomap mode"), before commit eef88fe45ac9 ("s390/uv: Split large folios in gmap_make_secure()"), we did not try splitting large folios at all. So it's all rather part of making SE compatible with file systems that support large folios. But to have some "Fixes:" tag, let's just use eef88fe45ac9. Not CCing stable, because there are a lot of dependencies, and it simply not working is not critical in stable kernels. Reported-by: Sebastian Mitterle <smitterl@redhat.com> Closes: https://issues.redhat.com/browse/RHEL-58218 Fixes: eef88fe45ac9 ("s390/uv: Split large folios in gmap_make_secure()") Signed-off-by: David Hildenbrand <david@redhat.com> Link: https://lore.kernel.org/r/20250516123946.1648026-4-david@redhat.com Message-ID: <20250516123946.1648026-4-david@redhat.com> Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com> Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
2025-06-19s390/uv: Always return 0 from s390_wiggle_split_folio() if successfulDavid Hildenbrand1-10/+12
[ Upstream commit bd428b8c79ed8e8658570e70c62c0092500e2eac ] Let's consistently return 0 if the operation was successful, and just detect ourselves whether splitting is required -- folio_test_large() is a cheap operation. Update the documentation. Should we simply always return -EAGAIN instead of 0, so we don't have to handle it in the caller? Not sure, staring at the documentation, this way looks a bit cleaner. Signed-off-by: David Hildenbrand <david@redhat.com> Link: https://lore.kernel.org/r/20250516123946.1648026-3-david@redhat.com Message-ID: <20250516123946.1648026-3-david@redhat.com> Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com> Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com> Stable-dep-of: ab73b29efd36 ("s390/uv: Improve splitting of large folios that cannot be split while dirty") Signed-off-by: Sasha Levin <sashal@kernel.org>
2025-06-19s390/uv: Don't return 0 from make_hva_secure() if the operation was not ↵David Hildenbrand1-1/+4
successful [ Upstream commit 3ec8a8330a1aa846dffbf1d64479213366c55b54 ] If s390_wiggle_split_folio() returns 0 because splitting a large folio succeeded, we will return 0 from make_hva_secure() even though a retry is required. Return -EAGAIN in that case. Otherwise, we'll return 0 from gmap_make_secure(), and consequently from unpack_one(). In kvm_s390_pv_unpack(), we assume that unpacking succeeded and skip unpacking this page. Later on, we run into issues and fail booting the VM. So far, this issue was only observed with follow-up patches where we split large pagecache XFS folios. Maybe it can also be triggered with shmem? We'll cleanup s390_wiggle_split_folio() a bit next, to also return 0 if no split was required. Fixes: d8dfda5af0be ("KVM: s390: pv: fix race when making a page secure") Cc: stable@vger.kernel.org Signed-off-by: David Hildenbrand <david@redhat.com> Link: https://lore.kernel.org/r/20250516123946.1648026-2-david@redhat.com Message-ID: <20250516123946.1648026-2-david@redhat.com> Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com> Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com> Stable-dep-of: ab73b29efd36 ("s390/uv: Improve splitting of large folios that cannot be split while dirty") Signed-off-by: Sasha Levin <sashal@kernel.org>
2025-06-19s390/bpf: Store backchain even for leaf progsIlya Leoshkevich1-7/+5
[ Upstream commit 5f55f2168432298f5a55294831ab6a76a10cb3c3 ] Currently a crash in a leaf prog (caused by a bug) produces the following call trace: [<000003ff600ebf00>] bpf_prog_6df0139e1fbf2789_fentry+0x20/0x78 [<0000000000000000>] 0x0 This is because leaf progs do not store backchain. Fix by making all progs do it. This is what GCC and Clang-generated code does as well. Now the call trace looks like this: [<000003ff600eb0f2>] bpf_prog_6df0139e1fbf2789_fentry+0x2a/0x80 [<000003ff600ed096>] bpf_trampoline_201863462940+0x96/0xf4 [<000003ff600e3a40>] bpf_prog_05f379658fdd72f2_classifier_0+0x58/0xc0 [<000003ffe0aef070>] bpf_test_run+0x210/0x390 [<000003ffe0af0dc2>] bpf_prog_test_run_skb+0x25a/0x668 [<000003ffe038a90e>] __sys_bpf+0xa46/0xdb0 [<000003ffe038ad0c>] __s390x_sys_bpf+0x44/0x50 [<000003ffe0defea8>] __do_syscall+0x150/0x280 [<000003ffe0e01d5c>] system_call+0x74/0x98 Fixes: 054623105728 ("s390/bpf: Add s390x eBPF JIT compiler backend") Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com> Link: https://lore.kernel.org/r/20250512122717.54878-1-iii@linux.ibm.com Signed-off-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
2025-05-07s390/pci: Fix missing check for zpci_create_device() error returnNiklas Schnelle1-0/+2
The zpci_create_device() function returns an error pointer that needs to be checked before dereferencing it as a struct zpci_dev pointer. Add the missing check in __clp_add() where it was missed when adding the scan_list in the fixed commit. Simply not adding the device to the scan list results in the previous behavior. Cc: stable@vger.kernel.org Fixes: 0467cdde8c43 ("s390/pci: Sort PCI functions prior to creating virtual busses") 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>
2025-05-05s390: Update defconfigsHeiko Carstens3-17/+8
Just the regular update of all defconfigs. Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
2025-05-05s390/entry: Fix last breaking event handling in case of stack corruptionHeiko Carstens1-1/+2
In case of stack corruption stack_invalid() is called and the expectation is that register r10 contains the last breaking event address. This dependency is quite subtle and broke a couple of years ago without that anybody noticed. Fix this by getting rid of the dependency and read the last breaking event address from lowcore. Fixes: 56e62a737028 ("s390: convert to generic entry") Acked-by: Ilya Leoshkevich <iii@linux.ibm.com> Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
2025-05-05s390/configs: Enable options required for TC flow offloadKonstantin Shkolnyy2-0/+12
While testing Open vSwitch with Nvidia ConnectX-6 NIC, it was noticed that it didn't offload TC flows into the NIC, and its log contained many messages such as: "failed to offload flow: No such file or directory: <network device name>" and, upon enabling more versose logging, additionally: "received NAK error=2 - TC classifier not found" The options enabled here are listed as requirements in Nvidia online documentation, among other options that were already enabled. Now all options listed by Nvidia are enabled.. This option is also added because Fedora has it: CONFIG_NET_EMATCH Signed-off-by: Konstantin Shkolnyy <kshk@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
2025-05-05s390/configs: Enable VDPA on Nvidia ConnectX-6 network cardKonstantin Shkolnyy2-0/+16
ConnectX-6 is the first VDPA-capable NIC. For earlier NICs, Nvidia implements a VDPA emulation in s/w, which hasn't been validated on s390. Add options necessary for VDPA to work. These options are also added because Fedora has them: CONFIG_VDPA_SIM CONFIG_VDPA_SIM_NET CONFIG_VDPA_SIM_BLOCK CONFIG_VDPA_USER CONFIG_VP_VDPA Signed-off-by: Konstantin Shkolnyy <kshk@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
2025-04-11Merge tag 's390-6.15-3' of ↵Linus Torvalds8-15/+198
git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux Pull s390 updates from Heiko Carstens: "Note that besides two bug fixes this includes three commits for IBM z17, which was announced this week. - Add IBM z17 bits: - Setup elf_platform for new machine types - Allow to compile the kernel with z17 optimizations - Add new performance counters - Fix mismatch between indicator bits and queue indexes in virtio CCW code - Fix double free in pmu setup error path" * tag 's390-6.15-3' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux: s390/cpumf: Fix double free on error in cpumf_pmu_event_init() s390/cpumf: Update CPU Measurement facility extended counter set support s390: Allow to compile with z17 optimizations s390: Add z17 elf platform s390/virtio_ccw: Don't allocate/assign airqs for non-existing queues
2025-04-09s390/cpumf: Fix double free on error in cpumf_pmu_event_init()Thomas Richter2-11/+1
In PMU event initialization functions - cpumsf_pmu_event_init() - cpumf_pmu_event_init() - cfdiag_event_init() the partially created event had to be removed when an error was detected. The event::event_init() member function had to release all resources it allocated in case of error. event::destroy() had to be called on freeing an event after it was successfully created and event::event_init() returned success. With commit c70ca298036c ("perf/core: Simplify the perf_event_alloc() error path") this is not necessary anymore. The performance subsystem common code now always calls event::destroy() to clean up the allocated resources created during event initialization. Remove the event::destroy() invocation in PMU event initialization or that function is called twice for each event that runs into an error condition in event creation. This is the kernel log entry which shows up without the fix: ------------[ cut here ]------------ refcount_t: underflow; use-after-free. WARNING: CPU: 0 PID: 43388 at lib/refcount.c:87 refcount_dec_not_one+0x74/0x90 CPU: 0 UID: 0 PID: 43388 Comm: perf Not tainted 6.15.0-20250407.rc1.git0.300.fc41.s390x+git #1 NONE Hardware name: IBM 3931 A01 704 (LPAR) Krnl PSW : 0704c00180000000 00000209cb2c1b88 (refcount_dec_not_one+0x78/0x90) R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:0 PM:0 RI:0 EA:3 Krnl GPRS: 0000020900000027 0000020900000023 0000000000000026 0000018900000000 00000004a2200a00 0000000000000000 0000000000000057 ffffffffffffffea 00000002b386c600 00000002b3f5b3e0 00000209cc51f140 00000209cc7fc550 0000000001449d38 ffffffffffffffff 00000209cb2c1b84 00000189d67dfb80 Krnl Code: 00000209cb2c1b78: c02000506727 larl %r2,00000209cbcce9c6 00000209cb2c1b7e: c0e5ffbd4431 brasl %r14,00000209caa6a3e0 #00000209cb2c1b84: af000000 mc 0,0 >00000209cb2c1b88: a7480001 lhi %r4,1 00000209cb2c1b8c: ebeff0a00004 lmg %r14,%r15,160(%r15) 00000209cb2c1b92: ec243fbf0055 risbg %r2,%r4,63,191,0 00000209cb2c1b98: 07fe bcr 15,%r14 00000209cb2c1b9a: 47000700 bc 0,1792 Call Trace: [<00000209cb2c1b88>] refcount_dec_not_one+0x78/0x90 [<00000209cb2c1dc4>] refcount_dec_and_mutex_lock+0x24/0x90 [<00000209caa3c29e>] hw_perf_event_destroy+0x2e/0x80 [<00000209cacaf8b4>] __free_event+0x74/0x270 [<00000209cacb47c4>] perf_event_alloc.part.0+0x4a4/0x730 [<00000209cacbf3e8>] __do_sys_perf_event_open+0x248/0xc20 [<00000209cacc14a4>] __s390x_sys_perf_event_open+0x44/0x50 [<00000209cb8114de>] __do_syscall+0x12e/0x260 [<00000209cb81ce34>] system_call+0x74/0x98 Last Breaking-Event-Address: [<00000209caa6a4d2>] __warn_printk+0xf2/0x100 ---[ end trace 0000000000000000 ]--- Fixes: c70ca298036c ("perf/core: Simplify the perf_event_alloc() error path") Signed-off-by: Thomas Richter <tmricht@linux.ibm.com> Reviewed-by: Sumanth Korikkar <sumanthk@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
2025-04-09s390/cpumf: Update CPU Measurement facility extended counter set supportThomas Richter2-4/+165
Update CPU Measurement counter facility support for the extended counter set for machine types 9175 and 9176. Signed-off-by: Thomas Richter <tmricht@linux.ibm.com> Acked-by: Sumanth Korikkar <sumanthk@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
2025-04-09s390: Allow to compile with z17 optimizationsVasily Gorbik4-0/+28
Add config and compile options which allow to compile with z17 optimizations if the compiler supports it. Add the miscellaneous-instruction-extension 4 facility to the list of facilities for z17. Reviewed-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
2025-04-09s390: Add z17 elf platformVasily Gorbik1-0/+4
Add detection for machine types 0x9175 and 0x9176 and set ELF platform name to z17. Reviewed-by: Heiko Carstens <hca@linux.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com> Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
2025-04-08Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvmLinus Torvalds4-12/+12
Pull kvm fixes from Paolo Bonzini: "ARM: - Rework heuristics for resolving the fault IPA (HPFAR_EL2 v. re-walk stage-1 page tables) to align with the architecture. This avoids possibly taking an SEA at EL2 on the page table walk or using an architecturally UNKNOWN fault IPA - Use acquire/release semantics in the KVM FF-A proxy to avoid reading a stale value for the FF-A version - Fix KVM guest driver to match PV CPUID hypercall ABI - Use Inner Shareable Normal Write-Back mappings at stage-1 in KVM selftests, which is the only memory type for which atomic instructions are architecturally guaranteed to work s390: - Don't use %pK for debug printing and tracepoints x86: - Use a separate subclass when acquiring KVM's per-CPU posted interrupts wakeup lock in the scheduled out path, i.e. when adding a vCPU on the list of vCPUs to wake, to workaround a false positive deadlock. The schedule out code runs with a scheduler lock that the wakeup handler takes in the opposite order; but it does so with IRQs disabled and cannot run concurrently with a wakeup - Explicitly zero-initialize on-stack CPUID unions - Allow building irqbypass.ko as as module when kvm.ko is a module - Wrap relatively expensive sanity check with KVM_PROVE_MMU - Acquire SRCU in KVM_GET_MP_STATE to protect guest memory accesses selftests: - Add more scenarios to the MONITOR/MWAIT test - Add option to rseq test to override /dev/cpu_dma_latency - Bring list of exit reasons up to date - Cleanup Makefile to list once tests that are valid on all architectures Other: - Documentation fixes" * tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (26 commits) KVM: arm64: Use acquire/release to communicate FF-A version negotiation KVM: arm64: selftests: Explicitly set the page attrs to Inner-Shareable KVM: arm64: selftests: Introduce and use hardware-definition macros KVM: VMX: Use separate subclasses for PI wakeup lock to squash false positive KVM: VMX: Assert that IRQs are disabled when putting vCPU on PI wakeup list KVM: x86: Explicitly zero-initialize on-stack CPUID unions KVM: Allow building irqbypass.ko as as module when kvm.ko is a module KVM: x86/mmu: Wrap sanity check on number of TDP MMU pages with KVM_PROVE_MMU KVM: selftests: Add option to rseq test to override /dev/cpu_dma_latency KVM: x86: Acquire SRCU in KVM_GET_MP_STATE to protect guest memory accesses Documentation: kvm: remove KVM_CAP_MIPS_TE Documentation: kvm: organize capabilities in the right section Documentation: kvm: fix some definition lists Documentation: kvm: drop "Capability" heading from capabilities Documentation: kvm: give correct name for KVM_CAP_SPAPR_MULTITCE Documentation: KVM: KVM_GET_SUPPORTED_CPUID now exposes TSC_DEADLINE selftests: kvm: list once tests that are valid on all architectures selftests: kvm: bring list of exit reasons up to date selftests: kvm: revamp MONITOR/MWAIT tests KVM: arm64: Don't translate FAR if invalid/unsafe ...
2025-04-06Merge tag 'timers-cleanups-2025-04-06' of ↵Linus Torvalds2-4/+4
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull timer cleanups from Thomas Gleixner: "A set of final cleanups for the timer subsystem: - Convert all del_timer[_sync]() instances over to the new timer_delete[_sync]() API and remove the legacy wrappers. Conversion was done with coccinelle plus some manual fixups as coccinelle chokes on scoped_guard(). - The final cleanup of the hrtimer_init() to hrtimer_setup() conversion. This has been delayed to the end of the merge window, so that all patches which have been merged through other trees are in mainline and all new users are catched. Doing this right before rc1 ensures that new code which is merged post rc1 is not introducing new instances of the original functionality" * tag 'timers-cleanups-2025-04-06' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: tracing/timers: Rename the hrtimer_init event to hrtimer_setup hrtimers: Rename debug_init_on_stack() to debug_setup_on_stack() hrtimers: Rename debug_init() to debug_setup() hrtimers: Rename __hrtimer_init_sleeper() to __hrtimer_setup_sleeper() hrtimers: Remove unnecessary NULL check in hrtimer_start_range_ns() hrtimers: Make callback function pointer private hrtimers: Merge __hrtimer_init() into __hrtimer_setup() hrtimers: Switch to use __htimer_setup() hrtimers: Delete hrtimer_init() treewide: Convert new and leftover hrtimer_init() users treewide: Switch/rename to timer_delete[_sync]()
2025-04-05Merge tag 'kbuild-v6.15' of ↵Linus Torvalds3-4/+3
git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild Pull Kbuild updates from Masahiro Yamada: - Improve performance in gendwarfksyms - Remove deprecated EXTRA_*FLAGS and KBUILD_ENABLE_EXTRA_GCC_CHECKS - Support CONFIG_HEADERS_INSTALL for ARCH=um - Use more relative paths to sources files for better reproducibility - Support the loong64 Debian architecture - Add Kbuild bash completion - Introduce intermediate vmlinux.unstripped for architectures that need static relocations to be stripped from the final vmlinux - Fix versioning in Debian packages for -rc releases - Treat missing MODULE_DESCRIPTION() as an error - Convert Nios2 Makefiles to use the generic rule for built-in DTB - Add debuginfo support to the RPM package * tag 'kbuild-v6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (40 commits) kbuild: rpm-pkg: build a debuginfo RPM kconfig: merge_config: use an empty file as initfile nios2: migrate to the generic rule for built-in DTB rust: kbuild: skip `--remap-path-prefix` for `rustdoc` kbuild: pacman-pkg: hardcode module installation path kbuild: deb-pkg: don't set KBUILD_BUILD_VERSION unconditionally modpost: require a MODUL