linux.git/arch/s390/kvm, branch master

KVM: s390: pci: Fix handling of AIF enable without AISB

2026-07-09T14:23:10Z

When a guest seeks to register IRQs without a summary bit specified, ensure that the associated GAITE then stores 0 for the guest AISB location instead of virt_to_phys(page_address(NULL)). Fixes: 3c5a1b6f0a18 ("KVM: s390: pci: provide routines for enabling/disabling interrupt forwarding") Cc: stable@vger.kernel.org Reviewed-by: Farhan Ali Signed-off-by: Matthew Rosato Signed-off-by: Christian Borntraeger

KVM: s390: Improve kvm_s390_vm_stop_migration()

2026-07-09T08:26:10Z

There is no need to clear cmma-dirty state if the VM is not using CMMA. Skip the CMMA-related code if CMMA is not in use. Fixes: 6cfd47f91f6a ("KVM: s390: Fix cmma dirty tracking") Fixes: 190df4a212a7 ("KVM: s390: CMMA tracking, ESSA emulation, migration mode") Signed-off-by: Claudio Imbrenda Reviewed-by: Christian Borntraeger Signed-off-by: Christian Borntraeger

KVM: s390: Fix dat_crste_walk_range() early return

2026-07-09T08:26:10Z

If a walk entry handler for a lower level returns a value, dat_crste_walk_range() will not return immediately, but instead loop again and move to the next entry. This means that some entries are potentially skipped, and early return is ignored. Skipped entries might lead to all kinds of issues, given that the caller expects them to not be skipped. Early return is often used to interrupt a walk when a rescheduling is needed; if it is ignored it can lead to stalls. Fix by breaking from the loop immediately if the walk to a lower level returned non-zero. Fixes: 2db149a0a6c5 ("KVM: s390: KVM page table management functions: walks") Signed-off-by: Claudio Imbrenda Reviewed-by: Christian Borntraeger Signed-off-by: Christian Borntraeger

KVM: s390: vsie: Avoid potential deadlock with real spaces

2026-07-09T08:26:10Z

The natural lock ordering is mmu_lock -> children_lock, but in gmap_create_shadow() the reverse order is used when handling shadowing of real address spaces. Convert the inner locking of kvm->mmu_lock to a trylock; return -EAGAIN if the lock is busy, and let the caller try again. This path is not expected to happen in real-life scenarios, so its performance is not important. Fixes: a2c17f9270cc ("KVM: s390: New gmap code") Signed-off-by: Claudio Imbrenda Reviewed-by: Christian Borntraeger Signed-off-by: Christian Borntraeger

KVM: s390: pci: Fix GISC refcount leak on AIF enable failure

2026-07-09T08:25:56Z

kvm_s390_gisc_register() registers the guest ISC before pinning the guest interrupt forwarding pages and allocating the AISB bit. If any of the later setup steps fails, the function unwinds the pinned pages and other local state, but does not unregister the GISC reference. Add the missing kvm_s390_gisc_unregister() to the error unwind path. Fixes: 3c5a1b6f0a18 ("KVM: s390: pci: provide routines for enabling/disabling interrupt forwarding") Cc: stable@vger.kernel.org Signed-off-by: Haoxiang Li Reviewed-by: Matthew Rosato Tested-by: Matthew Rosato Acked-by: Claudio Imbrenda Reviewed-by: Christian Borntraeger Signed-off-by: Claudio Imbrenda Message-ID: <20260624061910.2794734-1-haoxiang_li2024@163.com> Signed-off-by: Christian Borntraeger

Merge tag 'kvm-s390-next-7.2-2' of https://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux into HEAD

2026-06-24T11:41:41Z

* Fix S390_USER_OPEREXEC so it can now be enabled regardless of other unrelated capabilities * Fix handling of the _PAGE_UNUSED pte bit that could lead to guest memory corruption in some scenarios * A bunch of misc gmap fixes (locking, behaviour under memory pressure) * Fix CMMA dirty tracking

KVM: s390: Return failure in case of failure in kvm_s390_set_cmma_bits()

2026-06-24T08:08:57Z

If the allocation of the bits array failed, kvm_s390_set_cmma_bits() would return 0 instead of an error code. Rework the function to use the __free() macros and thus simplify the code flow; when the above mentioned allocation fails, simply return -ENOMEM. Fixes: e38c884df921 ("KVM: s390: Switch to new gmap") Reviewed-by: Christian Borntraeger Signed-off-by: Claudio Imbrenda Message-ID: <20260623153331.233784-10-imbrenda@linux.ibm.com>

KVM: s390: Fix cmma dirty tracking

2026-06-24T08:08:57Z

It is possible that some guest memory areas have not been touched yet when starting migration mode, and thus have no ptes allocated. Only existing and allocated ptes should count toward the total of dirty cmma entries. When starting migration mode, enable the migration_mode flag immediately, so that any subsequent ESSA will trap in the host and cause cmma_dirty_pages to be increased as needed. Subsequently, set the cmma_d bit on all existing cmma-clean PGSTEs, increasing cmma_dirty_pages as needed. Skipping cmma-dirty pages prevents double counting. Conversely, when disabling migration mode, set cmma_dirty_pages to 0 and clear the cmma_d bit in all existing PGSTEs. The invariant is that when migration mode is off, no PGSTE has its cmma_d bit set, and cmma_dirty_pages is 0. kvm->slots_lock protects kvm_s390_vm_start_migration() and kvm_s390_vm_stop_migration() from each other and from kvm_s390_get_cmma_bits(). Also fix dat_get_cmma() to properly wrap around if the first attempt reached the end of guest memory without finding cmma-dirty pages. [ imbrenda: Moved kvm_s390_sync_request_broadcast() before gmap_set_cmma_all_dirty() ] Fixes: e38c884df921 ("KVM: s390: Switch to new gmap") Signed-off-by: Claudio Imbrenda Message-ID: <20260623153331.233784-8-imbrenda@linux.ibm.com>

KVM: s390: Fix locking in kvm_s390_set_mem_control()

2026-06-24T08:08:57Z

Add the missing locking around dat_reset_cmma(). Fixes: e38c884df921 ("KVM: s390: Switch to new gmap") Signed-off-by: Claudio Imbrenda Message-ID: <20260623153331.233784-7-imbrenda@linux.ibm.com>

KVM: s390: Fix handle_{sske,pfmf} under memory pressure

2026-06-24T08:08:57Z

Under heavy memory pressure, handle_sske() and handle_pfmf() might cause an endless loop if the mmu cache runs empty, the atomic allocations fail, and the top-up function also fails. While quite unlikely, that scenario is not impossible. Fix the issue by not ignoring the return value of kvm_s390_mmu_cache_topup(), and appropriately returning an error code in case of failure. Fixes: e38c884df921 ("KVM: s390: Switch to new gmap") Reviewed-by: Christian Borntraeger Signed-off-by: Claudio Imbrenda Message-ID: <20260623153331.233784-6-imbrenda@linux.ibm.com>