kernel/linux.git/arch/s390, branch v6.6.155

KVM: s390: pci: Fix aisb calculation

2026-08-19T16:13:10+00:00

[ Upstream commit 0cfe660559e857d7c00ab86c73e4510ce069086f ] The current implementation of aisb calculation will erroneously index via an unsigned long * as well as multiply by 8B for every 64-bits in the offset; only one or the other is required. This throws off aisb calculations once the number of devices exceeds 64, and can result in out-of-bounds access as well as failure to indicate summary bits associated with those devices in guests. Fix this by converting to a physical address before applying the offset, as is already done in arch/s390/pci/pci_irq.c. Fixes: 3c5a1b6f0a18 ("KVM: s390: pci: provide routines for enabling/disabling interrupt forwarding") Signed-off-by: Matthew Rosato Reviewed-by: Niklas Schnelle Signed-off-by: Christian Borntraeger [alifm@linux.ibm.com: Resolved merge conflict] Signed-off-by: Farhan Ali Signed-off-by: Sasha Levin

KVM: s390: pci: Fix resource leak on IRQ registration failure

2026-08-19T16:13:10+00:00

[ Upstream commit 5580c9858f1e00f60191eb09c3add359836d60b6 ] Currently if kvm_zpci_set_airq() fails, kvm_s390_pci_aif_enable() returns the error code but doesn't do any resource cleanup thus leaking resources. Fix this by cleaning up all the resources such as the GAITE, AIBV, AISB and unpinning any pinned pages. While at it, remove dead code that stored FIB values that were never referenced. As part of the cleanup, we are also holding the aift_lock a bit longer, as we hold the lock while executing the MPCIFC instruction. Though this is not strictly necessary, it means we don't have to drop and re-acquire in the error case. Fixes: 3c5a1b6f0a18 ("KVM: s390: pci: provide routines for enabling/disabling interrupt forwarding") Cc: stable@vger.kernel.org Reviewed-by: Matthew Rosato Reviewed-by: Christian Borntraeger Signed-off-by: Farhan Ali Tested-by: Matthew Rosato Signed-off-by: Christian Borntraeger [alifm@linux.ibm.com: Resolved merge conflict] Signed-off-by: Farhan Ali Signed-off-by: Sasha Levin

KVM: s390: pci: Fix missing error codes and memory unaccounting

2026-08-19T16:13:10+00:00

[ Upstream commit f86842e4d6c482300f4567f492d512c9ccf5bc4f ] In kvm_s390_pci_aif_enable() two error paths failed to set an error code, causing the function to return 0 on failure. It also failed to rollback memory accounting on failure. Fix both by propagating an error code on failure and calling unaccount_mem() in the cleanup path. Fixes: 3c5a1b6f0a18 ("KVM: s390: pci: provide routines for enabling/disabling interrupt forwarding") Cc: stable@vger.kernel.org Reviewed-by: Christian Borntraeger Reviewed-by: Matthew Rosato Signed-off-by: Farhan Ali Tested-by: Matthew Rosato Signed-off-by: Christian Borntraeger [alifm@linux.ibm.com: Resolve merge conflict] Signed-off-by: Farhan Ali Signed-off-by: Sasha Levin

KVM: s390: pci: Fix memory accounting for pinned/unpinned pages

2026-08-19T16:13:10+00:00

[ Upstream commit 36f6999ecde3976731a8bfc0b8e667da6f593069 ] The account_mem() and unaccount_mem() functions call get_uid() which increments the reference count of struct user_struct on every invocation. But we don't decrement the count by calling free_uid(). It also accounted/unaccounted the pages against the current->mm. But its possible the unaccount_mem() can be called from a different process context than the one that originally pinned the pages. Let's fix this by storing the pinning process user_struct and mm_struct when accounting for pinned pages, and subsequently free these resources when the pages are unpinned. Fixes: 3c5a1b6f0a18 ("KVM: s390: pci: provide routines for enabling/disabling interrupt forwarding") Cc: stable@vger.kernel.org Reviewed-by: Christian Borntraeger Reviewed-by: Matthew Rosato Signed-off-by: Farhan Ali Tested-by: Matthew Rosato [borntraeger@linux.ibm.com: Fixed whitespace] Signed-off-by: Christian Borntraeger [alifm@linux.ibm.com: Resolve merge conflict] Signed-off-by: Farhan Ali Signed-off-by: Sasha Levin

KVM: s390: pci: Validate AIBV and AISB before pinning guest pages

2026-08-09T18:21:51+00:00

commit 868d32ac72cba21c5c6d8a66a814b7c25a3a5c01 upstream. The AIBV holds one bit per MSI-X vector for a given function. The size of the bit vector is derived from the NOI and the AIBVO. If the size of the AIBV exceeds a single page boundary, then reject the request as we cannot safely pin the guest AIBV. Similarly reject the request if the AISB address is not 8-byte aligned as the architecture requires doubleword alignment for the summary bit address. Since the AISBO can address up to 64 bits, the size of the AISB can only be 8 bytes for the function. This also ensures the AISB doesn't exceed a single page boundary. Fixes: 3c5a1b6f0a18 ("KVM: s390: pci: provide routines for enabling/disabling interrupt forwarding") Cc: stable@vger.kernel.org Reviewed-by: Christian Borntraeger Reviewed-by: Matthew Rosato Signed-off-by: Farhan Ali Tested-by: Matthew Rosato Signed-off-by: Christian Borntraeger Signed-off-by: Greg Kroah-Hartman

KVM: s390: pci: Fix NULL dereference on AIBV allocation failure

2026-08-09T18:21:51+00:00

commit 8bf09b9b7d3232806df95f409581f8a9fd99a3fa upstream. The airq_iv_create() can return NULL on failure, but the return value was never checked. If it fails, zdev->aibv will be NULL and fail when dereferenced in kvm_zpci_set_airq(). Add a NULL check and free the previously allocated AISB bit and zdev->aisb on failure. Fixes: 3c5a1b6f0a18 ("KVM: s390: pci: provide routines for enabling/disabling interrupt forwarding") Cc: stable@vger.kernel.org Reviewed-by: Christian Borntraeger Reviewed-by: Matthew Rosato Signed-off-by: Farhan Ali Tested-by: Matthew Rosato Signed-off-by: Christian Borntraeger Signed-off-by: Greg Kroah-Hartman

KVM: s390: pci: Reject adapter interrupt forwarding if already enabled

2026-08-09T18:21:51+00:00

commit 8fa01be5a6149404adb82c0979a78f6347edd3ef upstream. The MPCIFC instruction doesn't allow registering adapter interrupts without first unregistering. So reject any request to enable interrupt forwarding if its already enabled for the zPCI device. This also fixes overwriting and thus leaking resources when the ioctl is called multiple times for the same device. Fixes: 3c5a1b6f0a18 ("KVM: s390: pci: provide routines for enabling/disabling interrupt forwarding") Cc: stable@vger.kernel.org Reviewed-by: Christian Borntraeger Reviewed-by: Matthew Rosato Signed-off-by: Farhan Ali Tested-by: Matthew Rosato Signed-off-by: Christian Borntraeger Signed-off-by: Greg Kroah-Hartman

KVM: Introduce vcpu->wants_to_run

2026-08-03T09:15:40+00:00

[ Upstream commit a6816314af5749cd88944bfdceb270c627cdf348 ] Introduce vcpu->wants_to_run to indicate when a vCPU is in its core run loop, i.e. when the vCPU is running the KVM_RUN ioctl and immediate_exit was not set. Replace all references to vcpu->run->immediate_exit with !vcpu->wants_to_run to avoid TOCTOU races with userspace. For example, a malicious userspace could invoked KVM_RUN with immediate_exit=true and then after KVM reads it to set wants_to_run=false, flip it to false. This would result in the vCPU running in KVM_RUN with wants_to_run=false. This wouldn't cause any real bugs today but is a dangerous landmine. Signed-off-by: David Matlack Link: https://lore.kernel.org/r/20240503181734.1467938-2-dmatlack@google.com Signed-off-by: Sean Christopherson Stable-dep-of: e800decd9c0a ("KVM: x86: Only reset TSC Deadline Timer in apic_timer_expired on KVM_RUN") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

s390/perf_cpum_cf: Add missing array_index_nospec() to __hw_perf_event_init()

2026-07-24T14:03:33+00:00

commit 49145bce539117db4b6e9e83c0e5ef528e361050 upstream. ev variable is userspace controlled via event->attr.config and used as an array index after bounds checking, but without speculation barriers. Add the missing array_index_nospec() call to prevent speculative execution. Cc: stable@vger.kernel.org Fixes: 212188a596d1 ("[S390] perf: add support for s390x CPU counters") Signed-off-by: Sumanth Korikkar Reviewed-by: Ilya Leoshkevich Acked-by: Thomas Richter Signed-off-by: Vasily Gorbik Signed-off-by: Greg Kroah-Hartman

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

2026-07-24T14:03:30+00:00

commit 3e3aa6da87d30a0064a17b836685cd43c90a3572 upstream. 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 Signed-off-by: Greg Kroah-Hartman