[PATCH v8 00/13] KVM: s390: Misc fixes

[Claudio Imbrenda <imbrenda@linux.ibm.com>]

Fix a bunch of small issues that came up during the previous round of fixes.

They are mostly extremely unlikely races, but they should be fixed
nonetheless.

v7->v8
* Fix some patch descriptions.
* Remove KVM_BUG_ON() from code that should not be reached but could
  still be reached. Just return an appropriate error code.
* Drop the last patch. Will need a more complex fix, will be done in a
  different series.

v6->v7
* Do not free SCA in kvm_arch_init_vm() if it was not allocated
* Remove a KVM_BUG_ON() that could still be triggered from userspace
  with UCONTROL.
* Remove KVM_BUG_ON() if a memslot change could not be performed.
* Fence KVM_S390_INTERRUPT also for vCPUs for UCONTROL VMs.

v5->v6
* Move the memory accesses in sca_ext_call_pending() and
  sca_inject_ext_call() so that they only happen after the newly
  introduced checks. Otherwise an out of bounds access was still possible.
* Completely fence the KVM_S390_INTERRUPT ioctl for UCONTROL VMs.
* Move page table updates from kvm_arch_commit_memory_region() to
  kvm_arch_prepare_memory_region(), so that failures are not ignored.

v4->v5
* Improve / fix some comments
* Undo handle_mvpg_pei() changes
* cmma_d_count_pte() now clears the cmma_d bit, to avoid double counting
* Improve some patch descriptions
* Trigger KVM_BUG_ON() in sca_ext_call_pending() and
  sca_inject_ext_call() if called on UCONTROL vCPUs
* Reshuffle the order of the patches to hopefully get fewer false
  positives from sashiko
* Check and free cbrlo only if it's not zero

v3->v4
* Improve patch descriptions, add comments
* Use smp_store_release and smp_load_acquire in the first patch
* Multiple fixes in patch 4: potential NULL pointer dereference,
  incorrect behaviour in low memory condition
* Rework patch 8 to use scope-based cleanup instead of gotos.
* Three new patches:
  - KVM: s390: Fix kvm_arch_commit_memory_region() when low on memory
  - KVM: s390: Fix kvm_s390_vcpu_unsetup_cmma()
  - KVM: s390: Fix sca_clear_ext_call() for UCONTROL

v2->v3
* Use READ_ONCE to pair with WRITE_ONCE in the first patch
* Fix leaking PGM_ADDRESSING also in kvm_s390_keyop() and related functions
* Fix and improve commit messages
* Use slots_arch_lock instead of slots_lock for ESSA operations
* Use normal spin_{,un}lock() functions instead of scoped_guard to avoid
  mixing the two styles
* Use the newly introduced vcpu->arch.initialized to determine whether the
  SCA entry needs to be cleared
* Improve handling of -EINTR; handle_mvpg_pei() needed some refactoring to
  deal with it properly
* Three new patches:
  - Free the mmu cache when kvm_arch_vcpu_create() fails
  - Fix ordering when adding to SCA
  - Fix cleanup in kvm_s390_pv_create_cpu()

v1->v2
* Drop some patches that have been picked upstream in the meantime.
* Drop patch 3, as it was trying to fix a bug that does not exist
* Avoid the NULL gmap dereference by using a flag
* Fix the return value of kvm_s390_[gp]et_skeys too
* Use kvm->slots_arch_lock instead of kvm->slots_lock for CMMA and ESSA
  handling, to avoid potential deadlocks with the RCU.
* Three new patches to fix other issues that came out while fixing the
  other issues

Claudio Imbrenda (13):
  KVM: s390: Fix unlikely NULL gmap dereference
  KVM: s390: Do not free SCA if it was not allocated
  KVM: s390: Fix kvm_s390_vcpu_unsetup_cmma()
  KVM: s390: Fix overclearing ESCA in case of error
  KVM: s390: ucontrol: Fix sca_clear_ext_call()
  KVM: s390: Fix leaking of PGM_ADDRESSING to userspace
  KVM: s390: Fix race in __do_essa()
  KVM: s390: cmma: Fix dirty tracking when removing memslot
  KVM: s390: ucontrol: Add missing locking around gmap_remove_child()
  KVM: s390: Free the mmu cache when kvm_arch_vcpu_create() fails
  KVM: s390: Return -EINTR if a signal is pending while faulting-in
  KVM: s390: Fix ordering when adding to SCA
  KVM: s390: Fix cleanup in kvm_s390_pv_create_cpu()

 arch/s390/include/asm/kvm_host.h |   1 +
 arch/s390/kvm/dat.c              |  23 ++++--
 arch/s390/kvm/dat.h              |   2 +-
 arch/s390/kvm/faultin.c          |   6 +-
 arch/s390/kvm/interrupt.c        |  19 +++--
 arch/s390/kvm/kvm-s390.c         | 125 ++++++++++++++++++++-----------
 arch/s390/kvm/priv.c             |  10 ++-
 arch/s390/kvm/pv.c               |  43 +++++------
 8 files changed, 144 insertions(+), 85 deletions(-)

-- 
2.55.0