Re: [PATCH 13/15] KVM: arm64: vgic-its: Protect cached vgic_irq pointers with RCU

kernel test robot
2024-01-29T01:03:56Z

Hi Oliver,

kernel test robot noticed the following build warnings:

[auto build test WARNING on 6613476e225e090cc9aad49be7fa504e290dd33d]

url: https://github.com/intel-lab-lkp/linux/commits/Oliver-Upton/KVM-arm64-vgic-Store-LPIs-in-an-xarray/20240125-045255
base: 6613476e225e090cc9aad49be7fa504e290dd33d
patch link: https://lore.kernel.org/r/20240124204909.105952-14-oliver.upton%40linux.dev
patch subject: [PATCH 13/15] KVM: arm64: vgic-its: Protect cached vgic_irq pointers with RCU
config: arm64-randconfig-r112-20240128 (https://download.01.org/0day-ci/archive/20240129/202401290835.TjDnhUFI-lkp@intel.com/config)
compiler: clang version 18.0.0git (https://github.com/llvm/llvm-project a31a60074717fc40887cfe132b77eec93bedd307)
reproduce: (https://download.01.org/0day-ci/archive/20240129/202401290835.TjDnhUFI-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202401290835.TjDnhUFI-lkp@intel.com/

sparse warnings: (new ones prefixed by >>)
>> arch/arm64/kvm/vgic/vgic-its.c:705:41: sparse: sparse: incorrect type in argument 2 (different address spaces) @@ expected struct vgic_irq *irq @@ got struct vgic_irq [noderef] __rcu *irq @@
arch/arm64/kvm/vgic/vgic-its.c:705:41: sparse: expected struct vgic_irq *irq
arch/arm64/kvm/vgic/vgic-its.c:705:41: sparse: got struct vgic_irq [noderef] __rcu *irq
arch/arm64/kvm/vgic/vgic-its.c:727:38: sparse: sparse: incorrect type in argument 2 (different address spaces) @@ expected struct vgic_irq *irq @@ got struct vgic_irq [noderef] __rcu *irq @@
arch/arm64/kvm/vgic/vgic-its.c:727:38: sparse: expected struct vgic_irq *irq
arch/arm64/kvm/vgic/vgic-its.c:727:38: sparse: got struct vgic_irq [noderef] __rcu *irq
arch/arm64/kvm/vgic/vgic-its.c:891:17: sparse: sparse: cast to restricted __le64
arch/arm64/kvm/vgic/vgic-its.c:1031:24: sparse: sparse: cast to restricted __le64
arch/arm64/kvm/vgic/vgic-its.c:2245:13: sparse: sparse: incorrect type in assignment (different base types) @@ expected unsigned long long [assigned] [usertype] val @@ got restricted __le64 [usertype] @@
arch/arm64/kvm/vgic/vgic-its.c:2245:13: sparse: expected unsigned long long [assigned] [usertype] val
arch/arm64/kvm/vgic/vgic-its.c:2245:13: sparse: got restricted __le64 [usertype]
arch/arm64/kvm/vgic/vgic-its.c:2271:15: sparse: sparse: cast to restricted __le64
arch/arm64/kvm/vgic/vgic-its.c:2397:13: sparse: sparse: incorrect type in assignment (different base types) @@ expected unsigned long long [assigned] [usertype] val @@ got restricted __le64 [usertype] @@
arch/arm64/kvm/vgic/vgic-its.c:2397:13: sparse: expected unsigned long long [assigned] [usertype] val
arch/arm64/kvm/vgic/vgic-its.c:2397:13: sparse: got restricted __le64 [usertype]
arch/arm64/kvm/vgic/vgic-its.c:2424:17: sparse: sparse: cast to restricted __le64
arch/arm64/kvm/vgic/vgic-its.c:2525:17: sparse: sparse: cast to restricted __le64
arch/arm64/kvm/vgic/vgic-its.c:2584:13: sparse: sparse: incorrect type in assignment (different base types) @@ expected unsigned long long [assigned] [usertype] val @@ got restricted __le64 [usertype] @@
arch/arm64/kvm/vgic/vgic-its.c:2584:13: sparse: expected unsigned long long [assigned] [usertype] val
arch/arm64/kvm/vgic/vgic-its.c:2584:13: sparse: got restricted __le64 [usertype]
arch/arm64/kvm/vgic/vgic-its.c:2605:15: sparse: sparse: cast to restricted __le64
arch/arm64/kvm/vgic/vgic-its.c:39:24: sparse: sparse: context imbalance in 'vgic_add_lpi' - different lock contexts for basic block
arch/arm64/kvm/vgic/vgic-its.c:284:12: sparse: sparse: context imbalance in 'update_lpi_config' - different lock contexts for basic block
arch/arm64/kvm/vgic/vgic-its.c:458:9: sparse: sparse: context imbalance in 'its_sync_lpi_pending_table' - different lock contexts for basic block
arch/arm64/kvm/vgic/vgic-its.c: note: in included file (through include/linux/random.h, arch/arm64/include/asm/pointer_auth.h, arch/arm64/include/asm/processor.h, ...):
include/linux/list.h:83:21: sparse: sparse: self-comparison always evaluates to true
arch/arm64/kvm/vgic/vgic-its.c:796:12: sparse: sparse: context imbalance in 'vgic_its_trigger_msi' - different lock contexts for basic block
arch/arm64/kvm/vgic/vgic-its.c:818:5: sparse: sparse: context imbalance in 'vgic_its_inject_cached_translation' - wrong count at exit
include/linux/list.h:83:21: sparse: sparse: self-comparison always evaluates to true
include/linux/list.h:83:21: sparse: sparse: self-comparison always evaluates to true
include/linux/list.h:83:21: sparse: sparse: self-comparison always evaluates to true

vim +705 arch/arm64/kvm/vgic/vgic-its.c

73dcc3dd6274b9 arch/arm64/kvm/vgic/vgic-its.c Oliver Upton 2024-01-24 637
89489ee9ced892 virt/kvm/arm/vgic/vgic-its.c Marc Zyngier 2019-03-18 638 static void vgic_its_cache_translation(struct kvm *kvm, struct vgic_its *its,
89489ee9ced892 virt/kvm/arm/vgic/vgic-its.c Marc Zyngier 2019-03-18 639 u32 devid, u32 eventid,
89489ee9ced892 virt/kvm/arm/vgic/vgic-its.c Marc Zyngier 2019-03-18 640 struct vgic_irq *irq)
89489ee9ced892 virt/kvm/arm/vgic/vgic-its.c Marc Zyngier 2019-03-18 641 {
8fb2f0e370c963 arch/arm64/kvm/vgic/vgic-its.c Oliver Upton 2024-01-24 642 struct vgic_translation_cache_entry *new, *victim;
89489ee9ced892 virt/kvm/arm/vgic/vgic-its.c Marc Zyngier 2019-03-18 643 struct vgic_dist *dist = &kvm->arch.vgic;
89489ee9ced892 virt/kvm/arm/vgic/vgic-its.c Marc Zyngier 2019-03-18 644 unsigned long flags;
89489ee9ced892 virt/kvm/arm/vgic/vgic-its.c Marc Zyngier 2019-03-18 645 phys_addr_t db;
89489ee9ced892 virt/kvm/arm/vgic/vgic-its.c Marc Zyngier 2019-03-18 646
89489ee9ced892 virt/kvm/arm/vgic/vgic-its.c Marc Zyngier 2019-03-18 647 /* Do not cache a directly injected interrupt */
89489ee9ced892 virt/kvm/arm/vgic/vgic-its.c Marc Zyngier 2019-03-18 648 if (irq->hw)
89489ee9ced892 virt/kvm/arm/vgic/vgic-its.c Marc Zyngier 2019-03-18 649 return;
89489ee9ced892 virt/kvm/arm/vgic/vgic-its.c Marc Zyngier 2019-03-18 650
8fb2f0e370c963 arch/arm64/kvm/vgic/vgic-its.c Oliver Upton 2024-01-24 651 new = victim = kzalloc(sizeof(*new), GFP_KERNEL_ACCOUNT);
8fb2f0e370c963 arch/arm64/kvm/vgic/vgic-its.c Oliver Upton 2024-01-24 652 if (!new)
8fb2f0e370c963 arch/arm64/kvm/vgic/vgic-its.c Oliver Upton 2024-01-24 653 return;
89489ee9ced892 virt/kvm/arm/vgic/vgic-its.c Marc Zyngier 2019-03-18 654
8fb2f0e370c963 arch/arm64/kvm/vgic/vgic-its.c Oliver Upton 2024-01-24 655 raw_spin_lock_irqsave(&dist->lpi_list_lock, flags);
131b61b5cd90e9 arch/arm64/kvm/vgic/vgic-its.c Oliver Upton 2024-01-24 656 rcu_read_lock();
89489ee9ced892 virt/kvm/arm/vgic/vgic-its.c Marc Zyngier 2019-03-18 657
89489ee9ced892 virt/kvm/arm/vgic/vgic-its.c Marc Zyngier 2019-03-18 658 /*
89489ee9ced892 virt/kvm/arm/vgic/vgic-its.c Marc Zyngier 2019-03-18 659 * We could have raced with another CPU caching the same
89489ee9ced892 virt/kvm/arm/vgic/vgic-its.c Marc Zyngier 2019-03-18 660 * translation behind our back, so let's check it is not in
89489ee9ced892 virt/kvm/arm/vgic/vgic-its.c Marc Zyngier 2019-03-18 661 * already
89489ee9ced892 virt/kvm/arm/vgic/vgic-its.c Marc Zyngier 2019-03-18 662 */
89489ee9ced892 virt/kvm/arm/vgic/vgic-its.c Marc Zyngier 2019-03-18 663 db = its->vgic_its_base + GITS_TRANSLATER;
89489ee9ced892 virt/kvm/arm/vgic/vgic-its.c Marc Zyngier 2019-03-18 664 if (__vgic_its_check_cache(dist, db, devid, eventid))
89489ee9ced892 virt/kvm/arm/vgic/vgic-its.c Marc Zyngier 2019-03-18 665 goto out;
89489ee9ced892 virt/kvm/arm/vgic/vgic-its.c Marc Zyngier 2019-03-18 666
8fb2f0e370c963 arch/arm64/kvm/vgic/vgic-its.c Oliver Upton 2024-01-24 667 if (dist->lpi_cache_count >= vgic_its_max_cache_size(kvm)) {
73dcc3dd6274b9 arch/arm64/kvm/vgic/vgic-its.c Oliver Upton 2024-01-24 668 victim = vgic_its_cache_victim(dist);
73dcc3dd6274b9 arch/arm64/kvm/vgic/vgic-its.c Oliver Upton 2024-01-24 669 if (WARN_ON_ONCE(!victim)) {
73dcc3dd6274b9 arch/arm64/kvm/vgic/vgic-its.c Oliver Upton 2024-01-24 670 victim = new;
73dcc3dd6274b9 arch/arm64/kvm/vgic/vgic-its.c Oliver Upton 2024-01-24 671 goto out;
73dcc3dd6274b9 arch/arm64/kvm/vgic/vgic-its.c Oliver Upton 2024-01-24 672 }
73dcc3dd6274b9 arch/arm64/kvm/vgic/vgic-its.c Oliver Upton 2024-01-24 673
8fb2f0e370c963 arch/arm64/kvm/vgic/vgic-its.c Oliver Upton 2024-01-24 674 list_del(&victim->entry);
8fb2f0e370c963 arch/arm64/kvm/vgic/vgic-its.c Oliver Upton 2024-01-24 675 dist->lpi_cache_count--;
8fb2f0e370c963 arch/arm64/kvm/vgic/vgic-its.c Oliver Upton 2024-01-24 676 } else {
8fb2f0e370c963 arch/arm64/kvm/vgic/vgic-its.c Oliver Upton 2024-01-24 677 victim = NULL;
8fb2f0e370c963 arch/arm64/kvm/vgic/vgic-its.c Oliver Upton 2024-01-24 678 }
89489ee9ced892 virt/kvm/arm/vgic/vgic-its.c Marc Zyngier 2019-03-18 679
7f253bdb6144f3 arch/arm64/kvm/vgic/vgic-its.c Oliver Upton 2024-01-24 680 /*
7f253bdb6144f3 arch/arm64/kvm/vgic/vgic-its.c Oliver Upton 2024-01-24 681 * The irq refcount is guaranteed to be nonzero while holding the
7f253bdb6144f3 arch/arm64/kvm/vgic/vgic-its.c Oliver Upton 2024-01-24 682 * its_lock, as the ITE (and the reference it holds) cannot be freed.
7f253bdb6144f3 arch/arm64/kvm/vgic/vgic-its.c Oliver Upton 2024-01-24 683 */
7f253bdb6144f3 arch/arm64/kvm/vgic/vgic-its.c Oliver Upton 2024-01-24 684 lockdep_assert_held(&its->its_lock);
89489ee9ced892 virt/kvm/arm/vgic/vgic-its.c Marc Zyngier 2019-03-18 685 vgic_get_irq_kref(irq);
89489ee9ced892 virt/kvm/arm/vgic/vgic-its.c Marc Zyngier 2019-03-18 686
8fb2f0e370c963 arch/arm64/kvm/vgic/vgic-its.c Oliver Upton 2024-01-24 687 new->db = db;
8fb2f0e370c963 arch/arm64/kvm/vgic/vgic-its.c Oliver Upton 2024-01-24 688 new->devid = devid;
8fb2f0e370c963 arch/arm64/kvm/vgic/vgic-its.c Oliver Upton 2024-01-24 689 new->eventid = eventid;
131b61b5cd90e9 arch/arm64/kvm/vgic/vgic-its.c Oliver Upton 2024-01-24 690 rcu_assign_pointer(new->irq, irq);
89489ee9ced892 virt/kvm/arm/vgic/vgic-its.c Marc Zyngier 2019-03-18 691
89489ee9ced892 virt/kvm/arm/vgic/vgic-its.c Marc Zyngier 2019-03-18 692 /* Move the new translation to the head of the list */
8fb2f0e370c963 arch/arm64/kvm/vgic/vgic-its.c Oliver Upton 2024-01-24 693 list_add(&new->entry, &dist->lpi_translation_cache);
89489ee9ced892 virt/kvm/arm/vgic/vgic-its.c Marc Zyngier 2019-03-18 694
89489ee9ced892 virt/kvm/arm/vgic/vgic-its.c Marc Zyngier 2019-03-18 695 out:
131b61b5cd90e9 arch/arm64/kvm/vgic/vgic-its.c Oliver Upton 2024-01-24 696 rcu_read_unlock();
89489ee9ced892 virt/kvm/arm/vgic/vgic-its.c Marc Zyngier 2019-03-18 697 raw_spin_unlock_irqrestore(&dist->lpi_list_lock, flags);
8fb2f0e370c963 arch/arm64/kvm/vgic/vgic-its.c Oliver Upton 2024-01-24 698
8fb2f0e370c963 arch/arm64/kvm/vgic/vgic-its.c Oliver Upton 2024-01-24 699 /*
8fb2f0e370c963 arch/arm64/kvm/vgic/vgic-its.c Oliver Upton 2024-01-24 700 * Caching the translation implies having an extra reference
8fb2f0e370c963 arch/arm64/kvm/vgic/vgic-its.c Oliver Upton 2024-01-24 701 * to the interrupt, so drop the potential reference on what
8fb2f0e370c963 arch/arm64/kvm/vgic/vgic-its.c Oliver Upton 2024-01-24 702 * was in the cache, and increment it on the new interrupt.
8fb2f0e370c963 arch/arm64/kvm/vgic/vgic-its.c Oliver Upton 2024-01-24 703 */
8fb2f0e370c963 arch/arm64/kvm/vgic/vgic-its.c Oliver Upton 2024-01-24 704 if (victim && victim->irq)
8fb2f0e370c963 arch/arm64/kvm/vgic/vgic-its.c Oliver Upton 2024-01-24 @705 vgic_put_irq(kvm, victim->irq);
8fb2f0e370c963 arch/arm64/kvm/vgic/vgic-its.c Oliver Upton 2024-01-24 706
8fb2f0e370c963 arch/arm64/kvm/vgic/vgic-its.c Oliver Upton 2024-01-24 707 kfree(victim);
89489ee9ced892 virt/kvm/arm/vgic/vgic-its.c Marc Zyngier 2019-03-18 708 }
89489ee9ced892 virt/kvm/arm/vgic/vgic-its.c Marc Zyngier 2019-03-18 709

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