On Wed, Oct 09, 2024 at 07:36:03PM +0100, Marc Zyngier wrote: > As there is very little ordering in the KVM API, userspace can > instanciate a half-baked GIC (missing its memory map, for example) > at almost any time. The vgic_init selftest has started failing in mainline on multiple platforms, with a bisect pointing at this patch which is present there as commit df5fd75ee305cb5. The test reports: # selftests: kvm: vgic_init # Random seed: 0x6b8b4567 # Running GIC_v3 tests. # ==== Test Assertion Failure ==== # lib/kvm_util.c:724: false # pid=1947 tid=1947 errno=5 - Input/output error # 1 0x0000000000404edb: __vm_mem_region_delete at kvm_util.c:724 (discriminator 5) # 2 0x0000000000405d0b: kvm_vm_free at kvm_util.c:762 (discriminator 12) # 3 0x0000000000402d5f: vm_gic_destroy at vgic_init.c:101 # 4 (inlined by) test_vcpus_then_vgic at vgic_init.c:368 # 5 (inlined by) run_tests at vgic_init.c:720 # 6 0x0000000000401a6f: main at vgic_init.c:748 # 7 0x0000ffffa7b37543: ?? ??:0 # 8 0x0000ffffa7b37617: ?? ??:0 # 9 0x0000000000401b6f: _start at ??:? # KVM killed/bugged the VM, check the kernel log for clues not ok 10 selftests: kvm: vgic_init # exit=254 which does rather look like a test bug rather than a problem in the change itself. Full log from one run on synquacer at: https://validation.linaro.org/scheduler/job/4108424#L1846 bisect log (using a current mailine build of kselftests rather than one matching the tested kernel to avoid the build issues): git bisect start # status: waiting for both good and bad commits # bad: [c2ee9f594da826bea183ed14f2cc029c719bf4da] KVM: selftests: Fix build on on non-x86 architectures git bisect bad c2ee9f594da826bea183ed14f2cc029c719bf4da # status: waiting for good commit(s), bad commit known # good: [9852d85ec9d492ebef56dc5f229416c925758edc] Linux 6.12-rc1 git bisect good 9852d85ec9d492ebef56dc5f229416c925758edc # good: [a1029768f3931b31aa52790f1dde0c7d6a6552eb] Merge tag 'rcu.fixes.6.12-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/rcu/linux git bisect good a1029768f3931b31aa52790f1dde0c7d6a6552eb # good: [b1b46751671be5a426982f037a47ae05f37ff80b] mm: fix follow_pfnmap API lockdep assert git bisect good b1b46751671be5a426982f037a47ae05f37ff80b # good: [531643fcd98c8d045d72a05cb0aaf49e5a4bdf5c] Merge tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi git bisect good 531643fcd98c8d045d72a05cb0aaf49e5a4bdf5c # good: [c55228220dd33e7627ad9736b6fce4df5e7eac98] Merge tag 'char-misc-6.12-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc git bisect good c55228220dd33e7627ad9736b6fce4df5e7eac98 # good: [c1bc09d7bfcbe90c6df3a630ec1fb0fcd4799236] Merge tag 'probes-fixes-v6.12-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace git bisect good c1bc09d7bfcbe90c6df3a630ec1fb0fcd4799236 # bad: [5978d4ec7e82ffc472ac2645601dd10b09e61b0f] KVM: arm64: vgic: Don't check for vgic_ready() when setting NR_IRQS git bisect bad 5978d4ec7e82ffc472ac2645601dd10b09e61b0f # good: [6ded46b5a4fd7fc9c6104b770627043aaf996abf] KVM: arm64: nv: Keep reference on stage-2 MMU when scheduled out git bisect good 6ded46b5a4fd7fc9c6104b770627043aaf996abf # good: [d4a89e5aee23eaebdc45f63cb3d6d5917ff6acf4] KVM: arm64: Expose S1PIE to guests git bisect good d4a89e5aee23eaebdc45f63cb3d6d5917ff6acf4 # bad: [afa9b48f327c9ef36bfba4c643a29385a633252b] KVM: arm64: Shave a few bytes from the EL2 idmap code git bisect bad afa9b48f327c9ef36bfba4c643a29385a633252b # bad: [df5fd75ee305cb5927e0b1a0b46cc988ad8db2b1] KVM: arm64: Don't eagerly teardown the vgic on init error git bisect bad df5fd75ee305cb5927e0b1a0b46cc988ad8db2b1 # first bad commit: [df5fd75ee305cb5927e0b1a0b46cc988ad8db2b1] KVM: arm64: Don't eagerly teardown the vgic on init error
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