In Michal's words... kvm_recalculate_apic_map() creates the APIC map iterating over the list of vCPUs twice. First to find the max APIC ID and allocate a max-sized buffer, then again, calling kvm_recalculate_phys_map() for each vCPU. This opens a race window: value of max APIC ID can increase _after_ the buffer was allocated. v3: - s/race/test for the new test file - Use kvm_vm_free() instead of kvm_vm_release() in the test - Fix a few typos in the test v2: https://lore.kernel.org/all/20230526235048.2842761-1-seanjc@xxxxxxxxxx v1: https://lore.kernel.org/all/20230525183347.2562472-1-mhal@xxxxxxx Michal Luczaj (1): KVM: selftests: Add test for race in kvm_recalculate_apic_map() Sean Christopherson (2): KVM: x86: Bail from kvm_recalculate_phys_map() if x2APIC ID is out-of-bounds KVM: x86: Retry APIC optimized map recalc if vCPU is added/enabled arch/x86/kvm/lapic.c | 49 ++++++++++-- tools/testing/selftests/kvm/Makefile | 1 + .../kvm/x86_64/recalc_apic_map_test.c | 74 +++++++++++++++++++ 3 files changed, 118 insertions(+), 6 deletions(-) create mode 100644 tools/testing/selftests/kvm/x86_64/recalc_apic_map_test.c base-commit: 39428f6ea9eace95011681628717062ff7f5eb5f -- 2.41.0.rc2.161.g9c6817b8e7-goog
