diff options
| author | Sean Christopherson <seanjc@google.com> | 2024-02-09 14:20:47 -0800 |
|---|---|---|
| committer | Sean Christopherson <seanjc@google.com> | 2024-02-22 16:24:26 -0800 |
| commit | fc3c94142b3a4391cab94adde56fcfbea25723e5 (patch) | |
| tree | e07faa5ac0cf3d87f0d876b4e53be5271a440af3 | |
| parent | a78d9046696b88079a5696bccec4e4e439a3f2a2 (diff) | |
KVM: x86: Sanity check that kvm_has_noapic_vcpu is zero at module_exit()
WARN if kvm.ko is unloaded with an elevated kvm_has_noapic_vcpu to guard
against incorrect management of the key, e.g. to detect if KVM fails to
decrement the key in error paths. Because kvm_has_noapic_vcpu is purely
an optimization, in all likelihood KVM could completely botch handling of
kvm_has_noapic_vcpu and no one would notice (which is a good argument for
deleting the key entirely, but that's a problem for another day).
Note, ideally the sanity check would be performance when kvm_usage_count
goes to zero, but adding an arch callback just for this sanity check isn't
at all worth doing.
Link: https://lore.kernel.org/r/20240209222047.394389-3-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
| -rw-r--r-- | arch/x86/kvm/x86.c | 5 |
1 files changed, 1 insertions, 4 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 19b18679779c..019320580a84 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -13871,9 +13871,6 @@ module_init(kvm_x86_init); static void __exit kvm_x86_exit(void) { - /* - * If module_init() is implemented, module_exit() must also be - * implemented to allow module unload. - */ + WARN_ON_ONCE(static_branch_unlikely(&kvm_has_noapic_vcpu)); } module_exit(kvm_x86_exit); |