Will Deacon <will@xxxxxxxxxx> writes: > On Tue, Feb 11, 2025 at 01:08:51PM +0530, Aneesh Kumar K.V (Arm) wrote: >> The return value for the KVM_RUN ioctl is confusing and has led to >> errors in different kernel exit handlers. A return value of 0 indicates >> a return to the VMM, whereas a return value of 1 indicates resuming >> execution in the guest. Some handlers mistakenly return 0 to force a >> return to the guest. > > Oops. Did any of those broken handlers reach mainline? > Not that I noticed. We do have patches in review. https://lore.kernel.org/all/20241212155610.76522-18-steven.price@xxxxxxx >> This worked in kvmtool because the exit_reason defaulted to >> 0 (KVM_EXIT_UNKNOWN), and kvmtool did not error out on an unknown exit >> reason. However, forcing a KVM panic on an unknown exit reason would >> help catch these bugs early. >> >> Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@xxxxxxxxxx> >> --- >> kvm-cpu.c | 1 + >> 1 file changed, 1 insertion(+) >> >> diff --git a/kvm-cpu.c b/kvm-cpu.c >> index f66dcd07220c..66e30ba54e26 100644 >> --- a/kvm-cpu.c >> +++ b/kvm-cpu.c >> @@ -170,6 +170,7 @@ int kvm_cpu__start(struct kvm_cpu *cpu) >> >> switch (cpu->kvm_run->exit_reason) { >> case KVM_EXIT_UNKNOWN: >> + goto panic_kvm; >> break; > > The break is no longer needed. > ok. -aneesh
