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?
> 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.
Will
