[PATCH kvmtool 1/2] cpu: vmexit: Handle KVM_EXIT_UNKNOWN exit reason correctly

["Aneesh Kumar K.V (Arm)" <aneesh.kumar@kernel.org>]

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.

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@kernel.org>
---
 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;
 		case KVM_EXIT_DEBUG:
 			kvm_cpu__show_registers(cpu);

base-commit: 6d754d01fe2cb366f3b636d8a530f46ccf3b10d8
-- 
2.43.0