Fixed Error handling: Panic in hypercall handler caused remaining thr…

…eads never to finish

src/hypercall.rs

@@ -115,9 +115,20 @@ pub fn write(mem: &MmapMemory, syswrite: &WriteParams) -> io::Result<()> {
 	let mut bytes_written: usize = 0;
 	while bytes_written != syswrite.len {
 		unsafe {
+			use std::io::{Error, ErrorKind};
+
+			use crate::mem::MemoryError;
 			let step = libc::write(
 				syswrite.fd,
-				mem.host_address(syswrite.buf + bytes_written).unwrap() as *const libc::c_void,
+				mem.host_address(syswrite.buf + bytes_written)
+					.map_err(|e| match e {
+						MemoryError::BoundsViolation => {
+							unreachable!("Bounds violation after host_address function")
+						}
+						MemoryError::WrongMemoryError => {
+							Error::new(ErrorKind::AddrNotAvailable, e.to_string())
+						}
+					})? as *const libc::c_void,
 				syswrite.len - bytes_written,
 			);
 			if step >= 0 {

src/linux/mod.rs

@@ -124,7 +124,8 @@ impl UhyveVm<KvmCpu> {
 						}
 						Err(err) => {
 							error!("CPU {} crashed with {:?}", cpu_id, err);
-							None
+							barrier.wait();
+							Some(err.errno())
 						}
 					}
 				})
@@ -142,12 +143,11 @@ impl UhyveVm<KvmCpu> {
 			.into_iter()
 			.filter_map(|thread| thread.join().unwrap())
 			.collect::<Vec<_>>();
-		assert_eq!(
-			1,
-			code.len(),
-			"more than one thread finished with an exit code"
-		);
-		code[0]
+		match code.len() {
+			0 => panic!("No return code from any CPU? Maybe all have been kicked?"),
+			1 => code[0],
+			_ => panic!("more than one thread finished with an exit code (codes: {code:?})"),
+		}
 	}
 
 	fn run_gdb(self, cpu_affinity: Option<Vec<CoreId>>) -> i32 {

src/linux/x86_64/kvm_cpu.rs

@@ -14,7 +14,7 @@ use crate::{
 	vcpu::{VcpuStopReason, VirtualCPU},
 	virtio::*,
 	vm::UhyveVm,
-	HypervisorResult,
+	HypervisorError, HypervisorResult,
 };
 
 const CPUID_EXT_HYPERVISOR: u32 = 1 << 31;
@@ -425,7 +425,8 @@ impl VirtualCPU for KvmCpu {
 									hypercall::read(&self.parent_vm.mem, sysread)
 								}
 								Hypercall::FileWrite(syswrite) => {
-									hypercall::write(&self.parent_vm.mem, syswrite)?
+									hypercall::write(&self.parent_vm.mem, syswrite)
+										.map_err(|_e| HypervisorError::new(libc::EFAULT))?
 								}
 								Hypercall::FileUnlink(sysunlink) => {
 									hypercall::unlink(&self.parent_vm.mem, sysunlink)