Propagate MemoryFault exit reason in KVM_RUN

Signed-off-by: Nikita Kalyazin <[email protected]>

src/ioctls/vcpu.rs

@@ -166,6 +166,12 @@ pub enum VcpuExit<'a> {
     X86Rdmsr(ReadMsrExit<'a>),
     /// Corresponds to KVM_EXIT_X86_WRMSR.
     X86Wrmsr(WriteMsrExit<'a>),
+    /// Corresponds to KVM_EXIT_MEMORY_FAULT.
+    MemoryFault(
+        u64, /* flags */
+        u64, /* gpa */
+        u64, /* size */
+    ),
     /// Corresponds to an exit reason that is unknown from the current version
     /// of the kvm-ioctls crate. Let the consumer decide about what to do with
     /// it.
@@ -1568,6 +1574,17 @@ impl VcpuFd {
                 KVM_EXIT_HYPERV => Ok(VcpuExit::Hyperv),
                 r => Ok(VcpuExit::Unsupported(r)),
             }
+        } else if ret == -1 && errno::Error::last() == errno::Error::new(libc::EFAULT) {
+            let run = self.kvm_run_ptr.as_mut_ref();
+            match run.exit_reason {
+                KVM_EXIT_MEMORY_FAULT => {
+                    // SAFETY: Safe because the exit_reason (which comes from the kernel) told us
+                    // which union field to use.
+                    let fault = unsafe { &mut run.__bindgen_anon_1.memory_fault };
+                    Ok(VcpuExit::MemoryFault(fault.flags, fault.gpa, fault.size))
+                }
+                _ => Err(errno::Error::last())
+            }
         } else {
             Err(errno::Error::last())
         }