virt_mshv_vtl: Trace guest crash message

Cargo.lock

@@ -7978,6 +7978,7 @@ dependencies = [
  "bitvec",
  "build_rs_guest_arch",
  "cfg-if",
+ "cvm_tracing",
  "fs-err",
  "guestmem",
  "hcl",

openhcl/underhill_core/src/dispatch/mod.rs

@@ -737,7 +737,7 @@ impl LoadedVm {
     }
 
     fn notify_of_vtl_crash(&self, vtl_crash: VtlCrash) {
-        tracing::info!("Notifying the host of the guest system crash {vtl_crash:x?}");
+        tracelimit::info_ratelimited!("Notifying the host of the guest system crash");
 
         let VtlCrash {
             vp_index,

openhcl/virt_mshv_vtl/Cargo.toml

@@ -31,6 +31,7 @@ x86defs.workspace = true
 x86emu.workspace = true
 
 atomic_ringbuf.workspace = true
+cvm_tracing.workspace = true
 inspect_counters.workspace = true
 inspect = { workspace = true, features = ["std"] }
 mesh.workspace = true

openhcl/virt_mshv_vtl/src/processor/mod.rs

@@ -18,15 +18,16 @@ cfg_if::cfg_if! {
         use crate::VtlCrash;
         use bitvec::prelude::BitArray;
         use bitvec::prelude::Lsb0;
+        use cvm_tracing::CVM_CONFIDENTIAL;
         use hv1_emulator::synic::ProcessorSynic;
+        use hvdef::HvRegisterCrInterceptControl;
         use hvdef::HvX64RegisterName;
         use virt::vp::MpState;
         use virt::x86::MsrError;
         use virt_support_apic::LocalApic;
         use virt_support_x86emu::translate::TranslationRegisters;
         use virt::vp::AccessVpState;
         use zerocopy::IntoBytes;
-        use hvdef::HvRegisterCrInterceptControl;
     } else if #[cfg(guest_arch = "aarch64")] {
         use hv1_hypercall::Arm64RegisterState;
         use hvdef::HvArm64RegisterName;
@@ -1049,7 +1050,26 @@ impl<'a, T: Backing> UhProcessor<'a, T> {
                     control: self.crash_control,
                     parameters: self.crash_reg,
                 };
-                tracelimit::info_ratelimited!(?crash, "Guest has reported system crash");
+                tracelimit::warn_ratelimited!(?crash, "Guest has reported system crash");
+
+                if crash.control.crash_message() {
+                    let message_gpa = crash.parameters[3];
+                    let message_size = crash.parameters[4];
+                    let mut message = vec![0; message_size as usize];
+                    match self.partition.gm[vtl].read_at(message_gpa, &mut message) {
+                        Ok(()) => {
+                            let message = String::from_utf8_lossy(&message).into_owned();
+                            tracelimit::warn_ratelimited!(
+                                CVM_CONFIDENTIAL,
+                                message,
+                                "Guest has reported a system crash message"
+                            );
+                        }
+                        Err(e) => {
+                            tracelimit::warn_ratelimited!(?e, "Failed to read crash message");
+                        }
+                    }
+                }
 
                 self.partition.crash_notification_send.send(crash);
             }