[PATCH v2 4/4] accel/mshv: break the vCPU run loop on exit_request

["Doru Blânzeanu" <dblanzeanu@linux.microsoft.com>]

Ignored VM exits can cause mshv_cpu_exec() to re-enter MSHV_RUN_VP
without returning to qemu_process_cpu_events(). A busy vCPU may
prevent pause_all_vcpus() from completing.

Check exit_request before re-entering MSHV_RUN_VP and return
EXCP_INTERRUPT so pending stop requests can be processed.

Signed-off-by: Doru Blânzeanu <dblanzeanu@linux.microsoft.com>
---
 accel/mshv/mshv-all.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/accel/mshv/mshv-all.c b/accel/mshv/mshv-all.c
index afcb87b3b8..b7c1126fe0 100644
--- a/accel/mshv/mshv-all.c
+++ b/accel/mshv/mshv-all.c
@@ -780,6 +780,16 @@ static int mshv_cpu_exec(CPUState *cpu)
             cpu->vcpu_dirty = false;
         }
 
+        /*
+         * A kick/stop can't reliably break MSHV_RUN_VP out, so leave the run
+         * loop here too; otherwise a busy vCPU never reaches
+         * qemu_process_cpu_events() and pause_all_vcpus() hangs under the BQL.
+         */
+        if (cpu->stop || qatomic_load_acquire(&cpu->exit_request)) {
+            ret = EXCP_INTERRUPT;
+            break;
+        }
+
         ret = mshv_run_vcpu(mshv_state->vm, cpu, &mshv_msg, &exit_reason);
         if (ret < 0) {
             error_report("Failed to run on vcpu %d", cpu->cpu_index);
-- 
2.53.0