Update kvm.c

kernel/entry/kvm.c

@@ -3,47 +3,68 @@
 #include <linux/entry-kvm.h>
 #include <linux/kvm_host.h>
 
+/**
+ * xfer_to_guest_mode_work - Handle work for transitioning to guest mode
+ * @vcpu: Pointer to the virtual CPU structure
+ * @ti_work: Thread flags indicating the state of the vCPU
+ *
+ * This function processes various flags that indicate work to be done
+ * when transitioning a virtual CPU to guest mode. It handles signals,
+ * rescheduling, and architecture-specific work.
+ *
+ * Returns: 0 on success, or a negative error code on failure.
+ */
 static int xfer_to_guest_mode_work(struct kvm_vcpu *vcpu, unsigned long ti_work)
 {
-	do {
-		int ret;
+    do {
+        int ret;
 
-		if (ti_work & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL)) {
-			kvm_handle_signal_exit(vcpu);
-			return -EINTR;
-		}
+        // Check for pending signals and handle them
+        if (ti_work & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL)) {
+            kvm_handle_signal_exit(vcpu);
+            return -EINTR; // Interrupted by a signal
+        }
 
-		if (ti_work & (_TIF_NEED_RESCHED | _TIF_NEED_RESCHED_LAZY))
-			schedule();
+        // Check if rescheduling is needed
+        if (ti_work & (_TIF_NEED_RESCHED | _TIF_NEED_RESCHED_LAZY))
+            schedule();
 
-		if (ti_work & _TIF_NOTIFY_RESUME)
-			resume_user_mode_work(NULL);
+        // Resume user mode work if notified
+        if (ti_work & _TIF_NOTIFY_RESUME)
+            resume_user_mode_work(NULL);
 
-		ret = arch_xfer_to_guest_mode_handle_work(vcpu, ti_work);
-		if (ret)
-			return ret;
+        // Handle architecture-specific work
+        ret = arch_xfer_to_guest_mode_handle_work(vcpu, ti_work);
+        if (ret)
+            return ret; // Return on error
 
-		ti_work = read_thread_flags();
-	} while (ti_work & XFER_TO_GUEST_MODE_WORK);
-	return 0;
+        // Read thread flags for the next iteration
+        ti_work = read_thread_flags();
+    } while (ti_work & XFER_TO_GUEST_MODE_WORK); // Continue if more work is pending
+
+    return 0; // Success
 }
 
+/**
+ * xfer_to_guest_mode_handle_work - Check and handle guest mode work
+ * @vcpu: Pointer to the virtual CPU structure
+ *
+ * This function checks if there is any work pending for the vCPU
+ * before invoking xfer_to_guest_mode_work. It ensures that the work
+ * is only processed if the relevant flags are set.
+ *
+ * Returns: 0 if no work is pending, or the result of
+ *          xfer_to_guest_mode_work on success.
+ */
 int xfer_to_guest_mode_handle_work(struct kvm_vcpu *vcpu)
 {
-	unsigned long ti_work;
-
-	/*
-	 * This is invoked from the outer guest loop with interrupts and
-	 * preemption enabled.
-	 *
-	 * KVM invokes xfer_to_guest_mode_work_pending() with interrupts
-	 * disabled in the inner loop before going into guest mode. No need
-	 * to disable interrupts here.
-	 */
-	ti_work = read_thread_flags();
-	if (!(ti_work & XFER_TO_GUEST_MODE_WORK))
-		return 0;
-
-	return xfer_to_guest_mode_work(vcpu, ti_work);
+    unsigned long ti_work;
+
+    // Read thread flags to check for pending work
+    ti_work = read_thread_flags();
+    if (!(ti_work & XFER_TO_GUEST_MODE_WORK))
+        return 0; // No work to do
+
+    return xfer_to_guest_mode_work(vcpu, ti_work); // Delegate to work function
 }
 EXPORT_SYMBOL_GPL(xfer_to_guest_mode_handle_work);