From e6cc364703b464f6662e30e1fab8c4f9b5202962 Mon Sep 17 00:00:00 2001
From: Rob Bradford <robert.bradford@intel.com>
Date: Thu, 21 Apr 2022 10:12:56 +0100
Subject: [PATCH] virtio-devices: mem: Reject resize if device not activated by
 guest

If the guest has not activated the virtio-mem device then reject an
attempt to resize using it.

Fixes: #4001

Signed-off-by: Rob Bradford <robert.bradford@intel.com>
(cherry picked from commit c274ce4d4922a19cd64a9fba63987707d5c5a23a)
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
---
 virtio-devices/src/mem.rs | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/virtio-devices/src/mem.rs b/virtio-devices/src/mem.rs
index cf7167651..3f5e6d7db 100644
--- a/virtio-devices/src/mem.rs
+++ b/virtio-devices/src/mem.rs
@@ -137,6 +137,8 @@ pub enum Error {
     DmaUnmap(std::io::Error),
     // Invalid DMA mapping handler
     InvalidDmaMappingHandler,
+    // Not activated by the guest
+    NotActivatedByGuest,
 }
 
 #[repr(C)]
@@ -327,6 +329,7 @@ impl Request {
 
 pub struct ResizeSender {
     hotplugged_size: Arc<AtomicU64>,
+    activated: Arc<AtomicBool>,
     tx: mpsc::Sender<Result<(), Error>>,
     evt: EventFd,
 }
@@ -345,6 +348,7 @@ impl Clone for ResizeSender {
     fn clone(&self) -> Self {
         ResizeSender {
             hotplugged_size: self.hotplugged_size.clone(),
+            activated: self.activated.clone(),
             tx: self.tx.clone(),
             evt: self
                 .evt
@@ -356,6 +360,7 @@ impl Clone for ResizeSender {
 
 pub struct Resize {
     hotplugged_size: Arc<AtomicU64>,
+    activated: Arc<AtomicBool>,
     tx: mpsc::Sender<Result<(), Error>>,
     rx: mpsc::Receiver<Result<(), Error>>,
     evt: EventFd,
@@ -367,6 +372,7 @@ impl Resize {
 
         Ok(Resize {
             hotplugged_size: Arc::new(AtomicU64::new(hotplugged_size)),
+            activated: Arc::new(AtomicBool::default()),
             tx,
             rx,
             evt: EventFd::new(EFD_NONBLOCK)?,
@@ -376,12 +382,17 @@ impl Resize {
     pub fn new_resize_sender(&self) -> Result<ResizeSender, Error> {
         Ok(ResizeSender {
             hotplugged_size: self.hotplugged_size.clone(),
+            activated: self.activated.clone(),
             tx: self.tx.clone(),
             evt: self.evt.try_clone().map_err(Error::EventFdTryCloneFail)?,
         })
     }
 
     pub fn work(&self, desired_size: u64) -> Result<(), Error> {
+        if !self.activated.load(Ordering::Acquire) {
+            return Err(Error::NotActivatedByGuest);
+        }
+
         self.hotplugged_size.store(desired_size, Ordering::Release);
         self.evt.write(1).map_err(Error::EventFdWriteFail)?;
         self.rx.recv().map_err(Error::MpscRecvFail)?
@@ -1046,11 +1057,14 @@ impl VirtioDevice for Mem {
         )?;
         self.common.epoll_threads = Some(epoll_threads);
 
+        self.resize.activated.store(true, Ordering::Release);
+
         event!("virtio-device", "activated", "id", &self.id);
         Ok(())
     }
 
     fn reset(&mut self) -> Option<Arc<dyn VirtioInterrupt>> {
+        self.resize.activated.store(false, Ordering::Release);
         let result = self.common.reset();
         event!("virtio-device", "reset", "id", &self.id);
         result