[Qemu-devel] [PATCH v3 4/4] ivshmem: Disable irqfd on device reset

[Ladi Prosek <lprosek@redhat.com>]

The effects of ivshmem_enable_irqfd() was not undone on device reset.

This manifested as:
ivshmem_add_kvm_msi_virq: Assertion `!s->msi_vectors[vector].pdev' failed.

when irqfd was enabled before reset and then enabled again after reset, making
ivshmem_enable_irqfd() run for the second time.

To reproduce, run:

  ivshmem-server

and QEMU with:

  -device ivshmem-doorbell,chardev=iv
  -chardev socket,path=/tmp/ivshmem_socket,id=iv

then install the Windows driver, at the time of writing available at:

https://github.com/virtio-win/kvm-guest-drivers-windows/tree/master/ivshmem

and crash-reboot the guest by inducing a BSOD.

Signed-off-by: Ladi Prosek <lprosek@redhat.com>
---
 hw/misc/ivshmem.c | 24 +++++++++++++-----------
 1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/hw/misc/ivshmem.c b/hw/misc/ivshmem.c
index d1bb246d12..4be0d2627b 100644
--- a/hw/misc/ivshmem.c
+++ b/hw/misc/ivshmem.c
@@ -758,17 +758,6 @@ static void ivshmem_msix_vector_use(IVShmemState *s)
     }
 }
 
-static void ivshmem_reset(DeviceState *d)
-{
-    IVShmemState *s = IVSHMEM_COMMON(d);
-
-    s->intrstatus = 0;
-    s->intrmask = 0;
-    if (ivshmem_has_feature(s, IVSHMEM_MSI)) {
-        ivshmem_msix_vector_use(s);
-    }
-}
-
 static int ivshmem_setup_interrupts(IVShmemState *s, Error **errp)
 {
     /* allocate QEMU callback data for receiving interrupts */
@@ -855,6 +844,19 @@ static void ivshmem_disable_irqfd(IVShmemState *s)
 
 }
 
+static void ivshmem_reset(DeviceState *d)
+{
+    IVShmemState *s = IVSHMEM_COMMON(d);
+
+    ivshmem_disable_irqfd(s);
+
+    s->intrstatus = 0;
+    s->intrmask = 0;
+    if (ivshmem_has_feature(s, IVSHMEM_MSI)) {
+        ivshmem_msix_vector_use(s);
+    }
+}
+
 static void ivshmem_write_config(PCIDevice *pdev, uint32_t address,
                                  uint32_t val, int len)
 {
-- 
2.13.6