[RFC QEMU PATCH v9 1/2] virtio-pci: only reset pm state during resetting

[Jiqian Chen <Jiqian.Chen@amd.com>]

Fix bug imported by 27ce0f3afc9dd25d21b43bbce505157afd93d111
(fix Power Management Control Register for PCI Express virtio devices)

Only state of PM_CTRL is writable.
Only when flag VIRTIO_PCI_FLAG_INIT_PM is set, need to reset state.

Signed-off-by: Jiqian Chen <Jiqian.Chen@amd.com>
---
 hw/virtio/virtio-pci.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
index cb159fd0785c..a1b61308e7a0 100644
--- a/hw/virtio/virtio-pci.c
+++ b/hw/virtio/virtio-pci.c
@@ -2300,10 +2300,16 @@ static void virtio_pci_bus_reset_hold(Object *obj)
     virtio_pci_reset(qdev);
 
     if (pci_is_express(dev)) {
+        VirtIOPCIProxy *proxy = VIRTIO_PCI(dev);
+
         pcie_cap_deverr_reset(dev);
         pcie_cap_lnkctl_reset(dev);
 
-        pci_set_word(dev->config + dev->exp.pm_cap + PCI_PM_CTRL, 0);
+        if (proxy->flags & VIRTIO_PCI_FLAG_INIT_PM) {
+            pci_word_test_and_clear_mask(
+                dev->config + dev->exp.pm_cap + PCI_PM_CTRL,
+                PCI_PM_CTRL_STATE_MASK);
+        }
     }
 }
 
-- 
2.34.1