hw/vfio/pci: Re-order pre-reset

We want the device in the D0 power state going into reset, but the
config write can enable the BARs in the address space, which are
then removed from the address space once we clear the memory enable
bit in the command register.  Re-order to clear the command bit
first, so the power state change doesn't enable the BARs.

Cc: Cédric Le Goater <clg@redhat.com>
Reviewed-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Link: https://lore.kernel.org/qemu-devel/20250225215237.3314011-6-alex.williamson@redhat.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>

diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index a8db19d8d2f9707693500493eb237c7362d35c06..c1cee280ae4bbfc5a479aa5d1f2290065667a677 100644 (file)
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -2410,6 +2410,15 @@ void vfio_pci_pre_reset(VFIOPCIDevice *vdev)
 
     vfio_disable_interrupts(vdev);
 
+    /*
+     * Stop any ongoing DMA by disconnecting I/O, MMIO, and bus master.
+     * Also put INTx Disable in known state.
+     */
+    cmd = vfio_pci_read_config(pdev, PCI_COMMAND, 2);
+    cmd &= ~(PCI_COMMAND_IO | PCI_COMMAND_MEMORY | PCI_COMMAND_MASTER |
+             PCI_COMMAND_INTX_DISABLE);
+    vfio_pci_write_config(pdev, PCI_COMMAND, cmd, 2);
+
     /* Make sure the device is in D0 */
     if (pdev->pm_cap) {
         uint16_t pmcsr;
@@ -2429,15 +2438,6 @@ void vfio_pci_pre_reset(VFIOPCIDevice *vdev)
             }
         }
     }
-
-    /*
-     * Stop any ongoing DMA by disconnecting I/O, MMIO, and bus master.
-     * Also put INTx Disable in known state.
-     */
-    cmd = vfio_pci_read_config(pdev, PCI_COMMAND, 2);
-    cmd &= ~(PCI_COMMAND_IO | PCI_COMMAND_MEMORY | PCI_COMMAND_MASTER |
-             PCI_COMMAND_INTX_DISABLE);
-    vfio_pci_write_config(pdev, PCI_COMMAND, cmd, 2);
 }
 
 void vfio_pci_post_reset(VFIOPCIDevice *vdev)