[V1,08/26] pci: skip reset during cpr

Commit Message

Steven Sistare Jan. 29, 2025, 2:43 p.m. UTC

Do not reset a vfio-pci device during CPR.

Signed-off-by: Steve Sistare <[e-mail]>
---
 hw/pci/pci.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

Patch

diff --git a/hw/pci/pci.c b/hw/pci/pci.c
index 2afa423..16b4f71 100644
--- a/hw/pci/pci.c
+++ b/hw/pci/pci.c
@@ -32,6 +32,7 @@ 
 #include "hw/pci/pci_host.h"
 #include "hw/qdev-properties.h"
 #include "hw/qdev-properties-system.h"
+#include "migration/misc.h"
 #include "migration/qemu-file-types.h"
 #include "migration/vmstate.h"
 #include "net/net.h"
@@ -459,6 +460,18 @@  static void pci_reset_regions(PCIDevice *dev)
 
 static void pci_do_device_reset(PCIDevice *dev)
 {
+    /*
+     * A PCI device that is resuming for cpr is already configured, so do
+     * not reset it here when we are called from qemu_system_reset prior to
+     * cpr load, else interrupts may be lost for vfio-pci devices.  It is
+     * safe to skip this reset for all PCI devices, because cpr load will set
+     * all fields that would have been set here.
+     */
+    MigMode mode = migrate_mode();
+    if (mode == MIG_MODE_CPR_TRANSFER) {
+        return;
+    }
+
     pci_device_deassert_intx(dev);
     assert(dev->irq_state == 0);