vfio-pci: skip reset during cpr

Do not reset a vfio-pci device during CPR, and do not complain if the
kernel's PCI config space changes for non-emulated bits between the
vmstate save and load, which can happen due to ongoing interrupt activity.

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Link: https://lore.kernel.org/qemu-devel/1749569991-25171-12-git-send-email-steven.sistare@oracle.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>

1 files changed, 31 insertions, 0 deletions

diff --git a/hw/vfio/cpr.c b/hw/vfio/cpr.c
index 0e59612228..fdbb58e203 100644
--- a/hw/vfio/cpr.c
+++ b/hw/vfio/cpr.c
@@ -8,6 +8,8 @@
 #include "qemu/osdep.h"
 #include "hw/vfio/vfio-device.h"
 #include "hw/vfio/vfio-cpr.h"
+#include "hw/vfio/pci.h"
+#include "migration/cpr.h"
 #include "qapi/error.h"
 #include "system/runstate.h"
 
@@ -37,3 +39,32 @@ void vfio_cpr_unregister_container(VFIOContainerBase *bcontainer)
 {
     migration_remove_notifier(&bcontainer->cpr_reboot_notifier);
 }
+
+/*
+ * The kernel may change non-emulated config bits.  Exclude them from the
+ * changed-bits check in get_pci_config_device.
+ */
+static int vfio_cpr_pci_pre_load(void *opaque)
+{
+    VFIOPCIDevice *vdev = opaque;
+    PCIDevice *pdev = &vdev->pdev;
+    int size = MIN(pci_config_size(pdev), vdev->config_size);
+    int i;
+
+    for (i = 0; i < size; i++) {
+        pdev->cmask[i] &= vdev->emulated_config_bits[i];
+    }
+
+    return 0;
+}
+
+const VMStateDescription vfio_cpr_pci_vmstate = {
+    .name = "vfio-cpr-pci",
+    .version_id = 0,
+    .minimum_version_id = 0,
+    .pre_load = vfio_cpr_pci_pre_load,
+    .needed = cpr_incoming_needed,
+    .fields = (VMStateField[]) {
+        VMSTATE_END_OF_LIST()
+    }
+};