[V1,11/26] vfio-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, 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 <[e-mail]>
---
 hw/vfio/pci.c | 37 +++++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

Patch

diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index 24ebd69..fa77c36 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -29,6 +29,8 @@ 
 #include "hw/pci/pci_bridge.h"
 #include "hw/qdev-properties.h"
 #include "hw/qdev-properties-system.h"
+#include "migration/misc.h"
+#include "migration/cpr.h"
 #include "migration/vmstate.h"
 #include "qapi/qmp/qdict.h"
 #include "qemu/error-report.h"
@@ -3324,6 +3326,11 @@  static void vfio_pci_reset(DeviceState *dev)
 {
     VFIOPCIDevice *vdev = VFIO_PCI(dev);
 
+    /* Do not reset the device during qemu_system_reset prior to cpr load */
+    if (vdev->vbasedev.reused) {
+        return;
+    }
+
     trace_vfio_pci_reset(vdev->vbasedev.name);
 
     vfio_pci_pre_reset(vdev);
@@ -3447,6 +3454,35 @@  static void vfio_pci_set_fd(Object *obj, const char *str, Error **errp)
 }
 #endif
 
+/*
+ * The kernel may change non-emulated config bits.  Exclude them from the
+ * changed-bits check in get_pci_config_device.
+ */
+static int vfio_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;
+}
+
+static const VMStateDescription vfio_pci_vmstate = {
+    .name = "vfio-pci",
+    .version_id = 0,
+    .minimum_version_id = 0,
+    .pre_load = vfio_pci_pre_load,
+    .needed = cpr_needed_for_reuse,
+    .fields = (VMStateField[]) {
+        VMSTATE_END_OF_LIST()
+    }
+};
+
 static void vfio_pci_dev_class_init(ObjectClass *klass, void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(klass);
@@ -3457,6 +3493,7 @@  static void vfio_pci_dev_class_init(ObjectClass *klass, void *data)
 #ifdef CONFIG_IOMMUFD
     object_class_property_add_str(klass, "fd", NULL, vfio_pci_set_fd);
 #endif
+    dc->vmsd = &vfio_pci_vmstate;
     dc->desc = "VFIO-based PCI device assignment";
     set_bit(DEVICE_CATEGORY_MISC, dc->categories);
     pdc->realize = vfio_realize;