Re: [PATCH V1 11/26] vfio-pci: skip reset during cpr

2025-02-04 Thread Steven Sistare 

On 2/4/2025 9:56 AM, Cédric Le Goater wrote:

On 1/29/25 15:43, Steve Sistare wrote:

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 
---
  hw/vfio/pci.c | 37 +
  1 file changed, 37 insertions(+)

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;
+    }
+


sometime we use :

     MigMode mode = migrate_mode();
     if (mode == MIG_MODE_CPR_TRANSFER) {
     return;
     }

Why is this different ? This is confusing.


I try to use local state -- object's knowledge about themselves -- whenever 
possible.
Sometimes that is less desirable.  For example, in pci_do_device_reset I test 
mode, rather
than add a reused field to the generic PCIDevice, because the pci code would 
not use the
reused field anywhere else.

- Steve


  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;

Re: [PATCH V1 11/26] vfio-pci: skip reset during cpr

2025-02-04 Thread Cédric Le Goater 

On 1/29/25 15:43, Steve Sistare wrote:

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 
---
  hw/vfio/pci.c | 37 +
  1 file changed, 37 insertions(+)

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;
+}
+


sometime we use :

MigMode mode = migrate_mode();
if (mode == MIG_MODE_CPR_TRANSFER) {
return;
}

Why is this different ? This is confusing.


Thanks,

C.




  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;

[PATCH V1 11/26] vfio-pci: skip reset during cpr

2025-01-29 Thread Steve Sistare 
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 
---
 hw/vfio/pci.c | 37 +
 1 file changed, 37 insertions(+)

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;
-- 
1.8.3.1