Do not reset a vfio-pci device during CPR.

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
---
 hw/pci/pci.c         | 5 +++++
 hw/vfio/pci.c        | 7 +++++++
 include/hw/pci/pci.h | 2 ++
 3 files changed, 14 insertions(+)

diff --git a/hw/pci/pci.c b/hw/pci/pci.c
index 9b4bf48..c70b5ce 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/cpr.h"
 #include "migration/qemu-file-types.h"
 #include "migration/vmstate.h"
 #include "net/net.h"
@@ -537,6 +538,10 @@ static void pci_reset_regions(PCIDevice *dev)
 
 static void pci_do_device_reset(PCIDevice *dev)
 {
+    if ((dev->cap_present & QEMU_PCI_SKIP_RESET_ON_CPR) && cpr_is_incoming()) {
+        return;
+    }
+
     pci_device_deassert_intx(dev);
     assert(dev->irq_state == 0);
 
diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index b1250d8..4cd92c3 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -3408,6 +3408,13 @@ static void vfio_instance_init(Object *obj)
     /* QEMU_PCI_CAP_EXPRESS initialization does not depend on QEMU command
      * line, therefore, no need to wait to realize like other devices */
     pci_dev->cap_present |= QEMU_PCI_CAP_EXPRESS;
+
+    /*
+     * A device that is resuming for cpr is already configured, so do not
+     * reset it during qemu_system_reset prior to cpr load, else interrupts
+     * may be lost.
+     */
+    pci_dev->cap_present |= QEMU_PCI_SKIP_RESET_ON_CPR;
 }
 
 static void vfio_pci_base_dev_class_init(ObjectClass *klass, const void *data)
diff --git a/include/hw/pci/pci.h b/include/hw/pci/pci.h
index 35d59d7..df3cc7b 100644
--- a/include/hw/pci/pci.h
+++ b/include/hw/pci/pci.h
@@ -222,6 +222,8 @@ enum {
     QEMU_PCIE_EXT_TAG = (1 << QEMU_PCIE_EXT_TAG_BITNR),
 #define QEMU_PCI_CAP_PM_BITNR 14
     QEMU_PCI_CAP_PM = (1 << QEMU_PCI_CAP_PM_BITNR),
+#define QEMU_PCI_SKIP_RESET_ON_CPR_BITNR 15
+    QEMU_PCI_SKIP_RESET_ON_CPR = (1 << QEMU_PCI_SKIP_RESET_ON_CPR_BITNR),
 };
 
 typedef struct PCIINTxRoute {
-- 
1.8.3.1

On Tue, Jun 10, 2025 at 10:26:43AM -0700, Steve Sistare wrote:
> Do not reset a vfio-pci device during CPR.
> 
> Signed-off-by: Steve Sistare <steven.sistare@oracle.com>

Acked-by: Michael S. Tsirkin <mst@redhat.com>


> ---
>  hw/pci/pci.c         | 5 +++++
>  hw/vfio/pci.c        | 7 +++++++
>  include/hw/pci/pci.h | 2 ++
>  3 files changed, 14 insertions(+)
> 
> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> index 9b4bf48..c70b5ce 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/cpr.h"
>  #include "migration/qemu-file-types.h"
>  #include "migration/vmstate.h"
>  #include "net/net.h"
> @@ -537,6 +538,10 @@ static void pci_reset_regions(PCIDevice *dev)
>  
>  static void pci_do_device_reset(PCIDevice *dev)
>  {
> +    if ((dev->cap_present & QEMU_PCI_SKIP_RESET_ON_CPR) && cpr_is_incoming()) {
> +        return;
> +    }
> +
>      pci_device_deassert_intx(dev);
>      assert(dev->irq_state == 0);
>  
> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
> index b1250d8..4cd92c3 100644
> --- a/hw/vfio/pci.c
> +++ b/hw/vfio/pci.c
> @@ -3408,6 +3408,13 @@ static void vfio_instance_init(Object *obj)
>      /* QEMU_PCI_CAP_EXPRESS initialization does not depend on QEMU command
>       * line, therefore, no need to wait to realize like other devices */
>      pci_dev->cap_present |= QEMU_PCI_CAP_EXPRESS;
> +
> +    /*
> +     * A device that is resuming for cpr is already configured, so do not
> +     * reset it during qemu_system_reset prior to cpr load, else interrupts
> +     * may be lost.
> +     */
> +    pci_dev->cap_present |= QEMU_PCI_SKIP_RESET_ON_CPR;
>  }
>  
>  static void vfio_pci_base_dev_class_init(ObjectClass *klass, const void *data)
> diff --git a/include/hw/pci/pci.h b/include/hw/pci/pci.h
> index 35d59d7..df3cc7b 100644
> --- a/include/hw/pci/pci.h
> +++ b/include/hw/pci/pci.h
> @@ -222,6 +222,8 @@ enum {
>      QEMU_PCIE_EXT_TAG = (1 << QEMU_PCIE_EXT_TAG_BITNR),
>  #define QEMU_PCI_CAP_PM_BITNR 14
>      QEMU_PCI_CAP_PM = (1 << QEMU_PCI_CAP_PM_BITNR),
> +#define QEMU_PCI_SKIP_RESET_ON_CPR_BITNR 15
> +    QEMU_PCI_SKIP_RESET_ON_CPR = (1 << QEMU_PCI_SKIP_RESET_ON_CPR_BITNR),
>  };
>  
>  typedef struct PCIINTxRoute {
> -- 
> 1.8.3.1