On Sun, Jun 01, 2025 at 06:38:43PM +0200, Cédric Le Goater wrote:
> On 5/29/25 21:24, Steve Sistare wrote:
> > Do not reset a vfio-pci device during CPR.
> >
> > Signed-off-by: Steve Sistare <steven.sist...@oracle.com>
> > ---
> > include/hw/pci/pci_device.h | 3 +++
> > hw/pci/pci.c | 5 +++++
> > hw/vfio/pci.c | 7 +++++++
> > 3 files changed, 15 insertions(+)
> >
> > diff --git a/include/hw/pci/pci_device.h b/include/hw/pci/pci_device.h
> > index e41d95b..b481c5d 100644
> > --- a/include/hw/pci/pci_device.h
> > +++ b/include/hw/pci/pci_device.h
> > @@ -181,6 +181,9 @@ struct PCIDevice {
> > uint32_t max_bounce_buffer_size;
> > char *sriov_pf;
> > +
> > + /* CPR */
> > + bool skip_reset_on_cpr;
> > };
> > static inline int pci_intx(PCIDevice *pci_dev)
> > diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> > index f5ab510..21eb11c 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"
> > @@ -531,6 +532,10 @@ static void pci_reset_regions(PCIDevice *dev)
> > static void pci_do_device_reset(PCIDevice *dev)
> > {
> > + if (dev->skip_reset_on_cpr && cpr_is_incoming()) {
> > + return;
> > + }
>
> Since ->skip_reset_on_cpr is only true for vfio-pci devices, it could be
> replaced by : object_dynamic_cast(OBJECT(dev), "vfio-pci")
>
> Thanks,
>
> C.
True but I don't really like driver dependent hacks.
what exactly about vfio makes it survive without this reset?
>
> > +
> > pci_device_deassert_intx(dev);
> > assert(dev->irq_state == 0);
> > diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
> > index 7d3b9ff..56e7fdd 100644
> > --- a/hw/vfio/pci.c
> > +++ b/hw/vfio/pci.c
> > @@ -3402,6 +3402,13 @@ 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->skip_reset_on_cpr = true;
> > }> static void vfio_pci_base_dev_class_init(ObjectClass *klass,
> > const void *data)
