On Mon, 14 Jul 2025 at 15:29, Steve Sistare <steven.sist...@oracle.com> wrote:
>
> Close a race condition that causes cpr-transfer to lose VFIO
> interrupts on ARM.
>
> CPR stops VCPUs but does not disable VFIO interrupts, which may continue
> to arrive throughout the transition to new QEMU.
>
> CPR calls kvm_irqchip_remove_irqfd_notifier_gsi in old QEMU to force
> future interrupts to the producer eventfd, where they are preserved.
> Old QEMU then destroys the old KVM instance. However, interrupts may
> already be pended in KVM state. To preserve them, call ioctl
> KVM_DEV_ARM_VGIC_SAVE_PENDING_TABLES to flush them to guest RAM, where
> they will be picked up when the new KVM+VCPU instance is created.
>
> Signed-off-by: Steve Sistare <steven.sist...@oracle.com>
> ---
> hw/intc/arm_gicv3_kvm.c | 16 +++++++++++++++-
> include/hw/intc/arm_gicv3_common.h | 3 +++
> 2 files changed, 18 insertions(+), 1 deletion(-)
>
> diff --git a/hw/intc/arm_gicv3_kvm.c b/hw/intc/arm_gicv3_kvm.c
> index 43cba6e3f1..15245af2fd 100644
> --- a/hw/intc/arm_gicv3_kvm.c
> +++ b/hw/intc/arm_gicv3_kvm.c
> @@ -30,6 +30,7 @@
> #include "gicv3_internal.h"
> #include "vgic_common.h"
> #include "migration/blocker.h"
> +#include "migration/misc.h"
> #include "qom/object.h"
> #include "target/arm/cpregs.h"
>
> @@ -783,6 +784,15 @@ static void vm_change_state_handler(void *opaque, bool
> running,
> }
> }
>
> +static int kvm_arm_gicv3_notifier(NotifierWithReturn *notifier,
> + MigrationEvent *e, Error **errp)
> +{
> + if (e->type == MIG_EVENT_PRECOPY_DONE) {
> + GICv3State *s = container_of(notifier, GICv3State, cpr_notifier);
> + kvm_arm_save_pending_tables(s);
This kvm_arm_gicv3_notifier() function reports an error via
an Error pointer, and the function we call inside
kvm_arm_save_pending_tables() can report errors via an
Error pointer. So I think kvm_arm_save_pending_tables()
should propagate the Error up, not ignore it.
(Or if there's a good reason we should silently ignore
the error here, we should have a comment saying why.)
> + }
> + return 0;
> +}
thanks
-- PMM
