On Fri, Feb 22, 2019 at 02:13:14PM +0100, Cédric Le Goater wrote: > This handler is in charge of stabilizing the flow of event notifications > in the XIVE controller before migrating a guest. This is a requirement > before transferring the guest EQ pages to a destination. > > When the VM is stopped, the handler masks the sources (PQ=01) to stop > the flow of events and saves their previous state. The XIVE controller > is then synced through KVM to flush any in-flight event notification > and to stabilize the EQs. At this stage, the EQ pages are marked dirty > to make sure the EQ pages are transferred if a migration sequence is > in progress. > > The previous configuration of the sources is restored when the VM > resumes, after a migration or a stop. > > Signed-off-by: Cédric Le Goater <c...@kaod.org>
Reviewed-by: David Gibson <da...@gibson.dropbear.id.au>
> ---
> include/hw/ppc/spapr_xive.h | 1 +
> hw/intc/spapr_xive_kvm.c | 77 ++++++++++++++++++++++++++++++++++++-
> 2 files changed, 77 insertions(+), 1 deletion(-)
>
> diff --git a/include/hw/ppc/spapr_xive.h b/include/hw/ppc/spapr_xive.h
> index ebd65e7fe36b..298d204d54ef 100644
> --- a/include/hw/ppc/spapr_xive.h
> +++ b/include/hw/ppc/spapr_xive.h
> @@ -42,6 +42,7 @@ typedef struct sPAPRXive {
> /* KVM support */
> int fd;
> void *tm_mmap;
> + VMChangeStateEntry *change;
> } sPAPRXive;
>
> /*
> diff --git a/hw/intc/spapr_xive_kvm.c b/hw/intc/spapr_xive_kvm.c
> index 4b1ffb9835f9..44d80175b1b5 100644
> --- a/hw/intc/spapr_xive_kvm.c
> +++ b/hw/intc/spapr_xive_kvm.c
> @@ -419,9 +419,81 @@ static void kvmppc_xive_get_queues(sPAPRXive *xive,
> Error **errp)
> }
> }
>
> +/*
> + * The primary goal of the XIVE VM change handler is to mark the EQ
> + * pages dirty when all XIVE event notifications have stopped.
> + *
> + * Whenever the VM is stopped, the VM change handler masks the sources
> + * (PQ=01) to stop the flow of events and saves the previous state in
> + * anticipation of a migration. The XIVE controller is then synced
> + * through KVM to flush any in-flight event notification and stabilize
> + * the EQs.
> + *
> + * At this stage, we can mark the EQ page dirty and let a migration
> + * sequence transfer the EQ pages to the destination, which is done
> + * just after the stop state.
> + *
> + * The previous configuration of the sources is restored when the VM
> + * runs again.
> + */
> +static void kvmppc_xive_change_state_handler(void *opaque, int running,
> + RunState state)
> +{
> + sPAPRXive *xive = opaque;
> + XiveSource *xsrc = &xive->source;
> + Error *local_err = NULL;
> + int i;
> +
> + /*
> + * Restore the sources to their initial state. This is called when
> + * the VM resumes after a stop or a migration.
> + */
> + if (running) {
> + for (i = 0; i < xsrc->nr_irqs; i++) {
> + uint8_t pq = xive_source_esb_get(xsrc, i);
> + if (xive_esb_read(xsrc, i, XIVE_ESB_SET_PQ_00 + (pq << 8)) !=
> 0x1) {
> + error_report("XIVE: IRQ %d has an invalid state", i);
> + }
> + }
> +
> + return;
> + }
> +
> + /*
> + * Mask the sources, to stop the flow of event notifications, and
> + * save the PQs locally in the XiveSource object. The XiveSource
> + * state will be collected later on by its vmstate handler if a
> + * migration is in progress.
> + */
> + for (i = 0; i < xsrc->nr_irqs; i++) {
> + uint8_t pq = xive_esb_read(xsrc, i, XIVE_ESB_SET_PQ_01);
> + xive_source_esb_set(xsrc, i, pq);
> + }
> +
> + /*
> + * Sync the XIVE controller in KVM, to flush in-flight event
> + * notification that should be enqueued in the EQs and mark the
> + * XIVE EQ pages dirty to collect all updates.
> + */
> + kvm_device_access(xive->fd, KVM_DEV_XIVE_GRP_CTRL,
> + KVM_DEV_XIVE_EQ_SYNC, NULL, true, &local_err);
> + if (local_err) {
> + error_report_err(local_err);
> + return;
> + }
> +}
> +
> void kvmppc_xive_synchronize_state(sPAPRXive *xive, Error **errp)
> {
> - kvmppc_xive_source_get_state(&xive->source);
> + /*
> + * When the VM is stopped, the sources are masked and the previous
> + * state is saved in anticipation of a migration. We should not
> + * synchronize the source state in that case else we will override
> + * the saved state.
> + */
> + if (runstate_is_running()) {
> + kvmppc_xive_source_get_state(&xive->source);
> + }
>
> /* EAT: there is no extra state to query from KVM */
>
> @@ -501,6 +573,9 @@ void kvmppc_xive_connect(sPAPRXive *xive, Error **errp)
> "xive.tima", tima_len, xive->tm_mmap);
> sysbus_init_mmio(SYS_BUS_DEVICE(xive), &xive->tm_mmio);
>
> + xive->change = qemu_add_vm_change_state_handler(
> + kvmppc_xive_change_state_handler, xive);
> +
> kvm_kernel_irqchip = true;
> kvm_msi_via_irqfd_allowed = true;
> kvm_gsi_direct_mapping = true;
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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