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[Qemu-ppc] [PATCH v2 05/13] spapr/xive: introduce a VM state change hand
From: |
Cédric Le Goater |
Subject: |
[Qemu-ppc] [PATCH v2 05/13] spapr/xive: introduce a VM state change handler |
Date: |
Fri, 22 Feb 2019 14:13:14 +0100 |
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 <address@hidden>
---
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;
--
2.20.1
- [Qemu-ppc] [PATCH v2 00/13] spapr: add KVM support to the XIVE interrupt mode, Cédric Le Goater, 2019/02/22
- [Qemu-ppc] [PATCH v2 04/13] spapr/xive: add state synchronization with KVM, Cédric Le Goater, 2019/02/22
- [Qemu-ppc] [PATCH v2 05/13] spapr/xive: introduce a VM state change handler,
Cédric Le Goater <=
- [Qemu-ppc] [PATCH v2 07/13] spapr/xive: fix migration of the XiveTCTX under TCG, Cédric Le Goater, 2019/02/22
- [Qemu-ppc] [PATCH v2 11/13] spapr: check for the activation of the KVM IRQ device, Cédric Le Goater, 2019/02/22
- [Qemu-ppc] [PATCH v2 12/13] spapr: add KVM support to the 'dual' machine, Cédric Le Goater, 2019/02/22
- [Qemu-ppc] [PATCH v2 10/13] spapr: introduce routines to delete the KVM IRQ device, Cédric Le Goater, 2019/02/22
- [Qemu-ppc] [PATCH v2 02/13] spapr/xive: add hcall support when under KVM, Cédric Le Goater, 2019/02/22