xics: Write source state to KVM at claim time

The pseries machine only uses LSIs to support legacy PCI devices. Every
PHB claims 4 LSIs at realize time. When using in-kernel XICS (or upcoming
in-kernel XIVE), QEMU synchronizes the state of all irqs, including these
LSIs, later on at machine reset.

In order to support PHB hotplug, we need a way to tell KVM about the LSIs
that doesn't require a machine reset. An easy way to do that is to always
inform KVM when an interrupt is claimed, which really isn't a performance
path.

Signed-off-by: Greg Kurz <groug@kaod.org>
Message-Id: <155059668360.1466090.5969630516627776426.stgit@bahia.lab.toulouse-stg.fr.ibm.com>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

2 files changed, 47 insertions, 31 deletions

diff --git a/hw/intc/xics.c b/hw/intc/xics.c
index 767fdeb829..af7dc709ab 100644
--- a/hw/intc/xics.c
+++ b/hw/intc/xics.c
@@ -758,6 +758,10 @@ void ics_set_irq_type(ICSState *ics, int srcno, bool lsi)
 
     ics->irqs[srcno].flags |=
         lsi ? XICS_FLAGS_IRQ_LSI : XICS_FLAGS_IRQ_MSI;
+
+    if (kvm_irqchip_in_kernel()) {
+        ics_set_kvm_state_one(ics, srcno);
+    }
 }
 
 static void xics_register_types(void)
diff --git a/hw/intc/xics_kvm.c b/hw/intc/xics_kvm.c
index a00d0a7962..c6e1b630a4 100644
--- a/hw/intc/xics_kvm.c
+++ b/hw/intc/xics_kvm.c
@@ -213,45 +213,57 @@ void ics_synchronize_state(ICSState *ics)
     ics_get_kvm_state(ics);
 }
 
-int ics_set_kvm_state(ICSState *ics)
+int ics_set_kvm_state_one(ICSState *ics, int srcno)
 {
     uint64_t state;
-    int i;
     Error *local_err = NULL;
+    ICSIRQState *irq = &ics->irqs[srcno];
+    int ret;
 
-    for (i = 0; i < ics->nr_irqs; i++) {
-        ICSIRQState *irq = &ics->irqs[i];
-        int ret;
-
-        state = irq->server;
-        state |= (uint64_t)(irq->saved_priority & KVM_XICS_PRIORITY_MASK)
-            << KVM_XICS_PRIORITY_SHIFT;
-        if (irq->priority != irq->saved_priority) {
-            assert(irq->priority == 0xff);
-            state |= KVM_XICS_MASKED;
-        }
+    state = irq->server;
+    state |= (uint64_t)(irq->saved_priority & KVM_XICS_PRIORITY_MASK)
+        << KVM_XICS_PRIORITY_SHIFT;
+    if (irq->priority != irq->saved_priority) {
+        assert(irq->priority == 0xff);
+        state |= KVM_XICS_MASKED;
+    }
 
-        if (ics->irqs[i].flags & XICS_FLAGS_IRQ_LSI) {
-            state |= KVM_XICS_LEVEL_SENSITIVE;
-            if (irq->status & XICS_STATUS_ASSERTED) {
-                state |= KVM_XICS_PENDING;
-            }
-        } else {
-            if (irq->status & XICS_STATUS_MASKED_PENDING) {
-                state |= KVM_XICS_PENDING;
-            }
+    if (irq->flags & XICS_FLAGS_IRQ_LSI) {
+        state |= KVM_XICS_LEVEL_SENSITIVE;
+        if (irq->status & XICS_STATUS_ASSERTED) {
+            state |= KVM_XICS_PENDING;
         }
-        if (irq->status & XICS_STATUS_PRESENTED) {
-                state |= KVM_XICS_PRESENTED;
-        }
-        if (irq->status & XICS_STATUS_QUEUED) {
-                state |= KVM_XICS_QUEUED;
+    } else {
+        if (irq->status & XICS_STATUS_MASKED_PENDING) {
+            state |= KVM_XICS_PENDING;
         }
+    }
+    if (irq->status & XICS_STATUS_PRESENTED) {
+        state |= KVM_XICS_PRESENTED;
+    }
+    if (irq->status & XICS_STATUS_QUEUED) {
+        state |= KVM_XICS_QUEUED;
+    }
+
+    ret = kvm_device_access(kernel_xics_fd, KVM_DEV_XICS_GRP_SOURCES,
+                            srcno + ics->offset, &state, true, &local_err);
+    if (local_err) {
+        error_report_err(local_err);
+        return ret;
+    }
+
+    return 0;
+}
+
+int ics_set_kvm_state(ICSState *ics)
+{
+    int i;
+
+    for (i = 0; i < ics->nr_irqs; i++) {
+        int ret;
 
-        ret = kvm_device_access(kernel_xics_fd, KVM_DEV_XICS_GRP_SOURCES,
-                                i + ics->offset, &state, true, &local_err);
-        if (local_err) {
-            error_report_err(local_err);
+        ret = ics_set_kvm_state_one(ics, i);
+        if (ret) {
             return ret;
         }
     }