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[Qemu-devel] [PULL 34/50] xics: Write source state to KVM at claim time


From: David Gibson
Subject: [Qemu-devel] [PULL 34/50] xics: Write source state to KVM at claim time
Date: Tue, 26 Feb 2019 15:52:48 +1100

From: Greg Kurz <address@hidden>

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 <address@hidden>
Message-Id: <address@hidden>
Reviewed-by: C├ędric Le Goater <address@hidden>
Signed-off-by: David Gibson <address@hidden>
---
 hw/intc/xics.c        |  4 +++
 hw/intc/xics_kvm.c    | 74 +++++++++++++++++++++++++------------------
 include/hw/ppc/xics.h |  1 +
 3 files changed, 48 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;
         }
     }
diff --git a/include/hw/ppc/xics.h b/include/hw/ppc/xics.h
index d36bbe11ee..eb65ad7e43 100644
--- a/include/hw/ppc/xics.h
+++ b/include/hw/ppc/xics.h
@@ -195,6 +195,7 @@ void icp_synchronize_state(ICPState *icp);
 void icp_kvm_realize(DeviceState *dev, Error **errp);
 
 void ics_get_kvm_state(ICSState *ics);
+int ics_set_kvm_state_one(ICSState *ics, int srcno);
 int ics_set_kvm_state(ICSState *ics);
 void ics_synchronize_state(ICSState *ics);
 void ics_kvm_set_irq(ICSState *ics, int srcno, int val);
-- 
2.20.1




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