[Qemu-devel] [RFC PATCH v2 8/9] xics, xics_kvm: Handle CPU unplug correctly

[Bharata B Rao <bharata@linux.vnet.ibm.com>]

XICS is setup for each CPU during initialization. Provide a routine
to undo the same when CPU is unplugged. While here, move ss->cs management
into xics from xics_kvm since there is nothing KVM specific in it.
Also ensure xics reset doesn't set irq for CPUs that are already unplugged.

This allows reboot of a VM that has undergone CPU hotplug and unplug
to work correctly.

Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
---
 hw/intc/xics.c        | 14 ++++++++++++++
 hw/intc/xics_kvm.c    |  8 ++++----
 include/hw/ppc/xics.h |  1 +
 3 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/hw/intc/xics.c b/hw/intc/xics.c
index 213a370..9fdb551 100644
--- a/hw/intc/xics.c
+++ b/hw/intc/xics.c
@@ -45,6 +45,18 @@ static int get_cpu_index_by_dt_id(int cpu_dt_id)
     return -1;
 }
 
+void xics_cpu_destroy(XICSState *icp, PowerPCCPU *cpu)
+{
+    CPUState *cs = CPU(cpu);
+    ICPState *ss = &icp->ss[cs->cpu_index];
+
+    assert(cs->cpu_index < icp->nr_servers);
+    assert(cs == ss->cs);
+
+    ss->output = NULL;
+    ss->cs = NULL;
+}
+
 void xics_cpu_setup(XICSState *icp, PowerPCCPU *cpu)
 {
     CPUState *cs = CPU(cpu);
@@ -54,6 +66,8 @@ void xics_cpu_setup(XICSState *icp, PowerPCCPU *cpu)
 
     assert(cs->cpu_index < icp->nr_servers);
 
+    ss->cs = cs;
+
     if (info->cpu_setup) {
         info->cpu_setup(icp, cpu);
     }
diff --git a/hw/intc/xics_kvm.c b/hw/intc/xics_kvm.c
index 9fe0667..7aab4a1 100644
--- a/hw/intc/xics_kvm.c
+++ b/hw/intc/xics_kvm.c
@@ -110,8 +110,10 @@ static void icp_kvm_reset(DeviceState *dev)
     icp->pending_priority = 0xff;
     icp->mfrr = 0xff;
 
-    /* Make all outputs are deasserted */
-    qemu_set_irq(icp->output, 0);
+    /* Make all outputs as deasserted only if the CPU thread is in use */
+    if (icp->output) {
+        qemu_set_irq(icp->output, 0);
+    }
 
     icp_set_kvm_state(icp, 1);
 }
@@ -344,8 +346,6 @@ static void xics_kvm_cpu_setup(XICSState *icp, PowerPCCPU *cpu)
     if (icpkvm->kernel_xics_fd != -1) {
         int ret;
 
-        ss->cs = cs;
-
         ret = kvm_vcpu_enable_cap(cs, KVM_CAP_IRQ_XICS, 0,
                                   icpkvm->kernel_xics_fd, kvm_arch_vcpu_id(cs));
         if (ret < 0) {
diff --git a/include/hw/ppc/xics.h b/include/hw/ppc/xics.h
index f60b06a..9091054 100644
--- a/include/hw/ppc/xics.h
+++ b/include/hw/ppc/xics.h
@@ -167,5 +167,6 @@ int xics_alloc_block(XICSState *icp, int src, int num, bool lsi, bool align,
 void xics_free(XICSState *icp, int irq, int num);
 
 void xics_cpu_setup(XICSState *icp, PowerPCCPU *cpu);
+void xics_cpu_destroy(XICSState *icp, PowerPCCPU *cpu);
 
 #endif /* __XICS_H__ */
-- 
2.1.0