[Qemu-devel] [RFC PATCH v2 17/23] xics_kvm: Don't enable KVM_CAP_IRQ_XICS if already enabled

[Bharata B Rao]

When supporting CPU hot removal by parking the vCPU fd and reusing
it during hotplug again, there can be cases where we try to reenable
KVM_CAP_IRQ_XICS CAP for the vCPU for which it was already enabled.
Introduce a boolean member in ICPState to track this and don't
reenable the CAP if it was already enabled earlier.

This change allows CPU hot removal to work for sPAPR.

Signed-off-by: Bharata B Rao <address@hidden>
---
 hw/intc/xics_kvm.c    | 10 ++++++++++
 include/hw/ppc/xics.h |  1 +
 2 files changed, 11 insertions(+)

diff --git a/hw/intc/xics_kvm.c b/hw/intc/xics_kvm.c
index c15453f..5b27bf8 100644
--- a/hw/intc/xics_kvm.c
+++ b/hw/intc/xics_kvm.c
@@ -331,6 +331,15 @@ static void xics_kvm_cpu_setup(XICSState *icp, PowerPCCPU 
*cpu)
         abort();
     }
 
+    /*
+     * If we are reusing a parked vCPU fd corresponding to the CPU
+     * which was hot-removed earlier we don't have to renable
+     * KVM_CAP_IRQ_XICS capability again.
+     */
+    if (ss->cap_irq_xics_enabled) {
+        return;
+    }
+
     if (icpkvm->kernel_xics_fd != -1) {
         int ret;
 
@@ -343,6 +352,7 @@ static void xics_kvm_cpu_setup(XICSState *icp, PowerPCCPU 
*cpu)
                     kvm_arch_vcpu_id(cs), strerror(errno));
             exit(1);
         }
+        ss->cap_irq_xics_enabled = true;
     }
 }
 
diff --git a/include/hw/ppc/xics.h b/include/hw/ppc/xics.h
index a214dd7..355a966 100644
--- a/include/hw/ppc/xics.h
+++ b/include/hw/ppc/xics.h
@@ -109,6 +109,7 @@ struct ICPState {
     uint8_t pending_priority;
     uint8_t mfrr;
     qemu_irq output;
+    bool cap_irq_xics_enabled;
 };
 
 #define TYPE_ICS "ics"
-- 
2.1.0