xics_kvm: Don't enable KVM_CAP_IRQ_XICS if already enabled

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.

Re-enabling this CAP should ideally work, but currently it results in
kernel trying to create and associate ICP with this vCPU and that
fails since there is already an ICP associated with it. Hence this
patch is needed to work around this problem in the kernel.

This change allows CPU hot removal to work for sPAPR.

Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Alexander Graf <agraf@suse.de>

diff --git a/hw/intc/xics_kvm.c b/hw/intc/xics_kvm.c
index ea886dac7b30f897350d10a76c9eb05416a87f85..d58729cfae9142198ef13af6318427ef87f66d0c 100644 (file)
--- 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 a214dd7f28172caab6c110b34bbce41243e2d8f5..355a96623c70940d9dd21bd4456d34c0902c6b5c 100644 (file)
--- 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"