For confidential guests during the reset process, the old KVM VM file
descriptor is closed and a new one is created. When a new file descriptor is
created, a new openpic device needs to be created against this new KVM VM file
descriptor as well. Additionally, existing memory region needs to be reattached
to this new openpic device and proper CPU attributes set associating new file
descriptor. This change makes this happen with the help of a callback handler
that gets called when the KVM VM file descriptor changes as a part of the
confidential guest reset process.

Signed-off-by: Ani Sinha <anisinha@redhat.com>
---
 hw/intc/openpic_kvm.c | 108 ++++++++++++++++++++++++++++++++----------
 1 file changed, 83 insertions(+), 25 deletions(-)

diff --git a/hw/intc/openpic_kvm.c b/hw/intc/openpic_kvm.c
index 673ea9ca05..1b7a1d0d00 100644
--- a/hw/intc/openpic_kvm.c
+++ b/hw/intc/openpic_kvm.c
@@ -49,6 +49,7 @@ struct KVMOpenPICState {
     uint32_t fd;
     uint32_t model;
     hwaddr mapped;
+    NotifierWithReturn open_pic_vmfd_change_notifier;
 };
 
 static void kvm_openpic_set_irq(void *opaque, int n_IRQ, int level)
@@ -114,6 +115,83 @@ static const MemoryRegionOps kvm_openpic_mem_ops = {
     },
 };
 
+static int create_open_pic_device(KVMOpenPICState *opp, Error **errp)
+{
+    int kvm_openpic_model;
+    struct kvm_create_device cd = {0};
+    KVMState *s = kvm_state;
+    int ret;
+
+    switch (opp->model) {
+    case OPENPIC_MODEL_FSL_MPIC_20:
+        kvm_openpic_model = KVM_DEV_TYPE_FSL_MPIC_20;
+        break;
+
+    case OPENPIC_MODEL_FSL_MPIC_42:
+        kvm_openpic_model = KVM_DEV_TYPE_FSL_MPIC_42;
+        break;
+
+    default:
+        error_setg(errp, "Unsupported OpenPIC model %" PRIu32, opp->model);
+        return -1;
+    }
+
+    cd.type = kvm_openpic_model;
+    ret = kvm_vm_ioctl(s, KVM_CREATE_DEVICE, &cd);
+    if (ret < 0) {
+        error_setg(errp, "Can't create device %d: %s",
+                   cd.type, strerror(errno));
+        return -1;
+    }
+    opp->fd = cd.fd;
+
+    return 0;
+}
+
+static int open_pic_vmfd_handle_vmfd_change(NotifierWithReturn *notifier,
+                                            void *data, Error **errp)
+{
+    KVMOpenPICState *opp = container_of(notifier, KVMOpenPICState,
+                                        open_pic_vmfd_change_notifier);
+    uint64_t reg_base;
+    struct kvm_device_attr attr;
+    CPUState *cs;
+    int ret;
+
+    /* close the old descriptor */
+    close(opp->fd);
+
+    if (create_open_pic_device(opp, errp) < 0) {
+        return -1;
+    }
+
+    if (!opp->mapped) {
+        return 0;
+    }
+
+    reg_base = opp->mapped;
+    attr.group = KVM_DEV_MPIC_GRP_MISC;
+    attr.attr = KVM_DEV_MPIC_BASE_ADDR;
+    attr.addr = (uint64_t)(unsigned long)&reg_base;
+
+    ret = ioctl(opp->fd, KVM_SET_DEVICE_ATTR, &attr);
+    if (ret < 0) {
+        fprintf(stderr, "%s: %s %" PRIx64 "\n", __func__,
+                strerror(errno), reg_base);
+        return -1;
+    }
+
+    CPU_FOREACH(cs) {
+        ret = kvm_vcpu_enable_cap(cs, KVM_CAP_IRQ_MPIC, 0, opp->fd,
+                                   kvm_arch_vcpu_id(cs));
+        if (ret < 0) {
+            return ret;
+        }
+    }
+
+    return 0;
+}
+
 static void kvm_openpic_region_add(MemoryListener *listener,
                                    MemoryRegionSection *section)
 {
@@ -197,37 +275,14 @@ static void kvm_openpic_realize(DeviceState *dev, Error **errp)
     SysBusDevice *d = SYS_BUS_DEVICE(dev);
     KVMOpenPICState *opp = KVM_OPENPIC(dev);
     KVMState *s = kvm_state;
-    int kvm_openpic_model;
-    struct kvm_create_device cd = {0};
-    int ret, i;
+    int i;
 
     if (!kvm_check_extension(s, KVM_CAP_DEVICE_CTRL)) {
         error_setg(errp, "Kernel is lacking Device Control API");
         return;
     }
 
-    switch (opp->model) {
-    case OPENPIC_MODEL_FSL_MPIC_20:
-        kvm_openpic_model = KVM_DEV_TYPE_FSL_MPIC_20;
-        break;
-
-    case OPENPIC_MODEL_FSL_MPIC_42:
-        kvm_openpic_model = KVM_DEV_TYPE_FSL_MPIC_42;
-        break;
-
-    default:
-        error_setg(errp, "Unsupported OpenPIC model %" PRIu32, opp->model);
-        return;
-    }
-
-    cd.type = kvm_openpic_model;
-    ret = kvm_vm_ioctl(s, KVM_CREATE_DEVICE, &cd);
-    if (ret < 0) {
-        error_setg(errp, "Can't create device %d: %s",
-                   cd.type, strerror(errno));
-        return;
-    }
-    opp->fd = cd.fd;
+    create_open_pic_device(opp, errp);
 
     sysbus_init_mmio(d, &opp->mem);
     qdev_init_gpio_in(dev, kvm_openpic_set_irq, OPENPIC_MAX_IRQ);
@@ -236,6 +291,9 @@ static void kvm_openpic_realize(DeviceState *dev, Error **errp)
     opp->mem_listener.region_del = kvm_openpic_region_del;
     opp->mem_listener.name = "openpic-kvm";
     memory_listener_register(&opp->mem_listener, &address_space_memory);
+    opp->open_pic_vmfd_change_notifier.notify =
+        open_pic_vmfd_handle_vmfd_change;
+    kvm_vmfd_add_change_notifier(&opp->open_pic_vmfd_change_notifier);
 
     /* indicate pic capabilities */
     msi_nonbroken = true;
-- 
2.42.0