[Qemu-devel] [PATCH] spapr/xive: Add proper rollback to kvmppc_xive_connect()

[Greg Kurz <groug@kaod.org>]

Make kvmppc_xive_disconnect() able to undo the changes of a partial
execution of kvmppc_xive_connect() and use it to perform rollback.

Based-on: <20190614165920.12670-2-clg@kaod.org>
Signed-off-by: Greg Kurz <groug@kaod.org>
---
 hw/intc/spapr_xive_kvm.c |   48 ++++++++++++++++++++++++++++------------------
 1 file changed, 29 insertions(+), 19 deletions(-)

diff --git a/hw/intc/spapr_xive_kvm.c b/hw/intc/spapr_xive_kvm.c
index 5559f8bce5ef..3bf8e7a20e14 100644
--- a/hw/intc/spapr_xive_kvm.c
+++ b/hw/intc/spapr_xive_kvm.c
@@ -724,8 +724,7 @@ void kvmppc_xive_connect(SpaprXive *xive, Error **errp)
     xsrc->esb_mmap = kvmppc_xive_mmap(xive, KVM_XIVE_ESB_PAGE_OFFSET, esb_len,
                                       &local_err);
     if (local_err) {
-        error_propagate(errp, local_err);
-        return;
+        goto fail;
     }
 
     memory_region_init_ram_device_ptr(&xsrc->esb_mmio_kvm, OBJECT(xsrc),
@@ -743,8 +742,7 @@ void kvmppc_xive_connect(SpaprXive *xive, Error **errp)
     xive->tm_mmap = kvmppc_xive_mmap(xive, KVM_XIVE_TIMA_PAGE_OFFSET, tima_len,
                                      &local_err);
     if (local_err) {
-        error_propagate(errp, local_err);
-        return;
+        goto fail;
     }
     memory_region_init_ram_device_ptr(&xive->tm_mmio_kvm, OBJECT(xive),
                                       "xive.tima", tima_len, xive->tm_mmap);
@@ -760,21 +758,24 @@ void kvmppc_xive_connect(SpaprXive *xive, Error **errp)
 
         kvmppc_xive_cpu_connect(spapr_cpu_state(cpu)->tctx, &local_err);
         if (local_err) {
-            error_propagate(errp, local_err);
-            return;
+            goto fail;
         }
     }
 
     /* Update the KVM sources */
     kvmppc_xive_source_reset(xsrc, &local_err);
     if (local_err) {
-            error_propagate(errp, local_err);
-            return;
+        goto fail;
     }
 
     kvm_kernel_irqchip = true;
     kvm_msi_via_irqfd_allowed = true;
     kvm_gsi_direct_mapping = true;
+    return;
+
+fail:
+    error_propagate(errp, local_err);
+    kvmppc_xive_disconnect(xive, NULL);
 }
 
 void kvmppc_xive_disconnect(SpaprXive *xive, Error **errp)
@@ -796,23 +797,29 @@ void kvmppc_xive_disconnect(SpaprXive *xive, Error **errp)
     xsrc = &xive->source;
     esb_len = (1ull << xsrc->esb_shift) * xsrc->nr_irqs;
 
-    memory_region_del_subregion(&xsrc->esb_mmio, &xsrc->esb_mmio_kvm);
-    object_unparent(OBJECT(&xsrc->esb_mmio_kvm));
-    munmap(xsrc->esb_mmap, esb_len);
-    xsrc->esb_mmap = NULL;
+    if (xsrc->esb_mmap) {
+        memory_region_del_subregion(&xsrc->esb_mmio, &xsrc->esb_mmio_kvm);
+        object_unparent(OBJECT(&xsrc->esb_mmio_kvm));
+        munmap(xsrc->esb_mmap, esb_len);
+        xsrc->esb_mmap = NULL;
+    }
 
-    memory_region_del_subregion(&xive->tm_mmio, &xive->tm_mmio_kvm);
-    object_unparent(OBJECT(&xive->tm_mmio_kvm));
-    munmap(xive->tm_mmap, 4ull << TM_SHIFT);
-    xive->tm_mmap = NULL;
+    if (xive->tm_mmap) {
+        memory_region_del_subregion(&xive->tm_mmio, &xive->tm_mmio_kvm);
+        object_unparent(OBJECT(&xive->tm_mmio_kvm));
+        munmap(xive->tm_mmap, 4ull << TM_SHIFT);
+        xive->tm_mmap = NULL;
+    }
 
     /*
      * When the KVM device fd is closed, the KVM device is destroyed
      * and removed from the list of devices of the VM. The VCPU
      * presenters are also detached from the device.
      */
-    close(xive->fd);
-    xive->fd = -1;
+    if (xive->fd != -1) {
+        close(xive->fd);
+        xive->fd = -1;
+    }
 
     kvm_kernel_irqchip = false;
     kvm_msi_via_irqfd_allowed = false;
@@ -822,5 +829,8 @@ void kvmppc_xive_disconnect(SpaprXive *xive, Error **errp)
     kvm_cpu_disable_all();
 
     /* VM Change state handler is not needed anymore */
-    qemu_del_vm_change_state_handler(xive->change);
+    if (xive->change) {
+        qemu_del_vm_change_state_handler(xive->change);
+        xive->change = NULL;
+    }
 }