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

[Cédric Le Goater]

On 16/06/2019 19:22, Greg Kurz wrote:
> 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: <address@hidden>
> Signed-off-by: Greg Kurz <address@hidden>


Reviewed-by: Cédric Le Goater <address@hidden>

Thanks,

C.

> ---
>  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;
> +    }
>  }
>