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

[Cédric Le Goater]

Hello,

On 19/06/2019 11:36, David Gibson wrote:
> On Sun, Jun 16, 2019 at 07:22:23PM +0200, 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>
> 
> I'm afraid this doesn't apply clean on my current ppc-for-4.1.


You need these before :

  spapr/xive: simplify spapr_irq_init_device() to remove the emulated init
  spapr/xive: rework the mapping the KVM memory regions

  https://patchwork.ozlabs.org/patch/1116146/
  https://patchwork.ozlabs.org/patch/1116152/

Then, these should follow :

  xics/spapr: Only emulated XICS should use RTAS/hypercalls emulation
  xics/spapr: Drop unused function declaration
  xics/spapr: Rename xics_kvm_init()
  xics/kvm: Skip rollback when KVM XICS is absent
  xics/kvm: Always use local_err in xics_kvm_init()
  xics/kvm: Add error propagation to ic*_set_kvm_state() functions
  xics/kvm: Add proper rollback to xics_kvm_init()

You can take a look at :
  
  https://github.com/legoater/qemu/commits/xive-next

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;
>> +    }
>>  }
>>
>