Re: [Xen-devel] [PATCH][QEMU] Fix HVM guest hang in save/restore with the network load

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

I like this in principle, but I see no need to save irq_count[]. That should
be derivable from the individual devices' irq_state[] values, shouldn't it?
For example, call pci_set_irq() for each irq_state[] entry during pci-device
load?

Or... Could we avoid changing the qemu-dm save format by doing the following
in i440fx_load():
 for ( dev = 0; dev < 32; dev++ )
    for ( intx = 0; intx < 4; intx++ )
       xc_hvm_set_pci_intx_level(..., dev, intx, 0);

Which forcibly resets INTx levels down in the hypervisor? Would work as long
as hypervisor state is loaded before qemu-dm state, and does avoid an
annoying state format change which would prevent loading old state on new
qemu-dm (unless we add some versioning to your patch).

 -- Keir

On 22/4/08 05:52, "SUZUKI Kazuhiro" <kaz@xxxxxxxxxxxxxx> wrote:

> Hi all,
> 
> When we repeat migration(save/restore) of the HVM guest with the
> network load, the guest hangs. The attached patch fixes it.
> 
> We need to save PCIDevice.irq_state[] and PCIBus.irq_count[] in QEMU.
> Otherwise, xc_hvm_set_pci_intx_level() in
> tools/ioemu/target-i386-dm/piix_pci-dm.c:59 could not be called with
> level = 0 which calls hvm_pci_intx_deassert() in
> xen/arch/x86/hvm/irq.c:83 by hypercall.
> If gsi_assert_count[] could not be decreased because this function is
> not called, then vioapic_deliver() in xen/arch/x86/hvm/vioapic.c:473
> is called every time.
> So the guest enters endless IRQ loop and hangs.
> 
> Thanks,
> KAZ
> 
> Signed-off-by: Kazuhiro Suzuki <kaz@xxxxxxxxxxxxxx>
> diff -r a464af87c9db tools/ioemu/hw/pci.c
> --- a/tools/ioemu/hw/pci.c Fri Apr 11 17:29:26 2008 +0100
> +++ b/tools/ioemu/hw/pci.c Mon Apr 14 16:15:33 2008 +0900
> @@ -81,6 +81,7 @@ void pci_device_save(PCIDevice *s, QEMUF
>  {
>      qemu_put_be32(f, 1); /* PCI device version */
>      qemu_put_buffer(f, s->config, 256);
> +    qemu_put_buffer(f, (uint8_t*)s->irq_state, sizeof(s->irq_state));
>  }
>  
>  int pci_device_load(PCIDevice *s, QEMUFile *f)
> @@ -91,6 +92,18 @@ int pci_device_load(PCIDevice *s, QEMUFi
>          return -EINVAL;
>      qemu_get_buffer(f, s->config, 256);
>      pci_update_mappings(s);
> +    qemu_get_buffer(f, (uint8_t*)s->irq_state, sizeof(s->irq_state));
> +    return 0;
> +}
> +
> +void pci_bus_save(PCIBus *bus, QEMUFile *f, int nirq)
> +{
> +    qemu_put_buffer(f, (uint8_t*)bus->irq_count, nirq * sizeof(int));
> +}
> +
> +int pci_bus_load(PCIBus *bus, QEMUFile *f, int nirq)
> +{
> +    qemu_get_buffer(f, (uint8_t*)bus->irq_count, nirq * sizeof(int));
>      return 0;
>  }
>  
> diff -r a464af87c9db tools/ioemu/target-i386-dm/piix_pci-dm.c
> --- a/tools/ioemu/target-i386-dm/piix_pci-dm.c Fri Apr 11 17:29:26 2008 +0100
> +++ b/tools/ioemu/target-i386-dm/piix_pci-dm.c Mon Apr 14 16:15:33 2008 +0900
> @@ -64,6 +64,7 @@ static void i440fx_save(QEMUFile* f, voi
>  {
>      PCIDevice *d = opaque;
>      pci_device_save(d, f);
> +    pci_bus_save(d->bus, f, 128);
>  #ifndef CONFIG_DM
>      qemu_put_8s(f, &smm_enabled);
>  #endif /* !CONFIG_DM */
> @@ -79,6 +80,7 @@ static int i440fx_load(QEMUFile* f, void
>      ret = pci_device_load(d, f);
>      if (ret < 0)
>          return ret;
> +    pci_bus_load(d->bus, f, 128);
>  #ifndef CONFIG_DM
>      i440fx_update_memory_mappings(d);
>      qemu_get_8s(f, &smm_enabled);
> diff -r a464af87c9db tools/ioemu/vl.h
> --- a/tools/ioemu/vl.h Fri Apr 11 17:29:26 2008 +0100
> +++ b/tools/ioemu/vl.h Mon Apr 14 16:15:33 2008 +0900
> @@ -843,6 +843,9 @@ void pci_device_save(PCIDevice *s, QEMUF
>  void pci_device_save(PCIDevice *s, QEMUFile *f);
>  int pci_device_load(PCIDevice *s, QEMUFile *f);
>  
> +void pci_bus_save(PCIBus *bus, QEMUFile *f, int nirq);
> +int pci_bus_load(PCIBus *bus, QEMUFile *f, int nirq);
> +
>  typedef void (*pci_set_irq_fn)(void *pic, int irq_num, int level);
>  typedef int (*pci_map_irq_fn)(PCIDevice *pci_dev, int irq_num);
>  PCIBus *pci_register_bus(pci_set_irq_fn set_irq, pci_map_irq_fn map_irq,
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