[bug 1.1] -M pc-1.0 + vhost = SIGSEGV

[Michael Tokarev <mjt@tls.msk.ru>]

When running current git version of qemu-kvm with -M pc-1.0
and with vhost-net enabled, it crashes with SIGSEGV right when
linux guest loads a virtio-net module.

I haven't tried to debug this deeply.  The first result is:

(gdb) ru -M pc-1.0 -nodefconfig -nodefaults -rtc base=utc -device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -netdev tap,ifname=tap-kvm,script=no,id=hostnet0,vhost=on -device virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:b4:05:b5,bus=pci.0,addr=0x3 -vga cirrus
Starting program: /build/kvm/debian/build/x86_64-softmmu/qemu-system-x86_64 -M pc-1.0 -nodefconfig -nodefaults -rtc base=utc -device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -netdev tap,ifname=tap-kvm,script=no,id=hostnet0,vhost=on -device virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:b4:05:b5,bus=pci.0,addr=0x3 -vga cirrus
...
Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0xf65f4b70 (LWP 11245)]
0x5668b01a in virtio_pci_mask_vq (vector=vector@entry=1, vq=0x57064448,
    masked=masked@entry=0,
    dev=<error reading variable: Unhandled dwarf expression opcode 0xfa>)
    at /build/kvm/debian/hw/virtio-pci.c:546
546	    int r = kvm_set_irqfd(dev->msix_irq_entries[vector].gsi,

Now, my gdb can't read `dev' variable.  One level up the stack
this variable is shown correctly:

#1  0x5668b15d in virtio_pci_mask_notifier (dev=0x57062748, vector=1, masked=0)
    at /build/kvm/debian/hw/virtio-pci.c:576
576	        r = virtio_pci_mask_vq(dev, vector, virtio_get_queue(vdev, n), masked);
(gdb) p dev->msix_irq_entries[vector].gsi
Cannot access memory at address 0x10
(gdb) p dev
$1 = (PCIDevice *) 0x57062748
(gdb) p dev->msix_irq_entries
$4 = (KVMMsiMessage *) 0x0

So it looks like msix isn't initialized for -M pc-1.0 ?

Thanks,

/mjt