Re: [Qemu-devel] [PATCH V7 15/16] virtio-pci: increase the maximum number of virtqueues to 513

[Jason Wang <jasowang@redhat.com>]

On Thu, Apr 23, 2015 at 7:24 PM, Cornelia Huck 
<cornelia.huck@de.ibm.com> wrote:
> On Thu, 23 Apr 2015 14:21:48 +0800
> Jason Wang <jasowang@redhat.com> wrote:
> 
>>  This patch increases the maximum number of virtqueues for pci from 
>> 64
>>  to 513. This will allow booting a virtio-net-pci device with 256 
>> queue
>      ^^^
> 
>>  pairs on recent Linux host (which supports up to 256 tuntap queue 
>> pairs).
>>  
>>  To keep migration compatibility, 64 was kept for legacy machine
>>  types. This is because qemu in fact allows guest to probe the limit 
>> of
>>  virtqueues through trying to set queue_sel. So for legacy machine
>>  type, we should make sure setting queue_sel to more than 63 won't
>>  make effect.
>>  
>>  Cc: Paolo Bonzini <pbonzini@redhat.com>
>>  Cc: Richard Henderson <rth@twiddle.net>
>>  Cc: Michael S. Tsirkin <mst@redhat.com>
>>  Cc: Alexander Graf <agraf@suse.de>
>>  Cc: qemu-ppc@nongnu.org
>>  Signed-off-by: Jason Wang <jasowang@redhat.com>
>>  ---
>>   hw/i386/pc_piix.c      | 5 +++++
>>   hw/i386/pc_q35.c       | 5 +++++
>>   hw/ppc/spapr.c         | 5 +++++
>>   hw/virtio/virtio-pci.c | 6 +++++-
>>   4 files changed, 20 insertions(+), 1 deletion(-)
>>  
> (...)
>>  diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
>>  index 7d01500..c510cb7 100644
>>  --- a/hw/virtio/virtio-pci.c
>>  +++ b/hw/virtio/virtio-pci.c
>>  @@ -42,7 +42,11 @@
>>    * configuration space */
>>   #define VIRTIO_PCI_CONFIG_SIZE(dev)     
>> VIRTIO_PCI_CONFIG_OFF(msix_enabled(dev))
>>  
>>  -#define VIRTIO_PCI_QUEUE_MAX 64
>>  +/* The number was chose to be greater than both the the number of 
>> max
>>  + * vcpus supported by host and the number of max tuntap queues 
>> support
>>  + * by host and also leave some spaces for future.
>>  + */
>>  +#define VIRTIO_PCI_QUEUE_MAX 1024
>                                 ^^^^
> 
> I think you need to fixup subject and patch description :)

Yes, will fix this.

Thanks
> 
>>  
>>   static void virtio_pci_bus_new(VirtioBusState *bus, size_t 
>> bus_size,
>>                                  VirtIOPCIProxy *dev);
>