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How many msi-x vectors should be allocated for the virtio-serial device?

Message ID 512E08FC.1020805@redhat.com
State New
Headers show

Commit Message

Gal Hammer Feb. 27, 2013, 1:24 p.m. UTC 
On 27/02/2013 14:35, Amit Shah wrote:
> On (Mon) 04 Feb 2013 [11:59:02], Michael S. Tsirkin wrote:
>> On Mon, Feb 04, 2013 at 10:42:32AM +0100, Paolo Bonzini wrote:
>>> Il 03/02/2013 13:11, Michael S. Tsirkin ha scritto:
>>>>>>   static Property virtio_serial_properties[] = {
>>>>>>       DEFINE_PROP_BIT("ioeventfd", VirtIOPCIProxy, flags, VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT, true),
>>>>>> -    DEFINE_PROP_UINT32("vectors", VirtIOPCIProxy, nvectors, DEV_NVECTORS_UNSPECIFIED),
>>>>>> +    DEFINE_PROP_UINT32("vectors", VirtIOPCIProxy, nvectors, 2),
>>>>>>       DEFINE_PROP_HEX32("class", VirtIOPCIProxy, class_code, 0),
>>>>>>       DEFINE_VIRTIO_COMMON_FEATURES(VirtIOPCIProxy, host_features),
>>>>>>       DEFINE_PROP_UINT32("max_ports", VirtIOPCIProxy, serial.max_virtserial_ports, 31),
>>>>>>
>>>>>> plus the backwards-compatibility stuff.
>>>>>>
>>>>>> Paolo
>>>> Makes sense, but the logic in virtio_serial_init_pci is
>>>> then dead code and should go away.
>>>>
>>>
>>> It won't be dead code for the backwards-compatible machine types (that
>>> use DEV_NVECTORS_UNSPECIFIED).
>>>
>>> Paolo
>>
>> Good point. Ack. Want to post this with proper signature etc?
>
> Gal, do you want to submit a patch for this?
>
> 		Amit
>

Attached.

     Gal.
From ac35ad272744abb83e2dcafcd207471ff6bc1583 Mon Sep 17 00:00:00 2001
From: Gal Hammer <ghammer@redhat.com>
Date: Wed, 27 Feb 2013 15:15:31 +0200
Subject: [PATCH] Set virtio-serial device to have a default of 2 MSI vectors.

The virtio-serial device is expected to use 2 MSI vectors, one for
control queue and a second shared for all queues.

Signed-off-by: Gal Hammer <ghammer@redhat.com>
---
 hw/virtio-pci.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

Comments

Paolo Bonzini Feb. 27, 2013, 1:28 p.m. UTC | #1 
Il 27/02/2013 14:24, Gal Hammer ha scritto:
> On 27/02/2013 14:35, Amit Shah wrote:
>> On (Mon) 04 Feb 2013 [11:59:02], Michael S. Tsirkin wrote:
>>> On Mon, Feb 04, 2013 at 10:42:32AM +0100, Paolo Bonzini wrote:
>>>> Il 03/02/2013 13:11, Michael S. Tsirkin ha scritto:
>>>>>>>   static Property virtio_serial_properties[] = {
>>>>>>>       DEFINE_PROP_BIT("ioeventfd", VirtIOPCIProxy, flags,
>>>>>>> VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT, true),
>>>>>>> -    DEFINE_PROP_UINT32("vectors", VirtIOPCIProxy, nvectors,
>>>>>>> DEV_NVECTORS_UNSPECIFIED),
>>>>>>> +    DEFINE_PROP_UINT32("vectors", VirtIOPCIProxy, nvectors, 2),
>>>>>>>       DEFINE_PROP_HEX32("class", VirtIOPCIProxy, class_code, 0),
>>>>>>>       DEFINE_VIRTIO_COMMON_FEATURES(VirtIOPCIProxy, host_features),
>>>>>>>       DEFINE_PROP_UINT32("max_ports", VirtIOPCIProxy,
>>>>>>> serial.max_virtserial_ports, 31),
>>>>>>>
>>>>>>> plus the backwards-compatibility stuff.
>>>>>>>
>>>>>>> Paolo
>>>>> Makes sense, but the logic in virtio_serial_init_pci is
>>>>> then dead code and should go away.
>>>>>
>>>>
>>>> It won't be dead code for the backwards-compatible machine types (that
>>>> use DEV_NVECTORS_UNSPECIFIED).
>>>>
>>>> Paolo
>>>
>>> Good point. Ack. Want to post this with proper signature etc?
>>
>> Gal, do you want to submit a patch for this?
>>
>>         Amit
>>
> 
> Attached.

You need to add backwards-compatibility properties in hw/pc.h.

Paolo
diff mbox

Patch

diff --git a/hw/virtio-pci.c b/hw/virtio-pci.c
index a869f53..ba56ab2 100644
--- a/hw/virtio-pci.c
+++ b/hw/virtio-pci.c
@@ -975,6 +975,9 @@  static int virtio_serial_init_pci(PCIDevice *pci_dev)
     if (!vdev) {
         return -1;
     }
+
+    /* backwards-compatibility with machines that were created with
+       DEV_NVECTORS_UNSPECIFIED */
     vdev->nvectors = proxy->nvectors == DEV_NVECTORS_UNSPECIFIED
                                         ? proxy->serial.max_virtserial_ports + 1
                                         : proxy->nvectors;
@@ -1155,7 +1158,7 @@  static const TypeInfo virtio_net_info = {
 
 static Property virtio_serial_properties[] = {
     DEFINE_PROP_BIT("ioeventfd", VirtIOPCIProxy, flags, VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT, true),
-    DEFINE_PROP_UINT32("vectors", VirtIOPCIProxy, nvectors, DEV_NVECTORS_UNSPECIFIED),
+    DEFINE_PROP_UINT32("vectors", VirtIOPCIProxy, nvectors, 2),
     DEFINE_PROP_HEX32("class", VirtIOPCIProxy, class_code, 0),
     DEFINE_VIRTIO_COMMON_FEATURES(VirtIOPCIProxy, host_features),
     DEFINE_PROP_UINT32("max_ports", VirtIOPCIProxy, serial.max_virtserial_ports, 31),