On (Fri) 16 Dec 2011 [09:14:26], address@hidden wrote:
From: Hongyong Zang<address@hidden>
In pci_enable_msix(), the guest's virtio-serial driver tries to set msi-x
with one vector per queue. But it fails and eventually all virtio-serial
ports share one MSI-X vector. Because every virtio-serial port has *two*
virtqueues, virtio-serial needs (port+1)*2 vectors other than (port+1).
Ouch, good catch.
One comment below:
This patch allows every virtqueue to have its own MSI-X vector.
(When the MSI-X vectors needed are more than MSIX_MAX_ENTRIES defined in
qemu: msix.c, all the queues still share one MSI-X vector as before.)
Signed-off-by: Hongyong Zang<address@hidden>
---
hw/virtio-pci.c | 5 ++++-
1 files changed, 4 insertions(+), 1 deletions(-)
diff --git a/hw/virtio-pci.c b/hw/virtio-pci.c
index 77b75bc..2c9c6fb 100644
--- a/hw/virtio-pci.c
+++ b/hw/virtio-pci.c
@@ -718,8 +718,11 @@ static int virtio_serial_init_pci(PCIDevice *pci_dev)
return -1;
}
vdev->nvectors = proxy->nvectors == DEV_NVECTORS_UNSPECIFIED
- ? proxy->serial.max_virtserial_ports +
1
+ ? (proxy->serial.max_virtserial_ports
+ 1) * 2
: proxy->nvectors;
+ /*msix.c: #define MSIX_MAX_ENTRIES 32*/
+ if (vdev->nvectors> 32)
+ vdev->nvectors = 32;
This change isn't needed: if the proxy->nvectors value exceeds the max
allowed, virtio_init_pci() will end up using a shared vector instead
of separate ones.
Thanks,
Amit
.