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5.348. virtio-win

An updated virtio-win package that fixes two bugs is now available for Red Hat Enterprise Linux 6.
The virtio-win package provides paravirtualized network drivers for most Microsoft Windows operating systems. Paravirtualized drivers are virtualization-aware drivers used by fully virtualized guests running on Red Hat Enterprise Linux. Fully virtualized guests using the paravirtualized drivers gain significantly better I/O performance than fully virtualized guests running without the drivers.

Bug Fixes

BZ#838523
A bug in the virtio serial driver could cause a Stop Error (also known as Blue Screen of Death, or BSoD) which occurred on a guest machine when transferring data from the host. This update fixes the bug in the driver so that the guest machine no longer crashes with Blue Screen of Death in this scenario.
BZ#838655
The QXL driver included in the previous version of the virtio-win package was not digitally signed. The QXL driver provided in this update in digitally signed.
All users of virtio-win are advised to upgrade to this updated package, which fixes these bugs.
An updated virtio-win package that fixes multiple bugs and adds various enhancements is now available for Red Hat Enterprise Linux 6.
The virtio-win package provides paravirtualized network drivers for most Microsoft Windows operating systems. Paravirtualized drivers are virtualization-aware drivers used by fully virtualized guests running on Red Hat Enterprise Linux. Fully virtualized guests using the paravirtualized drivers gain significantly better I/O performance than fully virtualized guests running without the drivers.

Bug Fixes

BZ#492777
Previously, if a Microsoft Windows guest machine sent more tx fragments than 256 (the ring size), the NetKVM driver dropped packets. To prevent this problem, indirect ring support has been implemented in the NetKVM driver.
BZ#759361
Previously, user were not able to update the rx and tx parameters in Windows Registry by using the NetKVMConfig utility. Although the utility reported that the parameters had been changed, the change was not displayed in the Windows Device Manager. This was due to incorrect NetKVMConfig parameters changing handler, which has been fixed, so that NetKVMConfig now works as expected and users can update the rx and tx parameters.
BZ#753723
Previously, the block driver (viostor) did not provide support for obtaining serial numbers of virtio block devices from QEMU. The serial numbers were therefore not available on Windows guest machines. With this update, a serial number of a virtio block device is now retrieved from miniport during the find adapter phase.
BZ#752743
Prior to this update, the block driver (viostor) driver did not reject write requests to read-only volumes. Attempting to format a read-only volume caused the guest to stop with an EIO error. With this update, if the target volume has the read-only flag, the guest does not stop, and write requests are completed with an error. Attempting to format or write to a read-only volume are now rejected by the viostor driver.
BZ#751952
Previously, if the "Fix IP checksum on LSO" option in Microsoft Windows Device Manager was disabled, users were not able to transfer data from a guest machine to the host machine using the winscp utility. To prevent this problem, it is no longer possible to disable the "Fix IP checksum on LSO" option.
BZ#803950
A bug in the balloon driver could cause a stop error (also known as Blue Screen of Death, or BSoD) if a guest machine entered the S3 (suspend to RAM) or S4 (suspend to disk) state while performing memory balooning on it. The bug in the balloon driver has been fixed, and the stop error no longer occurs under these circumstances.
BZ#810694
Previously, incorrect flush requests handling could lead to a race condition in the block driver (viostor). Under heavy load, usually when using the "cache=writeback" option, the flush handler was executed asynchronously without proper synchronization with the rest of request processing logic. With this update, execution of the flush request is synchronized with the virtio Interrupt Service Routine (ISR), and the race condition no longer occurs in this scenario.
BZ#771390
The viostor utility did not check the size of an incoming buffer. Applications could send buffers larger than the maximum transfer size to the viostor driver directly by bypassing the file system stack. The buffer size is now reduced if it is bigger that the maximum transfer size. The viostor driver can now properly handle requests with buffers of any size.

Enhancements

BZ#677219
Previously, it was not possible to resize non-system disks online, without reboot. This update adds support for online resizing of VirtIO non-system disks.
BZ#713643
This update provides optimized offload RX IP checksum for the virtio_net driver.
BZ#808322
Offload parameters for the virtio-win network driver have been updated. Multiple parameters are now set to "enabled" by default. To edit parameters of an installed driver, open Microsoft Windows Device Manager, choose "Red Hat VirtIO Ethernet Adapter" from the "Network Adapters" list and click on the "Advanced" tab.
All users of virtio-win are advised to upgrade to this updated package, which fixes these bugs and adds these enhancements.