On 04.12.2013, at 21:43, Richard Yao <ryao@xxxxxxxxxx> wrote: > The 9p-virtio transport does zero copy on things larger than 1024 bytes > in size. It accomplishes this by returning the physical addresses of > pages to the virtio-pci device. At present, the translation is usually a > bit shift. > > However, that approach produces an invalid page address when we > read/write to vmalloc buffers, such as those used for Linux kernle > modules. This causes QEMU to die printing: > > qemu-system-x86_64: virtio: trying to map MMIO memory > > This patch enables 9p-virtio to correctly handle this case. This not > only enables us to load Linux kernel modules off virtfs, but also > enables ZFS file-based vdevs on virtfs to be used without killing QEMU. > > Also, special thanks to both Avi Kivity and Alexander Graf for their > interpretation of QEMU backtraces. Without their guidence, tracking down > this bug would have taken much longer. > > Signed-off-by: Richard Yao <ryao@xxxxxxxxxx> Looks good and clean to me, but I'm not expert on the mm subsystem. Acked-by: Alexander Graf <agraf@xxxxxxx> Alex _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
