On 4/8/2026 12:31 AM, Tianyu Lan wrote: > Hyper-V provides Confidential VMBus to communicate between > device model and device guest driver via encrypted/private > memory in Confidential VM. The device model is in OpenHCL > (https://openvmm.dev/guide/user_guide/openhcl.html) that > plays the paravisor role. > > For a VMBus device, there are two communication methods to > talk with Host/Hypervisor. 1) VMBUS Ring buffer 2) Dynamic > DMA transfer. > > The Confidential VMBus Ring buffer has been upstreamed by > Roman Kisel(commit 6802d8af47d1). > > The dynamic DMA transition of VMBus device normally goes > through DMA core and it uses SWIOTLB as bounce buffer in > a CoCo VM. > > The Confidential VMBus device can do DMA directly to > private/encrypted memory. Because the swiotlb is decrypted > memory, the DMA transfer must not be bounced through the > swiotlb, so as to preserve confidentiality. This is different > from the default for Linux CoCo VMs, so not use DMA(SWIOTLB) > API in VMBus driver when confidential dynamic DMA transfers > capability is present. > > Signed-off-by: Tianyu Lan <[email protected]> > --- > drivers/scsi/storvsc_drv.c | 28 +++++++++++++++++++++------- > include/linux/hyperv.h | 1 + > 2 files changed, 22 insertions(+), 7 deletions(-) >
Does netvsc not need this same sort of patch? Thanks, Easwar (he/him)
