On Wed, May 19, 2021 at 1:11 AM Greg KH gregkh@linuxfoundation.org wrote:
I still fail to understand why you can not just use the 5.10.y kernel or newer. What is preventing you from doing this if you wish to use this type of hardware? This is not a "regression" in that the 5.4.y kernel has never worked with this hardware before, it feels like a new feature.
NVMe + SWIOTLB is not a new feature. From my understanding it should be supported by 5.4.y kernel correctly. Currently without the patch, any NVMe device (along with some other devices that relies on offset to work correctly), could be broken if the SWIOTLB is used on a 5.4.y kernel.
Neither NVMe driver nor the SWIOTLB is new on 5.4.y kernel.
If by new feature you mean SEV, then yes SEV relies on NVMe and SWIOTLB to work correctly. But we can, and have reproduced the same bug without SEV. So I believe this patch is necessary even without considering SEV.
Thanks
Please, just use 5.10.y or newer, your life will be so much easier in the longrun.
thanks,
greg k-h