On Tue, Apr 20, 2021 at 04:38:13PM -0700, Jianxiong Gao wrote: > On Wed, Apr 7, 2021 at 5:51 AM Greg KH <greg@xxxxxxxxx> wrote: > > > > On Mon, Apr 05, 2021 at 09:02:22PM +0000, Jianxiong Gao wrote: > > > Hi all, > > > > > > This series of backports fixes the SWIOTLB library to maintain the > > > page offset when mapping a DMA address. The bug that motivated this > > > patch series manifested when running a 5.4 kernel as a SEV guest with > > > an NVMe device. However, any device that infers information from the > > > page offset and is accessed through the SWIOTLB will benefit from this > > > bug fix. > > > > But this is 5.10, not 5.4, why mention 5.4 here? > Oops. The cover letter shouldn't mention the kernel version. The bug > is present in both 5.4 and 5.10. Sorry for the confusion.> > > And you are backporting a 5.12-rc feature to 5.10, what happened to > > 5.11? > No. The goal is to backport a bug fix to the LTS releases. > > Why not just use 5.12 to get this new feature instead of using an older > > kernel? It's not like this has ever worked before, right? > > > It's true, that a new feature (SEV virtualization) is what motivated > the bug fix. However, I still think this makes sense to backport to > the LTS releases because it does fix a pre-existing bug that may be > impacting pre-existing setups. How? Anything that installed 5.10 when it was released never had this working, they had to move to 5.12 to get that to work. > In particular, while working on these patches, I got the following feedback: > "There are plenty of other hardware designs that rely on dma mapping > not adding offsets that did not exist, e.g. ahci and various RDMA > NICs." I do not understand that statement, how does that pertain to this patch set? confused, greg k-h
