Messages in this thread | | | Date | Sun, 13 Feb 2022 13:15:23 +0100 | From | Borislav Petkov <> | Subject | Re: [PATCH v10 21/45] x86/mm: Add support to validate memory when changing C-bit |
| |
On Fri, Feb 11, 2022 at 11:27:54AM -0600, Brijesh Singh wrote: > > Simply have them always present. They will have !0 values on the > > respective guest types and 0 otherwise. This should simplify a lot of > > code and another unconditionally present u64 won't be the end of the > > world. > > > > Any other aspect I'm missing? > > I think that's mostly about it. IIUC, the recommendation is to define a > new callback in x86_platform_op. The callback will be invoked > unconditionally; The default implementation for this callback is NOP; > The TDX and SEV will override with the platform specific implementation. > I think we may able to handle everything in one callback hook but having > pre and post will be a more desirable. Here is why I am thinking so: > > * On SNP, the page must be invalidated before clearing the _PAGE_ENC > from the page table attribute > > * On SNP, the page must be validated after setting the _PAGE_ENC in the > page table attribute.
Right, we could have a pre- and post- callback, if that would make things simpler/clearer.
Also, in thinking further about the encryption mask, we could make it a *single*, *global* variable called cc_mask which each guest type sets it as it wants to.
Then, it would use it in the vendor-specific encrypt/decrypt helpers accordingly and that would simplify a lot of code. And we can get rid of all the ifdeffery around it too.
So I think the way to go should be we do the common functionality, I queue it on the common tip:x86/cc branch and then SNP and TDX will be both based ontop of it.
Thoughts?
-- Regards/Gruss, Boris.
https://people.kernel.org/tglx/notes-about-netiquette
| |