Messages in this thread |  | | Date | Wed, 10 Nov 2021 19:43:59 +0100 | From | Borislav Petkov <> | Subject | Re: [PATCH v6 19/42] x86/mm: Add support to validate memory when changing C-bit |
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On Wed, Nov 10, 2021 at 08:21:21AM -0600, Brijesh Singh wrote: > I am assuming you mean add some compile time check to ensure that desc will > fit in the shared buffer ?
No:
struct ghcb {
...
u8 shared_buffer[2032];
so that memcpy needs to do:
memcpy(ghcb->shared_buffer, desc, min_t(int, 2032, sizeof(*desc)));
with that 2032 behind a proper define, ofc.
> I can drop the overlap comment to avoid the confusion, as you pointed it > more of the future thing. Basically overlap is the below condition > > set_memory_private(gfn=0, page_size=2m) > set_memory_private(gfn=10, page_size=4k) > > The RMPUPDATE instruction will detect overlap on the second call and return > an error to the guest. After we add the support to track the page validation > state (either in bitmap or page flag), the second call will not be issued > and thus avoid an overlap errors. For now, we use the page_size=4k for all > the page state changes from the kernel.
Yah, sounds like the comment is not needed now. You could put this in the commit message, though.
Thx.
-- Regards/Gruss, Boris.
https://people.kernel.org/tglx/notes-about-netiquette
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