x86, pcid, kaiser: allow flushing for future ASID switches
If we change the page tables in such a way that we need an
invalidation of all contexts (aka. PCIDs / ASIDs) we can
actively invalidate them by:
1. INVPCID for each PCID (works for single pages too).
2. Load CR3 with each PCID without the NOFLUSH bit set
3. Load CR3 with the NOFLUSH bit set for each and do
INVLPG for each address.
But, none of these are really feasible since we have ~6 ASIDs (12 with
KAISER) at the time that we need to do an invalidation. So, we just
invalidate the *current* context and then mark the cpu_tlbstate
_quickly_.
Then, at the next context-switch, we notice that we had
'all_other_ctxs_invalid' marked, and go invalidate all of the
cpu_tlbstate.ctxs[] entries.
This ensures that any futuee context switches will do a full flush
of the TLB so they pick up the changes.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Moritz Lipp <moritz.lipp@iaik.tugraz.at>
Cc: Daniel Gruss <daniel.gruss@iaik.tugraz.at>
Cc: Michael Schwarz <michael.schwarz@iaik.tugraz.at>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Kees Cook <keescook@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: x86@kernel.org
2 files changed
