iommu/amd: Use try_cmpxchg64 in alloc_pte and free_clear_pte

Use try_cmpxchg64 instead of cmpxchg64 (*ptr, old, new) != old in
alloc_pte and free_clear_pte.  cmpxchg returns success in ZF flag, so this
change saves a compare after cmpxchg (and related move instruction
in front of cmpxchg). Also, remove racy explicit assignment to pteval
when cmpxchg fails, this is what try_cmpxchg does implicitly from
*pte in an atomic way.

Signed-off-by: Uros Bizjak <[email protected]>
Cc: Joerg Roedel <[email protected]>
Cc: Suravee Suthikulpanit <[email protected]>
Cc: Will Deacon <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Joerg Roedel <[email protected]>

0 files changed, 0 insertions, 0 deletions