Re: [PATCH 2/3] iommu/vt-d: Use try_cmpxchg64() in intel_pasid_get_entry()

[Baolu Lu]

On 5/22/24 4:26 PM, Uros Bizjak wrote:
> Use try_cmpxchg64() instead of cmpxchg64 (*ptr, old, new) != old in
> intel_pasid_get_entry().  cmpxchg returns success in ZF flag, so
> this change saves a compare after cmpxchg (and related move
> instruction in front of cmpxchg).
>
> Signed-off-by: Uros Bizjak<ubizjak@xxxxxxxxx>
> Cc: David Woodhouse<dwmw2@xxxxxxxxxxxxx>
> Cc: Lu Baolu<baolu.lu@xxxxxxxxxxxxxxx>
> Cc: Joerg Roedel<joro@xxxxxxxxxx>
> Cc: Will Deacon<will@xxxxxxxxxx>
> Cc: Robin Murphy<robin.murphy@xxxxxxx>
> ---
>   drivers/iommu/intel/pasid.c | 7 +++++--
>   1 file changed, 5 insertions(+), 2 deletions(-)

Reviewed-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>

Best regards,
baolu