On Tue, May 10, 2022 at 6:55 PM Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote: > > On Tue, May 10, 2022 at 05:42:17PM +0200, Uros Bizjak wrote: > > This patch adds try_cmpxchg64 to improve code around cmpxchg8b. While > > the resulting code improvements on x86_64 are minor (a compare and a move saved), > > the improvements on x86_32 are quite noticeable. The code improves from: > > What user of cmpxchg64 is this? This is cmpxchg64 in pi_try_set_control from arch/x86/kvm/vmx/posted_intr.c, as shown in a RFC patch [1]. There are some more opportunities for try_cmpxchg64 in KVM, namely fast_pf_fix_direct_spte in arch/x86/kvm/mmu/mmu.c and tdp_mmu_set_spte_atomic in arch/x86/kvm/mmu/tdp_mmu.c [1] https://www.spinics.net/lists/kvm/msg266042.html Uros.
