On Wed, May 11, 2022 at 6:04 PM Sean Christopherson <seanjc@xxxxxxxxxx> wrote: > > On Wed, May 11, 2022, Uros Bizjak wrote: > > On Wed, May 11, 2022 at 9:54 AM Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote: > > > Still, does 32bit actually support that stuff? > > > > Unfortunately, it does: > > > > kvm-intel-y += vmx/vmx.o vmx/vmenter.o vmx/pmu_intel.o vmx/vmcs12.o \ > > vmx/evmcs.o vmx/nested.o vmx/posted_intr.o > > > > And when existing cmpxchg64 is substituted with cmpxchg, the > > compilation dies for 32bits with: > > ... > > > > Anyway, your patch looks about right, but I find it *really* hard to > > > care about 32bit code these days. > > > > Thanks, this is also my sentiment, but I hope the patch will enable > > better code and perhaps ease similar situation I have had elsewhere. > > IMO, if we merge this it should be solely on the benefits to 64-bit code. Yes, > KVM still supports 32-bit kernels, but I'm fairly certain the only people that > run 32-bit KVM are KVM developers. 32-bit KVM has been completely broken for > multiple releases at least once, maybe twice, and no one ever complained. Yes, the idea was to improve cmpxchg64 with the implementation of try_cmpxchg64 for 64bit targets. However, the issue with 32bit targets stood in the way, so the effort with 32-bit implementation was mainly to unblock progression for 64-bit targets. Uros.
