On 28/02/20 23:47, Wei Huang wrote: >> How extensively has this been tested? Why hasn't someone from AMD >> suggested this change? > > I personally don't suggest enable AVIC by default. There are cases of > slow AVIC doorbell delivery, due to delivery path and contention under a > large number of guest cores. To clarify, this is a hardware issue, right? Note that in practice this patch series wouldn't change much, because x2apic is enabled by default by userspace (it has better performance than memory-mapped APIC) and patch 1 in turn inhibits APICv if the guest has the X2APIC CPUID bit set. Paolo
