Tianyu Lan <ltykernel@xxxxxxxxx> writes: > Hi Vitaly: > Thanks for your review. > > On 11/6/2018 11:50 PM, Vitaly Kuznetsov wrote: >> ltykernel@xxxxxxxxx writes: >> >>> From: Lan Tianyu <Tianyu.Lan@xxxxxxxxxxxxx> >>> >>> This patch is to initialize ept_pointer to INVALID_PAGE and check it >>> before flushing ept tlb. If ept_pointer is invalidated, bypass the flush >>> request. >>> >> >> To be honest I fail to understand the reason behind the patch: instead >> of doing one unneeded flush request with ept_pointer==0 (after vCPU is >> initialized) we now do the check every time. Could you please elaborate >> on why this is needed? > > The reason to introduce the check here is to avoid flushing ept tlb > without valid ept table. When nested guest boots up and only BP is > active, we should not do flush for APs and L1 hypervisor hasn't set > valid EPT table for APs. Yes, I understand that but I'm trying to avoid additional checks on hotpath as during normal operation EPT pointer is always set. Could we just initialize ept_pointers_match to something like EPT_POINTERS_NOTSET and achive the same result? -- Vitaly
